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1

INITIAL MEASUREMENTS ON THE ANGULAR DISTRIBUTION OF DEUTERIUM PLASMA PRODUCED BY A PULSED SPARK SOURCE  

Microsoft Academic Search

The deuterium plasma which is ejected by a 6000ampere pulsed current ; through a rail-type spark source has a yield in the forward direction which is a ; factor of 5 to 10 greater than that in the perpendicular direction. This effect ; is believed to be due to the magnetic propulsion of the plasma. (auth);

Bostick

1955-01-01

2

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

3

Laser produced plasma affects on welding  

SciTech Connect

Acoustic data and high speed pictures indicate that a (laser-supported combustion wave (lscw) is generated and propagates away from the surface in the direction toward the laser. The high speed pictures also show that numerous plasmas are generated during one laser pulse. The optical data show that the number of plasmas generated and their initiation times depend upon laser power. The depth of penetration is also dependent upon the number of plasmas generated, with more plasmas producing more penetration. This latter fact supports the conclusion that the plasma improves the efficiency of the laser process. Thus, a plasma in the form of a laser supported combustion wave is generated and acts to convert the poorly absorbed laser radiation into blackbody radiaiation. The blackbody radiation has a broadband short wavelength spectrum which is readily absorbed by most materials.

Dixon, R.D.; Lewis, G.K.

1985-01-01

4

Plasma Properties of Microwave Produced Plasma in a Toroidal Device  

NASA Astrophysics Data System (ADS)

We have modified a small tokamak, STOR-1M, on loan from University of Saskatchewan, to operate as a low-temperature (˜5 eV) toroidal plasma machine with externally induced toroidal magnetic fields ranging from zero to ˜50 G. The plasma is produced using microwave discharges at relatively high pressures. Microwaves are produced by a kitchen microwave-oven magnetron operating at 2.45 GHz in continuous operating mode, resulting in pulses ˜0.5 s in duration. Initial measurements of plasma formation in this device with and without applied magnetic fields are presented. Plasma density and temperature profiles have been measured using Langmuir probes and the magnetic field profile inside the plasma has been obtained using Hall probes. When the discharge is created with no applied toroidal magnetic field, the plasma does not fill the entire torus due to high background pressure. However, when a toroidal magnetic field is applied, the plasma flows along the applied field, filling the torus. Increasing the applied magnetic field seems to aid plasma formation - the peak density increases and the density gradient becomes steeper. Above a threshold magnetic field, the plasma develops low-frequency density oscillations due to probable excitation of flute modes in the plasma.

Singh, Ajay; Edwards, W. F.; Held, Eric

2011-11-01

5

Laser-produced plasmas and hypervelocity acceleration  

NASA Astrophysics Data System (ADS)

Laser produced plasmas have properties that overlap those of armatures required for hypervelocity particle acceleration. This makes them useful as a test bed for advanced acceleration schemes and effects. In addition, sophisticated diagnostics have been developed for measuring laser produced plasma conditions; many of these techniques can be applied or adapted to KEW armature problems.

Ripin, Barrett H.

1987-05-01

6

Initial thermal plasma observations from ISEE-1  

Microsoft Academic Search

The initial measurements of magnetospheric thermal ions by the Plasma Composition Experiment on ISEE-1 are presented to demonstrate the surprising variety in this plasma population. The data provide evidence that the adiabatic mapping of the high latitude ionosphere to the equatorial plasma trough provides an insufficient description of the origin, transport, and accumulation processes which supply low energy ions to

C. R. Baugher; C. R. Chappell; J. L. Horwitz; E. G. Shelley; D. T. Young

1980-01-01

7

Initial thermal plasma observations from ISEE-1  

NASA Technical Reports Server (NTRS)

The initial measurements of magnetospheric thermal ions by the Plasma Composition Experiment on ISEE-1 are presented to demonstrate the surprising variety in this plasma population. The data provide evidence that the adiabatic mapping of the high latitude ionosphere to the equatorial plasma trough provides an insufficient description of the origin, transport, and accumulation processes which supply low energy ions to the outer plasmasphere and plasma trough.

Baugher, C. R.; Chappell, C. R.; Horwitz, J. L.; Shelley, E. G.; Young, D. T.

1980-01-01

8

Laser-produced plasmas in medicine  

NASA Astrophysics Data System (ADS)

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 for the application at hand to succeed. We 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 in cardiology and vascular surgery (e.g. laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included.

Gitomer, Steven J.; Jones, Roger D.

1990-06-01

9

Laser-produced plasmas in medicine  

NASA Astrophysics Data System (ADS)

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. Those areas of laser medicine are examined in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential for the application at hand to succeed. Examples are examined for 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 in cardiology and vascular surgery (e.g., laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included.

Gitomer, S. J.; Jones, R. D.

10

Laser-produced plasmas in medicine  

SciTech Connect

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, photodynamic cancer therapy, arterial plaque removal, dental drilling, etc. In this paper 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 application at hand to succeed. We 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 in cardiology and vascular surgery (e.g., laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented, along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included.

Gitomer, S.J. (Los Alamos National Lab., NM (United States)); Jones, R.D. (Los Alamos National Lab., NM (United States). Applied Theoretical Physics Div.)

1991-12-01

11

Hydrodynamics of UV Laser-Produced Plasma  

NASA Astrophysics Data System (ADS)

Energy balance, plasma temperature, ablation parameters and asymptotic behavior of ions are measured for plasma produced by laser beams at wavelengths of 0.25 ?m and 0.69 ?m and pulse lengths of 1 ns to 25 ns with irradiances of 10 ^{10}-10^{14 } W/cm^2. The results are consistent with inverse bremsstrahlung being the dominant absorption process. Energy balance and temperature intensity scaling are in reasonable agreement with analytic and numerical calculations. Scaling laws for the mass ablation rate and ablation pressure from aluminum plasma based on ion diagnostics are obtained at 0.25 ?m for intensities ranging from 10 ^{10}-10^{13 } W cm^{-2}. The results are in reasonable agreement with a 1 D steady state ablation model and results from other laboratories. Energy transport measurement for gold plasma indicate the results are consistent with a two region plasma model consisting of a high temperature electron thermal transport region and a low temperature high density radiation transport region. Detailed charge state distributions of the asymptotic plasma measured using a single shot electrodynamic analyzer and comparison with results from a hydrodynamic code that include time dependent ionization and recombination physics are reported for the first time. Reasonable agreement was found between the measured distributions and those calculated by recombination kinetics. However, discrepancies observed in detailed charge state spectrum and partial failure to predict the two peak behavior in aluminum may indicate inaccuracies in the recombination model and failure to include radiation energy transport in the modeling of the aluminum plasma.

Tsui, Ying Yin

1992-01-01

12

Producing Hydrogen by Plasma Pyrolysis of Methane  

NASA Technical Reports Server (NTRS)

Plasma pyrolysis of methane has been investigated for utility as a process for producing hydrogen. This process was conceived as a means of recovering hydrogen from methane produced as a byproduct of operation of a life-support system aboard a spacecraft. On Earth, this process, when fully developed, could be a means of producing hydrogen (for use as a fuel) from methane in natural gas. The most closely related prior competing process - catalytic pyrolysis of methane - has several disadvantages: a) The reactor used in the process is highly susceptible to fouling and deactivation of the catalyst by carbon deposits, necessitating frequent regeneration or replacement of the catalyst. b) The reactor is highly susceptible to plugging by deposition of carbon within fixed beds, with consequent channeling of flow, high pressure drops, and severe limitations on mass transfer, all contributing to reductions in reactor efficiency. c) Reaction rates are intrinsically low. d) The energy demand of the process is high.

Atwater, James; Akse, James; Wheeler, Richard

2010-01-01

13

A dusty plasma device for producing extended, steady state, magnetized, dusty plasma columns  

E-print Network

A dusty plasma device for producing extended, steady state, magnetized, dusty plasma columns Wenjun with an existing Q machine, to produce extended, steady state, magnetized plasma columns. The dusty plasma device (DPD) is to be used for the investigation of waves in dusty plasmas and of other plasma/dust aspects

Merlino, Robert L.

14

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

15

Magnetic Reconnection between Colliding Magnetized Laser-Produced Plasma Plumes  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

16

A laboratory produced extremely large beta plasma  

SciTech Connect

This paper discusses laboratory production of an extremely large-beta ({beta}{approx}10{sup 3}) plasma, termed ELB plasma, over an extended volume of 0.5 m{sup 3}. The plasma {beta} can be varied from <1 to values as large as 10{sup 3}, thereby allowing us to study physical processes through a large range of {beta}. Desired {beta} values are achieved by tailoring the ambient magnetic field by compensating fields over time scales far less than the plasma confinement time. We observe that during this compensation, the magnetic field penetration from the wall to the plasma occurs at Whistler speed. The Whistler mode is accompanied by excitation of electrostatic ion wave. We have shown that the diamagnetism of the ELB plasma is considerably modified essentially through the effect of finiteness of electron Larmor radius (r{sub Le}) in the force equilibrium. Application of these results to the space plasma is pointed out.

Banerjee, S. P.; Anitha, V. P.; Ravi, G.; Mattoo, S. K. [Institute for Plasma Research, Bhat, Gandhinagar (India)

2006-09-15

17

Storage of ions from laser-produced plasmas  

NASA Technical Reports Server (NTRS)

A method of storing large numbers of metal ions created in laser-produced plasmas is presented. The outer electrode of the electrostatic ion trap is designed to give a harmonic axial potential. The ions trapped by the technique included Be(+), C(+), Al(+), Fe(+), and Pb(+). The initial number of ions stored (2 x 10 to the 8th) appeared to be the trap maximum since increasing the laser power beyond 2-3 MW did not change the ion number. An initial rapid decay in the 30-50 msec range was generally followed by a long tail at the 10% level with times greater than 100 msec. The technique should be valuable for refractory elements which cannot be easily vaporized for electron impact ionization.

Knight, R. D.

1981-01-01

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

OPTICAL EMISSION DIAGNOSTICS OF LASER PRODUCED PLASMA FROM  

E-print Network

OPTICAL EMISSION DIAGNOSTICS OF LASER PRODUCED PLASMA FROM GRAPHITE AND YBa2Cu30 7 HARILAL. s irradiances, ionization occurs which leads to the plasma formation. Spectroscopic studies of optical emission and the resulting plasma. Optical emission spectroscopy is a technique which analyzes the light emitted from

Harilal, S. S.

20

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

21

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

22

Laser-produced plasma-wall interaction O. RENNER,1  

E-print Network

surfaces (walls). The pilot experiments carried out on the iodine laser system (5­200 J, 0.44 mm, 0Laser-produced plasma-wall interaction O. RENNER,1 R. LISKA,2 AND F.B. ROSMEJ3,4 1 Institute, France (RECEIVED 30 August 2009; ACCEPTED 21 September 2009) Abstract Jets of laser­generated plasma

Liska, Richard

23

High beta capture and mirror confinement of laser produced plasmas  

Microsoft Academic Search

A dense, mirror confined, target plasma is produced by high power laser irradiation of a solid lithium hydride particle, electrically suspended in a vacuum at the center of an established minimum-B magnetic field. Following expansion in and capture by the magnetic field, this target plasma is irradiated by an energetic neutral hydrogen beam. Charge exchange collisions with energetic beam particles

A. F. Haught; D. H. Polk; W. J. Fader; R. G. Tomlinson; R. A. Jong; W. B. Ard; A. E. Mensing; T. L. Churchill; J. L. Stufflebeam; F. J. Bresnock

1976-01-01

24

Optical diagnostics of laser-produced plasmas at UCLA  

SciTech Connect

This paper reviews some of the optical diagnostics employed in probing laser-produced plasmas, in conjunction with laser-plasma interaction experiments at UCLA. Experimental apparatus, techniques, and some results will be presented for the following diagnostics: (1) collective Thomson scattering, for analyzing the space and time dependence of nonthermal (driven) waves in plasmas. Here, cylindrical focusing allows us to illuminate and thus image an interaction region of approximately 1 cm in length. This 1D image is then time resolved using either a streak camera or image dissection techniques; (2) dark-field photography, for quantitatively probing small-scale plasmas or for probing small-scale perturbations within larger plasmas. Here, the plasma produces a phase perturbation on the probing beam's wave front. Measurement of the exposure level on the recording film gives a measurement of the magnitude of the phase perturbation (squared) and thus of the line integrated plasma density; and (3) CO/sub 2/ wavelength interferometry, for obtaining useful interferograms of plasmas of small density-length products.

Clayton, C.E.

1985-05-01

25

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

26

Effect of target purity of laser-produced plasma expansion  

Microsoft Academic Search

The effects of target surface impurities on the laser-produced plasma were studied by means of Thomson ion spectrograms and time-of-flight measurements of the plasma ions. Hydrocarbons were believed to be the most likely surface impurity. Consequently, polyethylene was used to characterise an impure target. For comparison, pure targets (5 to 20 ppm impurities) of C, Ti, and Ta and a

E. Ehler; F. Begay; T. H. Tan; J. Hayden; J. McLeod

1980-01-01

27

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

28

Collisional coupling in counterstreaming laser-produced plasmas  

NASA Technical Reports Server (NTRS)

The collisional processes which transfer momentum between counterstreaming plasmas are reviewed and applied to the example of a laser-produced plasma expanding into a partially ionized background. Experimental measurements of the dependence of the ion flow field on collisional momentum transfer demonstrate the validity of the simplified treatment of collision processes which have been adopted. A numerical model which simulates the laser-plasma interaction with the background confirms the importance of collisions in previous experimental studies of momentum coupling, and provides some insight into the distinction between collisional and collisionless flow regimes.

Koopman, D. W.; Goforth, R. R.

1974-01-01

29

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 the azimuthally uniform surface flashover which initiates plasma-puff under wide range of fill gas pressure of Ar, He and N2. The optimal fill gas pressure for the azimuthally uniform plasma-puff was about 120 mTorr and 450 Torr for He and N2, and between 120 mTorr and 5 Torr for Ar. 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 the hypocycloidal pinch plasma-puff triggering. The main discharge of inverse pinch switch with plasma-focus driven plasma-puff trigger is found to be more azimuthally uniform than that with hypocycloidal pinch plasma-puff trigger in a gas pressure region between 80 mTorr and 1 Torr.

Venable, D. D.; Choi, E. H.

1990-01-01

30

Interaction of plasma clouds produced from two laser targets  

SciTech Connect

Results are presented from studies of the interaction of two plasma clouds produced from two different-type laser targets in an ambient gas in the MKV-4 stand of the Iskra-5 facility. The experimental data are compared with the results of numerical simulations.

Annenkov, V. I.; Bessarab, A. V.; Bondarenko, G. A.; Dolgoleva, G. V.; Zhmailo, V. A.; Krotov, V. A.; Kovalenko, V. P.; Kunin, A. V.; Nikitin, I. N.; Novikiova, E. A.; Panov, A. I.; Sobolev, I. V.; Sokolov, S. S.; Starodubtsev, V. A.; Sungatullin, R. R.; Shirokov, A. E. [All-Russia Research Institute of Experimental Physics, Russian Federal Nuclear Center (Russian Federation)

2007-05-15

31

Interaction of plasma clouds produced from two laser targets  

Microsoft Academic Search

Results are presented from studies of the interaction of two plasma clouds produced from two different-type laser targets\\u000a in an ambient gas in the MKV-4 stand of the Iskra-5 facility. The experimental data are compared with the results of numerical\\u000a simulations.

V. I. Annenkov; A. V. Bessarab; G. A. Bondarenko; G. V. Dolgoleva; V. A. Zhma?lo; V. A. Krotov; V. P. Kovalenko; A. V. Kunin; I. N. Nikitin; E. A. Novikiova; A. I. Panov; I. V. Sobolev; S. S. Sokolov; V. A. Starodubtsev; R. R. Sungatullin; A. E. Shirokov

2007-01-01

32

High beta capture and mirror confinement of laser produced plasmas. Semiannual report, July 1, 1975January 31, 1976  

Microsoft Academic Search

The Laser Initiated Target Experiment (LITE) at the United Technologies Research Center is designed to address the target plasma buildup approach to a steady state mirror fusion device. A dense, mirror confined, target plasma is produced by high power laser irradiation of a solid lithium hydride particle, electrically suspended in a vacuum at the center of an established minimum-B magnetic

A. F. Haught; D. H. Polk; W. J. Fader; R. G. Tomlinson; R. A. Jong; W. B. Ard; A. E. Mensing; T. L. Churchill; J. H. Stufflebeam; F. J. Bresnock

1976-01-01

33

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

34

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

35

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

E-print Network

Kinetic equations are used to study thermalization of the anisotropic quark-gluon plasma produced by decays of color flux tubes possibly created at 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

2014-01-01

36

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

E-print Network

Kinetic equations are used to study thermalization of the anisotropic quark-gluon plasma produced by decays of color flux tubes possibly created at 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.

Wojciech Florkowski; Radoslaw Ryblewski

2014-07-14

37

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.

38

A US Strategy to Explore the Science and Technology of Energy-Producing Plasmas  

E-print Network

1 A US Strategy to Explore the Science and Technology of Energy-Producing Plasmas Discussion Draft, and plasma confinement innovations, and (3) explore the science and technology of energy producing plasmas strategy to explore the science and technology of energy-producing plasmas must change in the post

39

Emission and absorption in laser produced plasmas: processes and applications  

NASA Astrophysics Data System (ADS)

Laser produced plasmas have been used for many years as intense sources of extreme ultraviolet (EUV) and soft x-ray radiation. Depending on the choice and composition of target the EUV spectra can be dominated by line, unresolved transition array (UTA) or continuum emission. Line and UTA emission have found application in various proposed EUV sources for lithography, which is based on the availability of mirrors with high reflectivity in a 2% bandwidth at a wavelength of 13.5 nm. The results of recent experimental measurements of absolute in-band and out of band intensity, ion distribution and debris are presented. It was found that because of opacity effects, the conversion efficiency is sensitive to ion density and laser wavelength. Various schemes to improve the conversion efficiency are discussed as are the results of recent plasma modelling calculations. In addition, laser produced plasmas of some high Z elements emit intense line free continua over extensive energy ranges. Some recent results on inner shell photoabsorption spectra of Sn, I and Au ions obtained using these continua are presented also.

O'Sullivan, G.; Cummings, A.; Dong, C. Z.; Dunne, P.; Hayden, P.; Morris, O.; Sokell, E.; O'Reilly, F.; Su, M. G.; White, J.

2009-04-01

40

Influence of the focal point position on the properties of a laser-produced plasma  

SciTech Connect

This paper deals with investigations of the influence of the focusing lens focal point position on the properties of a plasma produced by a defocused laser beam. The experiment was carried out at the Prague Asterix Laser System iodine laser [K. Jungwirth, A. Cejnarova, L. Juha, B. Kralikova, J. Krasa, E. Krousky, P. Krupickova, L. Laska, K. Masek, T. Mocek, M. Pfeifer, A. Prag, O. Renner, K. Rohlena, B. Rus, J. Skala, P. Straka, and J. Ullschmied, Phys. Plasmas 8, 2495 (2001)] by using the third harmonic of laser radiation ({lambda}=0.438 {mu}m), laser energy of 70 J, pulse duration of 250 ps (full width at half-maximum), and beam spot radii of 250 and 400 {mu}m. Cu and Ta were chosen as target materials. The experimental data were obtained by means of a three-frame interferometric system, ion collectors, and crater replica techniques. The reported results allow formulating an important hypothesis that the laser-produced plasma modifies strongly the laser intensity distribution. It is shown how such a modification depends on the relative position and distance of the focal point to the target surface. Of particular importance is whether the focal point is located inside or in front of the target. The irradiation geometry is crucial for the possibility of generating plasma jets by laser radiation. Well-formed jet-like plasma structures can be created if an initially homogeneous laser intensity distribution is transformed in the plasma to an annular one.

Kasperczuk, A.; Pisarczyk, T.; Badziak, J.; Miklaszewski, R.; Parys, P.; Rosinski, M.; Wolowski, J.; Stenz, CH.; Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J.; Pisarczyk, P. [Institute of Plasma Physics and Laser Microfusion, 23 Hery St., 00-908 Warsaw (Poland); Centre Lasers Intenses et Applications, Universite Bordeaux, 33405 Talence (France); Institute of Plasma Physics AS CR, Za Slovankou 3, 182 00 Prague 8 (Czech Republic); Institute of Physics AS CR, Na Slovance 2, 182 21 Prague 8 (Czech Republic); Warsaw University of Technology, ICS, 15/19 Nowowiejska St., 00-665 Warsaw (Poland)

2007-10-15

41

Stainless steel patterning by combination of micro-patterning and driven strain produced by plasma assisted nitriding  

Microsoft Academic Search

Plasma-assisted nitriding treatments on austenitic stainless steel at low temperature produce the so called “expanded austenite”. The expansion of the nitrided layer that occurs from the initial surface of the substrate in a direction perpendicular to the surface is used here as a mean to produce patterned surfaces by selective nitrogen diffusion through masks. Using grids, a network of well

Gregory Marcos; Stephane Guilet; Franck Cleymand; Tony Thiriet; Thierry Czerwiec

2011-01-01

42

Monitoring of hydrocarbon concentrations in dust-producing RF plasmas  

NASA Astrophysics Data System (ADS)

In Ar and He radio-frequency (RF) plasmas with admixtures of C2H2 and CH4 the hydrocarbon chemistry has been studied in relation to dust particle formation by means of infrared tunable diode laser absorption spectroscopy (TDLAS) combined with Fourier transform infrared (FTIR) spectroscopy. The experiments were performed in a RF capacitively coupled parallel plate reactor at a frequency of f = 13.56 MHz, a pressure of p = 0.1 mbar and a flow rate of ? = 8 sccm of Ar or He with admixtures of 0.5 sccm C2H2 or 1 sccm CH4. The power was P = 15 W. Using TDLAS, the temporal evolution of the concentrations of the methyl radical and of four stable molecules, C2H2, CH4, C2H4 and CO, was monitored in the plasma. Simultaneously, the growth process of the dust particles was analysed by FTIR spectroscopy. The degree of dissociation of the acetylene precursor was found to be nearly constant in the range of 96% under stabilized conditions for both the Ar and He plasmas. In contrast, the degree of dissociation of the methane precursor varied between 45% and 90% depending (i) on the appearance of dust particles in the reactor volume and (ii) on the Ar or He plasma conditions. The methyl radical concentration was found to be in the range of 1011 molecules cm-3. The concentrations of all hydrocarbon species were strongly correlated with the dynamic of the dust formation. Fragmentation efficiencies of acetylene (RF (C2 H2) = 3.2 × 1016 molecules J-1) and of methane (RF (CH4) = (0.16-2.5) × 1016 molecules J-1) and conversion efficiencies to the produced hydrocarbons (RC = (0.23-8.5) × 1014 molecules J-1) could be estimated in dependence on the discharge conditions in the RF plasma.

Hempel, F.; Lopatik, D.; Sikimic, B.; Stefanovic, I.; Winter, J.; Röpcke, J.

2012-10-01

43

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

2005-03-15

44

Dynamics of femtosecond laser-produced plasma ions  

NASA Astrophysics Data System (ADS)

We investigated the ion laser-produced plasma plume generated during ultrafast laser ablation of copper and silicon targets in high vacuum. The ablation plasma was induced by ?50 fs, 800 nm Ti:Sa laser pulses irradiating the target surface at an angle of 45°. An ion probe was used to investigate the time-of-flight profiles of the emitted ions in a laser fluence range from the ablation threshold up to ?10 J/cm2. The angular distribution of the ion flux and average velocity of the produced ions were studied by moving the ion probe on a circle around the ablation spot. The angular distribution of the ion flux is well described by an adiabatic and isentropic model of expansion of a plume produced by laser ablation of solid targets. The angular distribution of the ion flux narrows as the laser pulse fluence increases. Moreover, the ion average velocity reaches values of several tens of km/s, evidencing the presence of ions with kinetic energy of several hundred eV. Finally, the ion flux energy is confined in a narrow angular region around the target normal.

Ni, Xiaochang; Anoop, K. K.; Wang, X.; Paparo, D.; Amoruso, S.; Bruzzese, R.

2014-10-01

45

Thermal Smoothing by Laser-Produced Plasma of Porous Matter  

SciTech Connect

Efficient energy transfer and smoothing effect in laser-irradiated polystyrene foam targets have been observed in preliminary experiments on the PALS iodine laser facility. A theory of laser light absorption region formation and ablation pressure generation in laser-produced plasma of porous matter has been developed and applied for discussion of the results obtained. In particular, two stages of homogenization of the porous matter, important for comprehension of the anomalously high absorption of laser radiation in supercritical foam matter, have been identified: the first, a considerably fast stage of partial homogenization, followed by a much slower second stage, leading to a uniform medium.

Kalal, M.; Limpouch, J.; Krousky, E.; Masek, K.; Rohlena, K.; Straka, P.; Ullschmied, J.; Kasperczuk, A.; Pisarczyk, T.; Gus'kov, S.Yu.; Gromov, A.I.; Rozanov, V.B.; Kondrashov, V.N

2003-05-15

46

Diagnostics of cadmium plasma produced by laser ablation  

SciTech Connect

Optical measurements of the cadmium plasma produced by the fundamental, second, and third harmonics of a Nd:YAG laser are reported. The excitation temperature and ionic temperature have been determined from the Boltzmann plot and Saha equation, whereas the number density is estimated from the Stark broadened profile of the spectral lines. The variations in the excitation temperature and number density with the ambient air pressure as well as with the laser irradiance have been studied. Besides, the spatial distributions of the temperature and number density have been investigated.

Shaikh, Nek M.; Rashid, B.; Hafeez, S.; Mahmood, S.; Saleem, M.; Baig, M. A. [Atomic and Molecular Physics Laboratory, Department of Physics, Quaid-i-Azam University, 45320 Islamabad (Pakistan)

2006-10-01

47

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

48

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

SciTech Connect

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 10{sup 17} cm{sup -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 [Department of Advanced Interdisciplinary Sciences, and Center for Optical Research and Education (CORE) Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Bobrova, Nadezhda; Sasorov, Pavel [Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya str. 25, 117259 Moscow (Russian Federation); Kikuchi, Takashi; Sasaki, Toru [Department of Electrical Engineering, Nagaoka University of Technology, Kami-tomiokamachi 1603-1, Nagaoka, Niigata 940-2188 Japan (Japan); Higashiguchi, Takeshi; Yugami, Noboru [Department of Advanced Interdisciplinary Sciences, and Center for Optical Research and Education (CORE) 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); 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)

2011-03-01

49

Electron temperature and average density in spherical laser-produced plasmas - Ultraviolet plasma spectroscopy  

NASA Technical Reports Server (NTRS)

The average values of the electron temperature Te and the electron density Ne in the corona plasmas of spherically irradiated high-Z targets have been estimated. Targets composed of the elements Cu through Br, Rb, and Mo were irradiated using the fundamental (1.06 microns) and the frequency-tripled (351 nm) output of the Omega laser system. Spectra were recorded in the wavelength region 15-200 A. Using various extreme ultraviolet spectroscopic techniques, it is found that for the case of a Mo plasma produced by frequency-tripled laser irradiation, Te = 2600 + or - 600 eV and Ne is greater than 6 x 10 to the 20th/cu cm. This is consistent with a 'flux limit' smaller than 0.1. The estimated values of Te and Ne are lower in the corona plasmas produced using the fundamental (1.06 micron) irradiation.

Goldsmith, S.; Seely, J. F.; Feldman, U.; Behring, W. E.; Cohen, L.

1985-01-01

50

Porous materials produced from incineration ash using thermal plasma technology.  

PubMed

This study presents a novel thermal plasma melting technique for neutralizing and recycling municipal solid waste incinerator (MSWI) ash residues. MSWI ash residues were converted into water-quenched vitrified slag using plasma vitrification, which is environmentally benign. Slag is adopted as a raw material in producing porous materials for architectural and decorative applications, eliminating the problem of its disposal. Porous materials are produced using water-quenched vitrified slag with Portland cement and foaming agent. The true density, bulk density, porosity and water absorption ratio of the foamed specimens are studied here by varying the size of the slag particles, the water-to-solid ratio, and the ratio of the weights of the core materials, including the water-quenched vitrified slag and cement. The thermal conductivity and flexural strength of porous panels are also determined. The experimental results show the bulk density and the porosity of the porous materials are 0.9-1.2 g cm(-3) and 50-60%, respectively, and the pore structure has a closed form. The thermal conductivity of the porous material is 0.1946 W m(-1) K(-1). Therefore, the slag composite materials are lightweight and thermal insulators having considerable potential for building applications. PMID:23948051

Yang, Sheng-Fu; Chiu, Wen-Tung; Wang, To-Mai; Chen, Ching-Ting; Tzeng, Chin-Ching

2014-06-01

51

Numerical simulation of fine structure in the Io plasma torus produced by the centrifugal interchange instability  

NASA Astrophysics Data System (ADS)

The Io plasma torus as a whole has a radial width scale ~1 R J , much larger than the width of the localized Io plasma source (~1 R Io ~ R J /39). One of the most prominent features of the Io torus observed by the Voyager spacecraft and Earth-based instruments is the ``ribbon'' structure near Io's orbit. The stability properties of this narrower ribbon structure embedded within the larger torus have been investigated by the Rice Convection Model for Jupiter. Four initial plasma distributions having different radial widths are each represented by 82 longitudinally symmetric edges establishing 41 levels of the flux tube mass content ? with the peak ? value at Io's orbit. The same initial perturbation is put on each of these edges and is subjected to centrifugal interchange. Our simulations produce regularly spaced long, thin fingers moving outward from the outer edges. It is shown that the azimuthal width of the interchange convection cells (the distance between outflowing fingers in the nonlinear stage of development) is proportional to the radial width scale of the initial distribution that produced them. The constant of proportionality is ~0.5. Since the exponential growth rate is essentially proportional to the azimuthal wave number of the disturbance and hence is inversely proportional to its azimuthal width, the ribbon-scale interchange structures grow faster than torus-scale interchange structures.

Wu, H.; Hill, T. W.; Wolf, R. A.; Spiro, R. W.

2007-02-01

52

Numerical Simulation Of Fine Structure In The Io Plasma Torus Produced By The Centrifugal Interchange Instability  

NASA Astrophysics Data System (ADS)

The Io plasma torus as a whole has a radial width scale ~1R_J, much larger than the width of the localized Io plasma source (~1RIo? R_J/39). One of the most prominent features of the Io torus observed by the Voyager spacecraft and earth-based instruments is the 'ribbon' structure near Io's orbit. The stability properties of this narrower ribbon structure embedded within the larger torus have been investigated by the Rice Convection Model for Jupiter (RCM-J). Four initial plasma distributions having different radial widths are each represented by 82 longitudinally symmetric edges establishing 41 levels of the flux-tube mass content ? with the peak ? value at Io's orbit. The same initial perturbation is put on each of these edges and is subjected to centrifugal interchange. Our simulations produce regularly spaced long thin fingers moving outward from the outer edges. It is shown that the dominant azimuthal width scale of the interchange convection cells (fingers) in their nonlinear stage of development is proportional to the radial width scale of the initial distribution that produced them. The constant of proportionality is ~ 0.5. Since the exponential growth rate is essentially proportional to the azimuthal wave number of the disturbance, and hence inversely proportional to its azimuthal width, the ribbon-scale interchange structures grow faster than torus-scale interchange structures.

Wu, H.; Hill, T. W.; Wolf, R. A.; Spiro, R. W.

2006-12-01

53

Detection of electromagnetic pulses produced by hypervelocity micro particle impact plasmas  

NASA Astrophysics Data System (ADS)

Hypervelocity micro particles (mass < 1 ng), including meteoroids and space debris, routinely impact spacecraft and produce plasmas that are initially dense (˜1028 m-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; Linscott, Ivan; Lee, Nicolas; Johnson, Theresa; Strauss, David; Goel, Ashish; Fletcher, Alexander; Lauben, David; Srama, Ralf; Mocker, Anna; Bugiel, Sebastian

2013-09-01

54

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

55

Initiation of nuclear reactions in femtosecond laser plasma  

NASA Astrophysics Data System (ADS)

Mechanisms of electron interaction with a nucleus via a direct electron-nucleus collision and via bremsstrahlung generated in electron scattering on a nucleus in a femtosecond laser plasma are considered. The description of this interaction is simplified substantially by using the instantaneous-impact and equivalent-photon approximations. The yields of photons, electron-positron pairs, and products of nuclear reactions initiated by a laser pulse for some nuclei are calculated. In particular, this is done for 235U, 236U, 238U, and 232Th fission in a laser field of intensity 1020 to 1022 W/cm2.

Golovinski, P. A.; Mikhin, E. A.

2013-01-01

56

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

NASA Astrophysics Data System (ADS)

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; Zhang, Lu; Yang, Jiamin; Shang, Wanli

2013-12-01

57

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

58

Angular emission of ions and mass deposition from femtosecond and nanosecond laser-produced plasmas  

E-print Network

-matter and laser-plasma interaction properties as well as the behavior of subsequently generated plasmas vary. The ion flux and kinetic energy studies show fs laser plasmas produce narrower angular distribution while ns laser plasmas provide narrower energy distribution. VC 2012 American Institute of Physics. [http

Harilal, S. S.

59

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

E-print Network

laser beam interacting with a solid foil, a plasma bubble 6­9 is similar to those plasmas confined 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

60

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

61

Experimental evidence for various mechanisms for suprathermal electron generation in P-polarized laser produced plasmas  

E-print Network

-polarized laser produced plasmas G. Bonnaud (*) and E. Fabre GRECO Interaction Laser Matière, CNRS, Laboratoire de les interactions laser-plasma, par les électrons suprathermiques a été étudiée en polarisation P. Deux and their temperature have been studied in P-polarization, in laser produced plasmas. We have used two laser wavelengths

Paris-Sud XI, Université de

62

Waves and Fine Structure in Expanding Laser-Produced Plasmas  

Microsoft Academic Search

The behavior of expanding dense plasmas has long been a topic of interest in space plasma research, particularly in the case of expansion within a magnetized background. Previous laser-plasma experiments at the UCLA Large Plasma Device have observed the creation of strong (deltaBB > 50%) diamagnetic cavities, along with large-scale wave activity and hints of fine-scale structure. A new series

Andrew Collette; Walter Gekelman

2009-01-01

63

Structure of an exploding laser-produced plasma  

SciTech Connect

Currents and instabilities associated with an expanding dense plasma embedded in a magnetized background plasma are investigated by direct volumetric probe measurements of the magnetic field and floating potential. A diamagnetic cavity is formed and found to collapse rapidly compared to the expected magnetic diffusion time. The three-dimensional current density within the expanding plasma includes currents along the background magnetic field, in addition to the diamagnetic current. Correlation measurements reveal that flutelike structures at the plasma surface translate with the expanding plasma across the magnetic field and extend into the current system that sustains the diamagnetic cavity, possibly contributing to its collapse.

Collette, A. [Laboratory for Atmospheric and Space Physics, UCB 392, Boulder, Colorado 80309 (United States); Gekelman, W. [Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095 (United States)

2011-05-15

64

Initial experiments of RF gas plasma source for heavy ionfusion  

SciTech Connect

The Source Injector Program for the US Heavy Ion Fusion Virtual National Laboratory is currently exploring the feasibility of using RF gas plasma sources for a HIF driver. This source technology is presently the leading candidate for the multiple aperture concept, in which bright millimeter size beamlets are extracted and accelerated electrostatically up to 1 MeV before the beamlets are allowed to merge and form 1 A beams. Initial experiments have successfully demonstrated simultaneously high current density, {approx} 100 mA/cm{sup 2} and fast turn on, {approx} 1 {micro}s. These experiments were also used to explore operating ranges for pressure and RF power. Results from these experiments are presented as well as progress and plans for the next set of experiments for these sources.

Ahle, L.; Hall, R.; Molvik, A.W.; Chacon-Golcher, E.; Kwan, J.W.; Leung, K.N.; Reijonen, J.

2002-05-22

65

Effect of Pressure Level on the Performance of an Auto-Initiated Pulsed Plasma Thruster  

NASA Astrophysics Data System (ADS)

Pulsed plasma thrusters (PPT) are micro-propulsion devices used in satellites for station keeping. Conventionally the plasma discharge in a PPT is initiated by a spark plug. The primary objective of the present work was to develop and characterize a PPT that does not need a spark plug to initiate the plasma discharge. If the spark plug is eliminated, the size of the thrusters can be reduced and arrays of such thrusters can be manufactured using micro electro mechanical systems (MEMS) techniques, which can provide tremendous control authority over the satellite positioning. A parallel rail thruster was built and its performances were characterized inside a vacuum chamber to elucidate the effect of vacuum level on the performance. The electrical performance of the thruster was quantified by measuring the voltage output from a Rogowski coil, and the thrust produced by the developed thruster was estimated by measuring the force exerted by the plume on a light weight pendulum, whose deflection was measured using a laser displacement sensor. It was observed that the thruster can operate without a spark plug. In general, the performance parameters such as thrust, mass ablation, impulse bit, and specific impulse per discharge, would increase with the increase in pressure up to an optimum level due to the increase in discharge energy as well as the decrease in the total impedance of the plasma discharge. The thrust efficiency is found to be affected by the discharge energy.

Kelvin, Loh; Abhijit, Kushari

2010-08-01

66

Initial operation of a large-scale Plasma Source Ion Implantation experiment  

SciTech Connect

In Plasma Source Ion Implantation (PSII), a workpiece to be implanted is immersed in a weakly ionized plasma and pulsed to a high negative voltage. Plasma ions are accelerated toward the workpiece and implanted in its surface. Experimental PSII results reported in the literature have been for small workpieces. A large scale PSII experiment has recently been assembled at Los Alamos, in which stainless steel and aluminum workpieces with surface areas over 4 m{sup 2} have been implanted in a 1.5 m-diameter, 4.6 m-length cylindrical vacuum chamber. Initial implants have been performed at 50 kV with 20 {mu}s pulses of 53 A peak current, repeated at 500 Hz, although the pulse modulator will eventually supply 120 kV pulses of 60 A peak current at 2 kHz. A 1,000 W, 13.56 MHz capacitively-coupled source produces nitrogen plasma densities in the 10{sup 15} m{sup {minus}3} range at neutral pressures as low as 0.02 mtorr. A variety of antenna configurations have been tried, with and without axial magnetic fields of up to 60 gauss. Measurements of sheath expansion, modulator voltage and current, and plasma density fill-in following a pulse are presented. The authors consider secondary electron emission, x-ray production, workpiece arcing, implant conformality, and workpiece and chamber heating.

Wood, B.P.; Henins, I.; Gribble, R.J.; Reass, W.A.; Faehl, R.J.; Nastasi, M.A.; Rej, D.J.

1993-10-01

67

Inactivation of Escherichia coli ATCC 11775 in fresh produce using atmospheric pressure cold plasma  

NASA Astrophysics Data System (ADS)

Food-borne outbreaks are associated with the presence of pathogenic bacteria in food products such as fresh produce. One of the target microorganisms is Escherichia coli which exhibits resistance to being inactivated with conventional disinfection methods for vegetables. Atmospheric pressure cold plasma (APCP) was tested to disinfect three vegetables with challenge surfaces, lettuce, carrots and tomatoes. The produce was inoculated with the bacteria to reach an initial microbial concentration of 10^7 cfu/g. Vegetables were initially exposed to the APCP discharges from a needle array at 5.7 kV RMS in argon, processing times of 0.5, 3 and 5 min. Initial results indicate that microbial decontamination is effective on the lettuce (1.2 log reduction) when compared with other vegetables. To claim disinfection, a 3 log reduction or more is needed, which makes APCP treatment very promising technology for decontamination of produce. We propose that with method refinements full disinfection can be achieved using APCP.

Bermudez-Aguirre, Daniela; Wemlinger, Erik; Barbosa-Canovas, Gustavo; Pedrow, Patrick; Garcia-Perez, Manuel

2011-11-01

68

Four-dimensional imaging of the initial stage of fast evolving plasmas  

NASA Astrophysics Data System (ADS)

Using an ultrafast electron probe capable of four-dimensional diagnosis, the initial stage of fast evolving plasmas produced by a 1014 W/cm2 laser irradiation of a metal target was investigated in real time with picosecond time resolution. The associated strong transient electric field was identified to have two components, which either focus or defocus the probe electron beam. The effects of this field on the probe electron beam can be reproduced by a self-expanding charge cloud containing about 5×107 suprathermal electrons with the outermost layer expanding at an average speed of 1.2×107 m/s.

Zhu, Pengfei; Zhang, Zhongchao; Chen, Long; Zheng, Jun; Li, Runze; Wang, Weimin; Li, Junjie; Wang, Xuan; Cao, Jianming; Qian, Dong; Sheng, Zhengming; Zhang, Jie

2010-11-01

69

Nonlinear regime of the filamentation of a microwave produced plasma  

NASA Astrophysics Data System (ADS)

The nonlinear dynamics of the magnetic field and anisotropic instability due to interaction of a plasma with microwave radiation, by making use of magnetohydrodynamic equations and Ampere-Maxwell law, are investigated. Also, it is shown that the Lienard nonlinear differential equation describes the evolution of the magnetic field in the plasma. We investigate the profiles of magnetic field and electron density variation in plasma and show that these profiles have a nonsinusoidal shape in the nonlinear regime. Furthermore, it is shown that the electron density becomes highly peaked in this regime. Also, due to the nonlinear effect, the cross section and shape of transverse filamentation can vary in the static limit.

Shokri, B.; Niknam, A. R.

2007-03-01

70

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

71

Persistence of uranium emission in laser-produced plasmas  

NASA Astrophysics Data System (ADS)

Detection of uranium and other nuclear materials is of the utmost importance for nuclear safeguards and security. Optical emission spectroscopy of laser-ablated U plasmas has been presented as a stand-off, portable analytical method that can yield accurate qualitative and quantitative elemental analysis of a variety of samples. In this study, optimal laser ablation and ambient conditions are explored, as well as the spatio-temporal evolution of the plasma for spectral analysis of excited U species in a glass matrix. Various Ar pressures were explored to investigate the role that plasma collisional effects and confinement have on spectral line emission enhancement and persistence. The plasma-ambient gas interaction was also investigated using spatially resolved spectra and optical time-of-flight measurements. The results indicate that ambient conditions play a very important role in spectral emission intensity as well as the persistence of excited neutral U emission lines, influencing the appropriate spectral acquisition conditions.

LaHaye, N. L.; Harilal, S. S.; Diwakar, P. K.; Hassanein, A.

2014-04-01

72

Short-Pulse Laser-Produced Plasmas Jean-Claude Gauthier  

E-print Network

on ultrafast plasmas In the "long" (nanosecond) pulse regime, laser-plasma interaction physics has been studied.6 details some practical applications of femtosec- ond laser-matter interaction. 2 Pioneering worksShort-Pulse Laser-Produced Plasmas Jean-Claude Gauthier Centre Lasers Intenses et Applications

Paris-Sud XI, Université de

73

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

74

Plasma waves near Saturn - Initial results from Voyager 1  

Microsoft Academic Search

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 electron cyclotron waves, and upper hybrid resonance emissions in the inner magnetosphere. A clocklike Saturn rotational control

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

1981-01-01

75

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

76

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

77

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

78

Development of Plasma Electron Guns to Produce Narrow Focusing Beams Under the Higher Operation Pressure  

Microsoft Academic Search

Summary form only given. One of the main advantages of the plasma cathode electron guns is its ability to produce electron beam under the higher operation pressure up to fore-pump pressure range. Present work is devoted to plasma electron guns that were designed especially to generate narrow focusing electron beams under the high pressure. To produce narrow focusing beam two

V. Burdovitsin; M. Eroshkin; I. Osipov; N. Rempe; I. Zhirkov; E. Oks

2005-01-01

79

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

80

Suprathermal electrons produced by beam-plasma-discharge  

NASA Technical Reports Server (NTRS)

Experiments conducted with a low energy plasma lens, HARP, in the electron beam of the large vacuum chamber at Johnson Space Center indicate that an enhanced population of 50 to 300 volt electrons appear when the beam goes into the Beam-Plasma Discharge (BPD) mode. Below the BPD instability the electron distribution appears to be characterized as non-energized single particle scattering and energy loss. At 100 cm from the beam core in the BPD mode the fluxes parallel to the beam are reduced by a factor of 20 with respect to the fluxes at 25 cm. Some evidence for isotropy near the beam core is presented.

Sharp, W. E.

1982-01-01

81

Suprathermal electrons produced by Beam-Plasma-Discharge  

SciTech Connect

Experiments conducted with a low energy plasma lens, HARP, in the electron beam of the large vacuum chamber at Johnson Space Center indicate that an enhanced population of 50 to 300 volt electrons appear when the beam goes into the Beam-Plasma Discharge (BPD) mode. Below the BPD instability the electron distribution appears to be characterized as non-energized single particle scattering and energy loss. At 100 cm from the beam core in the BPD mode the fluxes parallel to the beam are reduced by a factor of 20 with respect to the fluxes at 25 cm. Some evidence for isotropy near the beam core is presented.

Sharp, W.E.

1982-08-01

82

Microwave reflections from a vacuum ultraviolet laser produced plasma sheet  

E-print Network

. The reflectivity can be described by the plasma dielectric constant6 p 1 p 2 i , 1 where p 2 (ne2 )/(m detection system with a response time of 10 ns is utilized to determine the amplitude and phase wave at a dielectric boundary is given by the Fresnel reflection coef- ficient, Ereflected Eincident p

Scharer, John E.

83

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

84

Initial results from the Cassini radio and plasma wave science investigation at Saturn  

Microsoft Academic Search

On July 1, 2004, the Cassini spacecraft will arrive at Saturn and is expected to be injected into orbit around Saturn. This talk will report the initial results from the Radio and Plasma Wave Science (RPWS) investigation. The RPWS is designed to study radio emissions, plasma waves, thermal plasma, and dust in the vicinity of Saturn. Three nearly orthogonal electric

D. Gurnett

2004-01-01

85

Influence of low atomic number plasma component on the formation of laser-produced plasma jets  

SciTech Connect

The results of investigations are presented that are connected with a very simple method of plasma jet formation, which consists in irradiating a massive planar target made of material with relatively high atomic number by a partly defocused laser beam. This brief communication is aimed at investigations of interaction of axially symmetrical light (plastic-CH) plasma with heavy (copper) plasma. It demonstrates that a relatively thin plastic plasma envelope can compress the Cu plasma and control the Cu-jet formation.

Kasperczuk, A.; Pisarczyk, T.; Badziak, J.; Borodziuk, S.; Chodukowski, T. [Institute of Plasma Physics and Laser Microfusion, 23 Hery St., 00-908 Warsaw (Poland); Gus'kov, S. Yu.; Demchenko, N. N. [Institute of Plasma Physics AS CR, v.v.i., Za Slovankou 3, 182 00 Prague 8 (Czech Republic); Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J. [Institute of Physics AS CR, v.v.i., Na Slovance 2, 182 21 Prague 8 (Czech Republic); Pisarczyk, P. [Warsaw University of Technology, ICS, 15/19 Nowowiejska St., 00-665 Warsaw (Poland)

2010-11-15

86

Plasma waves near saturn: initial results from voyager 1.  

PubMed

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 electron cyclotron waves, and upper hybrid resonance emissions in the inner magnetosphere. A clocklike 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 upper hybrid resonance 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. PMID:17783836

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

1981-04-10

87

Plasma waves near Saturn - Initial results from Voyager 1  

NASA Technical Reports Server (NTRS)

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 electron cyclotron waves, and upper hybrid resonance emissions in the inner magnetosphere. A clocklike 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 upper hybrid resonance 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.

1981-01-01

88

Spectral modeling of laser-produced underdense titanium plasmas  

Microsoft Academic Search

Experiments were performed at the NIKE laser to create underdense low-Z plasmas with a small amount of high-Z dopant in order to study non-LTE population kinetics. An absolutely calibrated spectra in 470-3000 eV was measured in time-resolved and time-averaged fashion from SiO2 aerogel target with 3% Ti dopant. K-shell Ti emission was observed as well as L-shell Ti emission. Time-resolved

Hyun-Kyung Chung; Christina A. Back; Howard A. Scott; Carmen Constantin; Richard W. Lee

2004-01-01

89

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

90

Aminated graphene for DNA attachment produced via plasma functionalization  

NASA Astrophysics Data System (ADS)

We demonstrate the use of a unique plasma source to controllably functionalize graphene with nitrogen and primary amines, thereby tuning the chemical, structural, and electrical properties. Critically, even highly aminated graphene remains electronically conductive, making it an ideal transduction material for biosensing. Proof-of-concept testing of aminated graphene as a bio-attachment platform in a biologically active field-effect transistor used for DNA detection is demonstrated.

Baraket, Mira; Stine, Rory; Lee, Woo K.; Robinson, Jeremy T.; Tamanaha, Cy R.; Sheehan, Paul E.; Walton, Scott G.

2012-06-01

91

Pitch angle variations in magnetospheric thermal plasma - Initial observations from Dynamics Explorer-1  

NASA Technical Reports Server (NTRS)

Initial measurements of thermal plasma outside the plasmasphere, in the plasma trough and polar cap, reveal the presence of a great variety of pitch angle distributions which are dependent on ion composition and charge state. These observations present the first successful detection of the polar wind at high altitudes in the plasma trough, and show that detached plasma regions can be field-aligned in nature.

Chappell, C. R.; Green, J. L.; Johnson, J. F. E.; Waite, J. H., Jr.

1982-01-01

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

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

94

Producing titanium aluminide foil from plasma-sprayed preforms  

SciTech Connect

A new method was used to fabricate foils of Ti-6Al-4V (Ti-6-4) alloy and Ti-14Al-21Nb(Ti-14-21) titanium aluminide, starting from a plasma-sprayed (PS) preform. The foils were 100 percent dense, with microstructures similar to those of wrought (IM) foil material. The foil made from PS preforms were characterized by the mechanical properties equivalent to their IM-processed counterparts. It is concluded that the method of roll consolidation of a PS preform is well suited for alloys and intermetallics that do not possess extensive hot and cold workability. 6 refs.

Jha, S.C.; Forster, J.A. (Texas Instruments, Inc., Attleboro, MA (United States))

1993-07-01

95

In situ chitosan gelation initiated by atmospheric plasma treatment.  

PubMed

This work reports on the feasibility of atmospheric dielectric barrier discharge (DBD) plasma as a novel synthetic pathway for the liquid phase gelation of chitosan. The DBD plasma chitosan gelation process did not significantly alter the chemical structure of the biopolymer as confirmed by FTIR study. However, the oxidation processes and local heating effect associated with the solvent evaporation during the plasma treatment could provoke both reaction of chitosan degradation and the cleavage of ?-1-4-glycosidic linkages with the concomitant generation of aldehyde groups able to crosslink via Schiff-base with amino groups from other chitosan molecules. Shear viscosity measurements suggested the formation of chitosan fragments of lower molecular weight after the plasma treatment of 1% (w/v) chitosan and fragments of higher molecular weight after the plasma treatment of 2% (w/v) chitosan. The crosslinking density of hydrogels generated during the in situ DBD plasma chitosan gelation process increased as a function of the treatment time and concentration of chitosan. As of consequence of the increase of the cross-linking density, the equilibrium swelling ratio and water content decreased significantly. PMID:24528756

Molina, R; Jovancic, P; Vilchez, S; Tzanov, T; Solans, C

2014-03-15

96

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

97

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

NASA Astrophysics Data System (ADS)

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; Goto, Masaaki

2010-10-01

98

Stimulated Raman scattering in inhomogeneous collisional laser-produced plasmas  

SciTech Connect

Convective gain and absolute growth of stimulated Raman scattering (SRS) are determined for a hot inhomogeneous collisional plasma using an integrated global model that includes the effects of wave propagation and both collisional and Landau damping in a density ramp. This unifies the time asymptotic theory of SRS occurring near the quarter-critical density of the laser light and that occurring at lower densities. The level of collisions has a striking effect on the convective behavior of the instability. When collisions are weak, no significant regime of convective gain exists. In consequence, absolute resonances are very sensitive and susceptible to detuning, particularly so near the quarter-critical density. This is shown to be a key factor in understanding the Raman gap'' seen in experiments. No such gap appears in highly collisional regimes in which the absolute resonances are insensitive and significant convective gain occurs over the whole range of wavelengths.

Barr, H.C.; Boyd, T.J.M.; Mackwood, A.P. (Department of Physics, University of Essex, Colchester, C04 3SQ (United Kingdom))

1994-04-01

99

Specific features of microheterogeneous plasma produced by irradiation of a polymer aerogel target with an intense 500-ps-long laser pulse  

SciTech Connect

The properties of microheterogeneous plasma produced by irradiation of a polymer aerogel target with an intense (10{sup 14} W/cm{sup 3}) short (0.5 ps) 1.064-?m laser pulse were studied. It is found that, even at plasma densities exceeding the critical density, a small fraction of the incident laser radiation penetrates through the plasma in which the processes of density and temperature equalization still take place. The intensification (as compared to plasmas produced from denser foams and solid films) of transport processes in such plasma along and across the laser beam can be caused by the initial microheterogeneity of the solid target. The replacement of a small (10% by mass) part of the polymer with copper nanoparticles leads to a nearly twofold increase in the intensity of the plasma X-ray emission.

Borisenko, N. G.; Merkul’ev, Yu. A.; Orekhov, A. S., E-mail: orekhov@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Chaurasia, S.; Tripathi, S.; Munda, D. S.; Dhareshwar, L. J. [Bhabha Atomic Research Centre, High-Pressure and Synchrotron Radiation Physics Division (India)] [Bhabha Atomic Research Centre, High-Pressure and Synchrotron Radiation Physics Division (India); Pimenov, V. G.; Sheveleva, E. E. [Russian Academy of Sciences, Zelinksy Institute of Organic Chemistry (Russian Federation)] [Russian Academy of Sciences, Zelinksy Institute of Organic Chemistry (Russian Federation)

2013-08-15

100

Diamagnetic effect produced by the Fluxus-1 and -2 artificial plasma jet  

Microsoft Academic Search

The purpose of the Fluxus-1 and -2 active experiments is to study plasma jets injected parallel to the magnetic field and to study the interaction of these jets with the magnetic field. The experiments were conducted using a shaped-charge device, known as an explosive type generator (ETG), that produced an artificial aluminum plasma jet. In Fluxus-1 and -2 the jet

B. G. Gavrilov; A. I. Podgorny; I. M. Podgorny; D. B. Sobyanin; J. I. Zetzer; R. E. Erlandson; C.-I. Meng; B. J. Stoyanov

1999-01-01

101

Currents and shear Alfven wave radiation generated by an exploding laser-produced plasma: Perpendicular incidence  

E-print Network

Currents and shear Alfve´n wave radiation generated by an exploding laser-produced plasma: Perpendicular incidence M. VanZeeland,a) W. Gekelman, S. Vincena, and J. Maggs Department of Physics February 2003 Examples of one plasma expanding into another and the consequent radiation of wave energy

California at Los Angles, University of

102

Time-Resolved Analysis of High-Power-Laser Produced Plasma Expansion  

NASA Astrophysics Data System (ADS)

We consider the results of an experimental investigation of the temporal evolution of plasmas produced by high power laser irradiation of various materials. The experiment was done at the LULI Laboratory (Ecole Polytechnique, Paris). A comparative analysis is presented.

Aliverdiev, A.; Batani, D.; Malka, V.; Vinci, T.; Koenig, M.; Benuzzi-Mounaix, A.; Dezulian, R.

2006-04-01

103

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

104

Excitation of X-Ray Plasma Satellites in a Femtosecond Laser-Produced Plasma  

SciTech Connect

The excitation of X-ray plasma satellites was investigated in the plasma created by subpicosecond laser pulses with various intensities. It is shown that when laser flux density is greater then 6x10{sup 16} W/cm{sup 2} strong oscillating electrical fields with {omega}{approx}(1.5-1.6)x10{sup 15} s{sup -1} are excited in the plasma. These oscillations lead to modifications of profiles of X-Ray spectral lines observed.

Faenov, A. Ya. [Joint Institute for High Temperatures of Russian Academy of Sciences, Moscow (Russian Federation); Kansai Photon Science Institute, Japan Atomic Energy Agency, Kizu-gawa, Kyoto (Japan); Gavrilenko, V. P.; Magunov, A. I. [A.M. Prokhorov General Physics Institute of Russian Academy of Sciences, Moscow (Russian Federation); Pikuz, T. A.; Skobelev, I. Yu.; Gasilov, S. V. [Joint Institute for High Temperatures of Russian Academy of Sciences, Moscow (Russian Federation); Stagira, S.; Calegari, F.; Vozzi, C.; Nisoli, M.; Sansone, G.; De Silvestri, S. [National Laboratory for Ultrafast and Ultraintense Optical Science-CNR-INFM, Department of Physics, Politecnico, Milano (Italy); Poletto, L.; Villoresi, P. [Laboratory for Ultraviolet and X-Ray Optical Research-CNR-INFM, D.E.I.-Universita di Padova, Padova (Italy)

2008-06-24

105

Laser-produced plasmas as unique x-ray souces for industry and astrophysics  

Microsoft Academic Search

Laser produced plasma is one of the brilliant x-ray source that has unique capabilities for use in a wide range of science. Here we describe two examples of laser-produced plasma x-ray source application; one is for the semiconductor device industry and the other is for the astronomy. Extreme ultraviolet (EUV) light sources for microlithography are receiving much attention as an

S. Fujioka; H. Nishimura; H. Takabe; N. Yamamoto; K. Nishihara; D. Salzmann; T. Norimatsu; N. Miyanaga; K. Mima; H. Azechi; A. Sunahara; Y. Shimada; Y. Izawa; K. Nagai; F. Wang; J. Zhong; G. Zhao; Y. Li; Q. Dong; S. Wang; Y. Zhang; J. Zhang; Y.-J. Rhee; Y.-W. Lee; D.-H. Kwon

2010-01-01

106

Laser-produced aluminum plasma expansion inside a plastic plasma envelope  

SciTech Connect

Previous experimental results demonstrated that the plasma pressure decreases with the growing atomic number of the target material. In this context, a question arose if the Al plasma outflow could be collimated using the plastic plasma as a compressor. To solve this problem, an experiment using a plastic target with an Al cylindrical insert was performed. The focal spot diameter substantially larger than that of the insert ensured simultaneous heating both target materials. This experiment proved that a production of Al plasma jets collimated by an action of outer plastic plasma is feasible [Kasperczuk et al., Laser Part. Beams 30, 1 (2012)]. The results of investigations presented here provide additional information on distributions of electron temperature in the outflowing plasma and time and space characteristics of ion emission, both registered at bare and constrained-flow Al targets. The experiment was carried out at the Prague asterix laser system iodine laser facility. The laser provided a 250 ps (full width at half maximum) pulse with the energy of 130 J at the third harmonic frequency ({lambda}{sub 3} = 0.438 {mu}m). A plastic target with an Al cylindrical insert of 400 {mu}m in diameter as well as a bare Al target (for comparison) was used. The focal spot diameter ({Phi}{sub L}) 1200 {mu}m ensured the lateral pressure effect of the plastic plasma strong enough to guarantee the effective Al plasma compression. The electron temperature measurements have shown that such Al plasma compression is accompanied by the increase of its temperature, dominance of which starts at distance of 0.5 mm from the target surface. Measurements of ion emission characteristics confirm the earlier numerical simulation prediction that in these conditions the plasma expansion geometry is closer to planar. The constrained Al plasma jet is very narrow and its axial velocity is considerably larger than the velocity of freely expanding Al plasma stream. It means that the plastic plasma envelope, besides the Al plasma compression, also strongly accelerates the Al plasma in its axial motion.

Kasperczuk, A.; Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Parys, P. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Renner, O.; Rohlena, K. [Institute of Physics ASCR, v.v.i., Prague (Czech Republic); Gus'kov, S. Yu.; Demchenko, N. N. [P.N. Lebedev Physical Institute of RAS, Moscow (Russian Federation); Ullschmied, J.; Krousky, E.; Pfeifer, M.; Skala, J. [Institute of Plasma Physics ASCR, v.v.i., Prague (Czech Republic)

2012-09-15

107

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

108

Experimental observation of ion correlation in a dense laser-produced plasma  

SciTech Connect

We present what we believe are the first experimental observations of ion correlation effects in a dense plasma. The plasma is produced in aluminum by colliding shocks driven by high-power laser beams. Computer simulations suggest that a peak temperature of over 1 eV and densities of several times solid are produced. Short-range order within the plasma is observed by means of the extended x-ray-absorption fine-structure (EXAFS) spectrum of the aluminum K absorption edge. Densities measured from the EXAFS spectrum are in reasonable agreement with the computer predictions.

Hall, T.A.; Djaoui, A.; Eason, R.W.; Jackson, C.L.; Shiwai, B.; Rose, S.L.; Cole, A.; Apte, P.

1988-05-16

109

Initial results from the ISEE-1 and -2 plasma wave investigation  

Microsoft Academic Search

A survey of initial results from the plasma-wave investigation on the ISEE 1 and 2 spacecraft is presented. The plasma-wave instruments employed are designed to provide measurements of the electric and magnetic fields of plasma waves over the frequency range from about 5 Hz to 300 kHz. Several representative satellite passes are analyzed in detail and discussed. The results considered

D. A. Gurnett; R. R. Anderson; F. L. Scarf; R. W. Fredricks; E. J. Smith

1979-01-01

110

Comparison of nanosecond laser produced brass plasmas under low and moderate pressure air  

NASA Astrophysics Data System (ADS)

Nanosecond laser produced brass plasmas are studied at the ambient pressures of 10-3, 20, 100 and 500 Pa. Spatial and temporal dynamics of the plasmas are captured by fast photography and optical emission spectroscopy (OES). The phenomena of plasma free expansion, splitting, sharpening, and instability are observed, respectively. At different pressures and incident laser fluences, the plasma lengths are found to be in good agreement with the drag force model, and the plasma stopping distance are interpreted with the Dyer's model. By spatially resolved OES, we confirm that the excited target ions (Zn+, and Cu+) play a growing important role on the emission near plasma front with the increase of the ambient pressure. It also demonstrates that at the late time of 300 ns, there is no significant variation in the temperature distribution on axis in the explored ambient pressure range, while the electron density decreases rapidly in the near-surface region.

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

2013-11-01

111

Particle Dynamics in Neutral-Gas Confined Laser-Produced Plasmas  

NASA Astrophysics Data System (ADS)

Laser-produced plasma from a metallic target can be confined to higher plasma densities by immersing the target in an inert gas medium at increasingly high density. The plasma becomes Rayleigh-Taylor unstable, however, when the mass density of the neutral gas exceeds the plasma mass density substantially.[1] A new plasma diagnostic method is developed to help examine the early time development of the gas-plasma interfacial structure. A preliminary study based on plasma polarization spectroscopy is presented, in which the dynamics of atoms and ions are visualized in the presence of electromagnetic fields due to charge separation. The ambient gas pressure of argon is varied as active control in the low-pressure regime. Time-resolved multi-directional projections of an aluminum plasma are obtained in line and continuum emissions, polarization and spectral broadening including Doppler shifts. The electrostatic potential of the target is also followed. The results indicate a bifurcation of the phase-space distribution function and structural segmentation of the plasma into a thermalized core and a crown with highly aligned, energetic atoms and ions. Reconstruction of the plasma structure appears possible by generalization of the two new algorithms we have developed.[1,2] 1. Y.W. Kim and J.-C. Oh, Rev. Sci. Inst. 72, 948 (2001). 2. Y.W. Kim and C.D. Lloyd-Knight, Rev. Sci. Inst. 72, 944 (2001).

Kim, Yong W.

2001-10-01

112

LASER PLASMA Investigation of the optical characteristics of a laser-produced plasma cloud expanding into a background gas  

Microsoft Academic Search

An investigation is made of the dynamics and visible-range luminosity of the plasma cloud produced behind the front of a shock wave in air at a pressure of 1 Torr. The shock wave was produced on introducing the radiation of the twelve-channel Iskra-5 laser facility with a total energy of ~2300 J into a hollow spherical plastic target of mass

A. I. Annenkov; A. V. Bessarab; I. V. Galakhov; Sergey G. Garanin; A. V. Gusakov; N. V. Zhidkov; V. A. Zhmailo; V. M. Izgorodin; V. P. Kovalenko; V. A. Krotov; V. V. Mis'ko; E. A. Novikova; V. A. Starodubtsev; K. V. Starodubtsev; V. P. Statsenko; R. R. Sungatullin; G. V. Tachaev; Yu N. Sheremet'ev

2010-01-01

113

Density and temperature measurements of pulsed plasma produced inside a curved vacuum chamber  

NASA Astrophysics Data System (ADS)

Recent experimental evidence suggests the importance of fast radial plasma transport in the scrape-off-layer (SOL) of tokamaks. The outward transport appears to be convective rather than diffusive, extends into the far SOL, and can produce significant recycling from the main-chamber walls, partially by passing the divertor. A plausible theoretical mechanism to explain this phenomenon is the radial transport of locally dense plasma created by turbulent processes. In our experiment a blob of plasma is produced using a plasma-gun and injected radially to the curved vacuum chamber. In this paper we report the measurement of electron density and temperature of the plasma blob produced by the plasma-gun inside the curved vacuum chamber using cylindrical Langmuir probes. The probes are moved both radially and transversely to flow direction. The electron density and temperature are measured ~ 1016 m-3 and 10-1 eV respectively for radial flow at constant discharging potential, base pressure as well as plasma pulse time.

Sasini, N.; Paikaray, R.; Dinda, L.; Sahoo, G.; Ghosh, J.; Sanyasi, A. K.

2010-02-01

114

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

115

A study of subsurface crack initiation produced by rolling contact fatigue  

NASA Technical Reports Server (NTRS)

Results of subsurface crack initiation studies produced by pure rolling contact fatigue in 7075-T6 aluminum alloy are presented in this article. Microstructural changes and subsequent crack initiation below the contacting surface in cylindrical test specimens subjected to repeated rolling contact are illustrated. The rolling conditions are simulated in a three-dimensional elastic-plastic finite element model in order to estimate the plastic strains and residual stresses in the test material. The numerically estimated distribution of plastic strains in the model correlate well with the extent of microstructural changes observed in the test specimen. Results also indicate that a combination of plastic strains and low values of residual stresses is conducive to subsurface crack initiation and growth.

Kumar, Arun M.; Hahn, George T.; Rubin, Carol A.

1993-01-01

116

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

117

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

118

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

119

Apparatus for recording emissions from a rapidly generated plasma from a single plasma producing event  

DOEpatents

An optical fiber-coupled detector visible streak camera plasma diagnostic apparatus. Arrays of optical fiber-coupled detectors are placed on the film plane of several types of particle, x-ray and visible spectrometers or directly in the path of the emissions to be measured and the output is imaged by a visible streak camera. Time and spatial dependence of the emission from plasmas generated from a single pulse of electromagnetic radiation or from a single particle beam burst can be recorded.

Tan, Tai Ho (Los Alamos, NM); Williams, Arthur H. (Los Alamos, NM)

1985-01-01

120

Two-dimensional simulations of the population inversion in recombining laser-produced plasma  

Microsoft Academic Search

Simulations of gain in recombining laser-produced plasma of Li-like ions of aluminum were performed using the 2-D code GIDRA-2. Symmetrical 4-beam scheme of fiber irradiation was modeled in accordance with experimental arrangement described in Ref. (1). These simulations show good agreement with earlier 1-D simulations for optically thin plasma. Maximal angle-averaged value of gain on 3d5\\/2?4f7\\/2 transition in Li-like aluminum

V. C. Roerich; A. N. Starostin; A. E. Stepanov

1997-01-01

121

Generation of high-charge-state ions from CO2 laser-produced plasma  

Microsoft Academic Search

The measurement results are presented for angular dependency of the CO2 laser produced plasma parameters at power density of 4 by 1013W\\/cm2 and laser pulse duration of 14 ns. 2D numerical simulations are in sufficiently good agreement with experiment. It is shown that the light pressure effects on plasma expansion dynamics and the number of particles generated at the target

K. N. Makarov; S. V. Khomenko; S. G. Nischuk; V. C. Roerich; Yu. A. Satov; Yu. B. Smakovskii; A. E. Stepanov

2001-01-01

122

Two-dimensional simulations of the population inversion in recombining laser-produced plasma  

Microsoft Academic Search

Simulations of gain in recombining laser-produced plasma of Li-like ions of aluminum were performed using the 2-D code GIDRA-2. Symmetrical 4-beam scheme of fiber irradiation was modeled in accordance with experimental arrangement described in Ref. (1). These simulations show good agreement with earlier 1-D simulations for optically thin plasma. Maximal angle-averaged value of gain on 3d5\\/2-4f7\\/2 transition in Li-like aluminum

V. C. Roerich; A. N. Starostin; A. E. Stepanov

1997-01-01

123

In-situ carburized coating produced by reactive plasma spraying of low carbon steel using methane  

Microsoft Academic Search

In the present investigation, an in-situ carburized coating was produced by reactive plasma spraying of low carbon steel using 100% methane as powder carrier gas. Microstructural and chemical analysis revealed modification of the microstructure and a significant increase in carbon content from 0.13 to > 1 wt.% C in the reactive plasma sprayed low carbon steel. Micro-hardness of the reactive

X. Liang; A. Sickinger; J. Wolfenstine; E. J. Lavernia

1996-01-01

124

Carbon Nano-Flakes Produced by an Inductively Coupled Thermal Plasma System for Catalyst Applications  

Microsoft Academic Search

Carbon material was produced using an inductively coupled thermal plasma torch system of 35 kW and a conical shape reactor.\\u000a The carbon nanopowders were obtained by plasma decomposition of methane at various flow rates and show a uniform microstructure\\u000a throughout the reactor. The product has a crystalline graphitic structure, with a stacking of between 6 and 16 planes and\\u000a a nano-flake

Ramona Pristavita; Jean-Luc Meunier; Dimitrios Berk

2011-01-01

125

Experimental and theoretical study of artificial plasma layers produced by two intersecting beams in a chamber  

NASA Technical Reports Server (NTRS)

The work done on the Bragg scattering of electromagnetic waves by microwave produced plasma layers is reported. Also summarized is the work accomplished on the propagation of high power microwave pulses in an air breakdown environment. Ongoing work on the theoretical model and numerical results of pulse propagation in air is also presented as are the results of studying the decay of plasma density and temperature.

Kuo, S. P.; Zhang, Y. S.

1989-01-01

126

Scalable THz generation in two-color laser-produced plasma  

NASA Astrophysics Data System (ADS)

We report ultrafast, high-power terahertz (THz) generation in two-color laser-produced plasmas. For scalable THz generation, we have studied two schemes---long (one-dimensional) and fat (two-dimensional) plasma filamentation. In the case of long filament formation, we observe phase-matched THz generation, which occurs naturally due to off-axis constructive interference between locally produced THz waves. This emits conical THz radiation in the off-axis direction, peaked at 4˜7 degrees depending on the radiation frequencies. In this case, the total THz yield increases almost linearly with the filament length. Because of this, one can effectively increase THz output energy by simply extending the filament length. This overcomes the saturation effect previously reported, mainly caused by overdense plasma creation and laser intensity clamping in filamentation. In addition, we observe THz polarization rotation and control along long plasma filaments. In the second scheme, a cylindrical lens is used to produce two-dimensional plasma sheets. This also provides a simple method for scalable THz generation with enhanced plasma volume and coherent THz field addition.

Kim, Ki-Yong; You, Yong Sing; Oh, Taek Il

2012-10-01

127

Comparison of optical emission from nanosecond and femtosecond laser produced plasma in atmosphere and vacuum conditions  

NASA Astrophysics Data System (ADS)

In this study we examine the emission from brass plasma produced by ns and fs laser ablation under both vacuum and atmosphere environments using identical laser fluences in order to better understand the differences in emission features and plasma dynamics. Optical emission spectra show increased continuum and emission from lower-charged ions for ns laser-produced plasma (LPP), while fs plasma emission spectra show emission primarily from excited neutral species with negligible continuum. Plasma excitation temperature and electron density as a function of time show similar trends for both lasers, though fs LPP expansion appears to be approximately two times faster than ns LPP expansion for the conditions studied. Confinement by the ambient gas is shown to significantly enhance and maintain plasma temperature and density and hence, emission, at later times. ICCD images of plasma expansion showed a broader angular distribution for ns LPP, but narrower angular distribution for fs LPP. Images also confirm the significant effect that the ambient environment has in confining plume expansion.

Freeman, J. R.; Harilal, S. S.; Diwakar, P. K.; Verhoff, B.; Hassanein, A.

2013-09-01

128

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

129

Review of progress at the UK Central Laser Facility in developing XUV lasers based on recombining laser produced plasmas  

NASA Astrophysics Data System (ADS)

A program of research by UK universities and overseas collaborators at the SERC Central Laser Facility is directed to the development of XUV lasers based on recombining laser-produced plasmas. Laser amplification has been demonstrated for recombination to hydrogenic ions C VI and F IX with H-alpha laser amplification at 182 and 81 A respectively, and for lithiumlike ions. An initial study of Na-like Cu XIX has been made. Current work is looking for ways to improve the efficiency, increase the gain length and reduce the wavelength to reach the 44 A-edge of the water window.

Key, H. M.; Chenais-Popovics, C.; Carillon, A.; Corbett, R.; Edwards, J.

1988-01-01

130

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

131

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 is disclosed. 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. 8 figs.

Augustoni, A.L.; Gerardo, J.B.; Raymond, T.D.

1992-12-29

132

Use of an electron accelerator to produce nanopowders by evaporation of initial materials at atmospheric pressure  

NASA Astrophysics Data System (ADS)

High-purity nanodispersed powders with extraordinary properties that can be used in various technologies (electronics, catalysis, ceramics, modification of composite rheology, and so on) can be produced by evaporation of various initial materials at atmospheric pressure. In particular, the authors succeeded in producing nanodispersed powders of oxides [including silicon dioxide and oxide (SiO 2 and SiO) and magnesium (MgO), aluminum (Al 2 O 3), and cuprous (Cu 2 O) oxides], metals [including tantalum (Ta), molybdenum (Mo), aluminum (Al), silver (Ag), and some others] in various atmospheres, semiconductors [including silicon (Si)], nitrides [including aluminum (AlN) and titanium (TiN) nitrides], and other materials. It is important for the developed production process that the main component of the setup (an industrial accelerator) is capable of creating high temperatures for evaporation of any refractory materials. The production process has high efficiency and productivity (reaching several kilograms of oxides per hour).

Bardakhanov, S. P.; Korchagin, A. I.; Kuksanov, N. K.; Lavrukhin, A. V.; Salimov, R. A.; Fadeev, S. N.; Cherepkov, V. V.

2007-02-01

133

Energy Balance and Temperature in a Carbon Dioxide Laser Produced Plasma.  

NASA Astrophysics Data System (ADS)

The absorption of intense (LESSTHEQ)10('14) W/cm('2) CO(,2) laser radiation by an underdense plasma is investigated experimentally. The plasma is produced by the CO(,2) laser beam focussed onto a stabilized laminar gas jet emanating from a Laval nozzle. The electron temperature of the laser produced plasma is measured by soft x-ray diagnostics which yield a 300 eV thermal and a 2000 eV suprathermal temperature. Time resolved studies are made of the radial expansion of the plasma to determine the absorbed energy and temperature using a modified blast wave analysis that involves the identification of the Chapman-Jouguet detonation point in the expansion. The absorbed energy is also determined from Ulbricht sphere photometry. Information on the plasma dimensions and electron density is obtained by time resolved ruby laser interferometry. The electron temperature and absorbed energy measurements are used to corroborate one another and to provide a self -consistent picture of the laser plasma coupling. Although vacuum laser intensities are sufficiently high where saturation of collisional (inverse bremsstrahlung), absorption is expected to occur, the experimental evidence indicates that linear inverse bremsstrahlung accounts for the observed thermal electron temperature and measured level of absorption. The energy balance shows that there is a sufficient level of absorption to accommodate the measured thermal electron temperature as well as <15% of the electrons at a 2 keV suprathermal temperature.

Popil, Roman Ewhen

134

[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

135

Warm flux tubes in the E-ring plasma torus: Initial Cassini magnetometer observations  

Microsoft Academic Search

Initial Cassini magnetometer observations in the E-ring plasma torus reveal the presence of previously unreported diamagnetic decreases in the magnetic field. The decrease in magnetic pressure on these flux tubes implies the presence of additional plasma energy densities up to 1 keV\\/cm3. They are less stretched than surrounding flux tubes suggesting the centrifugal force acting on them is less, possibly

J. S. Leisner; C. T. Russell; K. K. Khurana; M. K. Dougherty; N. André

2005-01-01

136

Segmented thermal barrier coatings produced by atmospheric plasma spraying hollow powders  

Microsoft Academic Search

Segmented thermal barrier coatings were produced by plasma spraying hollow and solid ZrO2–8 wt.% Y2O3 powders. The solid powder (SP) had greater capability of producing segmentation cracks in coating compared with the hollow powder (HP). High substrate temperature (Ts) gave rise to an increased segmentation crack density (Ds). The segmentation crack network was still stable even after sintering at 1300

H. B. Guo; S. Kuroda; H. Murakami

2006-01-01

137

On the highly directional expansion of laser-produced plasmas. [metallic targets  

NASA Technical Reports Server (NTRS)

The expansion of plasmas produced by focusing a CO2 laser pulse onto solid planar targets is discussed. The plasmas are studied using an extreme-ultraviolet spectroheliograph. With titanium and iron targets the plasma blow-off observed in transitions within highly ionized species (e.g., Fe XVI) occurs parallel to the target normal. The plasma is tightly confined to narrow cylindrical structures about 0.7 mm in diameter and is observed as far as 1 cm from the target surface. The electron density is about 2.8 by 10 to the 18th power per cu cm at a distance of 0.7 mm from the target surface and decreases to approximately 6.5 by 10 to the 17th power per cu cm at a distance of 2.9 mm from the surface.

Doschek, G. A.; Feldman, U.; Burkhalter, P. G.; Finn, T.; Feibelman, W. A.

1977-01-01

138

Experimental Studies of Stimulated Brillouin Scattering from Krypton Fluoride Laser-Produced Plasma  

NASA Astrophysics Data System (ADS)

A comprehensive study of stimulated Brillouin scattering (SBS) in nanosecond KrF laser-produced plasma at intensity I_{rm L} ~eq 10^{14}W/cm^2 has been performed. Measurements of reflectivity and time -resolved backscattered spectra were done for CH, Al, and Au targets at various angles of incidence theta. The measured backscatter reflectivity ranged from 0.1% to 1.0% for Al and C plasma, with higher reflectivity being observed for larger theta. Au plasma showed significantly lower reflectivity ( ~eq0.005%). The time-resolved spectra of backscattered light were found to be correlated with laser intensity and pulse shape. Numerical codes developed to model the SBS process in homogeneous and inhomogeneous plasmas dominated by strong inverse bremsstrahlung absorption predicted an optimum density for SBS amplification. Two -dimensional hydrodynamic simulations predicted locally planar density and spherical pressure profiles as a consequence of the large mass ablation rate and localized plasma heating. Models for SBS in inhomogeneous plasma and non-uniform laser irradiation were proposed and used to explain the experimental data. Analytically and experimentally, we find evidence for the convective nature of the SBS instability. Supplementary experiments using thin foil targets showed strong temporal and spatial modulation in transmitted light. It was found that the laser beam non-uniformity was not smoothed out by the plasma but remained throughout the laser pulse.

Fujita, Masayuki

1992-01-01

139

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

140

Visual and Electrical Evidence Supporting a Two-Plasma Mechanism of Vacuum Breakdown Initiation  

SciTech Connect

The energy available during vacuum breakdown between copper electrodes at high vacuum was limited using resistors in series with the vacuum gap and arresting diodes. Surviving features observed with SEM in postmortem samples were tentatively correlated with electrical signals captured during breakdown using a Rogowski coil and a high-voltage probe. The visual and electrical evidence is consistent with the qualitative model of vacuum breakdown by unipolar arc formation by Schwirzke [1, 2]. The evidence paints a picture of two plasmas of different composition and scale being created during vacuum breakdown: an initial plasma made of degassed material from the metal surface, ignites a plasma made up of the electrode material.

Castano-Giraldo, C. [University of Illinois, Urbana-Champaign; Aghazarian, Maro [ORNL; Caughman, John B [ORNL; Ruzic, D. N. [University of Illinois, Urbana-Champaign

2012-01-01

141

Optimized method of producing washers of titanium hydride for plasma gun using occluded hydrogen gas  

Microsoft Academic Search

An optimized way of producing washers of titanium hydride for the application to a plasma gun using the occluded gas is presented. The amount of H2 gas (equivalently, gas pressure p) is entirely preadjusted in a gas reservoir of a simple instrument. The temperature T of a furnace is completely feedback controlled. Data show that when p is the order

H. Himura; Y. Saito; A. Sanpei; S. Masamune; N. Takeuchi; T. Shiono

2006-01-01

142

Time evolution of colliding laser produced magnesium plasmas investigated using a pinhole camera  

E-print Network

- pendent on irradiation conditions such as incident laser in- tensity, laser wavelength, irradiation spot and Thomson scattering.12 Fast photography and other imag- ing techniques add another dimension to ablation reports concern fast photography of laser produced plasmas at times 50 ns and in the visible spectral

Harilal, S. S.

143

Hard-x-ray radiation from short-pulse laser-produced plasmas  

Microsoft Academic Search

The generation of hard-x-ray radiation (???25 keV) from short-pulse Ti:sapphire laser-produced plasmas is studied. Solid targets are irradiated by 0.2–10 ps laser pulses in the intensity range of 5×1013?5×1016 W\\/cm2. It is shown that the measured dose rates obey a simple scaling law.

Boris N. Chichkov; Carsten Momma; Andreas Tünnermann; Susanne Meyer; Thomas Menzel; Bernd Wellegehausen

1996-01-01

144

Ion acoustic instability driven by a temperature gradient in laser-produced plasmas  

Microsoft Academic Search

The return current instability excited in laser-produced plasmas by a temperature gradient has been studied using a nonlocal theory of electron transport. The transport model is applicable for an arbitrary ratio of the temperature inhomogeneity scale length to the collisional mean free path. It is demonstrated that nonlocal thermal effects have a significant impact on the ion acoustic instability growth

A. V. Brantov; V. Yu. Bychenkov; W. Rozmus

2001-01-01

145

Electron energy transport in steep temperature gradients in laser-produced plasmas  

Microsoft Academic Search

The Fokker-Planck equation has been solved numerically in one spatial and two velocity dimensions in order to study thermal conduction in large temperature gradients occurring in laser-produced plasmas. The heat flow is an order of magnitude smaller than that predicted by the classical theory when the temperature scale length is a few electron mean free paths.

A. R. Bell; R. G. Evans; D. J. Nicholas

1981-01-01

146

Electron density and temperature measurements in a laser produced carbon plasma  

E-print Network

electron temperature and density at several sections located in front of the target surface. LineElectron density and temperature measurements in a laser produced carbon plasma S. S. Harilal, C. V intensities of successive ionization states of carbon were used for electron temperature calculations. Stark

Harilal, S. S.

147

Optimising hard X-ray generation from laser-produced plasmas.  

National Technical Information Service (NTIS)

The aim of this work is to increase the X-ray yield for a laser produced plasma by optimising the focusing conditions and temporal shape of the laser pulses. The focusing conditions are improved by introducing a control system that secures the laser targe...

C. Lindheimer

1995-01-01

148

Time-Resolved Analysis of High-Power-Laser Produced Plasma Expansion in Vacuum  

NASA Astrophysics Data System (ADS)

Here we consider the results of an experimental investigation of the temporal evolution of plasmas produced by high power laser irradiation of various types of target materials. The experiment was performed at the LULI Laboratory (Ecole Polytechnique, Paris). We have developed a method to analyze time-resolved streak-camera images and analyzed a number of results obtained with various materials.

Aliverdiev, A.; Batani, D.; Malka, V.; Vinci, T.; Koenig, M.; Benuzzi-Mounaix, A.; Dezulian, R.

2005-05-01

149

Grazing incidence reflectance of SiC films produced by plasma-assisted chemical vapor deposition  

NASA Technical Reports Server (NTRS)

The grazing incidence reflectance of silicon carbide films produced by plasma-assisted chemical vapor deposition has been evaluated in the spectral region from 256 to 1216 A. The results show that reflectivities higher than conventional coatings can be obtained on coatings deposited both on silicon wafers and quartz substrates. Potential application of silicon carbide films for EUV astronomical instruments will be discussed.

Keski-Kuha, Ritva A. M.; Osantowski, John F.; Toft, Albert R.; Partlow, William D.

1988-01-01

150

Comparison of optical emission from nanosecond and femtosecond laser produced plasma in atmosphere and vacuum conditions  

E-print Network

Comparison of optical emission from nanosecond and femtosecond laser produced plasma in atmosphere and atmosphere environments using identical laser fluences in order to better understand the differ- ences in an ambient atmosphere environment, the impact of low-pressure envi- ronments is also important for certain

Harilal, S. S.

151

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

152

The influence of target irradiation conditions on the parameters of laser-produced plasma jets  

SciTech Connect

Recent experimental results demonstrate that the forming of plasma jets is a fundamental process accompanying the laser-produced plasma expansion, if a massive planar target with relatively high atomic number is irradiated by a defocused laser beam. In this paper some new results on the influence of target irradiation conditions on plasma jet parameters are presented. The experiment was carried out at the Prague Asterix Laser System (PALS) iodine laser [K. Jungwirth, A. Cejnarova, L. Juha, B. Kralikova, J. Krasa, E. Krousky, P. Krupickova, L. Laska, K. Masek, A. Prag, O. Renner, K. Rohlena, B. Rus, J. Skala, P. Straka, and J. Ullschmied, Phys. Plasmas 8, 2495 (2001)]. with the third harmonic beam of the pulse duration of 250 ps. The beam energies varied in the range of 13-160 J. The planar massive targets used in the experiment were made of copper. For measurements of the electron density evolution a three frame interferometric system was employed. The jets were produced in the whole range of the laser energy used. Calculations of the efficiency of the plasma jet production show that it decreases with increasing the laser energy.

Kasperczuk, A.; Pisarczyk, T.; Borodziuk, S.; Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J.; Pisarczyk, P. [Institute of Plasma Physics and Laser Microfusion, 23 Hery Street, 00-908 Warsaw (Poland); Institute of Plasma Physics AS CR, Za Slovankou 3, 182 00 Prague 8 (Czech Republic); Institute of Physics AS CR, Na Slovance 2, 182 21 Prague 8 (Czech Republic); Warsaw University of Technology, ICS, 15/19 Nowowiejska St., 00-665 Warsaw (Poland)

2007-03-15

153

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

154

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

155

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

156

Effects of 2 mass % Si admixture in a laser-produced Fe plasma  

SciTech Connect

Emission of multiply charged ions and soft x-rays from the plasmas produced by laser pulses focused on (111) surface of Fe and Fe-2 mass % Si single crystals is investigated for wavelengths of 1064 and 248 nm and intensities up to {approx_equal}1x10{sup 10} W/cm{sup 2}. It is demonstrated that the Si admixture in the Fe plasma results in a higher emission of Fe{sup q+} ions (1{<=}q{<=}4) but in a markedly lower x-ray emission. The relation of wavelengths and pulse durations of laser beams used is figured in the fluence dependence of the ion emission.

Krasa, Josef; Laska, Leos; Rohlena, Karel; Velyhan, Andriy [Institute of Physics, ASCR, v.v.i., 182 21 Prague 8 (Czech Republic); Lorusso, Antonella; Nassisi, Vincenzo [Department of Physics of Lecce, Laboratorio di Elettronica Applicata e Strumentazione (LEAS), INFN of Lecce, 73100 Lecce (Italy); Czarnecka, Agata; Parys, Piotr; Ryc, Leszek; Wolowski, Jerzy [Institute of Plasma Physics and Laser Microfusion, EURATOM Association, 00-908 Warsaw (Poland)

2008-11-10

157

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

158

Optimum laser pulse duration for efficient extreme ultraviolet light generation from laser-produced tin plasmas  

SciTech Connect

Conversion efficiencies (CEs) from incident laser energy to 13.5 nm light within a 2% bandwidth were measured with changing laser pulse durations for laser-produced tin plasmas. Experimental results indicate that the optimum pulse duration is determined by two parameters: one is the optical depth of tin plasma for 13.5 nm light and the other is laser absorption rate in 13.5 nm emission-dominant region. The maximum CE of 2.2% is obtained with pulse duration of 2.3 ns.

Ando, Tsuyoshi; Fujioka, Shinsuke; Nishimura, Hiroaki; Ueda, Nobuyoshi; Yasuda, Yuzuri; Nagai, Keiji; Norimatsu, Takayoshi; Murakami, Masakatsu; Nishihara, Katsunobu; Miyanaga, Noriaki; Izawa, Yasukazu; Mima, Kunioki; Sunahara, Atsushi [Institute of Laser Engineering, Osaka University, 2-6 Yamada-Oka, Suita, Osaka 565-0871 (Japan); Institute for Laser Technology, 2-6 Yamada-Oka, Suita, Osaka 565-0871 (Japan)

2006-10-09

159

Kelvin-Helmholtz turbulence associated with collisionless shocks in laser produced plasmas.  

PubMed

We report the experimental results of a turbulent electric field driven by Kelvin-Helmholtz instability associated with laser produced collisionless shock waves. By irradiating an aluminum double plane target with a high-power laser, counterstreaming plasma flows are generated. As the consequence of the two plasma interactions, two shock waves and the contact surface are excited. The shock electric field and transverse modulation of the contact surface are observed by proton radiography. Performing hydrodynamic simulations, we reproduce the time evolutions of the reverse shocks and the transverse modulation driven by Kelvin-Helmholtz instability. PMID:23003052

Kuramitsu, Y; Sakawa, Y; Dono, S; Gregory, C D; Pikuz, S A; Loupias, B; Koenig, M; Waugh, J N; Woolsey, N; Morita, T; Moritaka, T; Sano, T; Matsumoto, Y; Mizuta, A; Ohnishi, N; Takabe, H

2012-05-11

160

Plasma-wall interaction studies with optimized laser-produced jets  

SciTech Connect

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{gamma} profiles emitted from Al/Si(PMMA) targets indicate charge exchange between the Al XIII and fully stripped C ions.

Renner, O.; Krousky, E.; Smid, M. [Institute of Physics ASCR, 18221 Prague (Czech Republic); Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z. [Institute of Plasma Physics and Laser Microfusion, 01-497 Warsaw (Poland); Pisarczyk, P. [Warsaw University of Technology, ICS, 00-665 Warsaw (Poland); Ullschmied, J. [Institute of Plasma Physics ASCR, 18200 Prague 8 (Czech Republic); Dalimier, E. [Sorbonne Universites, Pierre et Marie Curie, UMR 7605, LULI, 75252 Paris (France)

2011-09-15

161

Investigation of a Gas Jet-Produced Hollow Plasma Wakefield Accelerator  

SciTech Connect

The effect of ion motion and the need for practical positron propagation in a plasma wakefield accelerator (PWFA) have incited interest in hollow plasma channels. These channels are typically assumed to be cylindrically symmetric; however, a different geometry might be easier to achieve. The introduction of an obstruction into the outlet of a high Mach number gas jet can produce two parallel slabs of gas separated by a density depression. Here, there is a detailed simulation study of the density depression created in such a system. This investigation reveals that the density depression is insufficient at the desired plasma density. However, insights from the simulations suggest another avenue for the creation of the hollow slab geometry.

Kirby, N; Blumenfeld, I.; Hogan, M.J.; Siemann, R.H.; Walz, D.R.; /SLAC; Davidson, A.W.; Huang, C.; /UCLA

2009-05-21

162

Energy balance and temperature in a CO2-laser-produced plasma  

NASA Astrophysics Data System (ADS)

An underdense CO2-laser-produced plasma is experimentally investigated to determine the electron temperature explained in terms of an energy balance. Soft x-ray measurements show a 300 eV thermal and a 2000 eV suprathermal temperature. Ulbricht integrating sphere measurements along with interferometric data for the electron density indicate sufficient laser energy absorption to attain Te of the order of 600 eV. A novel method of analysis of streak records of the radial expansion is implemented where the conditions of a Chapman-Jouguet detonation wave are applied to allow an independent determination of the thermal plasma temperature and absorbed energy. The observed thermal Te is found to be consistent with linear inverse bremsstrahlung absorption using the measured degree of absorption provided by the Ulbricht sphere. The suprathermal temperature can be ascribed to be the result of the parametric processes in the plasma which are known to occur.

Popil, R.; Meyer, J.; Ahlborn, B.

1984-11-01

163

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

164

Momentum transfer interaction of a laser-produced plasma with a low-pressure background.  

NASA Technical Reports Server (NTRS)

The expansion of a laser-produced metallic plasma into a photoionized hydrogen background has been experimentally studied. Langmuir probe and microwave diagnostics have detected an interaction front which decelerates with a dependence on background density and time consistent with a momentum coupling between the laser plasma and the ionized fraction of the background. An ion percursor has also been observed. Calculations of scattering cross sections indicate that multiple-encounter Coulomb scattering will dominate collisional momentum transfer. The leading edge of the laser plasma contains multiply charged ions of charge state z greater than or equal to 5, and collisional effects appear adequate to explain the principal features of the momentum coupling. The ion precursor may have a collisionless origin.

Koopman, D. W.

1972-01-01

165

High-order harmonic generation from laser plasma produced by pulses of different duration  

SciTech Connect

The high-order harmonic generation was analyzed by interaction of the femtosecond pulses with the laser plasma produced on the surfaces of various targets. The plasma formation was accomplished by the interaction of the prepulse radiation of different pulse duration (160 fs, 1.5 ps, 210 ps, and 20 ns) with the low-Z (lithium, boron, carbon), medium-Z (manganese, zinc, nickel), and high-Z (silver, barium) targets. We showed that plasma formation conditions play a crucial role in harmonic generation and the optimization of this process mostly depends on the energy of prepulse rather than its intensity at the target surface. These studies also demonstrated that the delay between the prepulse and femtosecond pulse is another important parameter, which distinguishes harmonic generation in the cases of the low- and high-Z targets.

Ganeev, R. A. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Scientific Association Akadempribor, Academy of Sciences of Uzbekistan, Akademgorodok, Tashkent 700125 (Uzbekistan); Suzuki, M.; Baba, M.; Kuroda, H. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

2007-08-15

166

Initial planning for interferometry measurements on triggered plasma opening switch source.  

SciTech Connect

The Triggered Plasma Opening Switch (TPOS) at SNL is a unique device that exploits the high conductivity and low mass properties of plasma. The TPOS's objective is to take the initial {approx}0.8 MA ({approx}250 ns rise time) storage inductor current and deliver {approx}0.5 MA at {approx}2.4 MV ({approx}10 ns rise time) to a load of {approx}5-10 Omega. Configuration advantages include low current jitter and resistive voltage drop, power gain, and minimization of trigger input power as the result of using two stages in series. This two-stage design is novel and is the first to demonstrate operation of magnetically triggered stages. Study of TPOS characteristics is in progress via an offline interferometer diagnostic; specifically, a laser interferometer will be used to make density measurements of the source plasma. It is thought that the gross plasma source density is {approx}10{sup 14} cm{sup -3}, but details of the spatial structure and temporal evolution have not previously been studied. In order to better understand switch operation, these details are essential. Presently two interferometer systems are planned for testing: a temporary 1 mum system for initial plasma characterization, and a 10.6 mum laser system for routine use. We will start with a single chord measurement then upgrade to a multi-chord system. Future plans involve varying plasma source parameters, such as magnetic field strength and plasma fill time, in order to understand the density dependence on these parameters. Improved knowledge of the plasma source density behavior should allow for improved switch operation.

Lynn, Alan G. (University of New Mexico Albuquerque NM); Jackson, Daniel Peter Jr. (University of New Mexico Albuquerque NM); Savage, Mark Edward; Sharpe, Rob A.; Gilmore, Mark A. (University of New Mexico Albuquerque NM)

2005-06-01

167

Comparison of plasma-sprayed coatings produced in argon or nitrogen atmosphere  

NASA Astrophysics Data System (ADS)

When spraying is conducted at ambient atmosphere, the entrainment of air cools the plasma jet and affects its expansion. It can also cause oxidation or chemical decomposition of the sprayed materials. Inert plasma spraying (IPS), generally conducted in an argon atmosphere, prevents these phenomena. However, the main drawbacks of IPS in comparison with air plasma spraying are the capital and operating costs. This paper presents a study in which nitrogen is used as a substitute for conventional argon atmosphere, thus reducing costs by 25 to 30%. Titanium carbide and niobium powders were sprayed in both argon and nitrogen atmospheres. Cryogenic cooling of the substrate was used during the spray process. This helps to maintain a low temperature in the chamber, produce thick coatings, and allows the use of substrate materials that are sensitive to heat. The velocity, temperature, and composition fields of the argon-hydrogen plasma jet flowing in argon or nitrogen at atmospheric pressure are compared from numerical simulation. The adhesion, roughness, and microstructure of the niobium and TiC coatings produced in both atmospheres are discussed as well as their nitrogen content.

Leylavergne, M.; Vardelle, A.; Dussoubs, B.; Goubot, N.

1998-12-01

168

Astrophysics of magnetically collimated jets generated from laser-produced plasmas.  

PubMed

The generation of astrophysically relevant jets, from magnetically collimated, laser-produced plasmas, is investigated through three-dimensional, magnetohydrodynamic simulations. We show that for laser intensities I?10(12)-10(14)?W?cm(-2), a magnetic field in excess of ?0.1??MG, can collimate the plasma plume into a prolate cavity bounded by a shock envelope with a standing conical shock at its tip, which recollimates the flow into a supermagnetosonic jet beam. This mechanism is equivalent to astrophysical models of hydrodynamic inertial collimation, where an isotropic wind is focused into a jet by a confining circumstellar toruslike envelope. The results suggest an alternative mechanism for a large-scale magnetic field to produce jets from wide-angle winds. PMID:23383908

Ciardi, A; Vinci, T; Fuchs, J; Albertazzi, B; Riconda, C; Pépin, H; Portugall, O

2013-01-11

169

Design and operation of the electrogun, and electrothermal gun for producing metal and carbon plasma jets  

SciTech Connect

The electrogun is a type of electrothermal gun especially modified to produce metal and carbon plasma jets. These jets are capable of deep penetration into room temperature, atmospheric-pressure gases, so that the plasma composing the jet is vigorously mixed into an excess of cold gas. Reaction products are rapidly quenched and form a room-temperature gas suspension of nanoparticles which gradually settles to the reactor floor. These unusual and extreme conditions are ideal for the production of novel materials, especially novel nanostructured materials. An electrogun with a prestressed ceramic barrel has been tested and found to work well if certain simple rules are followed. Seal failure wastes material and precipitates destructive internal short circuits, so particular care must be paid to seal design. Seams to be sealed must be preloaded tightly together to prevent seam separation. The operating characteristics of titanium, aluminum, and carbon plasma have been measured. Operating with carbon plasma presents special difficulties. Graphite cathodes tend to fracture if overheated. Carbon plasma is prone to contamination by vaporized metal and by vaporized ceramic extracted from the bore.

Peterson, D.R. [Univ. of Texas, Austin, TX (United States). Inst. for Advanced Technology] [Univ. of Texas, Austin, TX (United States). Inst. for Advanced Technology

1997-01-01

170

Characterization of High-Temperature Laser-Produced Plasmas Using Thomson Scattering  

SciTech Connect

Ultraviolet Thomson scattering has been fielded at the Omega Laser Facility to achieve accurate measurements of the plasma conditions in laser-produced high-temperature plasmas. Recent applications to hohlraum targets that have been filled with CH gas or SiO{sub 2} foams have demonstrated a new high temperature plasma regime of importance to laser-plasma interaction studies in a strongly damped regime such as those occurring in indirect drive inertial confinement fusion experiments. The Thomson scattering spectra show the collective ion acoustic features that fit the theory for two ion species plasmas and from which we infer the electron and ion temperature. We find that the electron temperature scales from 2-4 keV when increasing the heater beam energy into the hohlraum from 8-17 kJ, respectively. Simultaneous measurements of the stimulated Raman scattering from a green 527 nm interaction beam show that the reflectivity decreases from 20% to 1% indicating that this instability is strongly damped at high temperatures. These findings support green laser beams as possible driver option for laser-driven fusion experiments.

Glenzer, S H; Froula, D H; Ross, S; Niemann, C; Meezan, N; Divol, L

2005-09-16

171

Enhancement of x-ray line emission from plasmas produced by short high-intensity laser double pulses  

E-print Network

Enhancement of x-ray line emission from plasmas produced by short high-intensity laser double laser-produced plasmas are bright ultrafast line x-ray sources potentially suitable for different onto a solid target into the x-ray emission is significantly enhanced when a laser prepulse precedes

Limpouch, Jiri

172

Study of angular dependences of ion component parameters in CO2-laser-produced plasma  

Microsoft Academic Search

CO2-laser-produced plasma ion component parameters were studied for aluminium and lead targets at laser intensity of P = 4×1013 W cm-2 and pulse duration of tau = 15 ns experimentally and numerically. Angular dependences of ion number density for different charge states, average velocity and its spread were measured by time-of-flight method. Ion charge state distribution shows high-charge and low-charge

A. E. Stepanov; Yu A. Satov; K. N. Makarov; V. C. Roerich; Yu B. Smakovskiy; D. D. Maluta; A. N. Starostin

2003-01-01

173

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

174

Formation of x-ray line emission spectra of excimer-laser-produced plasmas  

Microsoft Academic Search

Time and space-integrated emission spectra in the 748 eV to 1245 eV photon energy region have been measured in plasma produced by 308 nm wavelength XeCl laser radiation (IL = (4-10) × 1012 W\\/cm2, tau = 10 ns) and by 248 nm wavelength KrF laser pulse train radiation (IL = 5 × 1015 W\\/cm2, tau = 7 ps, 16 pulses

A. I. Magunov; A. Ya Faenov; I. Yu Skobelev; T. A. Pikuz; D. Batani; M. Milani; A. Conti; A. Masini; M. Costato; A. Pozzi; E. Turcu; R. Allot; N. Lisi; M. Koenig; A. Benuzzi; F. Flora; T. Letardi; L. Palladino; A. Reale

1997-01-01

175

X-ray spectral line shapes for the excimer-laser-produced high density plasma diagnostics  

Microsoft Academic Search

The time and space-integrated emission spectra measurements have been performed in plasma produced by 308 nm wavelength XeCl laser radiation (IL=(4-10).1012 W\\/cm2, tau=10 ns) and by 248 nm wavelength KrF laser pulse train radiation IL=5.1015 W\\/cm2, tau=7 ps, 16 pulses in train) on (CFn plane target. The lines' shapes and intensities modeling of Lyman series and He-like ion resonance series

A. Magunov; A. Faenov; I. Skobelev; T. Pikuz; D. Batani; M. Milani; A. Conti; A. Masini; M. Costato; A. Pozzi; E. Turcu; R. Allot; N. Lisi; M. Koenig; A. Benuzzi; F. Flora; T. Letardi; L. Palladino; A. Reale

1997-01-01

176

The development of a Krook model for nonlocal transport in laser produced plasmas. I. Basic theory  

SciTech Connect

This paper examines the Krook model as a means of quantifying the problem of nonlocal transport of electron energy in laser produced plasmas. The result is an expression for the nonlocal electron energy flux q. The roles of both flux limitation and preheat are clearly delineated. Furthermore, it develops a test for the validity of this model. This is a physics based, 'first principles' model that can be economically incorporated into a fluid simulation.

Manheimer, Wallace; Colombant, Denis [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20785 (United States); Goncharov, Valeri [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

2008-08-15

177

Dynamics of high-Z plasmas produced by a short-wavelength laser  

Microsoft Academic Search

The dynamics and energy flow in Au plasmas produced by a 0.35-mum laser have been studied with layered targets with 6- and 24-beam spherical illumination from the Omega laser, to understand the processes leading to sub-keV x-ray emission. A significant enhancement in x-ray conversion at low intensities is observed for the 24-beam irradiations with higher energy, greater uniformity, and larger

P. D. Goldstone; S. R. Goldman; W. C. Mead; J. A. Cobble; G. Stradling; R. H. Day; A. Hauer; M. C. Richardson; R. S. Marjoribanks; P. A. Jaanimagi; R. L. Keck; F. J. Marshall; W. Seka; O. Barnouin; B. Yaakobi; S. A. Letzring

1987-01-01

178

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

179

Proton radiography of dynamic electric and magnetic fields in laser-produced high-energy-density plasmas  

SciTech Connect

Time-gated, monoenergetic-proton radiography provides unique measurements of the electric (E) and magnetic (B) fields produced in laser-foil interactions and during the implosion of inertial-confinement-fusion capsules. These experiments resulted in the first observations of several new and important features: (1) observations of the generation, decay dynamics, and instabilities of megagauss B fields in laser-driven planar plastic foils, (2) the observation of radial E fields inside an imploding capsule, which are initially directed inward, reverse direction during deceleration, and are likely related to the evolution of the electron pressure gradient, and (3) the observation of many radial filaments with complex electromagnetic field striations in the expanding coronal plasmas surrounding the capsule. The physics behind and implications of such observed fields are discussed.

Li, C. K.; Seguin, F. H.; Frenje, J. A.; Manuel, M.; Casey, D.; Sinenian, N.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Amendt, P. A.; Landen, O. L.; Rygg, J. R.; Town, R. P. J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Betti, R.; Meyerhofer, D. D. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Department of Mechanical Engineering, Physics and Astronomy, University of Rochester, Rochester, New York 14623 (United States); Delettrez, J.; Knauer, J. P.; Marshall, F.; Sangster, T. C.; Smalyuk, V. A.; Soures, J. M. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Shvarts, D. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); NRCN, Negev and Ben Gurion University of the Negev, Beer-Sheva 84015 (Israel)] (and others)

2009-05-15

180

Evolution of Hot Plasma in Magnetar Magnetospheres and its Implications for Initial Spikes of Giant Flares  

NASA Astrophysics Data System (ADS)

In this presentation, we discuss a new mechanism describing the initial spike of magnetar giant flares. We performed one-dimensional numerical simulations of the relativistic magnetohydrodynamics in Schwarzschild geometry, and investigated the evolution of a plasma on a closed magnetic flux tube in a magnetar magnetosphere in the case of a sudden energy release. We assume energy is injected at the footpoints of the loop by a hot star surface containing random perturbations of the transverse velocity. This random motion generates Alfvén waves propagating upward, accompanying very hot plasma that is also continuously heated by nonlinearly generated compressive waves. We found that the front edges of the fireball regions collide at the top of the tube with their symmetrically launched counterparts, and this results in an enormous energy release. We also discuss the relation between this energy release and the light curve of initial spikes of giant flares.

Takamoto, Makoto; Terasawa, Toshio; Kisaka, Shota; Suzuki, Takeru

181

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

182

Initial results from the ISEE-1 and -2 plasma wave investigation  

Microsoft Academic Search

In this paper we present an initial survey of results from the plasma wave experiments on the ISEE-1 and -2 spacecraft which are in nearly identical orbits passing through the Earth's magnetosphere at radial distances out to about 22.5Re. Essentially every crossing of the Earth's bow shock can be associated with an intense burst of electrostatic and whistler-mode turbulence at

D. A. Gurnett; R. R. Anderson; F. L. Scarf; R. W. Fredricks; E. J. Smith

1979-01-01

183

Two-dimensional simulations of the population inversion in recombining laser-produced plasma  

SciTech Connect

Simulations of gain in recombining laser-produced plasma of Li-like ions of aluminum were performed using the 2-D code GIDRA-2. Symmetrical 4-beam scheme of fiber irradiation was modeled in accordance with experimental arrangement described in Ref. (1). These simulations show good agreement with earlier 1-D simulations for optically thin plasma. Maximal angle-averaged value of gain on 3d{sub 5/2}-4f{sub 7/2} transition in Li-like aluminum calculated using Sobolev approximation for photon escape probability and the Doppler line profile was 0.95 cm{sup -1}. These 2-D simulations also show more realistic laser energy absorption (25-30% in 2-D simulations compared to nearly 90% in 1-D simulations and 6% in experiments)

Roerich, V. C.; Starostin, A. N.; Stepanov, A. E. [Troitsk Institute for Innovation and Fusion Research, Troitsk, Moscow region, 142092 (Russian Federation)

1997-04-15

184

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

185

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

186

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

PubMed

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(15)?W/cm(2). The instrument demonstrated a resolving power of ?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. PMID:21034016

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

2010-10-01

187

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

NASA Astrophysics Data System (ADS)

A 2400 lines/mm variable-spaced grating spectrometer has been used to measure soft x-ray emission (8-22 Å) 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 1015 W/cm2. The instrument demonstrated a resolving power of ˜120 at 19 Å 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.; 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.

2010-10-01

188

In-package nonthermal plasma degradation of pesticides on fresh produce.  

PubMed

In-package nonthermal plasma (NTP) technology is a novel technology for the decontamination of foods and biological materials. This study presents the first report on the potential of the technology for the degradation of pesticide residues on fresh produce. A cocktail of pesticides, namely azoxystrobin, cyprodinil, fludioxonil and pyriproxyfen was tested on strawberries. The concentrations of these pesticides were monitored in priori and post-plasma treatment using GC-MS/MS. An applied voltage and time dependent degradation of the pesticides was observed for treatment voltages of 60, 70 and 80 kV and treatment durations ranging from 1 to 5 min, followed by 24h in-pack storage. The electrical characterisation revealed the operation of the discharge in a stable filamentary regime. The discharge was found to generate reactive oxygen and excited nitrogen species as observed by optical emission spectroscopy. PMID:24598029

Misra, N N; Pankaj, S K; Walsh, Tony; O'Regan, Finbarr; Bourke, Paula; Cullen, P J

2014-04-30

189

Discovery of Jet Quenching at RHIC and the Opacity of the Produced Gluon Plasma  

E-print Network

The predicted quenching of jets in A+A at RHIC energies has been discovered by STAR and PHENIX in preliminary data reported at this conference. We apply the GLV theory of QCD radiative energy loss to estimate the opacity, L/\\lambda_g, of the gluon plasma produced in Au+Au collisions at 130 AGeV. We show that (in contrast to the factor of two Cronin enhancement of \\pi^0 found at the SPS by WA98) the factor of 5-8 suppression of p_T \\sim 2-4 GeV \\pi^0 reported by PHENIX can be accounted for with an effective static plasma opacity L/\\lambda_g \\approx 3-4.

P. Levai; G. Papp; G. Fai; M. Gyulassy; G. G. Barnafoldi; I. Vitev; Y. Zhang

2001-04-10

190

Initial operation of the tangential x-ray pinhole camera system for KSTAR plasma  

NASA Astrophysics Data System (ADS)

The tangential soft x-ray pinhole camera (TXPC), which is a fast, two-dimensional (2-D), soft x-ray imaging system with a toroidal view, has been developed for studying MHD activities and transport in KSTAR plasmas. It consists of 50x50 channels multi-wire proportional counter (MWPC) filled with a gas mixture of 78% Kr, 20% C2H6, and 2% CF4 at atmospheric pressure. It can measure 2-D x-ray emissivity with a high and controllable intrinsic gain (> 10^4), high spatial (< 2 cm) and high temporal (> 100 kHz) resolution with a 100 MHz DAQ system. They can assist analysis of plasma profile, MHD modes, localization and effects of auxiliary heating and transport phenomena from core to edge. Also, the TXPC employs a duplex multi-wire proportional x-ray (DMPX) detector that combines two MWPCs in series. It will provide simultaneous measurements of plasma x-ray emission in two spectral ranges using the first MWPC as an absorber filter for the second one. The signals of the first and the second MWPC allow providing the fast 2-D measurement of the plasma electron temperature. The TXPC system is installed on KSTAR in 2011, and initial plasma data and an assessment of the system performance are presented.

Jang, Siwon; Lee, S. G.; Moon, M. K.; Lim, C. H.; Lee, S. H.; Choe, Wonho

2011-11-01

191

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

192

Initial results of parallel-plate plasma opening switch experiments on HAWK  

SciTech Connect

Results of parallel-plate plasma opening switch (POS) experiments on HAWK are presented. The Hawk generator produces a sinusoidal output current of amplitude {approximately}750 kA and quarter period {approximately} 1.2 {micro}s. The POS used is a tri-plate with a single cathode and two anode plates, each 15 cm wide. The plasma is injected from plasma guns through slots in the anodes. This POS performs almost as well as a comparable coaxial POS for short-circuit load shots with conduction times less than 700 ns. The parallel plate geometry provides much better diagnostic access than the standard coaxial POS. Framing camera images of the plasma imply that the current snow plows until it reaches the end of the injected plasma and opens near the cathode. A two-color laser interferometer is used to measure the electron and neutral densities of the plasma in the switch and in the magnetically insulated transmission line (MITL) between the switch and load integrated along chords in the {theta}-like direction. The electron density measured in the injected plasma region rises sharply during conduction and falls rapidly near the time of opening consistent with a snowplow traveling through the injection region. About 1 {micro}s after the switch opens, the density drops to near zero. A multi-chord He-Ne interferometer is used to measure the electron density integrated along several chords in the {theta}-like direction with different r-like positions. The density measurements are compared to framing camera images and models of POS operation.

Riley, R.A.; Weber, B.V.; Commisso, R.J. [Naval Research Lab., Washington, DC (United States). Plasma Physics Div.; Goodrich, P.J.; Hinshelwood, D.D. [JAYCOR, Inc., Vienna, VA (United States)

1995-12-31

193

Cylindrical stationary striations in surface wave produced plasma columns of argon  

SciTech Connect

Striations are a good example of manifestation of a glow discharge. In the present investigation, stationary striations in the surface wave produced plasma column are formed. Physical parameters (length, number, etc.) of such striations can be controlled by operating parameters. With the help of bifurcation theory, experimental results are explained by considering two-step ionization in the surface wave discharge mechanism in argon gas. It is also observed that the bifurcation parameter is a function of input power, working pressure, and tube radius.

Kumar, Rajneesh; Kulkarni, Sanjay V.; Bora, Dhiraj [Institute for Plasma Research, Bhat, Gandhinagar-382428 (India)

2007-12-15

194

Excimer laser produced plasmas in copper wire targets and water droplets  

NASA Technical Reports Server (NTRS)

Elastically scattered incident radiation (ESIR) from a copper wire target illuminated by a KrF laser pulse at lambda = 248 nm shows a dinstinct two-peak structure which is dependent on the incident energy. The time required to reach the critical electron density (n(sub c) approximately = 1.8 x 10(exp 22) electrons/cu cm) is estimated at 11 ns based on experimental results. Detailed ESIR characteristics for water have been reported previously by the authors. Initiation of the broadband emission for copper plasma begins at 6.5 +/- 1.45 ns after the arrival of the laser pulse. However, the broadband emission occurs at 11 +/- 0.36 ns for water. For a diatomic substance such as water, the electron energy rapidly dissipates due to dissociation of water molecules, which is absent in a monatomic species such as copper. When the energy falls below the excitation energy of the lowest electron state for water, it becomes a subexcitation electron. Lifetimes of the subexcited electrons to the vibrational states are estimated to be of the order of 10(exp -9) s. In addition, the ionization potential of copper (440-530 nm) is approximately 6 eV, which is about two times smaller than the 13 eV ionization potential reported for water. The higher ionization potential contributes to the longer observed delay time for plasma formation in water. After initiation, a longer time is required for copper plasma to reach its peak value. This time delay in reaching the maximum intensity is attributed to the energy loss during the interband transition in copper.

Song, Kyo-Dong; Alexander, D. R.

1994-01-01

195

Atmospheric cold plasma inactivation of Escherichia coli, Salmonella enterica serovar Typhimurium and Listeria monocytogenes inoculated on fresh produce.  

PubMed

Atmospheric cold plasma (ACP) represents a potential alternative to traditional methods for non-thermal decontamination of foods. In this study, the antimicrobial efficacy of a novel dielectric barrier discharge ACP device against Escherichia coli, Salmonella enterica Typhimurium and Listeria monocytogenes inoculated on cherry tomatoes and strawberries, was examined. Bacteria were spot inoculated on the produce surface, air dried and sealed inside a rigid polypropylene container. Samples were indirectly exposed (i.e. placed outside plasma discharge) to a high voltage (70 kVRMS) air ACP and subsequently stored at room temperature for 24 h. ACP treatment for 10, 60 and 120 s resulted in reduction of Salmonella, E. coli and L. monocytogenes populations on tomato to undetectable levels from initial populations of 3.1, 6.3, and 6.7 log10 CFU/sample, respectively. However, an extended ACP treatment time was necessary to reduce bacterial populations attached on the more complex surface of strawberries. Treatment time for 300 s resulted in reduction of E. coli, Salmonella and L. monocytogenes populations by 3.5, 3.8 and 4.2 log10 CFU/sample, respectively, and also effectively reduced the background microflora of tomatoes. PMID:24929725

Ziuzina, D; Patil, S; Cullen, P J; Keener, K M; Bourke, P

2014-09-01

196

Spectral line decomposition and frequency shifts in Al He? group emission from laser-produced plasma  

NASA Astrophysics Data System (ADS)

Precise spectroscopic observations of K-shell emission from highly stripped Al ions immersed in dense, constrained-flow laser-produced plasma is reported. By using a vertical dispersion Johann spectrometer, the time-integrated spectra of the Al He? group were measured with a high spectral and spatial resolution. The complex spectral profiles modified by the satellite formation, line broadening and frequency shifts were decomposed into individual pseudo-Voigt components by using a code GASPED based on a problem-dependent genetic algorithm. The method uses eight operators tailored to the problem of spectral decomposition and variable-size genomes to fit the data with a varying number of spectral lines. The spectra fitting was based on anticipatory theoretical knowledge of the satellite structure simulated by the multilevel collisional-radiative code MARIA and on an assumption of the aggregate plasma-induced shift of the parent lines and their satellites. The analysis of the spectral profiles revealed systematic red shifts of the resonance and the intercombination lines. Their magnitude is commensurate with predictions of the atomic data and spectral line shape codes combined with the 1D hydrodynamic modeling of the plasma conditions and independent electron density measurements. The results obtained corroborate the feasibility of an accurate decomposition of the spectral profiles encompassing optically thick and thin lines overlapped by a strong satellite emission.

Renner, O.; Adámek, P.; Angelo, P.; Dalimier, E.; Förster, E.; Krousky, E.; Rosmej, F. B.; Schott, R.

2006-05-01

197

Emission dynamics of an expanding ultrafast-laser produced Zn plasma under different ambient pressures  

SciTech Connect

We report time and space resolved spectral measurements of neutral Zn emission from an ultrafast laser produced plasma, generated by the irradiation of a Zn target with laser pulses of 100 femtoseconds duration, carried out in a broad ambient pressure range of 0.05 to 100 Torr. The measurement is done for three different axial positions in the expanding plume. The spectra are rich in neutral Zn (Zn I) emissions at 334.5 nm, 468 nm, 472 nm, 481 nm, and 636 nm, respectively, depicting the characteristic triplet structure of Zn. Fast as well as slow peaks are observed in the time of flight data of 481 nm emission, which arise from recombination and atomic contributions, respectively, occurring at different time scales. Average speeds of the fast atomic species do not change appreciably with ambient pressure. The plasma parameters (electron temperature and number density) are evaluated from the measured optical emission spectra. The rates of ionization and recombination can be enhanced by a double-pulse excitation configuration in which optical energy is coupled to the ultrafast plasma through a delayed laser pulse.

Smijesh, N.; Philip, Reji [Raman Research Institute, C.V. Raman Avenue, Sadashivanagar, Bangalore 560080 (India)] [Raman Research Institute, C.V. Raman Avenue, Sadashivanagar, Bangalore 560080 (India)

2013-09-07

198

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

199

Magnetic enhancement of thermal conductivity in coppercarbon nanotube composites produced by electroless plating, freeze drying, and spark plasma sintering  

E-print Network

Available online 9 April 2012 Keywords: Magnetic Carbon nanotube Spark plasma sintering Thermal conductivityMagnetic enhancement of thermal conductivity in copper­carbon nanotube composites produced by electroless plating, freeze drying, and spark plasma sintering Evan Khaleghi a, , Milton Torikachvili b , Marc

Meyers, Marc A.

200

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

E-print Network

bubbles using Thomson scattering and proton radiography M. J. Rosenberg,1,* J. S. Ross,2 C. K. Li,1 R. P-produced plasma bubbles or the interaction of bubble pairs, where reconnection of azimuthal magnetic fields occurs. Measurements of ion and electron temperatures agree with LASNEX simulations of single plasma bubbles, which

201

Investigation of the laser-induced plasma produced in a gas-filled chamber and in a gas jet  

Microsoft Academic Search

In the current study, characteristics of the laser-induced plasma were investigated in a gas filled chamber or in a gas jet by using a relatively low intensity laser (I <= 5 x 1012 W\\/cm2). Temporal evolutions of the produced plasma were measured using the shadow visualization and the shock wave propagation as well as the electron density profiles in the

Jong-Uk Kim; Gaung-Hoon Kim; Hyyong Suk

2003-01-01

202

Initiation of atomic layer deposition of metal oxides on polymer substrates by water plasma pretreatment  

SciTech Connect

The role of surface hydroxyl content in atomic layer deposition (ALD) of aluminum oxide (AO) on polymers is demonstrated by performing an atomic layer deposition of AO onto a variety of polymer types, before and after pretreatment in a plasma struck in water vapor. The treatment and deposition reactions are performed in situ in a high vacuum chamber that is interfaced to an x-ray photoelectron spectrometer to prevent adventitious exposure to atmospheric contaminants. X-ray photoelectron spectroscopy is used to follow the surface chemistries of the polymers, including theformation of surface hydroxyls and subsequent growth of AO by ALD. Using dimethyl aluminum isopropoxide and water as reactants, ALD is obtained for water-plasma-treated poly(styrene) (PS), poly(propylene) (PP), poly(vinyl alcohol) (PVA), and poly(ethylene naphthalate) (PEN). For PS, PP, and PEN, initial growth rates of AO on the native (untreated) polymers are at least an order of magnitude lower than on the same polymer surface following the plasma treatment. By contrast, native PVA is shown to initiate ALD of AO as a result of the presence of intrinsic surface hydroxyls that are derived from the repeat unit of this polymer.

Steven Brandt, E.; Grace, Jeremy M. [Eastman Kodak Company, 1999 Lake Avenue, Rochester, New York 14650-2022 (United States)

2012-01-15

203

Efficacy of experimentally produced spray-dried plasma on infectivity of porcine circovirus type 2.  

PubMed

The value of incorporating spray-dried plasma (SDP) into the diet of weanling pigs to improve feed intake and growth performance has been well documented. However, limited work has been done to confirm that the spray-drying process eliminates all viral contaminates including porcine circovirus type 2 (PCV2). To determine the effect of spray-drying on PCV2 infectivity, colostrum-fed, crossbred, specific-pathogen-free (SPF) pigs were inoculated with PCV2-contaminated SDP intraperitoneally (SDP-IP) or by oral gavage (SDP-OG), inoculated intraperitoneally with PCV2-positive plasma (POS), or left uninoculated (NEG). The plasma used for the experimentally produced SDP was collected from a SPF pig experimentally infected with a PCV2b isolate. Pigs in the NEG group remained seronegative, and PCV2 viremia was not detected. All pigs in the POS group became PCV2 viremic by 14 d postinoculation (DPI) and seroconverted by 28 DPI. In the SDP-IP group, all pigs became viremic by 35 DPI and seroconverted by 49 DPI. In the SDP-OG group, all animals became viremic by 35 DPI and 2/3 pigs seroconverted by 35 DPI. There were no significant (P > 0.05) differences between anti-PCV2-IgG antibody sample-to-positive ratios among pigs in the POS, SDP-OG, or SDP-IP groups. This work provides direct evidence that the experimental spray-drying process used in this study was not effective in inactivating PCV2b in the plasma of a PCV2-infected pig based on a swine bioassay using PCV2-naïve pigs. This work suggests that SDP sourced from pigs could represent a biosecurity risk for the industry. PMID:20675601

Patterson, A R; Madson, D M; Opriessnig, T

2010-12-01

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

Specific aquaporins facilitate Nox-produced hydrogen peroxide transport through plasma membrane in leukaemia cells.  

PubMed

In the last decade, the generation and the role of reactive oxygen species (ROS), particularly hydrogen peroxide, in cell signalling transduction pathways have been intensively studied, and it is now clear that an increase of ROS level affects cellular growth and proliferation pathways related to cancer development. Hydrogen peroxide (H2O2) has been long thought to permeate biological membranes by simple diffusion since recent evidence challenged this notion disclosing the role of aquaporin water channels (AQP) in mediating H2O2 transport across plasma membranes. We previously demonstrated that NAD(P)H oxidase (Nox)-generated ROS sustain glucose uptake and cellular proliferation in leukaemia cells. The aim of this study was to assess whether specific AQP isoforms can channel Nox-produced H2O2 across the plasma membrane of leukaemia cells affecting downstream pathways linked to cell proliferation. In this work, we demonstrate that AQP inhibition caused a decrease in intracellular ROS accumulation in leukaemia cells both when H2O2 was produced by Nox enzymes and when it was exogenously added. Furthermore, AQP8 overexpression or silencing resulted to modulate VEGF capacity of triggering an H2O2 intracellular level increase or decrease, respectively. Finally, we report that AQP8 is capable of increasing H2O2-induced phosphorylation of both PI3K and p38 MAPK and that AQP8 expression affected positively cell proliferation. Taken together, the results here reported indicate that AQP8 is able to modulate H2O2 transport through the plasma membrane affecting redox signalling linked to leukaemia cell proliferation. PMID:24440277

Vieceli Dalla Sega, Francesco; Zambonin, Laura; Fiorentini, Diana; Rizzo, Benedetta; Caliceti, Cristiana; Landi, Laura; Hrelia, Silvana; Prata, Cecilia

2014-04-01

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

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

208

Investigation of the optical characteristics of a laser-produced plasma cloud expanding into a background gas  

SciTech Connect

An investigation is made of the dynamics and visible-range luminosity of the plasma cloud produced behind the front of a shock wave in air at a pressure of 1 Torr. The shock wave was produced on introducing the radiation of the twelve-channel Iskra-5 laser facility with a total energy of {approx}2300 J into a hollow spherical plastic target of mass {approx}10{sup -4} g. Experimental data are compared with simulations. (laser plasma)

Annenkov, A I; Bessarab, A V; Galakhov, I V; Garanin, Sergey G; Gusakov, A V; Zhidkov, N V; Zhmailo, V A; Izgorodin, V M; Kovalenko, V P; Krotov, V A; Mis'ko, V V; Novikova, E A; Starodubtsev, V A; Starodubtsev, K V; Statsenko, V P; Sungatullin, R R; Tachaev, G V; Sheremet'ev, Yu N [Russian Federal Nuclear Center 'All-Russian Research Institute of Experimental Physics', Sarov, Nizhnii Novgorod region (Russian Federation)

2010-12-09

209

Warm flux tubes in the E-ring plasma torus: Initial Cassini magnetometer observations  

NASA Astrophysics Data System (ADS)

Initial Cassini magnetometer observations in the E-ring plasma torus reveal the presence of previously unreported diamagnetic decreases in the magnetic field. The decrease in magnetic pressure on these flux tubes implies the presence of additional plasma energy densities up to 1 keV/cm3. They are less stretched than surrounding flux tubes suggesting the centrifugal force acting on them is less, possibly because they have a lower mass content or lower azimuthal velocity than their neighbors. Outward from these isolated tubes, at about 6 Saturn radii, an irregular transition from predominantly cool to predominantly warm flux tubes is observed. A similar boundary is observed in the jovian magnetosphere at the outer edge of the Io torus. Both the saturnian and jovian boundaries are candidates for the interchange instability but other processes may also be acting. ULF waves are associated with some, but not all, of these flux tubes.

Leisner, J. S.; Russell, C. T.; Khurana, K. K.; Dougherty, M. K.; André, N.

2005-06-01

210

Report Initial Work on Developing Plasma Modeling Capability in WARP for NDCX Experiments  

SciTech Connect

This milestone has been accomplished. The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL) has developed and implemented an initial beam-in-plasma implicit modeling capability in Warp; has carried out tests validating the behavior of the models employed; has compared the results of electrostatic and electromagnetic models when applied to beam expansion in an NDCX-I relevant regime; has compared Warp and LSP results on a problem relevant to NDCX-I; has modeled wave excitation by a rigid beam propagating through plasma; and has implemented and begun testing a more advanced implicit method that correctly captures electron drift motion even when timesteps too large to resolve the electron gyro-period are employed. The HIFS-VNL is well on its way toward having a state-of-the-art source-to-target simulation capability that will enable more effective support of ongoing experiments in the NDCX series and allow more confident planning for future ones.

Friedman, A; Cohen, R H; Grote, D P; Vay, J

2007-12-14

211

Initial confinement studies of ohmically heated plasmas in the Tokamak Fusion Test Reactor  

SciTech Connect

Initial operation of the Tokamak Fusion Test Reactor (TFTR) has concentrated upon confinement studies of ohmically heated hydrogen and deuterium plasmas. Total energy confinement times (tau/sub E/) are 0.1 to 0.2 s for a line-average density range (anti n/sub e/) of 1 to 2.5 x 10/sup 19/ m/sup -3/ with electron temperatures of T/sub e/(o) approx. 1.2 to 2.2 keV, ion temperatures of T/sub i/(o) approx. 0.9 to 1.5 keV, and Z/sub eff/ approx. 3. A comparison of PLT, PDX, and TFTR plasma confinement supports a dimension-cubed scaling law.

Efthimion, P.C.; Bell, M.; Blanchard, W.R.; Bretz, N.; Cecchi, J.L.; Coonrod, J.; Davis, S.; Dylla, H.F.; Fonck, R.; Furth, H.P.

1984-06-01

212

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

213

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

SciTech Connect

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. [Center for Materials under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette 47907 (United States)] [Center for Materials under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette 47907 (United States)

2013-05-15

214

Numerical study of strong plasma shock waves produced in an electromagnetic shock tube.  

NASA Technical Reports Server (NTRS)

A set of two-fluid Navier-Stokes equations with classical physical transport coefficients is used to compute the evolution and structure of collisional plasma shock waves in an electromagnetic shock tube. Shock speeds up to 200 cm/microsec and shocked-plasma temperatures of the order of kilovolts are studied. A strong transverse bias magnetic field is employed, which significantly alters the size and shape of the shock profiles, when compared with the zero bias field case. The wave structure is different from that of a two-fluid gasdynamic shock without transverse magnetic field. Especially significant is the effect of the small ion Larmor radius in reducing the gasdynamic shock thickness by at least an order of magnitude in the transverse shock case, which permits collisional shocks to have thicknesses much smaller than the post-shock mean free path. These collisional shock waves produce very hot ions, the ion temperature increasing with shock speed, although the formation time and distances also increase substantially with shock speed.

Schneider, S. H.

1972-01-01

215

Gaussian energy distribution of fast ions emitted by laser-produced plasmas  

NASA Astrophysics Data System (ADS)

The analysis of ion collector signals with the use of a time-of-fight signal function derived from a shifted Maxwell-Boltzmann velocity distribution is used to quantify the ion characteristics as the ion temperature and velocity of centre-of-mass motion of groups of ionized species constituting the ablated plasma. The analysis is also focused on velocity and energy distributions derived from the signal of a time-of-flight detector taking into account the underlying principle of sensor operation. The energy Maxwell spectra of ions are compared with the Gauss distribution with respect to the ratio of the centre-of-mass energy of ions to their temperature. The difference threshold between the Gauss and energy Maxwell spectra is determined via the limited validity of the basic relationship between spreads in energy and time-of-flight spectra ½?E/E = ?t/t. The analysis of velocity spectrum of fast ions emitted by Ti plasma produced with 300 ps, kJ-class iodine laser operating at PALS facility shows that ion bursts consist of almost monoenergetic ion beams.

Krása, J.

2013-05-01

216

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

217

Large airglow enhancements produced via wave-plasma interactions in sporadic E  

NASA Astrophysics Data System (ADS)

In the past there has been great interest in monitoring enhanced 557.7 nm O(¹S) emissions from the thermosphere in connection with high-power, high-frequency (HF) radio wave modification of the F region ionosphere. These emissions are considered to be evidence that the HF-modified electron distribution function is non-Maxwellian because a significant flux of ˜5-6 eV electrons is required to produce the airglow. The suprathermal tail is believed to develop as a result of nonlinear plasma processes. Past F region observations of 557.7 nm airglow at Arecibo Observatory, Puerto Rico have yielded only a few Rayleighs of enhanced emissions. Recently, airglow enhancements were monitored in sporadic E above Arecibo. Surprisingly, these experiments yielded ˜55 Rayleighs of enhanced 557.7 nm airglow and the first observations of emissions from the N2 first positive molecular bands. The observations imply that a large flux of energetic (5-10 eV) electrons is generated as part of the wave-plasma interaction in sporadic E.

Djuth, F. T.; Bernhardt, P. A.; Tepley, C. A.; Gardner, J. A.; Kelley, M. C.; Broadfoot, A. L.; Kagan, L. M.; Sulzer, M. P.; Elder, J. H.; Selcher, C.; Isham, B.; Brown, C.; Carlson, H. C.

218

On the Rydberg transitions and elemental compositions in the laser produced Al (6063) plasma  

SciTech Connect

We present new studies on the optical emission spectra of the laser produced Al 6063 alloy plasma generated by the 1064 nm Nd: YAG laser. The spectrum reveals Rydberg transitions; nd {sup 2}D{sub 3/2,5/2}{yields} 3p {sup 2}P{sub 1/2,3/2} (n = 3 - 8), ns {sup 2}S{sub 1/2}{yields} 3p {sup 2}P{sub 1/2,3/2} (n 4-6), and the dominant spectral lines of the other constituent elements. We have extracted the relative abundance of the impurities using the relative intensity ratio method. Besides, we have calculated the electron temperature ({approx}7580 K) from the Boltzmann plot method and the electron number densities ({approx}1.4 x 10{sup 17}/cm{sup 3}) from the Stark widths of the aluminum spectral lines. The plasma parameters determined in the present work are in agreement with that reported in the literature. The molecular vibrational transitions of the AlO free radical associated with the B {sup 2}{Sigma}{yields}X {sup 2}{Sigma} band system have also been identified.

Baig, M. A.; Fareed, M. A.; Rashid, B.; Ali, R. [Atomic and Molecular Physics Laboratory, Department of Physics, Quaid-i-Azam University, 45320 Islamabad (Pakistan)

2011-08-15

219

Optical and Electrical Properties of Heterogeneous Coatings Produced by Aluminum Powder and Boehmite Suspension Plasma Spraying  

NASA Astrophysics Data System (ADS)

Spectral selective materials have attracted an increasing interest because of Concentration Solar Power Plant. Those materials are expected to exhibit specific optical properties at temperatures higher than 450 °C. Plasma-spraying process is commonly used to manufacture high-temperature coatings. In this study, heterogeneous coatings made of aluminum and alumina were produced by spraying both powder and suspension of boehmite clusters. Both optical and electrical properties were measured because, according to the Hagen-Ruben's law, the higher the resistivity the lower the reflectivity. The reflectivity was assessed by spectrometry at 10 µm and the resistivity by the four-points technique. The results were combined with the diameter of flattened lamellae and the volume fraction of alumina in the coatings. Then the highest reflectivity is achieved with a metallic coating exhibiting high flattening degree, while the coatings containing a large amount of alumina exhibit the lowest reflectivity and the highest resistivity.

Brousse-Pereira, E.; Wittmann-Teneze, K.; Bianchi, V.; Longuet, J. L.; Del Campo, L.

2012-12-01

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 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

221

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

222

Time-resolved soft x-ray spectra from laser-produced Cu plasma.  

PubMed

The volumetric heating of a thin copper target has been studied with time resolved x-ray spectroscopy. The copper target was heated by a plasma produced using the Lawrence Livermore National Laboratory's Compact Multipulse Terawatt (COMET) laser. A variable spaced grating spectrometer coupled to an x-ray streak camera measured soft x-ray emission (800-1550 eV) from the back of the copper target to characterize the bulk heating of the target. Radiation hydrodynamic simulations were modeled in two-dimensions using the HYDRA code. The target conditions calculated by HYDRA were post-processed with the atomic kinetics code CRETIN to generate synthetic emission spectra. A comparison between the experimental and simulated spectra indicates the presence of specific ionization states of copper and the corresponding electron temperatures and ion densities throughout the laser-heated copper target. PMID:23126959

Cone, K V; Baldis, H A; Dunn, J; May, M J; Purvis, M A; Schneider, M B; Scott, H A

2012-10-01

223

High bandwidth data recording systems for pulsed power and laser produced plasma experiments  

SciTech Connect

We present two high bandwidth data transmission and recording systems for the measurement of transient signals during pulsed power and laser produced plasmas. These systems use fiber optic cables to transmit analog data over long distances to high bandwidth digitizing oscilloscopes. One system is based on the direct modulation of a laser diode and has a bandwidth of 1.5 GHz. The other system is based upon a Mach-Zehnder modulator and has a bandwidth of 12 GHz, and is limited by the photoreceiver. The signals are recorded on commercial digitizing oscilloscopes that have approximately six effective bits. The transmission systems use many off-the-shelf components from the telecommunications industry and thus have a high reliability and a moderate cost. Investigation of the reduction in optical transmission of the fibers during exposure to high dose radiation will also be discussed.

May, M. J.; Clancy, T.; Fittinghoff, D.; Halvorson, C.; Mills, T.; Nikitin, A.; Perry, T.; Roberson, G. P.; Smith, D.; Teruya, A.; Miller, E. K.; Trainham, C. [Lawrence Livermore National Laboratory, 7000 East Avenue Livermore, California 94550 (United States); Special Technologies Laboratory, Bechtel Nevada, 5520 Ekwill Street, Suite B, Santa Barbara, California 93111 (United States)

2006-10-15

224

High Bandwidth Data Recording Systems for Pulsed Power and Laser Produced Plasma Experiments.  

SciTech Connect

We present two high bandwidth data transmission and recording systems for the measurement of transient signals during pulsed power and laser produced plasmas. These systems use fiber optic cables to transmit analog data over long distances to high bandwidth digitizing oscilloscopes. One system is based on the direct modulation of a laser diode and has a bandwidth of 1.5 GHz. The other system is based upon a fiber-optic Mach-Zehnder modulator and has a bandwidth of 12 GHz, and is limited by the photo receiver. The signals are recorded on commercial digitizing oscilloscopes that have approximately 6 effective bits. The transmission systems use many off-the-shelf components from the telecommunications industry and thus have a high reliability and a moderate cost. Results from recent measurements will be presented. Investigation of the reduction in optical transmission by the fibers during exposure to high dose radiation will also be discussed.

May, M J; Clancy, T; Fittinghoff, D; Halvorson, C; MIlls, T; Nikitin, A; Perry, T; Roberson, P; Smith, D; Teruya, A; Miller, K; Trainham, C

2006-05-02

225

Statistical analysis of word-initial \\/k\\/ and \\/t\\/ produced by normal and phonologically disordered children  

Microsoft Academic Search

The acoustic characteristics of voiceless velar and alveolar stop consonants were investigated for normally articulating and phonologically disordered children using spectral moments. All the disordered children were perceived to produce It\\/ for \\/k\\/, with \\/k\\/ being absent from their phonetic inventories. Approximately 82% of the normally articulating children's consonants were classified correctly by discriminant function analysis, on the basis of

Karen Forrest; Gary Weismer; Megan Hodge; Daniel A. Dinnsen; Mary Elbert

1990-01-01

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

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

228

Prediction of pregnancy viability in bovine in vitro-produced embryos and recipient plasma with Fourier transform infrared spectroscopy  

PubMed Central

We analyzed embryo culture medium (CM) and recipient blood plasma using Fourier transform infrared (FTIR) metabolomics to predict pregnancy outcome. Individually cultured, in vitro-produced (IVP) blastocysts were transferred to recipients as fresh and vitrified-warmed. Spent CM and plasma samples were evaluated using FTIR. The discrimination capability of the classifiers was assessed for accuracy, sensitivity (pregnancy), specificity (nonpregnancy), and area under the receiver operator characteristic curve (AUC). Within all IVP fresh embryos (birth rate = 52%), high AUC were obtained at birth, especially with expanded blastocysts (CM: 0.80 ± 0.053; plasma: 0.89 ± 0.034). The AUC of vitrified IVP embryos (birth rate = 31%) were 0.607 ± 0.038 (CM, expanded blastocysts) and 0.672 ± 0.023 (plasma, all stages). Recipient plasma generally predicted pregnancy outcome better than did embryo CM. Embryos and recipients with improved pregnancy viability were identified, which could increase the economic benefit to the breeding industry. PMID:24997663

Munoz, M.; Uyar, A.; Correia, E.; Diez, C.; Fernandez-Gonzalez, A.; Caamano, J. N.; Martinez-Bello, D.; Trigal, B.; Humblot, P.; Ponsart, C.; Guyader-Joly, C.; Carrocera, S.; Martin, D.; Marquant Le Guienne, B.; Seli, E.; Gomez, E.

2014-01-01

229

Absolute soft x-ray calibration of laser produced plasmas using a focusing crystal von Hamos spectrometer  

NASA Astrophysics Data System (ADS)

Absolute x-ray calibration of laser-produced plasmas was performed using a focusing crystal von Hamos spectrometer. The plasmas were created by a high repetition rate Nd-YAG laser (0.53 ?m/200 mJ/3 ns/10 Hz) on massive solid targets (Mg, Al, Fe, Cu, Mo, Ta). Cylindrical mica crystal (radius of curvature R=20 mm) and a CCD linear array as a detector (Toshiba model TCD 1304AP) were used in the spectrometer. Both the mica crystal and CCD linear array were absolutely calibrated in a spectral range of ?=7-15 å. The spectrometer was used for absolute spectral measurements and the determination of the plasma parameters. High spectrometer efficiency allows for the monitoring of absolute x-ray spectra, x-ray yield and plasma parameters in each laser shot. This spectrometer is promising for absolute spectral measurements and for monitoring of laser-plasma sources intended for proximity print lithography.

Weeks, Tyler; Shevelko, Alexander

2005-05-01

230

Morphology of laser-produced carbon nanoparticle plasmas and high-order harmonic generation of ultrashort pulses in clustered media  

NASA Astrophysics Data System (ADS)

We analyse the morphology of the laser plasmas produced on surfaces containing various carbon clusters (nanotubes, nanofibres, fullerenes, and nanoparticles). It is shown that the presence of C5-C25 nanoparticles in the laser plasmas coincides with the enhancement of harmonics in the spectral range of 40-80 nm. We suggest that these nanoparticles, rather than larger clusters, play a decisive role in the observed growth of harmonic yield.

Ganeev, R. A.; Baba, M.; Suzuki, M.; Kuroda, H.

2014-07-01

231

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

232

Group velocity measurement from the propagation of the ionization front in a surface-wave-produced plasma  

SciTech Connect

During the first instant, previous to steady-state in a surface-wave-produced plasma, an ionization front advance front the launcher to the plasma column end. The velocity of the ionization front is much slower than the group velocity of the surface wave, this give a reflection of the incident signal on the moving ionization front. In this paper, the authors use this effect to calculate the surface wave group velocity.

Cotrino, J.; Gamero, A.; Sola, A.; Lao, C. (Departamento de Fisica Aplicada, Universidad de Cordoba, San Alberto Magno, s/n. 14071 Cordoba (ES))

1989-05-01

233

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

234

INVESTIGATION OF SUPERSONIC AIR PLASMA JET PRODUCED IN THE VKI PLASMATRON FACILITY  

E-print Network

using the Inductively Coupled Plasma (ICP) Plasmatron facil- ity operating with air mixture.1. Plasmatron facility and supersonic plasma jet generation The VKI Plasmatron Inductively Coupled Plasma (ICP a single-turn inductor [B. 97], [B. 00]. For the present ex- periments, the Plasmatron is operating at 490

Paris-Sud XI, Université de

235

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

NASA Astrophysics Data System (ADS)

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.; Anvari, A.

2014-02-01

236

Purification and characterization of a motility initiating protein from caprine epididymal plasma.  

PubMed

Numerous reports have appeared on the occurrence of undefined protein factors in male reproductive fluids that promote motility of mature sperm and initiate forward motility in the immature (immotile) caput-epididymal sperm. This study reports for the first time purification to apparent homogeneity of a motility initiating protein (MIP) from epididymal plasma and its characterization using the caprine sperm model. It is a 125 kDa (approximately) dimeric protein made up of two subunits: 70 and 54 kDa. MIP is an acidic protein with an isoelectric point of 4.75. The motility protein at 30 microg/ml (240 nM) level showed nearly maximal motility-promoting activity. MIP is heat stable and it is maximally active at pH 8. It is a glycoprotein that binds with high affinity to concanavalin A and it contains mannose, galactose, and N-acetyl glucosamine approximately in the ratios of 6:1:6. It is sensitive to the actions of alpha-mannosidase and beta-N-acetylglucoseaminidase thereby demonstrating that the sugar side chain of the glycoprotein is essential for its biological activity. Epididymal plasma is its richest source. It is also capable of enhancing forward motility of mature cauda-sperm. Its antibody markedly inhibits sperm motility. MIP antibody is highly immunospecific and it recognizes both the subunits. MIP causes significant increase of the intrasperm level of cyclic AMP. MIP: the physiological motility-activating protein has potential for use as a contraceptive vaccine and for solving some of the problems of human infertility and animal breeding. PMID:19795390

Jaiswal, Bijay Shankar; Das, Kaushik; Saha, Sudipta; Dungdung, Sandhya Rekha; Majumder, Gopal C

2010-01-01

237

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

238

Experimental astrophysics with magnetised laser-produced plasma: UV\\/X-ray spectroscopy, interferometry and pulsed magnetic fields  

Microsoft Academic Search

This work presents an experimental investigation of the scaled simulation of high Mach number collisionless shocks found in supernovae remnants, which is part of the experimental collaboration initiated by Woolsey et al. , (Physics of Plasmas, 8, 2439, 2001). Supernovae are one of the most energetic astrophysical phenomena. They distribute new matter created inside stars throughout space and are believed

Andrew David Ash

2006-01-01

239

Plasma Membrane Potential Oscillations in Insulin Secreting Ins-1 832/13 Cells Do Not Require Glycolysis and Are Not Initiated by Fluctuations in Mitochondrial Bioenergetics*  

PubMed Central

Oscillations in plasma membrane potential play a central role in glucose-induced insulin secretion from pancreatic ?-cells and related insulinoma cell lines. We have employed a novel fluorescent plasma membrane potential (??p) indicator in combination with indicators of cytoplasmic free Ca2+ ([Ca2+]c), mitochondrial membrane potential (??m), matrix ATP concentration, and NAD(P)H fluorescence to investigate the role of mitochondria in the generation of plasma membrane potential oscillations in clonal INS-1 832/13 ?-cells. Elevated glucose caused oscillations in plasma membrane potential and cytoplasmic free Ca2+ concentration over the same concentration range required for insulin release, although considerable cell-to-cell heterogeneity was observed. Exogenous pyruvate was as effective as glucose in inducing oscillations, both in the presence and absence of 2.8 mm glucose. Increased glucose and pyruvate each produced a concentration-dependent mitochondrial hyperpolarization. The causal relationships between pairs of parameters (??p and [Ca2+]c, ??p and NAD(P)H, matrix ATP and [Ca2+]c, and ??m and [Ca2+]c) were investigated at single cell level. It is concluded that, in these ?-cells, depolarizing oscillations in ??p are not initiated by mitochondrial bioenergetic changes. Instead, regardless of substrate, it appears that the mitochondria may simply be required to exceed a critical bioenergetic threshold to allow release of insulin. Once this threshold is exceeded, an autonomous ??p oscillatory mechanism is initiated. PMID:22418435

Goehring, Isabel; Gerencser, Akos A.; Schmidt, Sara; Brand, Martin D.; Mulder, Hindrik; Nicholls, David G.

2012-01-01

240

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

241

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

242

Laser-produced plasma measurement of thermal diffusivity of molten metals  

NASA Astrophysics Data System (ADS)

We have shown that a laser-produced plasma plume which is representative in elemental 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 Ievitator-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 exercised 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 the specimen heating in the molten metal source and the physical basis of the new method are also presented.

Kim, Y. W.; Park, C. S.

1996-09-01

243

Rapid, Absolute Calibration of X-ray Filters Employed By Laser-Produced Plasma Diagnostics  

SciTech Connect

The electron beam ion trap (EBIT) facility at the Lawrence Livermore National Laboratory is being used to absolutely calibrate the transmission efficiency of X-ray filters employed by diodes and spectrometers used to diagnose laser-produced plasmas. EBIT emits strong, discrete monoenergetic lines at appropriately chosen X-ray energies. X-rays are detected using the high-resolution EBIT calorimeter spectrometer (ECS), developed for LLNL at the NASA/Goddard Space Flight Center. X-ray filter transmission efficiency is determined by dividing the X-ray counts detected when the filter is in the line of sight by those detected when out of the line of sight. Verification of filter thickness can be completed in only a few hours, and absolute efficiencies can be calibrated in a single day over a broad range from about 0.1 to 15 keV. The EBIT calibration lab has been used to field diagnostics (e.g., the OZSPEC instrument) with fully calibrated X-ray filters at the OMEGA laser. Extensions to use the capability for calibrating filter transmission for the DANTE instrument on the National Ignition Facility are discussed.

Brown, G V; Beiersdorfer, P; Emig, J; Frankel, M; Gu, M F; Heeter, R F; Magee, E; Thorn, D B; Widmann, K; . Kelley, R L; Kilbourne, C A; Porter, F S

2008-05-11

244

Rapid, absolute calibration of x-ray filters employed by laser-produced plasma diagnostics  

SciTech Connect

The Electron Beam Ion Trap (EBIT) facility at the Lawrence Livermore National Laboratory is being used to absolutely calibrate the transmission efficiency of x-ray filters employed by diodes and spectrometers used to diagnose laser-produced plasmas. EBIT emits strong, discrete monoenergetic lines at appropriately chosen x-ray energies. X rays are detected using the high resolution EBIT Calorimeter Spectrometer (ECS), developed for LLNL at the NASA/Goddard Space Flight Center. X-ray filter transmission efficiency is determined by dividing the x-ray counts detected when the filter is in the line of sight by those detected when out of the line of sight. Verification of filter thickness can be completed in only a few hours, and absolute efficiencies can be calibrated in a single day over a broad range from about 0.1 to 15 keV. The EBIT calibration lab has been used to field diagnostics (e.g., the OZSPEC instrument) with fully calibrated x-ray filters at the OMEGA laser. Extensions to use the capability for calibrating filter transmission for the DANTE instrument on the National Ignition Facility are discussed.

Brown, G. V.; Beiersdorfer, P.; Emig, J.; Frankel, M.; Gu, M. F.; Heeter, R. F.; Magee, E.; Thorn, D. B.; Widmann, K. [Department of Physical Sciences, High Energy Density Physics and Astrophysics Division, Lawrence Livermore National Laboratory, 7000 East Avenue, L-260, Livermore, California 94550 (United States); Kelley, R. L.; Kilbourne, C. A.; Porter, F. S. [NASA/Goddard Space Flight Center, Greenbelt, Maryland 20770 (United States)

2008-10-15

245

Xenon target performance characteristics for laser-produced plasma EUV sources  

NASA Astrophysics Data System (ADS)

Laser-produced plasmas (LPPs) are being developed as light sources for EUV lithography. To meet the requirements for high-volume manufacturing, LPP EUV sources must generate intense EUV output in the 13.5 nm band, and minimize source-induced degradation of EUV optics allowing hundreds of hours of clean operation. Xenon has been identified as a promising target material for LPP EUV light sources, with the potential for both high-efficiency EUV generation, and low optics contamination. Several dense xenon target configurations have been tested including aerosol sprays, continuous liquid streams, condensed xenon droplets, and frozen solid xenon. Important LPP performance characteristics, such as conversion efficiency, EUV radiation distribution, EUV optics degradation by material erosion and/or deposition, and the physical interface to the EUV optical system, are strongly influenced by the xenon target design. The performance of xenon targets with measured conversion efficiencies in the 0.4 percent to 1.4 percent range is reported. Prospects for xenon targets to reach the EUV power generation and contamination goals for production lithography tools are addressed.

Shields, Harry; Fornaca, Steven W.; Petach, Michael B.; Michaelian, Mark; McGregor, R. Daniel; Moyer, Richard H.; St. Pierre, Randall J.

2002-07-01

246

Measurements of Electron Temperature and Density Profiles of Plasmas Produced by Nike KrF Laser for Laser Plasma Instability (LPI) Research  

NASA Astrophysics Data System (ADS)

ExperimentsfootnotetextJ. Oh, et al, GO5.4, APS DPP (2010).^,footnotetextJ. L. Weaver, et al, GO5.3, APS DPP (2010). using Nike KrF laser observed LPI signatures from CH plasmas at the laser intensities above ˜1x10^15 W/cm^2. Knowing spatial profiles of temperature (Te) and density (ne) in the underdense coronal region (0 < n < nc/4) of the plasma is essential to understanding the LPI observation. However, numerical simulation was the only way to access the profiles for the previous experiments. In the current Nike LPI experiment, a side-on grid imaging refractometer (GIR)footnotetextR. S. Craxton, et al, Phys. Fluids B 5, 4419 (1993). is being deployed for measuring the underdense plasma profiles. The GIR will resolve Te and ne in space taking a 2D snapshot of probe laser (?= 263 nm, ?t = 10 psec) beamlets (50?m spacing) refracted by the plasma at a selected time during the laser illumination. Time-resolved spectrometers with an absolute-intensity-calibrated photodiode array and a streak camera will simultaneously monitor light emission from the plasma in spectral ranges relevant to Raman (SRS) and two plasmon decay (TDP) instabilities. The experimental study of effects of the plasma profiles on the LPI initiation will be presented.

Oh, Jaechul; Weaver, J. L.; Obenschain, S. P.; Schmitt, A. J.; Kehne, D. M.; Karasik, M.; Chan, L.-Y.; Serlin, V.; Phillips, L.

2012-10-01

247

Investigation of the optical characteristics of a laser-produced plasma cloud expanding into a background gas  

Microsoft Academic Search

An investigation is made of the dynamics and visible-range luminosity of the plasma cloud produced behind the front of a shock wave in air at a pressure of 1 Torr. The shock wave was produced on introducing the radiation of the twelve-channel Iskra-5 laser facility with a total energy of 2300 J into a hollow spherical plastic target of mass

A I Annenkov; A V Bessarab; I V Galakhov; Sergey G Garanin; A V Gusakov; N V Zhidkov; V A Zhmailo; V M Izgorodin; V P Kovalenko; V A Krotov; V V Misko; E A Novikova; V A Starodubtsev; K V Starodubtsev; V P Statsenko; R R Sungatullin; G V Tachaev; Yu N Sheremetev

2010-01-01

248

Plasma ion spectra from laser produced plasmas at lambda = 1.06 microns and lambda = 0.53 microns  

NASA Astrophysics Data System (ADS)

Wavelength dependent absorption in laser-plasma interactions was investigated by measuring the energy spectra of freely expanding plasmas in their asymptotic stage of expansion. The experiments were performed with both 1.06- and 0.53-micron-wavelength light incident on flat tantalum targets. The experimental conditions were chosen adequately to ensure that inverse bremsstrahlung was the dominating absorption mechanisms. As a result, it is found that the absorption is enhanced at the shorter wavelength by a factor of 1.3. Primarily this leads to a higher ionization state of the plasma and higher kinetic ion energies and temperatures, respectively, while the amount of ablated mass is approximately the same.

Dinger, R.; Rohr, K.; Weber, H.

1986-05-01

249

Artificial plasma density structures produced by energetic electron beams from rockets and spacecraft  

NASA Technical Reports Server (NTRS)

Recent rocket and Space Shuttle experiments have demonstrated the capability to launch electron beams of moderate power (100 W to 10 kW) into the earth's ionosphere and magnetosphere. This letter describes how such beams, when fired from rockets or satellites, can create significant ionization in the E- and F-regions of the ionosphere. Through proper selection of beam-related parameters, an interesting variety of plasma density structures, including plasma sheets and plasma filaments, can be created and studied over periods of 30 minutes to 1 hour, depending on the rate of plasma recombination and the density of the ambient plasma. Observations of these structures can give new information relating to the physics of plasma density structures in the ionosphere, and the effects these features have upon the scattering of radio waves. It is also possible that observations of the density structures will provide a new means for studying neutral winds and electrodynamic phenomena in the ionosphere.

Banks, P. M.; Gilchrist, B. E.

1985-01-01

250

High-order harmonic generation in a plasma plume of in situ laser-produced silver nanoparticles  

SciTech Connect

The results of the experimental study of high-order harmonic generation (HHG) from the interaction of 45-fs Ti:sapphire laser pulses with plasma plumes of Ag nanoparticles produced in situ are presented in this article. The nanoparticles were generated by the interaction of 300-ps, 20-mJ laser pulses with bulk silver targets at an intensity of {approx}1x10{sup 13} W/cm{sup 2}. The spectral characteristics of the HHG from nanoparticles produced in situ are compared with the HHG from monoparticle plasma plumes and with the HHG from preformed nanoparticle-containing plasma plumes. The cutoff harmonic order generated using the in situ silver nanoparticles is at the 21st harmonic order.

Singhal, H.; Naik, P. A.; Chakera, J. A.; Chakravarty, U.; Vora, H. S.; Srivastava, A. K.; Mukherjee, C.; Navathe, C. P.; Deb, S. K.; Gupta, P. D. [Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India); Ganeev, R. A. [Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India); Institute of Electronics, 33, Dormon Yoli street, Tashkent 100125 (Uzbekistan)

2010-10-15

251

Short Wavelength Laser Gain Studies in Plasmas Produced by a Small NEODYMIUM:GLASS Slab Laser  

NASA Astrophysics Data System (ADS)

A high-power, high-repetition-rate Nd:glass laser system was developed and used to study a collisionally pumped x-ray laser scheme near 200 A. The laser system used a commercial oscillator injecting 60-psec modelocked pulses at 1053 nm into a Nd:glass zig-zag slab amplifier which was developed for this project. The amplifier was capable of producing 2-J, near-diffraction-limited pulses at repetition rates of up to 0.3 Hz. Single-pass gains of up to 7.5 were measured with storage efficiencies of 3-4%, and the gain profile was flat to within 10%. Use of air cooling and subhertz repetition rates alleviated thermal distortion, stringent coolant channel sealing requirements, and optical surface degradation. An optical system was designed which incorporated flattop rectangular beams and relay imaging to generate 15-?m -wide, uniform line foci on the target. The focused laser radiation was used to generate linear plasma columns suitable for amplified-spontaneous -emission laser output near 200 A. An electron collisionally pumped scheme in Ni-like Nb, analogous to previously demonstrated Ni-like schemes at higher Z, was investigated experimentally. A solid Nb target was irradiated with modelocked trains of pump pulses; a gain at 204 A of about 5 cm^ {-1} in a length of 3 mm at pump energies of 1.1 J/pulse was inferred from experiments in which the line focus length was varied. Comparable amounts of gain were seen following the second and third pump pulses, suggesting that an x-ray cavity might be feasible using this pumping scheme. Supporting evidence for gain was observed in the angular and temporal dependence of the emission. The measured gain was low compared to predictions, and the pump laser power appeared therefore to have been insufficient to achieve a high gain-length product. Theoretical work supporting the experimental efforts included calculation of ionization and recombination rate coefficients, development of a hydrodynamics model for the plasma cooling phase between pulses, and study of the extension of nonlinear four-wave-mixing and tripling processes to the soft x-ray regime. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.).

Muendel, Martin Heinrich

252

Circular periodic motion of plasma produced by a small-scale vacuum arc  

NASA Astrophysics Data System (ADS)

A small-scale plasma source based on a low-current vacuum arc is described. Temporal and spatial evolution of the ion current is measured. The plasma plume circular motion follows the cathode spot motion in the retrograde direction and is guided along the magnetic field line. It is observed that the applied magnetic field efficiently guide the plasma leading to an increase in the output ion current by a factor of 50 in comparison with that without the magnetic field.

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

2011-02-01

253

Laser-produced plasma with large amplitude density modulation of controllable wavelength  

SciTech Connect

A 6 nsec 10{sup 10} W/cm{sup 2} ruby laser pulse irradiates a grating with spacing in the 6--35 {mu}m range. The expansion of the plasma above the surface is observed using interferometry and shadowgraphy. The plasma is found to be modulated with {ital {tilde n}}/{ital n} up to 8%. Such a plasma can be used to accelerate charged particles.

Laberge, M.; Meyer, J. (Department of Physics, University of British Columbia, Vancouver, BC (Canada))

1990-11-01

254

Observation and modelling of hollow multicharged ion x-ray spectra radiated by laser produced plasma  

SciTech Connect

The role of the highly charged hollow ions in the X-Ray emission plasma spectTa is investigated for 2 cases: (1) plasma obtained under inadiation of Ar clusters by ultrashort laser pulses and (2) Mg-plasma heated by a short-wavelength long (nanosecond) laser pulse. Experimental measurements are presented. Calculations in support of these measurements have been performed using a detailed atomic kinetics model with the ion distributions found from solution of the time-dependent rate equations.

Colgan, James P [Los Alamos National Laboratory; Abdallah, Joseph [Los Alamos National Laboratory; Faenov, A Ya [JAPAN/RUSSIA; Pikuz, T A [JAPAN/RUSSIA; Akobelev, I Yu [JAPAN/RUSSIA; Fukuda, Y [JAPAN/RUSSIA

2008-01-01

255

1316 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 36, NO. 4, AUGUST 2008 Schlieren Imaging of Flow Actuation Produced  

E-print Network

comprises the supersonic free stream flowing parallel to a flat plate and abruptly turned by a 30 wedge Actuation Produced by Direct-Current Surface Glow Discharge in Supersonic Flows Jichul Shin, Noel T. Clemens. Index Terms--DC sheath, dc surface discharge, electrostatic force, plasma actuation, supersonic flow

Raja, Laxminarayan L.

256

Laser wavelength effects on the charge state resolved ion energy distributions from laser-produced Sn plasma  

E-print Network

Laser wavelength effects on the charge state resolved ion energy distributions from laser of laser wavelength on the charge state resolved ion energy distributions from laser-produced Sn plasma freely expanding into vacuum are investigated. Planar Sn targets are irradiated at laser wavelengths

Najmabadi, Farrokh

257

Emission spectra of laser-produced plasmas for EUV and soft x-ray sources  

NASA Astrophysics Data System (ADS)

The plasma emission of tin, aluminum and cupper targets irradiated with laser intensities ranging from 1011 to 1016 W/cm2 has been measured beween 7nm and 18 nm. A chirped pulse amplified Ti:Sapphire laser oscillating at 790- nm with either 100 fs or 300 ps pulse duration and a Nd:YAG laser oscillating at 1064 nm with 10 ns pulse duration (fwhm) have been used. The observed plasma emission was strongest for the 300 ps laser pulse irradiation, which might be due to the additional laser plasma heating during plasma formation.

Soumagne, Georg; Abe, Tamotsu; Ikeda, Kenichi; Komori, Hiroshi; Someya, Hiroshi; Suganuma, Takashi; Nakajima, Kazuhisa; Endo, Akira

2004-06-01

258

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

SciTech Connect

A volume self-sustained discharge (VSD) in iodides (C{sub 3}H{sub 7}I, C{sub 4}H{sub 9}I) and in their mixtures with SF{sub 6}, N{sub 2}, and O{sub 2} 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 SF{sub 6} or N{sub 2} to the iodides improves the stability and homogeneity of the SIVD, while adding up to 300 % (relative to the partial iodide pressure) of O{sub 2} 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 C{sub 4}H{sub 9}I:O{sub 2}:SF{sub 6}=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{sup -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. (lasers)

Belevtsev, A A [Institute for High Energy Densities, Associated Institute for High Temperatures, Russian Academy of Sciences, Moscow (Russian Federation); Kazantsev, S Yu; Saifulin, A V; Firsov, K N [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2003-06-30

259

Collisionless Damping of Localized Plasma Waves and Stimulated Raman Scattering in Filaments in Laser-Produced Plasmas  

NASA Astrophysics Data System (ADS)

In an accompanying talk,(A. Simon and R. W. Short, this conference.)* it is shown that the collisionless damping of plasma waves in a localized region may differ substantially from what would be expected on the basis of the familiar theory of Landau damping in an infinite homogeneous medium. Here we apply this analysis to the damping of plasma oscillations driven in a cylindrical region as a model of stimulated Raman scattering in a self-focused filament of laser light. We find that for large radii the Landau result is recovered as expected, but for radii smaller than a few wavelengths the damping is greatly reduced. Thus filaments of this size with high intensity and correspondingly low density provide a possible source of the strong short-wavelength SRS emission observed in NIF-scale laser--plasma interaction experiments,(B. J. MacGowan et al)., Phys. Plasmas 3, 2029 (1996).*^,*(D. S. Montgomery et al)., 25th Anom. Abs. Conf., Aspen CO (1995).* which would otherwise be expected to be strongly suppressed by Landau damping. The filament sizes and intensities required to explain the observations are shown to be consistent with recent simulations of the final state of the filamentation process.(F. Vidal and T. W. Johnston, Phys. Rev. Lett. 77), 1282 (1996).* This work was supported by the U.S. DOE Office of Inertial Confinement Fusion under Co-op Agreement No. DE-FC03-92F19460.

Short, R. W.; Simon, A.

1997-11-01

260

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

261

Temperature measurements in plasmas produced by high-power lasers interacting with solid targets  

SciTech Connect

One of the main goals of the study of plasmas generated by short or ultrashort laser pulses is the estimation of a complex parameter as the evaluation of the plasma temperature. Considering the laser-target and laser-plasma interactions as nonequilibrium processes, it is not possible to define a unique plasma temperature because the behavior of the different subsystems such as ions, electrons, neutral particles, and photons is not uniformly correlated, and the physical parameters can be different in different values of the plasma plume. In this work different experimental setups and techniques and different empirical and theoretical approaches are compared by using a Nd:YAG laser with an intensity of 10{sup 10} W/cm{sup 2} and an iodine laser with an intensity of 10{sup 15}-10{sup 16} W/cm{sup 2}. Time-of-flight measurements have been performed with an ion-energy analyzer and by using a number of Faraday cups in order to measure the velocity and the kinetic energy of ions and electrons emitted by the plasma. The obtained results have been relevant to confirm that by using a Nd:YAG laser the plasma ion temperature in the plasma core is about 400 eV. The electron emission indicates the presence of hot electrons with an energy of about 1 keV. These results will be compared with the ones obtained with the powerful iodine laser at Prague Asterix Laser System.

Torrisi, L.; Gammino, S.; Picciotto, A.; Margarone, D.; Laska, L.; Krasa, J.; Rohlena, K.; Wolowski, J. [INFN-Laboratori Nazionali del Sud, Via Santa Sofia 44, 95123 Catania, Italy and Dipartimento di Fisica, Universita di Messina, Contrada Papardo 33, 98166 Sant'Agata, Messina (Italy); INFN-Laboratori Nazionali del Sud, Via Santa Sofia 44, 95123 Catania (Italy); Dipartimento di Fisica, Universita di Messina, Contrada Papardo 33, 98166 Sant'Agata, Messina (Italy); Institute of Physics, ASCR, Na Slovance 2, 182 21 Prague 8 (Czech Republic); Institute of Plasma Physics and Laser Microfusion, Hery Street, P.O. Box 49, 2300-908 Warsaw, Warsaw (Poland)

2006-03-15

262

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

263

Thermal and mechanical properties of cordierite, mullite and steatite produced by plasma spraying  

Microsoft Academic Search

Cordierite, mullite and steatite are silicate materials widely used in the ceramics industry. There is, however, only sparse information on their application in plasma spraying and properties of sprayed materials. Plasma sprayed deposits of cordierite, mullite and steatite contain amorphous phases as the result of rapid cooling of molten particles. The amorphous phase has a significant influence on physical properties,

P Rohan; K Neufuss; J Mat?jí?ek; J Dubský; L Prchl??k; C Holzgartner

2004-01-01

264

Isolation, identification and biological activity of a phyllanthoside metabolite produced in vitro by mouse plasma  

Microsoft Academic Search

The antitumor agent phyllanthoside is rapidly metabolized in vitro by mouse plasma [4]. This metabolite has now been isolated from mouse plasma and its structural properties and cytotoxicity characterized. The isolated metabolite was estimated to be >98% pure by HPLC analysis. Mass spectral analysis (fast atom bombardment and tandem mass spectrometry) indicated that the metabolite was the aglycone of phyllanthoside

Dennis E. Chapman; David J. Moore; Deborah C. Melder; Alan Breau; Garth Powis

1989-01-01

265

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

266

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

267

Plasma-beta dependence of the fast reconnection mechanism in an initially force-free current sheet  

SciTech Connect

The present paper systematically studies the spontaneous fast reconnection mechanism in an initially force-free current sheet in a wide range of plasma beta ({beta}); in our previous work it was studied for a special case of {beta} = 0.15. In each case, the evolution as well as the resulting structure of the fast reconnection is qualitatively similar to the one that was already reported for the case of {beta} = 0.15. Quantitatively, the fast reconnection evolution becomes more rapid and drastic for the lower plasma beta. For the cases of very low plasma beta ({beta} = 0.01 or 0.02), the plasma temperature is extremely enhanced to the value almost 1/{beta} times larger than its initial value in the resulting fast reconnection jet and large-scale plasmoid regions. Once the fast reconnection mechanism is ignited in a local spot-like region, its basic structure eventually established is sustained almost steadily, giving rise to the plasmoid swelling with time and propagating outwards. Accordingly, the characteristic reconnection regions, where plasma thermodynamic quantities are remarkably enhanced, rapidly expand in all (x, y, and z) directions in Alfven time scales, which may be responsible for the explosive expansion of large flares as well as for the distinct plasma heating observed in the solar corona.

Ugai, M. [Research Center for Space and Cosmic Evolution, Ehime University, Matsuyama 790-8577 (Japan)

2011-10-15

268

Absolute soft x-ray calibration of laser produced plasmas using a focusing crystal von Hamos spectrometer  

NASA Astrophysics Data System (ADS)

Absolute x-ray calibration of laser-produced plasmas was performed using a focusing crystal von Hamos spectrometer. The plasmas were created by an Nd-YAG laser (0.53 ?m/200 mJ/3 ns/10 Hz) on massive solid targets (Mg, Cu, Zn, Sn, Mo, Ta, Ti, Steel). Cylindrical mica crystal (radius of curvature R=20 mm) and a CCD linear array detector (Toshiba model TCD 1304AP) were used in the spectrometer. Both the mica crystal and CCD linear array were absolutely calibrated in the spectral range of ?=7-15 Å. The spectrometer was used for absolute spectral measurements and the determination of the plasma parameters. The unique target design allowed for multiple instruments to observe the plasma simultaneously which improved analysis. High spectrometer efficiency allows for the monitoring of absolute x-ray spectra, x-ray yield and plasma parameters in each laser shot. This spectrometer is promising for absolute spectral measurements and for monitoring laser-plasma sources intended for proximity print lithography.

Weeks, T.; Harrison, M.; Johnson, M.; Shevelko, A. P.; Ellsworth, J.; Bergeson, S.; Asplund, M.; Knight, L. V.

2005-08-01

269

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

270

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

E-print Network

- resolved field measurements are a necessity [7,8], and experiments involving strongly coupled, warm dense,10,13­15]. The laser heats the material, forming an expanding, hemispherical plasma bubble with an intense, toroidal B

271

Thermal inequilibrium of atmospheric helium microwave plasma produced by an axial injection torch  

SciTech Connect

The population density of several excited states has been obtained spectroscopically in a helium plasma sustained by a torch device at atmospheric pressure as a function of the radius in the plasma for different conditions of microwave power and plasma gas flow. The ground-state atom density is determined from the gas temperature, which is deduced from the rotational temperature of the molecular nitrogen ions. The population distribution is fitted to the theoretical results of a collisional-radiative model that includes particle transport. A large deviation of the measured populations is found from the theoretical populations for local thermodynamic equilibrium. The plasma at any radial position is far from local thermodynamic equilibrium; the equilibrium deviation parameter of the ground state is larger than 10 000. The equilibrium deviation parameters of the measured excited-state populations obey the theoretical p{sub k}{sup -6} exponential law.

Alvarez, R.; Rodero, A.; Quintero, M.C.; Sola, A.; Gamero, A.; Ortega, D. [Department of Physics, University of Cordoba, Rabanales Campus, Albert Einstein Building, E-14071 Cordoba (Spain)

2005-11-01

272

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

273

Propagation velocities of laser-produced plasmas from copper wire targets and water droplets  

NASA Technical Reports Server (NTRS)

Experiments were performed to determine the plasma propagation velocities resulting from KrF laser irradiation of copper wire target (75 microns diameter) and water droplets (75 microns diameter) at irradiance levels ranging from 25 to 150 GW/sq cm. Plasma propagation velocities were measured using a streak camera system oriented orthogonally to the high-energy laser propagation axis. Plasma velocities were studied as a function of position in the focused beam. Results show that both the shape of the plasma formation and material removal from the copper wire are different and depend on whether the targets are focused or slightly defocused (approximately = 0.5 mm movement in the beam axis). Plasma formation and its position relative to the target is an important factor in determining the practical focal point during high-energy laser interaction with materials. At irradiance of 100 GW/sq cm, the air plasma has two weak-velocity components which propagate toward and away from the incident laser while a strong-velocity component propagates away from the laser beam as a detonation wave. Comparison of the measured breakdown velocities (in the range of 2.22-2.27 x 10(exp 5) m/s) for air and the value calculated by the nonlinear breakdown wave theory at irradiance of 100 GW/sq cm showed a quantitative agreement within approximately 50% while the linear theory and Gaussian pulse theory failed. The detonation wave velocities of plasma generated from water droplets and copper wire targets for different focused cases were measured and analyzed theoretically. The propagation velocities of laser-induced plasma liquid droplets obtained by previous research are compared with current work.

Song, Kyo-Dong; Alexander, Dennis R.

1994-01-01

274

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.

275

Internal tests and improvements of the Krook model for nonlocal electron energy transport in laser produced plasmas  

SciTech Connect

Electron thermal transport in a laser produced plasma cannot be described with a local approximation in many regions of a laser produced plasma because the electron mean free path is longer than the temperature gradient scale length. Since a Krook model for the electron Vlasov equation is analytically solvable in the nonlocal limit, one can find simple expressions for the electron thermal flux in the nonlocal limit, and these can be economically incorporated into fluid simulations. The Krook model provides reasonable descriptions of both preheat and flux limitation. We have analyzed the Krook model in a series of publications. Here we streamline the presentation of the model, show qualitatively just what the model predicts in certain situations, give internal tests to check the validity of the model, and provide more accurate analytic approximations to the integral formulas which the model gives rise to.

Colombant, Denis G.; Manheimer, Wallace M. [Naval Research Laboratory, Code 6730, Plasma Physics Division, Washington, DC 20375 (United States)

2010-11-15

276

A hemispherical Langmuir probe array detector for angular resolved measurements on droplet-based laser-produced plasmas.  

PubMed

In this work, a new diagnostic tool for laser-produced plasmas (LPPs) is presented. The detector is based on a multiple array of six motorized Langmuir probes. It allows to measure the dynamics of a LPP in terms of charged particles detection with particular attention to droplet-based LPP sources for EUV lithography. The system design permits to temporally resolve the angular and radial plasma charge distribution and to obtain a hemispherical mapping of the ions and electrons around the droplet plasma. The understanding of these dynamics is fundamental to improve the debris mitigation techniques for droplet-based LPP sources. The device has been developed, built, and employed at the Laboratory for Energy Conversion, ETH Zürich. The experimental results have been obtained on the droplet-based LPP source ALPS II. For the first time, 2D mappings of the ion kinetic energy distribution around the droplet plasma have been obtained with an array of multiple Langmuir probes. These measurements show an anisotropic expansion of the ions in terms of kinetic energy and amount of ion charge around the droplet target. First estimations of the plasma density and electron temperature were also obtained from the analysis of the probe current signals. PMID:25273714

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

2014-09-01

277

A hemispherical Langmuir probe array detector for angular resolved measurements on droplet-based laser-produced plasmas  

NASA Astrophysics Data System (ADS)

In this work, a new diagnostic tool for laser-produced plasmas (LPPs) is presented. The detector is based on a multiple array of six motorized Langmuir probes. It allows to measure the dynamics of a LPP in terms of charged particles detection with particular attention to droplet-based LPP sources for EUV lithography. The system design permits to temporally resolve the angular and radial plasma charge distribution and to obtain a hemispherical mapping of the ions and electrons around the droplet plasma. The understanding of these dynamics is fundamental to improve the debris mitigation techniques for droplet-based LPP sources. The device has been developed, built, and employed at the Laboratory for Energy Conversion, ETH Zürich. The experimental results have been obtained on the droplet-based LPP source ALPS II. For the first time, 2D mappings of the ion kinetic energy distribution around the droplet plasma have been obtained with an array of multiple Langmuir probes. These measurements show an anisotropic expansion of the ions in terms of kinetic energy and amount of ion charge around the droplet target. First estimations of the plasma density and electron temperature were also obtained from the analysis of the probe current signals.

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

2014-09-01

278

Emission study of alumina plasma produced by a KrF laser  

NASA Astrophysics Data System (ADS)

We report on the plasma emission formed from an ?-alumina target when irradiated by laser into vacuum and through oxygen gas. Two diagnostic tools have been used: ICCD camera fast imaging and optical emission spectroscopy. The alumina plasma was induced by a KrF laser beam at a wavelength of 248 nm and pulse duration of 25 ns. The laser fluence was set to 8 J/cm2 and the oxygen pressure was varied from 0.01 to 5 mbar. By using the ICCD camera, two dimensional images of the plasma expansion were taken at different times. Depending on oxygen pressure and time delay, the expansion behavior of the plasma showed free expansion, plume splitting, shock wave formation, hydrodynamic instability and deceleration of the plume. Using optical emission spectroscopy, the plasma emission revealed the presence of neutral Al I, Al II, Al III into vacuum and under oxygen ambiance. The molecular emission of aluminum oxide (AlO) was detected only in oxygen ambiance. It should be noted that no oxygen lines were observed. Finally, the evolution of the electronic temperature along the normal axis from the target surface, into vacuum, was estimated using the Boltzmann plot method.

Yahiaoui, K.; Abdelli-Messaci, S.; Messaoud-Aberkane, S.; Kerdja, T.; Kellou, H.

279

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

Microsoft Academic Search

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

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

1981-01-01

280

Note: Study of extreme ultraviolet and soft x-ray emission of metal targets produced by laser-plasma-interaction  

Microsoft Academic Search

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\\/Deltalambda = 150 at 1 nm up to lambda\\/Deltalambda = 1100 at 15 nm. Intense line emission features of highly ionized species as well as continuum-like

I. Mantouvalou; R. Jung; J. Tuemmler; H. Legall; T. Bidu; H. Stiel; W. Malzer; B. Kanngießer; W. Sandner

2011-01-01

281

Dust charge measurement in a strongly coupled dusty plasma produced by an rf discharge  

NASA Astrophysics Data System (ADS)

The electric charge on silica microparticles (5 µm in diameter) levitating in the sheath of an rf discharge plasma is determined in a newly installed device for dusty plasma experiments at the IASST. The sheath potential profile is measured using an emissive probe and the electric field is obtained in order to determine the dust charge. The measured dust charge in the pressure range 0.50-5.0 Pa using the electric field value at the levitation height is found to be of the order of 104 elementary charges. Dust charge is also examined using the vertical resonance method which gives a similar order of charges. The experimentally measured charge is compared with the estimated values based on the orbital motion limited charging model. The coupling strength between the particles forming a 2D plasma crystal lattice is estimated using the measured dust charge.

Sharma, S. K.; Kalita, Ranjan; Nakamura, Y.; Bailung, H.

2012-08-01

282

Modeling of strongly collimated jets produced by high energy density plasmas on COBRA  

NASA Astrophysics Data System (ADS)

Jet collimation in astrophysical plasmas and in the laboratory has recently received much attention. When the magnetohydrodynamics (MHD) model is used to represent both systems, scale invariance allows for the simple extension of the parameters encountered in laboratory experiments to much larger systems, like astrophysical outflows. However, the validation of such a model requires a precise comparison of numerical simulations with experimental data. Using radial foils as an experimental setup to generate strongly collimated plasma jets, we show that the Hall MHD model included in the PERSEUS code does well to capture the plasma dynamics of collimated jets, even with restrictive conditions such as a constant ionization number and the neglect of normally important transport processes. Very importantly, we show that jet collimation is not only the result of magnetic forces, but also converging radial flows.

Gourdain, P.-A.; Seyler, C. E.

2014-03-01

283

Bragg scattering of electromagnetic waves by microwave-produced plasma layers  

NASA Technical Reports Server (NTRS)

A set of parallel plasma layers is generated by two intersecting microwave pulses in a chamber containing dry air at a pressure comparable to the upper atmosphere. The dependencies of breakdown conditions on the pressure and pulse length are examined. The results are shown to be consistent with the appearance of tail erosion of the microwave pulse caused by air breakdown. 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 experimental results are found to agree very well with the theory.

Kuo, S. P.; Zhang, Y. S.

1990-01-01

284

Time-resolved evolution of laser-produced plasmas in spherical expansion regime  

SciTech Connect

We report experimental results deduced from quantitative Schlieren imaging of plasmas combined with streak camera recording. Flat or spherical targets are illuminated with one laser beam, at different wavelengths (1.06 ..mu..m, 0.53 ..mu..m, 10.6 ..mu..m): We show that time-resolved density profiles are more stationary for shorter wavelength. We measure the rear displacement and front expansion of plasmas created on glass microballoons and solid microspheres. Comparison with hydrocode simulations shows that transport is inhibited for 1.06-..mu..m interaction, and that ablation processes are more efficient for shorter wavelength.

Benattar, R.; Popovics, C.

1983-02-01

285

Clathrin-dependent and -independent internalization of plasma membrane sphingolipids initiates two Golgi targeting pathways  

Microsoft Academic Search

phingolipids (SLs) are plasma membrane constituents in eukaryotic cells which play important roles in a wide variety of cellular functions. However, little is known about the mechanisms of their internalization from the plasma membrane or subsequent intracellular targeting. We have begun to study these issues in human skin fibroblasts using fluorescent SL analogues. Using selective endocytic inhibitors and dominant negative

Vishwajeet Puri; Rikio Watanabe; Raman Deep Singh; Michel Dominguez; Jennifer C. Brown; Christine L. Wheatley; David L. Marks; Richard E. Pagano

2001-01-01

286

Multidimensional non local effects in hot spot relaxation in laser-produced plasmas  

NASA Astrophysics Data System (ADS)

The control of parametric instabilities, such as filamentation and stimulated scattering is a necessity for the Inertial Confinement Fusion (ICF). The plasma temperature and density distribution directly affect the laser beam propagation and the energy deposition. Under sharp gradients created by non-uniform laser heating, the size of hot spots is often comparable to the electron mean free path and the electron heat transport becomes nonlocal. Furthermore, the hot spot form is not necessarily spherical and a one dimensional analysis is insufficient. This work presents the multi-dimensional effects of the non local electron transport on the plasma response induced by a single hot spot or multi hot spots. In addition, in non spherical speckles, we show that crossed gradients of density and temperature generate vortical flows and magnetic fields. These self generated magnetic fields combined with nonlocal heat transport effects [Ph. Nicolai et al Phys. PLasmas 13, 032701 (2006)] could strongly change the life time of hot spots. Thanks to the use of a 2D multi-physics hydrodynamic code, we investigate the LIL facility quadruplet conditions for long time periods and large plasma conditions [the LIL facility is a full scale bundle of 4 Laser Mega Joule (LMJ) beams]. It appears that in a realistic case, our model indicates a dramatic change of the temperature and density distributions.

Nicolai, P. H.; Feugeas, J. L.; Ribeyre, X.; Grech, M.; Schurtz, G.

2007-11-01

287

The Formation of a Tokamak-like Plasma in Initial Experiments Using an Outboard Plasma Gun Current Source  

Microsoft Academic Search

Solenoid-free tokamak startup via point-source DC helicity injection is demonstrated on the Pegasus Toroidal Experiment using\\u000a a high current density, low impurity plasma gun mounted near the outboard midplane. A threshold in the vacuum vertical magnetic\\u000a field strength that allows the injected current filament to relax into a tokamak-like topology is observed. A simple 2-D model\\u000a of the vacuum magnetic

D. J. Battaglia; M. W. Bongard; R. J. Fonck; A. J. Redd; A. C. Sontag

2009-01-01

288

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

289

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

290

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

291

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

NASA Astrophysics Data System (ADS)

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.

2013-01-01

292

Expansion dynamics of ultrafast laser produced plasmas in the presence of ambient argon  

NASA Astrophysics Data System (ADS)

We investigated the expansion dynamics of fs laser ablated brass plasma in Ar at various pressure levels ranging from 10-5 Torr to atmospheric conditions using time-resolved and spectrally resolved two-dimensional imaging. Significant changes in plume morphology were noticed at varying pressure levels which included free expansion, spherical to cylindrical geometry changes, sharpening, and confinement. The temporal evolution of excited Cu and Zn species in the plume were imaged using narrow band-pass interference filters, and their hydrodynamic expansion features were compared. 2D imaging coupled with monochromatic line selection showed velocity differences, uneven distribution, and aspect ratio differences among the plume species. Plume morphological changes were found to be significant at intermediate pressure levels (˜10 Torr) where plasma emissivity was found to be maximum. The expansion features of plume were compared with various models and found to be generally in good agreement.

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

2014-10-01

293

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/2πsr 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

294

Studies of the optical properties of laser plasmas produced by irradiating spherical targets  

Microsoft Academic Search

Results are presented from studies of the spectral characteristics of a glowing plasma object that forms behind a shock wave\\u000a propagating in a background gas at a pressure of 1 Torr after laser irradiation of a spherical organic target in the MKV-4\\u000a device (a component of the Iskra-5 facility). The experimental data are compared to the results of calculations.

V. D. Atamanenko; A. V. Bessarab; G. A. Bondarenko; G. V. Dolgoleva; V. A. Zhma?lo; A. G. Kravchenko; V. V. Mis’ko; V. M. Murugov; E. A. Novikova; A. S. Pavlunin; I. V. Popov; V. A. Starodubtsev; V. P. Statsenko

2006-01-01

295

Heating dynamics and extreme ultraviolet radiation emission of laser-produced Sn plasmas  

E-print Network

. A multilayer concave Mo/Si mirror is placed perpendicular to the pump beam and focuses the EUV light with FWHM.e., multilayer Mo/Si mirrors.1 For Sn based plasmas the major- ity of the in-band EUV is generated elsewhere.5 A back-illuminated x-ray CCD camera was employed in a time-integrated in-band EUV imaging system

Najmabadi, Farrokh

296

Characterization of low-temperature silicon nitride films produced by inductively coupled plasma chemical vapor deposition  

Microsoft Academic Search

Silicon nitride films were synthesized at 170 deg. C by using inductively coupled plasma chemical vapor deposition under three microwave power conditions of 500, 800, and 1000 W. The chemical, physical and electrical properties of the deposited silicon nitride films were characterized by Fourier transform infrared, wet etching, atomic force microscopy, ellipsometry, J-V, and C-V measurements of metal-insulator-semiconductor. The microwave

Q. Xu; Y. Ra; M. Bachman; G. P. Li

2009-01-01

297

X-Ray Spectroscopy of Dense Plasmas Produced by Isochoric Heating with Ultrashort Laser Pulses  

SciTech Connect

Hot plasma with temperatures up to 500 eV and densities close to solid state have been generated by focusing intense ultrashort laser pulses on flat solid targets. The heating process is attributed to the energetic electrons, which are created during the laser plasma interaction. They propagate deeply into the target and heat it isochorically. The laser was a frequency-doubled Ti:Sapphire laser with an energy of 60 mJ and a pulse duration of 150 fs. It was focused on layered plane solid targets with an incidence angle of 45 deg. and p-polarized. The K-shell spectra emitted from thin Al sample layers embedded in solid carbon show features such as line broadening, line shift and strong satellite emission, which are characteristic of dense plasmas. The typical duration of the x-ray emission is a few ps. Al targets covered by a diamond layer show that the depth (expressed through areal density) up to which the target is heated is close to 1 mg/cm2, which corresponds to the range of 20 keV electrons. This means that a considerable fraction of 20 to 25% of the incident laser energy is deposited by the hot electrons in the target.

Eidmann, K.; Andiel, U.; Pisani, F.; Witte, K. [Max Planck Institut fuer Quantenoptik, D-85740 Garching (Germany); Hakel, P.; Abdallah, J.; Junkel-Vives, G.C. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Mancini, R.C. [Department of Physics, University of Nevada, Reno, NV 89557-0058 (United States)

2004-10-20

298

Non-inductive plasma initiation and plasma current ramp-up on the TST-2 spherical tokamak  

NASA Astrophysics Data System (ADS)

Plasma current (Ip) start-up in a spherical tokamak (ST) by waves in the lower-hybrid (LH) frequency range was investigated on TST-2. A low current (˜1 kA) ST configuration can be formed by waves over a broad frequency range (21 MHz-8.2 GHz in TST-2), but further Ip ramp-up (to ˜10 kA) is most efficient with waves in the LH frequency range. Ip ramp-up to 15 kA was achieved with 60 kW of net RF power PRF in the fast wave (FW) polarization at 200 MHz excited by the inductively coupled combline antenna. X-ray measurements showed that the photon flux and temperature are higher in the direction opposite to Ip, consistent with acceleration of electrons by a uni-directional RF wave. There is evidence that the LH wave is excited nonlinearly by the FW, based on the frequency spectra measured by magnetic probes. Similar efficiencies of Ip ramp-up were obtained with the inductive combline antenna and the dielectric-loaded waveguide array (‘grill’) antenna, and tendencies for the current drive efficiency to increase with plasma current and toroidal field were observed. During operation of the grill antenna, wavevector components were measured by an array of magnetic probes. Results were qualitatively consistent with expectations based on dispersion relations for the FW and the LH wave. A capacitively coupled combline antenna has been developed to improve coupling to the plasma and the wavenumber spectrum of the excited LH wave, and will be tested in 2013.

Takase, Y.; Ejiri, A.; Kakuda, H.; Oosako, T.; Shinya, T.; Wakatsuki, T.; Ambo, T.; Furui, H.; Hashimoto, T.; Hiratsuka, J.; Kasahara, H.; Kato, K.; Kumazawa, R.; Moeller, C. P.; Mutoh, T.; Nakanishi, A.; Nagashima, Y.; Saito, K.; Sakamoto, T.; Seki, T.; Sonehara, M.; Shino, R.; Togashi, H.; Watanabe, O.; Yamaguchi, T.

2013-06-01

299

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

300

Detection of energetic ions emitted from laser-produced plasma by means of CR39 solid state nuclear track detectors  

NASA Astrophysics Data System (ADS)

The iodine laser PALS, operated at the fundamental and third harmonic frequencies (wavelengths 1315 and 438 nm, respectively), was used to generate plasmas on various targets (Au,CF2, etc.). The investigation was performed at energies up to 400 and 250 J for 1? and 3?, respectively, in the 300 ps pulses. In these conditions several samples of solid state nuclear track detectors CR39 type, have been located at suitable geometrical positions to explore their capability to measure main parameters of ions emitted from the laser-produced plasmas. Track diameters and densities were observed on the uncovered detectors exposed to a lot of laser shots. Emitted ions in the energy range up to few tens of MeV, have been observed on the basis of ion collector TOF spectra. Track pattern results are shown and discussed in comparison with mentioned spectra and simulations.

Cavallaro, S.; Margarone, D.; Torrisi, L.; Laska, L.; Krasa, J.; Ullschmied, J.

301

Chemically produced tungsten-praseodymium oxide composite sintered by spark plasma sintering  

NASA Astrophysics Data System (ADS)

Pr2O3 doped W composite were synthesized by a novel wet chemical method and spark plasma sintering. The grain size, relative density and the Vicker hardness HV0.2 of Pr2O3/W samples were 4 ?m, 98.3% and 377.2, respectively. The tensile strength values of Pr2O3/W were higher than those of pure W. As the temperature rises from 25 °C to 800 °C, the conductivity of pure W and W-1 wt% Pr2O3 composites decreased with the same trend, was above 150 W/m K.

Ding, Xiao-Yu; Luo, Lai-Ma; Lu, Ze-Long; Luo, Guang-Nan; Zhu, Xiao-Yong; Cheng, Ji-Gui; Wu, Yu-Cheng

2014-11-01

302

Erosion performance of coatings produced by shrouded plasma spray process on a Co-based superalloy  

Microsoft Academic Search

Erosion studies were carried out using an air-jet erosion test rig at a velocity of 40 m s?1 and impingement angles of 30° and 90° on uncoated Co-based Superalloy (3Fe–10Ni–20Cr–1.5Mn–0.3Si–0.08C–15W–Balance Co) as well as plasma spray NiCrAlY-, Ni–20Cr- and Ni3Al-coated superalloy specimens at room temperature. Coatings were characterised before the erosion test. The eroded surfaces have been examined by SEM\\/EDAX and optical

S. B. Mishra; K. Chandra; S. Prakash; B. Venkataraman

2006-01-01

303

Polyurethane coating with thin polymer films produced by plasma polymerization of diglyme  

NASA Astrophysics Data System (ADS)

Aqueous-based polyurethane dispersions have been widely utilized as lubricants in textile, shoes, automotive, biomaterial and many other industries because they are less aggressive to surrounding environment. In this work thin films with different thickness were deposited on biocompatible polyurethane by plasma polymerization process using diethylene glycol dimethyl ether (Diglyme) as monomer. Molecular structure of the films was analyzed by Fourier Transform Infrared spectroscopy. The spectra exhibited absorption bands of O-H (3500-3200cm-1), C-H (3000-2900cm-1), C=O (1730-1650cm-1), C-O and C-O-C bonds at 1200-1600cm-1. The samples wettability was evaluated by measurements of contact angle using different liquids such as water, glycerol, poly-ethane and CMC. The polyurethane surface showed hydrophilic behavior after diglyme plasma-deposition with contact angle dropping from 85° to 22°. Scanning Electron Microscopy revealed that diglyme films covered uniformly the polyurethane surfaces ensuring to it a biocompatible characteristic.

Ribeiro, M. A.; Ramos, A. S.; Manfredini, M. I.; Alves, H. A.; Y Honda, R.; Kostov, K. G.; Lucena, E. F.; Ramos, E. C. T.; Mota, R. P.; Algatti, M. A.; Kayama, M. E.

2009-05-01

304

Direct observation of turbulent magnetic fields in hot, dense laser produced plasmas  

PubMed Central

Turbulence in fluids is a ubiquitous, fascinating, and complex natural phenomenon that is not yet fully understood. Unraveling turbulence in high density, high temperature plasmas is an even bigger challenge because of the importance of electromagnetic forces and the typically violent environments. Fascinating and novel behavior of hot dense matter has so far been only indirectly inferred because of the enormous difficulties of making observations on such matter. Here, we present direct evidence of turbulence in giant magnetic fields created in an overdense, hot plasma by relativistic intensity (1018W/cm2) femtosecond laser pulses. We have obtained magneto-optic polarigrams at femtosecond time intervals, simultaneously with micrometer spatial resolution. The spatial profiles of the magnetic field show randomness and their k spectra exhibit a power law along with certain well defined peaks at scales shorter than skin depth. Detailed two-dimensional particle-in-cell simulations delineate the underlying interaction between forward currents of relativistic energy “hot” electrons created by the laser pulse and “cold” return currents of thermal electrons induced in the target. Our results are not only fundamentally interesting but should also arouse interest on the role of magnetic turbulence induced resistivity in the context of fast ignition of laser fusion, and the possibility of experimentally simulating such structures with respect to the sun and other stellar environments. PMID:22566660

Mondal, Sudipta; Narayanan, V.; Ding, Wen Jun; Lad, Amit D.; Hao, Biao; Ahmad, Saima; Wang, Wei Min; Sheng, Zheng Ming; Sengupta, Sudip; Kaw, Predhiman; Das, Amita; Kumar, G. Ravindra

2012-01-01

305

Direct observation of turbulent magnetic fields in hot, dense laser produced plasmas.  

PubMed

Turbulence in fluids is a ubiquitous, fascinating, and complex natural phenomenon that is not yet fully understood. Unraveling turbulence in high density, high temperature plasmas is an even bigger challenge because of the importance of electromagnetic forces and the typically violent environments. Fascinating and novel behavior of hot dense matter has so far been only indirectly inferred because of the enormous difficulties of making observations on such matter. Here, we present direct evidence of turbulence in giant magnetic fields created in an overdense, hot plasma by relativistic intensity (10(18) W/cm(2)) femtosecond laser pulses. We have obtained magneto-optic polarigrams at femtosecond time intervals, simultaneously with micrometer spatial resolution. The spatial profiles of the magnetic field show randomness and their k spectra exhibit a power law along with certain well defined peaks at scales shorter than skin depth. Detailed two-dimensional particle-in-cell simulations delineate the underlying interaction between forward currents of relativistic energy "hot" electrons created by the laser pulse and "cold" return currents of thermal electrons induced in the target. Our results are not only fundamentally interesting but should also arouse interest on the role of magnetic turbulence induced resistivity in the context of fast ignition of laser fusion, and the possibility of experimentally simulating such structures with respect to the sun and other stellar environments. PMID:22566660

Mondal, Sudipta; Narayanan, V; Ding, Wen Jun; Lad, Amit D; Hao, Biao; Ahmad, Saima; Wang, Wei Min; Sheng, Zheng Ming; Sengupta, Sudip; Kaw, Predhiman; Das, Amita; Kumar, G Ravindra

2012-05-22

306

Absolute evaluation of out-of-band radiation from laser-produced tin plasmas for extreme ultraviolet lithography  

SciTech Connect

Out-of-band (OOB) radiation (at wavelengths longer than 130 nm) from an extreme ultraviolet (EUV) light source reduces the precision of lithography. The energy of the OOB radiation from laser-produced Sn plasmas were measured by using an absolutely calibrated transmission grating spectrometer equipped with a charge-coupled device. The dependence of the OOB radiant energy on the mass and size of the tin fuel was clarified. The dominant source of the OOB radiation is peripheral heating around the laser spot via electron thermal conduction and radiation from the high-temperature EUV emission region.

Sakaguchi, Hirokazu; Fujioka, Shinsuke; Shimomura, Masashi; Nakai, Yuki; Kimura, Yasuko; Yasuda, Yuzuri; Nishimura, Hiroaki; Norimatsu, Takayoshi; Nishihara, Katsunobu; Miyanaga, Noriaki; Izawa, Yasukazu; Mima, Kunioki [Institute of Laser Engineering, Osaka University, 2-6 Yamada-Oka, Suita, Osaka 565-0871 Japan (Japan); Namba, Shinichi [Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527 (Japan); Tanuma, Hajime; Ohashi, Hayato; Suda, Shintaro [Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397 (Japan); Sunahara, Atsushi [Institute of Laser Technology, 2-6 Yamada-Oka, Suita, Osaka 565-0871 Japan (Japan)

2008-03-17

307

Density measurements in exploding wire-initiated plasmas using tungsten wires  

Microsoft Academic Search

Calibrated density measurements have been obtained of the coronal plasmas around exploding 7.5-40 mum W wires carrying 15-120 kA per wire for 30-70 ns. X-ray radiographs of the exploding wire plasmas using 2.5-10 keV photons from a Mo wire X-pinch backlighter enabled measurements of areal densities of W ranging from 2×1017\\/cm2, equivalent to 0.03 mum of solid density W, to

S. A. Pikuz; T. A. Shelkovenko; A. R. Mingaleev; D. A. Hammer; H. P. Neves

1999-01-01

308

Density measurements in exploding wire-initiated plasmas using tungsten wires  

Microsoft Academic Search

Calibrated density measurements have been obtained of the coronal plasmas around exploding 7.5–40 ?m W wires carrying 15–120 kA per wire for 30–70 ns. X-ray radiographs of the exploding wire plasmas using 2.5–10 keV photons from a Mo wire X-pinch backlighter enabled measurements of areal densities of W ranging from 2×1017\\/cm2, equivalent to 0.03 ?m of solid density W, to

S. A. Pikuz; T. A. Shelkovenko; A. R. Mingaleev; D. A. Hammer; H. P. Neves

1999-01-01

309

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

310

Three dimensional analysis of longitudinal plasma oscillations in a thermal relativistic electron beam: Application to an initial value problem  

SciTech Connect

In this paper, we study the initial value problem of longitudinal plasma oscillations in a relativistic electron beam. Our analysis is based on the formalism developed in Marinelli et al.[Phys. Plasmas 18, 103105 (2011)]. We study the evolution of an arbitrary six-dimensional phase-space perturbation under the effect of longitudinal space-charge forces, with the inclusion of three-dimensional effects due to the finite size of the beam, transverse betatron motion, and longitudinal thermal motion induced by both energy-spread and transverse emittance. We expand the phase-space perturbation in a series of eigenmodes of a Schroedinger-like equation, corresponding to a set of propagating space-charge waves. We develop a general formalism, which we use to find explicit expressions for the evolution of an initial perturbation coupled to the fundamental plasma eigenmode. This work has important applications in the theory of space-charge instabilities in high brightness electron beams and control of shot-noise in seeded free-electron lasers. We discuss the application of the present theory to a specific experimental scenario corresponding to a shot-noise suppression scheme at optical wavelengths.

Marinelli, Agostino [Particle Beam Physics Laboratory, Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095 (United States); Universita degli Studi di Roma La Sapienza, Via Antonio Scarpa 14, Rome 00161 (Italy); Hemsing, Erik [SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Rosenzweig, James B. [Particle Beam Physics Laboratory, Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095 (United States)

2012-06-15

311

X-ray Polarization Spectroscopy to Study Hot Electron Transport in High Intensity Laser Produced Plasma  

NASA Astrophysics Data System (ADS)

X-ray polarization spectroscopy was used to study anisotropy of hot electron velocity distribution functions (VDFs) in a plasma generated at 10^18W/cm^2. Chlorinated triple-layer targets were irradiated and polarization degree of Cl Hea line was measured as a function of overcoat thickness. The polarization degree, nearly zero at the surface, becomes negative then positive, and finally becomes zero with increase in the thickness. This result indicate that VDF in under-dens region is affected with laser field, and that in over-dense region is with acceleration along the laser propagation. Depolarization seen in the surface and dense region is consistent with predictions with a time-dependent atomic kinetics code [1]. [1] T. Kawamura, et al., PRL 99, 115003 (2007)

Nishimura, H.; Inubushi, Y.; Okano, Y.; Fujioka, S.; Kai, T.; Kawamura, T.; Batani, D.; Morace, A.; Redaelli, R.; Fourment, C.; Santos, J.; Malka, G.; Boscheron, A.; Casner, A.; Koenig, M.; Jhozaki, T.; Nagatomo, H.; Mima, K.

2008-11-01

312

The sound produced by a fast parton in the quark-gluon plasma is a "crescendo"  

E-print Network

We calculate the total energy deposited into the medium per unit length by fast partons traversing a quark-gluon plasma. The medium excitation due to collisions is taken to be given by the well known expression for the collisional drag force. The radiative energy loss of the parton contributes to the energy deposition because each radiated gluon acts as an additional source of collisional energy loss in the medium. We derive a differential equation which governs how the spectrum of radiated gluons is modified when this energy loss is taken into account. This modified spectrum is then used to calculate the additional energy deposition due to the interactions of radiated gluons with the medium. Numerical results are presented for the medium response for the case of two energetic back-to-back partons created in a hard interaction.

R. B. Neufeld; B. Muller

2009-02-17

313

Optimizing conversion efficiency and reducing ion energy in a laser-produced Gd plasma  

SciTech Connect

We have demonstrated an efficient extreme ultraviolet (EUV) source at 6.7 nm by irradiating Gd targets with 0.8 and 1.06 {mu}m laser pulses of 140 fs to 10 ns duration. Maximum conversion efficiency of 0.4% was observed within a 0.6% bandwidth. A Faraday cup observed ion yield and time of flight signals for ions from plasmas generated by each laser. Ion kinetic energy was lower for shorter pulse durations, which yielded higher electron temperatures required for efficient EUV emission, due to higher laser intensity. Picosecond laser pulses were found to be the best suited to 6.7 nm EUV source generation.

Cummins, Thomas; Li Bowen; O'Gorman, Colm; Dunne, Padraig; Sokell, Emma; O'Sullivan, Gerry [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Otsuka, Takamitsu [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); Yugami, Noboru; Higashiguchi, Takeshi [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); Jiang Weihua [Department of Electrical Engineering, Nagaoka University of Technology, Kami-tomiokamachi 1603-1, Nagaoka, Niigata 940-2188 (Japan); Endo, Akira [Research Institute for Science and Engineering, Waseda University, Okubo 3-4-1, Shinjuku, Tokyo 169-8555 (Japan)

2012-02-06

314

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

315

High-power EUV lithography sources based on gas discharges and laser-produced plasmas  

Microsoft Academic Search

Semiconductor chip manufacturers are expecting to use extreme UV lithography for production in 2009. EUV tools require high power, brilliant light sources at 13.5 nm with collector optics producing 120 W average power at entrance of the illuminator system. Today the power and lifetime of the EUV light source are considered as the most critical issue for EUV lithography. The

Uwe Stamm; Imtiaz Ahmad; Istvan Balogh; H. Birner; D. Bolshukhin; J. Brudermann; S. Enke; Frank Flohrer; Kai Gäbel; S. Götze; G. Hergenhan; Jürgen Kleinschmidt; Diethard Klöpfel; Vladimir Korobotchko; Jens Ringling; Guido Schriever; C. D. Tran; C. Ziener

2003-01-01

316

Study and modelling of a RF plasma producing analogues of Titan's aerosols  

Microsoft Academic Search

The aerosols of the Titan's atmosphere are produced in the Titan's stratosphere by photochemical reactions induced by the solar photons. The Cassini Huygens mission has provided for the first time in situ observations and measurements in the Titan's atmosphere. For instance, reflectance of the Titan's haze or Titan surface have to be compared with models including optical properties of the

C. Szopa; G. Cernogora; C. D. Pintassilgo; M. Cavarroc; L. Boufendi; J. Loureiro

2006-01-01

317

Getting the most out of your cerium oxide glass polishing slurry: reducing risk and improving performance with plasma produced particles  

NASA Astrophysics Data System (ADS)

Recent dramatic price volatility and assurance of supply concerns with cerium oxide have left many users of this material in an uncertain and vulnerable position. Since few viable alternatives to ceria for precision glass polishing exist, and much of the supply is very concentrated geographically, technology which conserves ceria, improves absolute removal rate and promotes slurry longevity becomes extremely attractive under these circumstances. Using a plasma-based process to produce cerium oxide confers some unique attributes to the particles which make them particularly well suited for precision glass polishing operations. Many of those same particle characteristics, such as full crystallinity, near theoretical density, very high surface and bulk purity and extremely high zeta potentials in water can also be useful in mitigating the risks associated with a limited and costly ceria supply. This paper will explore how plasma-derived particles, in combination with a high performance chemistry package, can together constitute a fully formulated precision glass polishing slurry with very high activity, extended slurry lifetime, ability to recycle, and excellent overall process economics. Results showing the effect of particle longevity and chemical additives on removal rate and process stability will be discussed in detail, and selected examples which distinguish the benefits of a fully formulated, plasma-derived cerium oxide polishing slurry over conventional milled ceria will be shown.

Murray, Patrick G.; Hooper, Abigail; Keleher, Jason; Kaiser, Jordan; Nichol, Meghan

2013-09-01

318

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

319

Shift and width of the Balmer series H? line at high electron density in a laser-produced plasma  

NASA Astrophysics Data System (ADS)

Time-resolved profiles of the Balmer series H? line emitted by a laser-produced hydrogen plasma have been measured to determine the shift and width for electron densities from below 1018 to above 1020 cm-3 at an average temperature of 28000 K. Fits of the profiles that allow for self-absorption in the plasma yield shifts and widths that are consistent with experiments on lower density and cooler gas-liner pinch plasmas. The width scales as N_{e}^{0.70+/- 0.03} and the shift as N_{e}^{0.92+/- 0.03} between 8.7\\times {{10}^{17}} and 1.4\\times {{10}^{20}} cm-3. H? shifts monotonically and nearly linearly to the red with increasing density under the reported conditions. A comparison to theory calculations using exact potentials for H_{2}^{+} shows that an intrinsic asymmetry becomes significant only in the upper limit of this range when a satellite develops in the far red wing.

Kielkopf, John F.; Allard, Nicole F.

2014-08-01

320

Fundamentals of Discharge Initiation in Gas-Fed Pulsed Plasma Thrusters  

E-print Network

at the 29th International Electric Propulsion Conference, Princeton University October 31 ­ November 4, 2005 James E. Cooley and Edgar Y. Choueiri Electric Propulsion and Plasma Dynamics Laboratory (EPPDy. A GFPPT is a pulsed electromagnetic accelerator in which small puffs of gas are injected between two

Choueiri, Edgar

321

High-resolution measurement of the He-[beta] spectra of heliumlike chromium for possible diagnostic of laser-produced plasmas  

SciTech Connect

High-resolution He-[beta] spectra of heliumlike chromium have been recorded in an effort to provide accurate atomic data useful for the development of diagnostics of the electron temperature and density for laser-produced plasmas. The He-[beta] spectra are of particular interest for these very-high-density plasmas ([ital n][sub [ital e

Decaux, V.; Beiersdorfer, P.; Elliott, S.; Osterheld, A. (Lawrence Livermore National Laboratory, University of California, Livermore, California 94551 (United States)); Clothiaux, E. (Department of Physics, Auburn University, Auburn, Alabama 36849 (United States))

1995-01-01

322

Time and space resolved visible spectroscopic imaging CO{sub 2} laser produced extreme ultraviolet emitting tin plasmas  

SciTech Connect

Experiments involving laser produced tin plasma have been carried out using a CO{sub 2} laser with an energy of 800 mJ/pulse and a full width at half maximum (FWHM) of 80 ns in vacuum. Time-integrated extreme ultraviolet spectral measurement showed that the peak of the extreme ultraviolet lithography spectrum was located at 13.5 nm and the spectrum profile's FWHM of the unresolved transition arrays was 1.1 nm. Plasma parameters of the electron temperature and density measurements in both axial and radial directions at later times had been obtained from a two-dimensional time and space resolved image spectra analysis. The axial spatial distribution of the electron density showed a 1/d{sup 2.6} decrease profile, and the radial spatial distribution of the electron density showed a 1/r{sup 1.1} profile, in which d is the axial distance from the target surface and r is the radial distance. The electron density was found to maintain symmetry across the radial distance at all delay times. Near the plasma plume center, the electron temperature T{sub e} varied slightly with increasing axial or radial distance, which was related to collisional decoupling and reheating of the ionized species in the plasma at distances longer than 3 to 4 mm. The space averaged electron temperature was measured in the range of 3.4-1.0 eV, and the space averaged electron density was measured in the range of 2.0 x 10{sup 17} to 2.2 x 10{sup 16} cm{sup -3}, as the time delay varied from 1.6 {mu}s to 3.6 {mu}s with respect to the pulse discharge. Time evolutions of the plasma temperature and density were found to have an apparent rise at a delay time of 2.4 {mu}s in the corresponding time of the laser pulse tail peak. This suggests that plasma parameters and extreme ultraviolet emission intensity can be controlled by a double pulse combined laser.

Wu Tao [Wuhan National Laboratory for Optoelectronics, College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Science, Wuhan Institute of Technology, Wuhan 430074 (China); Wang Xinbing; Wang Shaoyi; Tang Jian; Lu Peixiang; Lu Hong [Wuhan National Laboratory for Optoelectronics, College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

2012-03-15

323

Initial Study Comparing the Radiating Divertor Behavior in Single-Null and Double-Null Plasmas in DIII-D  

SciTech Connect

'Puff and pump' radiating divertor scenarios [1,2] were applied to upper SN and DN H-mode plasmas. Under similar operating conditions, argon (Ar) accumulated in the main plasma of single-null (SN) plasmas more rapidly and reached a higher steady-state concentration when the B x {del}B ion drift direction was toward the divertor than when the B x {del}B ion drift direction was out of the divertor. The initial rate that Ar accumulated inside double-null (DN) plasmas was more than twice that of comparably-prepared SNs with the same B x {del}B direction. One way to reduce power loading at the divertor targets is to 'seed' the divertor plasma with impurities that radiatively reduce the conducted power. Studies have shown that the concentration of impurities in the divertor are increased by raising the flow of deuterium ions (D{sup +}) into the divertor by a combination of upstream deuterium gas puffing and active particle exhaust at the divertor targets, i.e., puff-and-pump. An enhanced D{sup +} particle flow toward the divertor targets exerts a frictional drag on impurities, and inhibits their escape from the divertor. A puff-and-pump approach using Ar as the impurity was successfully applied in recent DIII-D experiments to SN plasmas [3] while maintaining good H-mode performance. Studies on DIII-D and other tokamaks have shown that both the direction of the toroidal magnetic field B{sub T} and the degree of magnetic balance between divertors [i.e., the degree to which the plasma shape is considered SN or DN] are important factors in determining recycling and particle pumping [4,5]. It is unclear whether the favorable results of Ref. [3] can be extended to cases with different magnetic balance and/or B{sub T} direction. We show in this paper that reversing the direction of B{sub T} or altering the divertor magnetic balance does have an impact on how plasmas behave under puff-and-pump conditions. Our study takes advantage of DIII-D's capabilities to actively pump SN and DN shapes with high-triangularity. In-vessel pumping of deuterium and Ar, shown schematically in Fig. 1, was done by cryopumps located inside the upper outer ('plus'), upper inner ('minus'), and lower outer (dotted) divertor pumping plenums. To increase the ion D{sup +} flow toward these pumps, deuterium gas was introduced at an outboard location, as shown. Argon was injected directly into the private flux region (PFR) of the upper outer divertor.

Petrie, T; Brooks, N; Fenstermacher, M; Groth, M; Hyatt, A; Isler, R; Lasnier, C; Leonard, A; Porter, G; Schaffer, M; Watkins, J; Wade, M; West, W

2007-06-27

324

Characteristics of laser-produced plasmas in a gas filled chamber and in a gas jet by using a long pulse laser  

Microsoft Academic Search

The dynamics of the laser-produced plasma in a gas filled chamber and in a gas jet were investigated using a relatively low intensity laser (I<=5×1012 W\\/cm2) with long pulse duration (7 ns). Visualization methods such as the Mach-Zehnder interferometry and the shadow imaging were employed to characterize the shock velocity, electron densities, and temperatures in the laser-produced plasma. The electron

J. U. Kim; H. J. Lee; C. Kim; G. H. Kim; H. Suk

2003-01-01

325

Characteristics of laser-produced plasmas in a gas filled chamber and in a gas jet by using a long pulse laser  

Microsoft Academic Search

The dynamics of the laser-produced plasma in a gas filled chamber and in a gas jet were investigated using a relatively low intensity laser (I?5×1012 W\\/cm2) with long pulse duration (7 ns). Visualization methods such as the Mach–Zehnder interferometry and the shadow imaging were employed to characterize the shock velocity, electron densities, and temperatures in the laser-produced plasma. The electron

J. U. Kim; H. J. Lee; C. Kim; G. H. Kim; H. Suk

2003-01-01

326

Measurements of the optical emission produced during the laboratory beam plasma discharge  

NASA Technical Reports Server (NTRS)

Optical observations of a beam-plasma discharge (BPD) in the laboratory showed that the discharge remained confined to a diameter little more than double that of the beam for injection parallel to the magnetic field and approximately equal to that of the beam for injection at large pitch angles. The diameter was independent of beam current but varied linearly with beam velocity and inversely with magnetic field strength. The ionization rate inferred from the total emission of 3914 A, integrated over the radial extent of the beam, was proportional to the excess beam current above that requied for BPD ignition. The proportionality constant ( 12 + or - 2) x 10 to the 14th ions/cm s A was valid over a wide range of pressure and of magnetic field strength. Power loss to ionization in a 20 m path was estimated at up to 4 percent of the beam power. Evidence is presented for effective confinement of suprathermal electrons (parallel to B) by some unidentified process other than electrostatic confinement.

Hallinan, T. J.; Leinbach, H.; Mantjoukis, G.; Bernstein, W.

1984-01-01

327

Effects of Sintering Conditions on Mechanical Properties of Biomedical Porous Ti Produced by Spark Plasma Sintering  

NASA Astrophysics Data System (ADS)

Because of its excellent biocompatibility, good corrosion resistance and relatively lower Young's modulus, Ti was suitable for biomaterial. It, however, showed still bigger Young's modulus comparing to the living bone. It was necessary to decrease the Young's modulus in order to avoid adversely affect to the bone, such as stress sheilding. In this study, porous Ti were fablicated to decrease the Young's modulus by space holder method from Ti/NaCl composites sintered using spark plasma sintering (SPS) method. The sintering condition and the size of NaCl affected to the porous structure and mechanical properties. According to the scanning electron microscope (SEM) observation and the relative density measurement of specimens sintered with several sintering conditions, the desirable sintering condition was concluded as 973 K of sintering temperature and 1.2 ks of sintering time. The specimens made from NaCl powder whose size were from 106 to 214 µm showed almost opened and connected pores. The Young's modulus was decreased with increasing the porosity.

Hasebe, Tatsuya; Kobayashi, Equo; Tezuka, Hiroyasu; Sato, Tatsuo

2013-01-01

328

The effect of positively charged plasma polymerization on initial osteoblastic focal adhesion on titanium surfaces.  

PubMed

The crucial factor of metal implant ingrowth in the bone is the rapid cellular acceptance. Therefore, the knowledge about additionally used adhesion mechanisms of osteoblasts, like their negatively charged hyaluronan coat, generates new surface functionalization strategies. Here, titanium was coated with a very thin, adherent, cross-linked, pinhole- and additive-free allylamine plasma polymer layer (PPAAm) resistant to hydrolysis and delamination and equipped with a high density of positively charged amino groups. This plasma polymer-functionalization of titanium is advantageous concerning osteoblastic focal adhesion formation as vinculin and paxillin, actin cytoskeleton development and, in consequence in differentiated cell functions, compared to a pure titanium surface-but similar such as the collagen I bonded surface via a polyethylenglycol-diacid (PEG DA)-spacer. PMID:17628662

Finke, Birgit; Luethen, Frank; Schroeder, Karsten; Mueller, Petra D; Bergemann, Claudia; Frant, Marion; Ohl, Andreas; Nebe, Barbara J

2007-10-01

329

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

330

Enhancing the energy of terahertz radiation from plasma produced by intense femtosecond laser pulses  

SciTech Connect

Terahertz (THz) radiation from atomic clusters illuminated by intense femtosecond laser pulses is investigated. By studying the angular distribution, polarization properties and energy dependence of THz waves, we aim to obtain a proper understanding of the mechanism of THz generation. The properties of THz waves measured in this study differ from those predicted by previously proposed mechanisms. To interpret these properties qualitatively, we propose that the radiation is generated by time-varying quadrupoles, which are produced by the ponderomotive force of the laser pulse.

Jahangiri, Fazel [Advanced Research Center for Beam Science, ICR, Kyoto University, Kyoto (Japan) [Advanced Research Center for Beam Science, ICR, Kyoto University, Kyoto (Japan); Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Hashida, Masaki; Tokita, Shigeki; Sakabe, Shuji [Advanced Research Center for Beam Science, ICR, Kyoto University, Kyoto (Japan) [Advanced Research Center for Beam Science, ICR, Kyoto University, Kyoto (Japan); Department of Physics, GSS, Kyoto University, Kyoto (Japan); Nagashima, Takeshi; Hangyo, Masanori [Department of Physics, GSS, Kyoto University, Kyoto (Japan) [Department of Physics, GSS, Kyoto University, Kyoto (Japan); Institute of Laser Engineering, Osaka University, Osaka (Japan)

2013-05-13

331

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

332

Theory of field-reversed mirrors and field-reversed plasma-gun experiments  

Microsoft Academic Search

Experimental and theoretical studies of field reversal in a mirror machine are reported. Plasma-gun experiments demonstrate that reversed field plasma layers are formed. Low energy plasma flowing behind the initially produced plasma front prevents tearing of the layer from the gun muzzle. MHD simulation shows that tearing can be obtained impeding the slow plasma flow with a plasma divider. It

D. V. Anderson; S. P. Auerbach; H. L. Berk; J. K. Boyd; T. A. Brengle; J. A. Byers; B. I. Cohen; W. C. Condit; J. C. Eddleman; R. P. Freis

1980-01-01

333

Ionic regulation of the plasma membrane potential of rainbow trout (Salmo gairdneri) spermatozoa: role in the initiation of sperm motility.  

PubMed

The ionic dependence of the trout sperm plasma membrane potential was analysed by measuring the accumulation of the lipophilic ions 3H-tetraphenylphosphonium (TPP) and 14C-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. PMID:2358473

Gatti, J L; Billard, R; Christen, R

1990-06-01

334

Quantitative measurement of hard x-ray spectra for high intensity laser produced plasma  

SciTech Connect

X-ray line spectra ranging from 17 to 77 keV were quantitatively measured with a Laue spectrometer, composed of a cylindrically curved crystal and a detector. Either a visible CCD detector coupled with a CsI phosphor screen or an imaging plate can be chosen, depending on the signal intensities and exposure times. The absolute sensitivity of the spectrometer system was calibrated using pre-characterized laser-produced x-ray sources and radioisotopes. The integrated reflectivity for the crystal is in good agreement with predictions by an open code for x-ray diffraction. The energy transfer efficiency from incident laser beams to hot electrons, as the energy transfer agency for specific x-ray line emissions, is derived as a consequence of this work.

Zhang, Z.; Nishimura, H.; Namimoto, T.; Fujioka, S.; Arikawa, Y.; Hosoda, H.; Azechi, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Nishikino, M.; Kawachi, T.; Sagisaka, A.; Orimo, S.; Ogura, K.; Pirozhkov, A.; Yogo, A.; Kiriyama, H.; Kondo, K. [Quantum Beam Science Directorate, Kansai Photon Science Institute, JAEA, Kyoto 619-0215 (Japan); Okano, Y. [Laser Research Center for Molecular Science, Institute for Molecular Science, National Institute of Natural Science 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585 (Japan); Ohshima, S. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Pioneering Research Unit for Next Generation, Kyoto University, Uji 611-0011 (Japan)

2012-05-15

335

Analysis of initial energies of fragments produced by 65keV proton-molecule collisions using a time-of-flight mass spectrometer  

Microsoft Academic Search

A method is described to evaluate initial-energy distributions of fragments produced by proton-molecule collisions. The fragments are analysed by means of a time-of-flight mass spectrometer and their initial energies are evaluated from their time-of-flight spectrum. These energies are presented for various fragments of H2, N2, O2, CO2, CH3Cl, CH3Br, CH3I, C2H6 and C3H8 produced with 65-keV protons. The results indicate

K. Schäfer; W. Y. Baek; K. Förster; D. Gassen; W. Neuwirth

1991-01-01

336

Mechanical Behavior of Al-SiC Nanocomposites Produced by Ball Milling and Spark Plasma Sintering  

NASA Astrophysics Data System (ADS)

Al-SiC nanocomposites were prepared by high energy ball milling of mixtures of pure Al and 50-nm-diameter SiC nanoparticles, followed by spark plasma sintering. The final composites had grains of approximately 100 nm dimensions, with SiC particles located mostly at grain boundaries. The samples were tested in uniaxial compression by nano- and microindentation in order to establish the effect of the SiC volume fraction, stearic acid addition to the powder, and the milling time on the mechanical properties. The results are compared with those obtained for pure Al processed under similar conditions and for AA1050 aluminum. The yield stress of the nanocomposite with 1 vol pct SiC is more than ten times larger than that of AA1050. The largest increase is due to grain size reduction; nanocrystalline Al without SiC and processed by the same method has a yield stress seven times larger than AA1050. Adding 0.5 vol pct SiC increases the yield stress by an additional 47 pct, while the addition of 1 vol pct SiC leads to 50 pct increase relative to the nanocrystalline Al without SiC. Increasing the milling time and adding stearic acid to the powder during milling lead to relatively small increases of the flow stress. The hardness measured in nano- and microindentation experiments confirms these trends, although the numerical values of the gains are different. The stability of the microstructure was tested by annealing samples to 423 K and 523 K (150 °C and 250 °C) for 2 hours, in separate experiments. The heat treatment had no effect on the mechanical properties, except when treating the material with 1 vol pct SiC at 523 K (250 °C), which led to a reduction of the yield stress by 13 pct. The data suggest that the main strengthening mechanism is associated with grain size reduction, while the role of the SiC particles is mostly that of stabilizing the nanograins.

Grácio, José J.; Picu, Catalin R.; Vincze, Gabriela; Mathew, Nithin; Schubert, Thomas; Lopes, Augusto; Buchheim, Claudia

2013-11-01

337

Laser-plasma diamagnetism in the presence of an ambient magnetized plasma  

E-print Network

Laser-plasma diamagnetism in the presence of an ambient magnetized plasma M. VanZeelanda) and W cavity created by a dense laser-produced plasma initially, nlpp /n0 1) expanding into an ambient magnetized background plasma (n0 2 1012 cm 3 ) capable of supporting Alfve´n waves. The experiments

California at Los Angles, University of

338

Initial Results of DC Electric Fields, Associated Plasma Drifts, Magnetic Fields, and Plasma Waves Observed on the C/NOFS Satellite  

NASA Technical Reports Server (NTRS)

Initial results are presented from the Vector Electric Field Investigation (VEFI) on the Air Force Communication/Navigation Outage Forecasting System (C/NOFS) satellite, a mission designed to understand, model, and forecast the presence of equatorial ionospheric irregularities. The VEFI instrument includes a vector DC electric field detector, a fixed-bias Langmuir probe operating in the ion saturation regime, a flux gate magnetometer, an optical lightning detector, and associated electronics including a burst memory. Compared to data obtained during more active solar conditions, the ambient DC electric fields and their associated E x B drifts are variable and somewhat weak, typically < 1 mV/m. Although average drift directions show similarities to those previously reported, eastward/outward during day and westward/downward at night, this pattern varies significantly with longitude and is not always present. Daytime vertical drifts near the magnetic equator are largest after sunrise, with smaller average velocities after noon. Little or no pre-reversal enhancement in the vertical drift near sunset is observed, attributable to the solar minimum conditions creating a much reduced neutral dynamo at the satellite altitude. The nighttime ionosphere is characterized by larger amplitude, structured electric fields, even where the plasma density appears nearly quiescent. Data from successive orbits reveal that the vertical drifts and plasma density are both clearly organized with longitude. The spread-F density depletions and corresponding electric fields that have been detected thus far have displayed a preponderance to appear between midnight and dawn. Associated with the narrow plasma depletions that are detected are broad spectra of electric field and plasma density irregularities for which a full vector set of measurements is available for detailed study. Finally, the data set includes a wide range of ELF/VLF/HF oscillations corresponding to a variety of plasma waves, in particular banded ELF hiss, whistlers, and lower hybrid wave turbulence triggered by lightning-induced sferics. The VEFI data represents a new set of measurements that are germane to numerous fundamental aspects of the electrodynamics and irregularities inherent to the Earth's low latitude ionosphere.

Pfaff, R.; Freudenreich, H.; Bromund, K.; Klenzing, J.; Rowland, D.; Maynard, N.

2010-01-01

339

Initial Results of DC Electric Fields, Associated Plasma Drifts, Magnetic Fields, and Plasma Waves Observed on the C/NOFS Satellite  

NASA Astrophysics Data System (ADS)

Initial results are presented from the Vector Electric Field Investigation (VEFI) on the Air Force Communication/Navigation Outage Forecasting System (C/NOFS) satellite, a mission designed to understand, model, and forecast the presence of equatorial ionospheric irregulari-ties. The VEFI instrument includes a vector DC electric field detector, a fixed-bias Langmuir probe operating in the ion saturation regime, a flux gate magnetometer, an optical lightning de-tector, and associated electronics including a burst memory. Compared to data obtained during more active solar conditions, the ambient DC electric fields and their associated E x B drifts are variable and somewhat weak, typically <¡ 1 mV/m. Although average drift directions show sim-ilarities to those previously reported, eastward/outward during day and westward/downward at night, this pattern varies significantly with longitude and is not always present. Daytime vertical drifts near the magnetic equator are largest after sunrise, with smaller average ve-locities after noon. Little or no pre-reversal enhancement in the vertical drift near sunset is observed, attributable to the solar minimum conditions creating a much reduced neutral dy-namo at the satellite altitude. The nighttime ionosphere is characterized by larger amplitude, structured electric fields, even where the plasma density appears nearly quiescent. Data from successive orbits reveal that the vertical drifts and plasma density are both clearly organized with longitude. The spread-F density depletions and corresponding electric fields that have been detected thus far have displayed a preponderance to appear between midnight and dawn. Associated with the narrow plasma depletions that are detected are broad spectra of electric field and plasma density irregularities for which a full vector set of measurements is available for detailed study. Finally, the data set includes a wide range of ELF/VLF/HF oscillations corresponding to a variety of plasma waves, in particular banded ELF hiss, whistlers, and lower hybrid wave turbulence triggered by lightning-induced sferics. The VEFI data represents a new set of measurements that are germane to numerous fundamental aspects of the electrodynamics and irregularities inherent to the Earth's low latitude ionosphere.

Pfaff, Robert

340

A Radiation-Hydrodynamics Code Comparison for Laser-Produced Plasmas: FLASH versus HYDRA and the Results of Validation Experiments  

E-print Network

The potential for laser-produced plasmas to yield fundamental insights into high energy density physics (HEDP) and deliver other useful applications can sometimes be frustrated by uncertainties in modeling the properties and expansion of these plasmas using radiation-hydrodynamics codes. In an effort to overcome this and to corroborate the accuracy of the HEDP capabilities recently added to the publicly available FLASH radiation-hydrodynamics code, we present detailed comparisons of FLASH results to new and previously published results from the HYDRA code used extensively at Lawrence Livermore National Laboratory. We focus on two very different problems of interest: (1) an Aluminum slab irradiated by 15.3 and 76.7 mJ of "pre-pulse" laser energy and (2) a mm-long triangular groove cut in an Aluminum target irradiated by a rectangular laser beam. Because this latter problem bears a resemblance to astrophysical jets, Grava et al., Phys. Rev. E, 78, (2008) performed this experiment and compared detailed x-ray int...

Orban, Chris; Chawla, Sugreev; Wilks, Scott C; Lamb, Donald Q

2013-01-01

341

Detailed-term-accounting-approximation simulation of x-ray transmission through laser-produced Al plasmas  

PubMed

An extensive configuration interaction (CI) scheme and the R-matrix method are combined to calculate the x-ray transmission spectrum for high-power laser-produced Al plasmas in local thermodynamic equilibrium by using the detailed-term-accounting (DTA) approximation. All atomic parameters such as state levels and photoabsorption cross sections for different ionization stages are obtained by using the CI and R-matrix method. Special attention is given to the effects of autoionizing resonance broadening on the transmission. A large difference exists between the convergence of the results with and without taking account of autoionizing resonance broadening when the autoionization resonance broadening is the major broadening mechanism. This shows that autoionizing resonance widths of the K-shell excited states have large effects and should be considered to interpret the spectral-resolved transmission. PMID:11102083

Zeng; Jin; Yuan; Lu; Sun

2000-11-01

342

Initial observations of thermal plasma composition and energetics from Dynamics Explorer-1  

NASA Technical Reports Server (NTRS)

Initial measurements of thermal ions (0 to 50 eV) at mid-latitudes by the Retarding Ion Mass Spectrometer (RIMS) on DE-1 are presented. These measurements show the plasmapause signature in H(+), He(+), and m/q = 2 ions, an enhancement or torus of O(+) and O(++) in the outer plasmasphere and the suggestion of a disconnection between the ionosphere and the bulge region of the plasmasphere.

Chappell, C. R.

1982-01-01

343

Initial observations of thermal plasma composition and energetics from Dynamics Explorer1  

Microsoft Academic Search

Initial measurements of thermal ions (0 to 50 eV) at mid-latitudes by the Retarding Ion Mass Spectrometer (RMS) on DE-1 are presented. These measurements show the plasmapause signature in H\\/sup +\\/, He\\/sup +\\/, and m\\/q = 2 ions, an enhancement or torus of O\\/sup +\\/ and O\\/sup + +\\/ in the outer plasmasphere and the suggestion of a disconnection between

C. R. Chappell

1982-01-01

344

Fluoride ions as modifiers of the oxide layer produced by plasma electrolytic oxidation on AZ91D magnesium alloy  

NASA Astrophysics Data System (ADS)

Plasma electrolytic oxidation (PEO) is a powerful technique allowing hardening and corrosion protection of valve metals due to formation of an oxide layer on the metal surface. PEO produces much thicker oxide layers as compared to anodizing, which is of critical importance for many technological applications. The present research investigated the influence of the fluoride ion concentration on the composition, structure and morphology of PEO layers on the magnesium alloy AZ91D. The obtained oxide layers were characterized with XRD, SEM, EDS and tested for corrosion resistance by linear sweep voltammetry in 3.5% NaCl medium. During this investigation it was found that KF addition produces significant changes in the structure and properties of the oxide layers. Fluorine was detected as an amorphous phase in the vicinity of the base metal for both alloys and plausible mechanism was suggested to explain these phenomena. Fluoride ions have pronounced catalytic activity and their presence considerably increases the thickness of the oxide layer. Depending on the process parameters, significant improvement of the corrosion stability of AZ91D alloy is achieved by the use of PEO.

Kazanski, Barbara; Kossenko, Alexey; Zinigrad, Michael; Lugovskoy, Alex

2013-12-01

345

Interaction of Cu and plastic plasmas as a method of forming laser produced Cu plasma streams with a narrow jet or pipe geometry  

SciTech Connect

This brief communication is aimed at investigations of interaction of axially symmetrical light (plastic) plasma with heavy (copper) plasma. The use of axially symmetrical target compositions consisting of materials with low and high atomic numbers makes it possible to create different plasma stream configurations (e.g., very narrow jet or pipe). In the paper certain their applications are suggested.

Kasperczuk, A.; Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Parys, P. [Institute of Plasma Physics and Laser Microfusion, 23 Hery St., 00-908 Warsaw (Poland); Ullschmied, J. [Institute of Plasma Physics ASCR, v.v.i., Za Slovankou 3, 182 00 Prague 8 (Czech Republic); Krousky, E.; Pfeifer, M.; Skala, J. [Institute of Physics ASCR, v.v.i., Na Slovance 2, 182 21 Prague 8 (Czech Republic); Klir, D.; Kravarik, J.; Kubes, P.; Rezac, K. [Czech Technical University in Prague, Faculty of Electrical Engineering (FEE), Prague (Czech Republic); Pisarczyk, P. [Warsaw University of Technology, Institute of Computer Sciences (ICS), 15/19 Nowowiejska St., 00-665 Warsaw (Poland)

2011-04-15

346

Atmospheric pressure plasma produced inside a closed package by a dielectric barrier discharge in Ar/CO2 for bacterial inactivation of biological samples  

NASA Astrophysics Data System (ADS)

The generation and evaluation of a dielectric barrier discharge produced inside a closed package made of a commercially available packaging film and filled with gas mixtures of Ar/CO2 at atmospheric pressure is reported. The discharge parameters were analysed by electrical measurements and optical emission spectroscopy in two modes of operation: trapped gas atmosphere and flowing gas atmosphere. Gas temperature was estimated using the OH(A-X) emission spectrum and the rotational temperature reached a saturation level after a few minutes of plasma running. The rotational temperature was almost three times higher in the Ar/CO2 plasma compared with an Ar plasma. The efficiency of the produced plasma for the inactivation of bacteria on food inside the closed package was investigated.

Chiper, A. S.; Chen, W.; Mejlholm, O.; Dalgaard, P.; Stamate, E.

2011-04-01

347

Evaluation of plasma produced by first and second harmonic nano-second laser for enhancing the capability of laser induced breakdown spectroscopy technique  

NASA Astrophysics Data System (ADS)

Evaluation of plasmas produced and optimized for improving the capability of convenential laser induced breakdown spectroscopy (LIBS) for analytical purposes of solid samples is the main goal of the present work. The plasma produced in the present study was generated by focusing a single nano-second Nd:YAG laser at the fundamental wavelength of 1064 nm and at the second harmonic wavelength of 532 nm on an Al target in air at atmospheric pressure. The emission spectrum was recorded time resolved over the whole UV-NIR (200-1000 nm) spectral range. This work describes an extension of previously reported studies and focuses now on the determination of the plasma parameters at the optimum condition - highest signal-to-noise ratio (SNR) and minimum limit of detection (LOD) - of the LIBS technique, which is now widely applied to the elemental analysis of materials in atmospheric air. Parameters of the produced plasma in the time interval from 0 to 10 ?s are determined for to further understanding the LIBS plasma dynamics. O I and Mn I spectral lines are used in the present work as thermometric lines for the determination of the plasma temperature based on Boltzmann plots. Stark broadening of lines yields the electron density. The widths of the H?-line at 656.27 nm, of the O I line at 844.65 nm, of Al II lines at 281.65 nm and 466.30 nm and of the Si I line at 288.15 nm has been utilized for that. The plasma temperature ranged from 0.73 eV to around 1 eV for the different laser energies with both laser wavelengths for the optimized plasma used for LIBS analysis. This temperature is very close to that well known for the other spectrochemical analytical techniques or in excitation sources such as inductively coupled plasma-optical emission spectrometry (ICP-OES).

Hegazy, Hosam; Abdel-Wahab, Essam A.; Abdel-Rahim, Farid M.; Allam, Sami H.; Nossair, Abd ElDaim M. A.

2014-05-01

348

Structure of the dense cores and ablation plasmas in the initiation phase of tungsten wire-array Z pinches  

NASA Astrophysics Data System (ADS)

The early stages of tungsten (W) wire-array Z-pinch implosions have been studied using two-frame point projection x-ray backlighting on the 1MA COBRA pulsed power generator [J. D. Douglass, J. B. Greenly, D. A. Hammer, and B. R. Kusse, in Proceedings of the 15th IEEE International Pulsed Power Conference, Monterey, 2005 (to be published)]. X-pinch backlighter images with subnanosecond time resolution and 4-10?m spatial resolution have been obtained of individual W exploding wires in 8-wire arrays that show evolution of wire-core and coronal plasma structures. The timing of the X-pinch x-ray bursts relative to the Z-pinch initiation time was adjusted over a 50ns time interval by varying the X-pinch mass per unit length. Wire-cores seen in two images separated in view by 120° show that the expansion is remarkably azimuthally symmetric. A strong correlation is observed between the structure on the dense exploding wire-cores and the structure of the ?1018/cm3 ablation plasma being drawn from radial prominences. Plasma ablation velocity was estimated to have a lower bound of 24km/s. The wire-core expansion rate was found to be approximately constant with time over the interval 50-100ns after the start of the current pulse. Finally, micron-scale axial gaps, seen as early as 70ns into the current pulse and persisting from that time, were observed along the wire-core.

Douglass, J. D.; Pikuz, S. A.; Shelkovenko, T. A.; Hammer, D. A.; Bland, S. N.; Bott, S. C.; McBride, R. D.

2007-01-01

349

Structure of the dense cores and ablation plasmas in the initiation phase of tungsten wire-array Z pinches  

SciTech Connect

The early stages of tungsten (W) wire-array Z-pinch implosions have been studied using two-frame point projection x-ray backlighting on the 1 MA COBRA pulsed power generator [J. D. Douglass, J. B. Greenly, D. A. Hammer, and B. R. Kusse, in Proceedings of the 15th IEEE International Pulsed Power Conference, Monterey, 2005 (to be published)]. X-pinch backlighter images with subnanosecond time resolution and 4-10 {mu}m spatial resolution have been obtained of individual W exploding wires in 8-wire arrays that show evolution of wire-core and coronal plasma structures. The timing of the X-pinch x-ray bursts relative to the Z-pinch initiation time was adjusted over a 50 ns time interval by varying the X-pinch mass per unit length. Wire-cores seen in two images separated in view by 120 deg. show that the expansion is remarkably azimuthally symmetric. A strong correlation is observed between the structure on the dense exploding wire-cores and the structure of the {>=}10{sup 18}/cm{sup 3} ablation plasma being drawn from radial prominences. Plasma ablation velocity was estimated to have a lower bound of 24 km/s. The wire-core expansion rate was found to be approximately constant with time over the interval 50-100 ns after the start of the current pulse. Finally, micron-scale axial gaps, seen as early as 70 ns into the current pulse and persisting from that time, were observed along the wire-core.

Douglass, J. D.; Hammer, D. A.; McBride, R. D. [Laboratory of Plasma Studies, 439 Rhodes Hall, Cornell University, Ithaca, New York 14853 (United States); Pikuz, S. A.; Shelkovenko, T. A. [Laboratory of Plasma Studies, 439 Rhodes Hall, Cornell University, Ithaca, New York 14853 (United States); P. N. Lebedev Physical Institute, Leninsky Prospect 53, Moscow 117924 (Russian Federation); Bland, S. N.; Bott, S. C. [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)

2007-01-15

350

Initial design and results from an ion current collection diagnostic for the triggered plasma opening switch experiment.  

SciTech Connect

Study of the triggered plasma opening switch (TPOS) characteristics is in progress via an ion current collection diagnostic (ICCD), in addition to offline apparatus. This initial ion current collection diagnostic has been designed, fabricated, and tested on the TPOS in order to explore the opening profile of the main switch. The initial ion current collection device utilizes five collectors which are positioned perpendicularly to the main switch stage in order to collect radially traveling ions. It has been shown through analytical prowess that this specific geometry can be treated as a planar case of the Child-Langmuir law with only a 6% deviation from the cylindrical case. Additionally, magnetostatic simulations with self consistent space charge emitting surfaces of the main switch using the Trak code are under way. It is hoped that the simulations will provide evidence in support of both the analytical derivations and experimental data. Finally, an improved design of the ICCD (containing 12 collectors in the axial direction) is presently being implemented.

Jackson, Daniel Peter Jr.; Seidel, David Bruce; Gilmore, Mark; Mendel, Clifford Will, Jr.

2005-06-01

351

Efficient multiline nanosecond pulse amplification in planar waveguide CO? amplifier for extreme UV laser-produced plasma source.  

PubMed

In this Letter, we report on recent experimental results of a short pulse amplification at 10.6 ?m wavelength required to drive a tin laser-produced plasma (LPP) extreme ultraviolet (UV) source. We report for the first time, to our best knowledge, a highly efficient pulsed amplification in a multipass amplifier built on RF-discharge-excited, diffusion-cooled CO2, planar waveguide industrial CO2 laser. About 2 kW of output average power was obtained from about 100 W input average power in ?15??ns pulses at 100 kHz pulse repetition frequency. As much as 60% relative extraction efficiency, as compared to continuous-wave amplification in similar conditions, and 5.8% wall-plug efficiency was recorded and believed to be the highest reported so far. An improvement of extraction efficiency by ?10% is reported when driving the amplifier with two lines of CO2 regular band in good agreement with expectations. PMID:24686647

Nowak, Krzysztof M; Ohta, Takeshi; Suganuma, Takashi; Fujimoto, Junichi; Mizoguchi, Hakaru; Sumitani, Akira; Endo, Akira

2014-04-01

352

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

353

Secondary reactive oxygen species extend the range of photosensitization effects in cells: DNA damage produced via initial membrane photosensitization.  

PubMed

The type-II photosensitization process is mediated by the formation of singlet oxygen (O2[1deltag]). The short lifetime of this species dictates that chemical reactions with biological substrates can only occur when O2(1deltag) is in very close proximity to the photosensitizer itself. In this study, deuteroporphyrin, a type-II, membrane-localized photosensitizer, was used to generate O2(1deltag) in human lymphoblast WTK-1 cells, and the range of influence was determined by a variety of biological assays. Surprisingly, the initial membrane-confined events were shown, by comet assay, to induce DNA damage in these cells. DNA damage was inhibited both by membrane-localized (alpha-tocopherol acetate) and by cytoplasmic (trolox) free radical scavengers. Comet formation also was inhibited by treatment at low temperature. DNA fragmentation was not influenced by treatment with the pan-caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone, showing that apoptosis was not responsible for fragmentation. Taken together, these results show that primary photosensitization reactions involving O2(1deltag), even when tightly confined in extranuclear locations, leads to the production of secondary reactive oxygen species, probably as a result of lipid peroxidation, that can act at greater distances from the photosensitizer itself. These experiments were carried out under conditions where cell survival was significant and raise questions regarding DNA damage and mutagenesis pathways, even when extranuclear O2(1deltag)-generating compounds are used. PMID:12785059

Ouédraogo, Gladys D; Redmond, Robert W

2003-02-01

354

Experimental test chamber design for optics exposure testing and debris characterization of a xenon discharge produced plasma source for extreme ultraviolet lithography  

Microsoft Academic Search

A commercial EUV light source is currently used in the MS-13 EUV Micro Exposure Tool (MET) produced by Exitech Ltd. The source uses a xenon z-pinch discharge to produce 13.5nm light intended for use in extreme ultraviolet lithography (EUVL). During operation, an erosive flux of particles is ejected from the pinch plasma, contributing to limitations in the lifetime of nearby

Keith C. Thompson; Erik L. Antonsen; Matthew R. Hendricks; Brian E. Jurczyk; M. Williams; D. N. Ruzic

2006-01-01

355

Drug-resistant colon cancer cells produce high carcinoembryonic antigen and might not be cancer-initiating cells  

PubMed Central

Purpose We evaluated the higher levels of carcinoembryonic antigen (CEA) secreted by the LoVo human colon carcinoma cells in a medium containing anticancer drugs. Drug-resistant LoVo cells were analyzed by subcutaneously xenotransplanting them into mice. The aim of this study was to evaluate whether the drug-resistant cells isolated in this study were cancer-initiating cells, known also as cancer stem cells (CSCs). Methods The production of CEA was investigated in LoVo cells that were cultured with 0–10 mM of anticancer drugs, and we evaluated the increase in CEA production by the LoVo cells that were stimulated by anticancer drug treatment. The expression of several CSC markers in LoVo cells treated with anticancer drugs was also evaluated. Following anticancer drug treatment, LoVo cells were injected subcutaneously into the flanks of severe combined immunodeficiency mice in order to evaluate the CSC fraction. Results Production of CEA by LoVo cells was stimulated by the addition of anticancer drugs. Drug-resistant LoVo cells expressed lower levels of CSC markers, and LoVo cells treated with any of the anticancer drugs tested did not generate tumors within 8 weeks from when the cells were injected subcutaneously into severe combined immunodeficiency mice. These results suggest that the drug-resistant LoVo cells have a smaller population of CSCs than the untreated LoVo cells. Conclusion Production of CEA by LoVo cells can be stimulated by the addition of anticancer drugs. The drug-resistant subpopulation of LoVo colon cancer cells could stimulate the production of CEA, but these cells did not act as CSCs in in vivo tumor generation experiments. PMID:23818760

Lee, Hsin-chung; Ling, Qing-Dong; Yu, Wan-Chun; Hung, Chunh-Ming; Kao, Ta-Chun; Huang, Yi-Wei; Higuchi, Akon

2013-01-01

356

Discharge-produced plasma extreme ultraviolet (EUV) source and ultra high vacuum chamber for studying EUV-induced processes  

E-print Network

An experimental setup that directly reproduces Extreme UV-lithography relevant conditions for detailed component exposure tests is described. The EUV setup includes a pulsed plasma radiation source, operating at 13.5 nm; a debris mitigation system; collection and filtering optics; and an UHV experimental chamber, equipped with optical and plasma diagnostics. The first results, identifying the physical parameters and evolution of EUV-induced plasmas are presented. Finally, the applicability and accuracy of the in situ diagnostics is briefly discussed.

Dolgov, A; Abrikosov, A; Snegirev, E; Krivtsun, V M; Lee, C J; Bijkerk, F

2014-01-01

357

Development status of gas discharge produced plasma Z-pinch EUV sources for use in beta-tools and high volume chip manufacturing tools  

Microsoft Academic Search

In the paper we report about the progress made at XTREME technologies in the development of EUV sources based on gas discharge produced plasma (GDPP) technologies as well as the integration of collector optics. Optics from different suppliers were integrated to the source and the performance of the radiation in the intermediate focus and in the far field behind the

U. Stamm; J. Kleinschmidt; K. Gabel; G. Hergenhan; C. Ziener; I. Ahmad; D. Bolshukhin; V. Korobotchko; A. Keller; A. Geier; J. Ringling; C. D. Tran; B. Mader; R. de Bruijn; S. Gotze; J. Brudermann; G. Schriever

2005-01-01

358

Guiding of high intensity ultrashort laser pulses in plasma channels produced with the dual laser pulse Ignitor-Heater technique  

Microsoft Academic Search

We 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 (5×1017 W\\/cm2, 75 fs laser pulse.

P. Volfbeyn; W. P. Leemans

1999-01-01

359

Guiding of high intensity ultrashort laser pulses in plasma channels produced with the dual laser pulse ignitor-heater technique  

Microsoft Academic Search

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

P. Volfbeyn; W. P. Leemans

1998-01-01

360

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

361

The Role of Plasma Renin Activity, Age, and Race in Selecting Effective Initial Drug Therapy for Hypertension  

PubMed Central

BACKGROUND Strategies for initial drug therapy of hypertension are a thiazide diuretic for all or drug selection based on age/race criteria or on plasma renin activity (PRA). It is uncertain which of these strategies will achieve the highest control rate among patients with stage 1 essential hypertension. We sought to compare control rates among 3 drug selection strategies: (i) thiazide diuretic for all, (ii) thiazide diuretic for all black subjects and white subjects aged ?50 years and a renin-angiotensin system blocker for white subjects aged <50 years, or (iii) thiazide diuretic for PRA < 0.6ng/ml/h (suppressed PRA) and a renin-angiotensin system blocker for PRA ? 0.6ng/ml/h (nonsuppressed PRA). METHODS Blood pressure responses from the Genetic Epidemiology of Responses to Antihypertensives (GERA) study were used to determine control rates for each of the 3 strategies. In GERA, hypertensive adults were treated with hydrochlorothiazide (n = 286 black subjects and 284 white subjects) or with candesartan (n = 248 black subjects and 278 white subjects). RESULTS In the overall sample, the PRA strategy was associated with the highest control rate of 69.4% vs. 61.3% with the age/race strategy (P < 0.001) and 53.8% with the thiazide for all strategy (P < 0.001). This was also true in each racial subgroup (in black subjects: 62.1% vs. 55.2% for the other 2 strategies, P = 0.02; in white subjects: 76.3% vs. 67.1% with the age/race strategy (P < 0.001) and 52.4% with the thiazide for all strategy (P < 0.001)). CONCLUSIONS This exploratory analysis suggests that choice of initial therapy for hypertension using a PRA strategy may be associated with higher control rates than alternative strategies recommended in current guidelines. PMID:23591988

2013-01-01

362

LC-MS/MS analysis of plasma polyunsaturated fatty acids in type 2 diabetic patients after insulin analog initiation therapy  

PubMed Central

Background Eicosanoids derived from omega-6 (n6) polyunsaturated fatty acids (PUFAs) have proinflammatory functions whereas eicosanoids derived from omega-3 (n3) PUFAs have anti-inflammatory properties. This study was designed to evaluate the effect of insulin analog initiation therapy on n6 and n3 PUFAs in type 2 diabetic patients during early phase. Methods Sixteen type 2 diabetic patients with glycosylated hemoglobin (HbA1c) levels above 10% despite ongoing combination therapy with sulphonylurea and metformin were selected. Former treatment regimen was continued for the first day followed by substitution of sulphonylurea therapy with different insulin analogs (0.4 U/kg/day) plus metformin. Blood samples were obtained from all patients at 24 and 72 hours. Plasma levels of arachidonic acid (AA, C20:4n6), dihomo-gamma-linolenic acid (DGLA, C20:3n6), eicosapentaenoic acid (EPA, C20:5n3) and docosahexaenoic acid (DHA, C22:6n3) were determined by an optimized multiple reaction monitoring (MRM) method using ultra fast-liquid chromatography (UFLC) coupled with tandem mass spectrometry (MS/MS). Prostaglandin E2 (PGE2) was measured in serum samples by enzyme immunoassay. Results All measured PUFAs were significantly increased after treatment with insulin analogs plus metformin compared to before treatment levels. The mean AA/EPA ratio was significantly lower after treatment with insulin analogs plus metformin. A 22% decrease was observed in PGE2 levels after treatment with insulin analogs plus metformin compared to pretreatment levels (p?>?0.05). Conclusion The significant decrease in AA/EPA ratio indicates that insulin analog initiation therapy has anti-inflammatory properties by favoring the increase of n3 fatty acid EPA. PMID:24195588

2013-01-01

363

Application of laser-produced extended plasma plumes for generation and characterization of the high-order harmonics of 64 fs pulses  

NASA Astrophysics Data System (ADS)

Harmonics with the photon energy of up to ~150 eV were studied using extended ablation plumes as the nonlinear media. The application of the ablation pulses of different duration covering the range between a few tens of femtoseconds and a few tens of nanoseconds revealed the advanced features of the extended plasmas produced by the subnanosecond pulses for efficient harmonic generation. The examples of the quasi-phase-matching of a group of harmonics in the plateau range and the advantages of using the two-color pump and cluster-containing plasmas are presented. We analyze the spatial and coherence characteristics of the high-order harmonics produced during propagation of the 64 fs pulse through the extended plasma plume produced by 370 ps pulses. It is shown that the divergence of plasma harmonics in the plateau range is 7 times smaller than the divergence of the driving radiation used for high-order harmonic generation. The measurements of the coherence properties of the lower-order harmonics showed that the visibility of interference fringes in the far field was in the range of 0.54-0.73.

Ganeev, Rashid A.; Suzuki, Masayuki; Kuroda, Hiroto

2014-11-01

364

Experimental Characterization Of The Asymmetry And The Dip Form Of The H{sub {beta}}-Line Profiles In Microwave-Produced Plasmas At Atmospheric Pressure  

SciTech Connect

An experimental study on the asymmetry of the Balmer H{sub {beta}} profile in plasmas produced by microwaves at atmospheric pressure is presented. The asymmetry of the whole profile is studied with the help of one function that quantified this characteristic. The asymmetry and shape of the central valley is also studied with the definition of several parameters. The study shows the presence of the Stark asymmetry in plasmas with electron density of the order of 10{sup 21}m{sup -3}.

Palomares, J. M.; Torres, J.; Gamero, A.; Sola, A. [Departamento de Fisica, Universidad de Cordoba. Campus Universitario de Rabanales C2. E-14071 Cordoba (Spain); Gigosos, M. A. [Departamento de Optica, Universidad de Valladolid. Campus Universitario de la Merced. E-47072 Valladolid Spain (Spain); Mullen, J. J. A. M. van der [Department of Applied Physics, Eindhoven University of Technology. P.O. Box 513. 5600 MD Eindhoven (Netherlands)

2008-10-22

365

Characteristics of surface-wave and volume-wave plasmas produced with internally mounted large-area planar microwave launcher  

SciTech Connect

We studied discharge characteristics of microwave plasmas excited with a large-area planar microwave launcher installed internally in a 600-mm-diam cylindrical vacuum chamber. With the microwave power less than roughly 400 W, we demonstrated the large volumetric volume-wave plasma (VWP) spread in the entire chamber at a pressure of 14-27 Pa in He. Above 400 W, the plasma discharge made a sudden transition to higher-density, uniform surface-wave plasma (SWP) having a spatial uniformity of {+-}3.5% over 300 mm in diameter. Electron energy probability functions in the downstream region were studied using Langmuir probe measurements with Druyvesteyn method in both the SWP and VWP discharges.

Nagatsu, Masaaki; Naito, Katsutoshi; Ogino, Akihisa; Ninomiya, Keigo; Nanko, Shohei [Graduate School of Science and Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8561 (Japan); Nissin Inc., 10-7 Kamei-cho, Takarazuka 665-0047 (Japan)

2005-10-17

366

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

E-print Network

was also investigated using spatially resolved spectra and optical time-of-flight measurements. The results methods used for ele- mental and isotope detection are LA-inductively coupled plasma-mass spectrometry (LA

Harilal, S. S.

367

Influence of plasma and ultraviolet treatment of zirconia on initial attachment of human oral keratinocytes: Expressions of laminin ?2 and integrin ?4.  

PubMed

Initial attachment of human oral keratinocytes cultured on yttria-stabilized tetragonal zirconia polycrystal (TZP) surfaces that were subjected to UV or oxygen plasma (O2-plasma) treatment was investigated. The viability of the attached cells, mRNA expression of laminin ?2 and integrin ?4, distribution of laminin ?2 and integrin ?4, cell area, and cell morphology were assessed. The results showed that no differences in the viability of attached cells were recognized among the conditions. However, expression of laminin ?2 and integrin ?4 as well as cell morphology were promoted only in O2-plasma specimens even though superhydrophilicity was obtained in both the UV and O2-plasma specimens compared with the untreated control specimen. The photocatalytic activity was believed to be closely involved in the above-mentioned differences. The results of this study suggest that TZP surface treated with oxygen plasma promotes the initial attachment capability of human oral keratinocytes with enhancing the extracellular matrix such as laminin ?2. PMID:25273051

Kobune, Kazuhiro; Miura, Tadashi; Sato, Toru; Yotsuya, Mamoru; Yoshinari, Masao

2014-01-01

368

Fluorescent lamp recycling initiatives in the United States and a recycling proposal based on extended producer responsibility and product stewardship concepts.  

PubMed

This paper presents an overview of mercury-containing lamp (MCL) recycling initiatives currently available in the world, especially in the United States. The majority of MCLs contain mercury which is a neurotoxin, a persistent pollutant in the environment, and can bioaccumulate in the food chain. Although there are some recycling options in the United States, collection rates are still at 23% of all potential used MCLs. This shows that citizens are either indifferent to or unaware of the recycling alternatives. On the other hand, MCL recycling seems not to be a cost-effective process and, for this reason, in the United States, take-back programmes are still sponsored only by consumers or municipalities. A few retailers have recently initiated limited take-back alternatives and manufacturers have not yet supported financially any consistent recycling alternative in the country. Considering successful experiences, this paper makes a suggestion for an MCL recycling system based on the concepts of extended producer responsibility and product stewardship. A manufacturer-importer advance recycling fee is proposed to finance the collection and recycling system while a MCL-energy recycling fee supported by the energy sector creates a lamp refund process. 'PRO Lamp', a producer responsibility organization, will manage the entire system through a widespread public-private agreement. PMID:20837557

Silveira, Geraldo Tr; Chang, Shoou-Yuh

2011-06-01

369

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

370

Design a 10 kJ IS Mather Type Plasma Focus for Solid Target Activation to Produce Short-Lived Radioisotopes 12C(d,n)13N  

NASA Astrophysics Data System (ADS)

A 10 kJ (15 kV, 88 ?F) IS (Iranian Sun) Mather type plasma focus device has been studied to determine the activity of a compound exogenous carbon solid target through 12C(d,n)13N nuclear reaction. The produced 13N is a short-lived radioisotope with a half-life of 9.97 min and threshold energy of 0.28 MeV. The results indicate that energetic deuterons impinging on the solid target can produce yield of = 6.7 × 10-5 with an activity of A = 6.8 × 104 Bq for one plasma focus shut and A ? = 4 × 105 Bq for 6 shut per mint when the projectile maximum deuterons energy is E max = 3 MeV.

Sadat Kiai, S. M.; Adlparvar, S.; Sheibani, S.; Elahi, M.; Safarien, A.; Farhangi, S.; Zirak, A. R.; Alhooie, S.; Mortazavi, B. N.; Khalaj, M. M.; Khanchi, A. R.; Dabirzadeh, A. A.; Kashani, A.; Zahedi, F.

2010-10-01

371

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

372

Analysis of time- and space-resolved Na-, Ne-, and F-like emission from a laser-produced bromine plasma  

SciTech Connect

Advances in the efficiency and accuracy of computational atomic physics and collisional radiative modeling promise to place the analysis and diagnostic application of L-shell emission on a par with the simpler K-shell regime. Coincident improvements in spectroscopic plasma measurements yield optically thin emission spectra from small, homogeneous regions of plasma, localized both in space and time. Together, these developments can severely test models for high-density, high-temperature plasma formation and evolution, and non-LTE atomic kinetics. In this paper we present highly resolved measurements of n=3 to n=2 X-ray line emission from a laser-produced bromine micro-dot plasma. The emission is both space- and time-resolved, allowing us to apply simple, steady-state, 0-dimensional spectroscopic models to the analysis. These relativistic, multi-configurational, distorted wave collisional-radiative models were created using the HULLAC atomic physics package. Using these models, we have analyzed the F-like, Ne-like and Na-like (satellite) spectra with respect to temperature, density and charge-state distribution. This procedure leads to a full characterization of the plasma conditions. 9 refs., 3 figs.

Goldstein, W.H.; Young, B.K.F.; Osterheld, A.L.; Stewart, R.E.; Walling, R.S. (Lawrence Livermore National Lab., CA (USA)); Bar-Shalom, A. (Israel Atomic Energy Commission, Beersheba (Israel). Nuclear Research Center-Negev); Klapisch, M. (Lawrence Berkeley Lab., CA (USA))

1991-01-16

373

Guiding of high intensity ultrashort laser pulses in plasma channels produced with the dual laser pulse Ignitor-Heater technique  

SciTech Connect

We 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 >5x10{sup 17} W/cm{sup 2}, 75 fs laser pulse.

Volfbeyn, P.; Leemans, W. P. [LBNL, Berkeley, California 94720 (United States)

1999-07-12

374

Time of flight mass spectra of ions in plasmas produced by hypervelocity impacts of organic and mineralogical microparticles on a cosmic dust analyser  

Microsoft Academic Search

The ionic plasma produced by a hypervelocity particle impact can be analysed to determine compositional information for the original particle by using a time-of-flight mass spectrometer. Such methods have been adopted on interplanetary dust detectors to perform in-situ analyses of encountered grains, for example, the Cassini Cosmic Dust Analyser (CDA). In order to more fully understand the data returned by

B. J. Goldsworthy; M. J. Burchell; M. J. Cole; S. P. Armes; M. A. Khan; S. F. Lascelles; S. F. Green; J. A. M. McDonnell; R. Srama; S. W. Bigger

2003-01-01

375

Time of flight mass spectra of ions in plasmas produced by hypervelocity impacts of organic and mineralogicalmicroparticles on a cosmic dust analyser  

Microsoft Academic Search

The ionic plasma produced by a hypervelocity particle impact can be analysed to determine compositional informa- tion for the original particle by using a time-of-flight mass spectrometer. Such methods have been adopted on interplanetary dust detectors to perform in-situ analyses of encountered grains, for example, the Cassini Cosmic Dust Analyser (CDA). In order to more fully understand the data returned

B. J. Goldsworthy; M. J. Burchell; M. J. Cole; S. P. Armes; M. A. Khan; S. F. Lascelles; S. F. Green; J. A. M. McDonnell; R. Srama; S. W. Bigger

2003-01-01

376

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

377

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

378

EBT2 dosimetry of x-rays produced by the electron beam from a Plasma Focus for medical applications  

NASA Astrophysics Data System (ADS)

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 ?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.; Rocchi, F.; Mostacci, D.; Sumini, M.; Tartari, A.; Mariotti, F.

2012-09-01

379

A prospective cohort study of the effect of depot medroxyprogesterone acetate on detection of plasma and cervical HIV-1 in women initiating and continuing antiretroviral therapy.  

PubMed

Depot medroxyprogesterone acetate (DMPA) use among HIV-1-infected women may increase transmission by increasing plasma and genital HIV-1 RNA shedding. We investigated associations between DMPA use and HIV-1 RNA in plasma and cervical secretions. One hundred two women initiated antiretroviral therapy, contributing 925 follow-up visits over a median of 34 months. Compared with visits with no hormonal contraception exposure, DMPA exposure did not increase detection of plasma (adjusted odds ratio: 0.81, 95% confidence interval: 0.47 to 1.39) or cervical HIV-1 RNA (adjusted odds ratio: 1.41, 95% confidence interval: 0.54 to 3.67). Our results suggest that DMPA is unlikely to increase infectivity in HIV-positive women who are adherent to effective antiretroviral therapy. PMID:24798764

Day, Summer; Graham, Susan M; Masese, Linnet N; Richardson, Barbra A; Kiarie, James N; Jaoko, Walter; Mandaliya, Kishorchandra; Chohan, Vrasha; Overbaugh, Julie; McClelland, R Scott

2014-08-01

380

Kinetics of ion and prompt electron emission from laser-produced plasma N. Farid,1,2  

E-print Network

study of plasma properties employing fast photography, time, and space resolved optical emission application. The most important parameters that influence LA properties include laser wavelength, pulse width, laser pulse duration,18 wavelength,19 and power density20 of the laser and as well as physical

Harilal, S. S.

381

Role of the laser pulse-length in producing high-quality electron beams in a homogenous plasma  

SciTech Connect

In laser wakefield acceleration, the pulse-length of the laser is an important parameter that affects the laser evolution and electron beam injection and acceleration in the bubble regime. Here, we use three-dimensional simulations to find, for a given plasma density, the optimal pulse-length that gives the best quality electron beam. For three different pulse lengths, we study the evolution dynamics of the laser spot-size and quality of the injected electron beam. We find that a pulse-length that is less than the theoretical optimum, {tau}{sub L} = {lambda}{sub p}/{radical}2{pi}c, derived from linear theory, gives the best beam quality. Conversely, our simulations suggest that for a given laser system, with a fixed pulse-length, there is an optimal value of the plasma density that will give the best quality accelerated beams in experiments. For an rms pulse-length of 10 fs (around 24 fs FWHM), this corresponds to a plasma density of around 3.4 Multiplication-Sign 10{sup 18}/cm{sup 3}. For these parameters, we obtain, in a homogenous plasma and with a single laser, an electron beam with an energy of around 700 MeV, an energy-spread less than 2%, and rms normalized emittance of a few {pi} mm-mrad.

Upadhyay, Ajay K. [Centre for Excellence in Basic Sciences, University of Mumbai, Mumbai 400098 (India); Arun Samant, Sushil [Centre for Excellence in Basic Sciences, University of Mumbai, Mumbai 400098 (India); Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Department of Physics, University of Mumbai, Mumbai 400098 (India); Krishnagopal, Srinivas [Centre for Excellence in Basic Sciences, University of Mumbai, Mumbai 400098 (India); Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

2012-07-15

382

Parameters of a laser produced plasma from XUV line profiles E. Jannitti, P. Nicolosi and G. Tondello  

E-print Network

set-up. The laser beam is deflected and focused by mirror A and lens L both having a hole through which the XUV radiation emitted by the plasma can be collected by the toroidal mirror M. The latter is used for compensating the astigmatism of the spherical concave grating G of 2 m radius, used

Boyer, Edmond

383

Viral particles drive rapid differentiation of memory B cells into secondary plasma cells producing increased levels of antibodies.  

PubMed

Extensive studies have been undertaken to describe naive B cells differentiating into memory B cells at a cellular and molecular level. However, relatively little is known about the fate of memory B cells upon Ag re-encounter. We have previously established a system based on virus-like particles (VLPs), which allows tracking of VLP-specific B cells by flow cytometry as well as histology. Using allotype markers, it is possible to adoptively transfer memory B cells into a naive mouse and track responses of naive and memory B cells in the same mouse under physiological conditions. We have observed that VLP-specific memory B cells quickly differentiated into plasma cells that drove the early onset of a strong humoral IgG response. However, neither IgM(+) nor IgG(+) memory B cells proliferated extensively or entered germinal centers. Remarkably, plasma cells derived from memory B cells preferentially homed to the bone marrow earlier and secreted increased levels of Abs when compared with primary plasma cells derived from naive B cells. Hence, memory B cells have the unique phenotype to differentiate into highly effective secondary plasma cells. PMID:24821969

Zabel, Franziska; Mohanan, Deepa; Bessa, Juliana; Link, Alexander; Fettelschoss, Antonia; Saudan, Philippe; Kündig, Thomas M; Bachmann, Martin F

2014-06-15

384

The use of ultraviolet Thomson scattering as a versatile diagnostic for detailed measurements of a collisional laser produced plasma  

SciTech Connect

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. 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{sub 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 where the laser light is absorbed mostly in the corona. The experimental results and LASNEX 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 {le} k{sub ia}{lambda}{sub ii} {le} {infinity}) and ZT{sub e}/T{sub i}, where k{sub ia} is the ion- acoustic wave number, {lambda}{sub ii} is the ion-ion mean free path, Z is the ionization state of the plasma, and T{sub e}, T{sub i} are the electron and ion temperatures in electron volts respectively. The model is valid for plasmas in which the electrons are approximately collisionless, (k{sub ia}{lambda}{sub ei}, k{sub ia}{lambda}{sub ee} {ge} 1), and quasineutrality holds, ({alpha} {much_gt}1), where {alpha} = 1/k{lambda}{sub DE} and {lambda}{sub 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.

Tracy, M.D.

1993-01-08

385

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

386

Fluid and kinetic models of the low temperature H{sub 2} plasma produced by a radio-frequency reactor  

SciTech Connect

A comparative study of two models, a kinetic and a fluid one, for the numerical simulation of H{sub 2} plasmas in parallel plate capacitively coupled rf discharges in one space dimension is presented. Both models adopt a multicomponent plasma description including several ionic species, take into account the self-consistent electric field by solving the Poisson equation and include a self-consistent coupling with the vibrational kinetics of the electronic ground state of H{sub 2} molecules. The peculiarities of this particular test case for model comparison with respect to previous studies are highlighted. The merits and the limitations of both approaches are discussed and the results are compared, in particular the steady-state density of charged species, the space-time variation of the electron energy, the vibrational distribution, and the atomic density.

Diomede, P. [Dipartimento di Chimica dell'Universita' di Bari, Via Orabona 4, 70126 Bari (Italy); Michau, A.; Redolfi, M.; Hassouni, K. [LIMHP, CNRS-UPR 1311, Institut Galilee-Universite Paris 13, 99 Avenue J. B. Clement, 93430 Villetaneuse (France); Morscheidt, W. [LGPPTS, ENSCP-Universite Pierre et Marie Curie, 11 Rue Pierre et Marie Curie, 75005 Paris (France); Longo, S.; Capitelli, M. [Dipartimento di Chimica dell'Universita' di Bari, Via Orabona 4, 70126 Bari (Italy); IMIP/CNR, Via Orabona 4, 70126 Bari (Italy)

2008-10-15

387

Using FLUKA to Study Concrete Square Shield Performance in Attenuation of Neutron Radiation Produced by APF Plasma Focus Neutron Source  

NASA Astrophysics Data System (ADS)

In 2010, representatives from the Nuclear Engineering and physics Department of Amirkabir University of Technology (AUT) requested development of a project with the objective of determining the performance of a concrete shield for their Plasma Focus as neutron source. The project team in Laboratory of Nuclear Engineering and physics department of Amirkabir University of Technology choose some shape of shield to study on their performance with Monte Carlo code. In the present work, the capability of Monte Carlo code FLUKA will be explored to model the APF Plasma Focus, and investigating the neutron fluence on the square concrete shield in each region of problem. The physical models embedded in FLUKA are mentioned, as well as examples of benchmarking against future experimental data. As a result of this study suitable thickness of concrete for shielding APF will be considered.

Nemati, M. J.; Habibi, M.; Amrollahi, R.

2013-04-01

388

Mutation breeding of lycopene-producing strain Blakeslea trispora by a novel atmospheric and room temperature plasma (ARTP).  

PubMed

To improve the fermentation efficiency of lycopene, a plasma jet, driven by an active helium atom supplied with atmospheric and room temperature plasma (ARTP) biological breeding system, was used as a new method to generate mutations in Blakeslea trispora (-). After several rounds of screening, a mutant A5 with high concentration of lycopene and dry biomass was isolated, which showed a maximum lycopene concentration (26.4 ± 0.2 mg/g dry biomass) which was 55 % higher than the parent strain (16.9 ± 0.3 mg/g dry biomass) in the production of lycopene. Compared with parent strain, B. trispora A5 required less dissolved oxygen (10 % less than that of parent strain) to reach maximum concentration in a 5-L stirred tank reactor batch fermentation. PMID:24903962

Qiang, Wang; Ling-ran, Feng; Luo, Wei; Han-guang, Li; Lin, Wang; Ya, Zhou; Xiao-bin, Yu

2014-09-01

389

Investigation of the spatial and temporal distribution of plasma excited species produced in laser ablation-glow discharge  

NASA Astrophysics Data System (ADS)

Laser Ablation and Glow Discharge (LAGD) plasmas have been coupled and optical emission measurements have been performed in order to study the spatial and temporal distribution of LA and GD species and hence to get further insights into the interaction between them. The relative delay between the laser event and the emission measurement along the GD pulse has been found as a crucial parameter. In addition, no post excitation of the ablated material has been observed when laser ablation takes place during GD prepeak or plateau. In contrast, emission enhancements (e.g. Al I lines at ~ 877 nm presented an enhancement of up to 4 times in the LAGD plasma) were obtained during the afterglow or late plateau, when firing the laser at delays close (< 100 ?s) to GD pulse termination. Penning ionization of the ablated material within the GD afterglow, followed by recombination processes, seems to account for the emission enhancements obtained when combining laser ablation and glow discharge.

Valledor, Rebeca; Tarik, Mohamed; Pisonero, Jorge; Bordel, Nerea; Günther, Detlef

2014-10-01

390

Density diagnostic of a uranium laser-produced plasma from the line ratio of Delta n = 1 transitions in Ni-like uranium  

NASA Astrophysics Data System (ADS)

The intensity ratio of the electric quadrupole 3p(6)3d(10) - 3p(5)3/2(4)f(7/2) (J=2) line to the electric dipole 3p(6)3d(10) - 3p(5)1/2(4)s line is used as a density diagnostic of a highly ionized uranium laser-produced plasma for electron densities of 10 exp 19 - 10 exp 23/cu cm. Calculations show that this ratio is insensitive to the plasma temperature in the range of 1000-4000 eV. Self-absorption of the lines is shown to be unimportant in this density range. Experimental line ratios are compared to the predictions of a Ni-like uranium-ion model that includes 138 excited levels. The densities inferred from this analysis applied to a measured line ratio yield densities of (4.0 +/- 0.5) x 10 exp 22/cu cm. This is in good agreement with models of X-ray production in laser-produced plasmas.

Mandelbaum, P.; Seely, J. F.; Feldman, U.; Brown, C. M.; Kania, D. R.; Goldstein, W. H.; Kauffman, R. L.; Langer, S.; Bar-Shalom, A.

1992-05-01

391

Investigation of fast-electron-induced K? x rays in laser-produced blow-off plasma  

NASA Astrophysics Data System (ADS)

Refluxing of fast electrons generated by high-intensity, short-pulse lasers was investigated by measuring electron-induced K? x rays from a buried tracer layer. Using planar foils of Au/Cu/CH, the 150-J, 0.7-ps TITAN short-pulse laser was focused on the gold foil to generate fast electrons and the 3-ns, 300-J long pulse beam irradiated on the CH side to create expanding plasma as a conducting medium. By delaying the short-pulse beam timing from the long pulse laser irradiation, the plasma size was varied to change electron refluxing in the target rear. The total yields and two-dimensional images of 8.05-keV Cu-K? x ray were recorded with an x-ray spectrometer and two monochromatic crystal imagers. The measurements show that the integrated yields decrease by a factor of 10 from refluxing to the nonrefluxing limit. Similar radial profiles of the K? images in the rear were observed at all delays. Hybrid-particle-in-cell simulations using plasma profiles calculated by a radiation-hydrodynamic code HYDRA agree well with the measured K? yields. The simulations suggest that conducting plasma with the size of ˜300 ?m in the laser direction and ˜600 ?m in the lateral direction at the density of 2 × 1020 1/cm3 is sufficiently large to prevent electrons from refluxing in the target. The parameters found in this study can be useful in designing experiments utilizing a K? x-ray source in refluxing regime or a tracer layer in nonrefluxing regime.

Sawada, H.; Wei, M. S.; Chawla, S.; Morace, A.; Akli, K.; Yabuuchi, T.; Nakanii, N.; Key, M. H.; Patel, P. K.; Mackinnon, A. J.; McLean, H. S.; Stephens, R. B.; Beg, F. N.

2014-03-01

392

Investigation of fast-electron-induced K? x rays in laser-produced blow-off plasma.  

PubMed

Refluxing of fast electrons generated by high-intensity, short-pulse lasers was investigated by measuring electron-induced K? x rays from a buried tracer layer. Using planar foils of Au/Cu/CH, the 150-J, 0.7-ps TITAN short-pulse laser was focused on the gold foil to generate fast electrons and the 3-ns, 300-J long pulse beam irradiated on the CH side to create expanding plasma as a conducting medium. By delaying the short-pulse beam timing from the long pulse laser irradiation, the plasma size was varied to change electron refluxing in the target rear. The total yields and two-dimensional images of 8.05-keV Cu-K? x ray were recorded with an x-ray spectrometer and two monochromatic crystal imagers. The measurements show that the integrated yields decrease by a factor of 10 from refluxing to the nonrefluxing limit. Similar radial profiles of the K? images in the rear were observed at all delays. Hybrid-particle-in-cell simulations using plasma profiles calculated by a radiation-hydrodynamic code HYDRA agree well with the measured K? yields. The simulations suggest that conducting plasma with the size of ?300 ?m in the laser direction and ?600 ?m in the lateral direction at the density of 2 × 1020 1/cm3 is sufficiently large to prevent electrons from refluxing in the target. The parameters found in this study can be useful in designing experiments utilizing a K? x-ray source in refluxing regime or a tracer layer in nonrefluxing regime. PMID:24730954

Sawada, H; Wei, M S; Chawla, S; Morace, A; Akli, K; Yabuuchi, T; Nakanii, N; Key, M H; Patel, P K; Mackinnon, A J; McLean, H S; Stephens, R B; Beg, F N

2014-03-01

393

Apparatus and method for enhanced chemical processing in high pressure and atmospheric plasmas produced by high frequency electromagnetic waves  

DOEpatents

An apparatus and method for creating high temperature plasmas for enhanced chemical processing of gaseous fluids, toxic chemicals, and the like, at a wide range of pressures, especially at atmospheric and high pressures includes an electro-magnetic resonator cavity, preferably a reentrant cavity, and a wave guiding structure which connects an electro-magnetic source to the cavity. The cavity includes an intake port and an exhaust port, each having apertures in the conductive walls of the cavity sufficient for the intake of the gaseous fluids and for the discharge of the processed gaseous fluids. The apertures are sufficiently small to prevent the leakage of the electro-magnetic radiation from the cavity. Gaseous fluid flowing from the direction of the electro-magnetic source through the guiding wave structure and into the cavity acts on the plasma to push it away from the guiding wave structure and the electro-magnetic source. The gaseous fluid flow confines the high temperature plasma inside the cavity and allows complete chemical processing of the gaseous fluids at a wide range of pressures.

Efthimion, Philip C. (Bedminister, NJ); Helfritch, Dennis J. (Flemington, NJ)

1989-11-28

394

Formation Of Carbon Oxides In CH4/O2 Plasmas Produced By Inductively Coupled RF Discharges At Low Pressure  

NASA Astrophysics Data System (ADS)

The formation of CO and CO2 has been studied in inductively coupled rf (13.56 MHz) discharges with varied mixtures of CH4 and O2 as feed gases at a total pressure of 10 Pa, flow rates of <10 sccm, and input powers of <500 W. The primary diagnostic tool has been TDLAS (tunable diode laser absorption spectroscopy) to measure absolute concentrations of molecular species as well as their kinetic and rovibrational temperatures. Of particular interest is the sudden transition between different modes of power coupling (capacitive and inductive mode, resp.) and the related changes of the plasma composition. We have found that the power threshold for this transition exhibits a clear hysteresis and depends on the oxygen content. Comparing the ratio of the CO- and CO2-concentrations in capacitive mode with corresponding data from a parallel-plate discharge, clear differences have been observed. The findings can partly be explained on the basis of plasma-chemical reaction chains using tabulated cross-sections in combination with estimations of the electron energy distribution function. Some observations (as, e.g. the presence of CO in inductively coupled plasmas that are fed by pure oxygen) cannot be understood from volume reactions only but point to an important role of surface processes, which depend on the materials of the discharge chamber and on its history and cleaning method.

Möller, Ivonne; Soltwisch, Henning

2003-06-01

395

[Characteristic study of plasma plume produced by nanosecond pulsed laser ablation of silicon using optical emission spectroscopy].  

PubMed

The 355 nm laser pulse from THG (Third Harmonic Generation) of a Qswitched Nd3+ : YAG laser was used to ablate silicon mounted in air. The time-and space-resolved optical emission spectra were measured for different pulse energy in the wavelength range of 380-420 nm, the emission spectra of N+ was found for impact ionization of air near target surface on the early stage of plasma plume expansion. Under the model of local thermodynamic equilibrium, the electronic temperature of plasma was deduced to be in the range of 18 000-40 000 K using the Saha equation by the relative line intensities, and the electron density was deduced to be in the 10(17) cm(-3) scale by FWHM (the full width at half maximum) of Si spectral lines, the temporal and spatial evolution of the electronic temperature and electron density was given, showing that the electronic temperature and electron density exhibited second order exponential decreasing with laser delay time and a Lorentz distribution in space. The reason for the spatial position deviation of the maximum electron density from the maximum spectral intensity was analyzed. The relationship between the plasma plume parameters and laser pulse energy was discussed. PMID:20707170

Gao, Xun; Jin, Ming-Xing; Ding, Da-Jun; Lin, Jing-Quan

2010-06-01

396

The effect of a UV preionization pulse on short-wave radiation output from a laser-produced-plasma source with a Xe gas-jet target  

NASA Astrophysics Data System (ADS)

Experiments aimed to raise the emissivity of a laser-produced plasma source with a Xe gas target in the far-UV spectral range are described. In these experiments, the main pulse of the IR Nd:YAG laser was preceded by a pre-ionization pulse of a UV KrF excimer laser. The consequences of applying the prepulse and its influence on the short-wavelength emission intensity were traced up to main-pulse delays of about 5 ?s with respect to the prepulse. It is supposed that the main mechanism by which the prepulse affects the evolution of the plasma and its emission intensity is related to the density waves excited in the gas target by this pulse.

Zabrodskii, V. V.; Zadiranov, Yu. M.; Kalmykov, S. G.; Mozharov, A. M.; Petrenko, M. V.; Sasin, M. E.; Seisyan, R. P.

2014-08-01

397

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

398

The absorbed HF power per electron in an open air helium microwave-induced-plasma flame produced by an axial injection torch  

SciTech Connect

Electromagnetic devices permitting the production of microwave plasmas (M.I.P.), especially those working at atmospheric pressure, have deserved a lot of attention by scientists from their utilization as a source of excitation in atomic emission spectroscopy (A.E.S.). Among them, those so-called {open_quotes}torches{close_quotes} have been intensely studied and new designs of such devices are being continuously proposed. The interest of the microwave plasma structures lies in their ability to operate at low HF power and atmospheric pressure, as well as to support plasmas of various gases. Among them, helium seems to be of particular importance for the excitation of analytes because of its high ionization potential (24.6 eV) and, as a consequence, a high metastable energy, which determines its capability of exciting non-metals (e.g., halogens). In addition, helium offers a simpler overall background spectrum. The axial injection torch ({open_quotes}torche a injection axiale{close_quotes} or T.I.A.) designed by Moisan et al. avoids some of the problems presented by previous torches, especially the problem associated with the alteration of the discharge quartz tube normally used as a plasma container because the {open_quotes}plasma flame{close_quotes} is produced in {open_quotes}open{close_quotes} air at the tip of a metallic nozzle throughout the discharge gas flows. At the same time, T.I.A. provides a stable discharge using high HF power levels (300-900 W) and relatively low gas flow (3-13 L/min) without the necessity of additional cooling.

Sola, A.; Quintero, M.C.; Rodero, A. [Univ. of Cordoba (Spain)] [and others

1995-12-31

399

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

400

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

401

Investigation of long-range temporal correlation in electron cyclotron resonance produced linear magnetized plasma of the MaPLE device  

NASA Astrophysics Data System (ADS)

Long range temporal correlation of the low frequency fluctuations is investigated in a linear electron cyclotron resonance produced magnetized plasma at different radial positions and filling gas pressures. These fluctuations turn from chaotic to coherent and again chaotic as one moves radially outwards from the center towards the edge region. The power spectrum of these fluctuations shows three distinct frequency regions characterized by their power exponents. Long range temporal correlation of these fluctuations is investigated by estimating the self similarity parameter (Hurst exponents) using rescaled range (R/S) statistics as well as from power spectrum analysis. Dependence of this long range temporal correlation on filling gas pressure has also been investigated.

Biswas, Subir; Iyengar, A. N. S.; Pal, Rabindranath

2012-03-01

402

Soft x-ray contact imaging of biological specimens using a laser-produced plasma as an x-ray source  

SciTech Connect

The use of a laser-produced plasma as an x-ray source provides significant advantages over other types of sources for x-ray microradiography of, particularly, living biological specimens. The pulsed nature of the x-rays enables imaging of the specimen in a living state, and the small source size minimizes penumbral blurring. This makes it possible to make an exposure close to the source, thereby increasing the x-ray intensity. In this article, we will demonstrate the applications of x-ray contact microradiography in structural and developmental botany such as the localization of silica deposition and the floral morphologenesis of maize.

Cheng, P.C.

1990-01-01

403

Study of the glow dynamics in a laser-produced plasma jet expanding across the magnetic field  

SciTech Connect

Results are presented from experimental studies of the glow dynamics of a plasma jet generated during the irradiation of a plane aluminum target by an iodine laser pulse with the wavelength 1.315 {mu}m. The laser pulse energy was 330-480 J, the pulse duration was 0.5 ns, and the focal spot diameter was 3 mm, the laser intensity on the target surface being {approx}10{sup 13} W/cm{sup 2}. The jet expanded across an external magnetic field with the strength {approx}1 kOe. The residual air pressure in the vacuum chamber was {approx}10{sup -5} Torr. The spatiotemporal behavior of the jet glow was investigated using a nine-frame camera in two mutually perpendicular directions (along and across the magnetic field). The results of measurements indicate azimuthal asymmetry of the jet expansion.

Bessarab, A. V.; Bondarenko, G. A.; Garanin, S. G.; Zhidkov, N. V.; Nikitin, I. N.; Starodubtsev, V. A.; Sungatullin, R. R. [All-Russia Research Institute of Experimental Physics, Russian Federal Nuclear Center (Russian Federation)

2011-09-15

404

Effect of Nano-crystalline Ceramic Coats Produced by Plasma Electrolytic Oxidation on Corrosion Behavior of AA5083 Aluminum Alloy  

SciTech Connect

High specific strength offered by aluminum and magnesium alloys makes them desirable in modern transportation industries. Often the restrictions imposed on the usage of these alloys are due to their poor tribological and corrosion properties. However, their corrosion properties can be further enhanced by synthesizing ceramic coating on the substrate through Plasma Electrolytic Oxidation (PEO) process. In this study, nano-crystalline alumina coatings were formed on the surface of AA5083 aluminum alloy test coupons using PEO process in aqueous alkali-silicate electrolyte with and without addition of sodium aluminate. X-ray diffraction (XRD) studies showed that the crystallite size varied between 38 and 46 nm and {alpha}- and {gamma}- alumina were the dominant phases present in the coatings. Corrosion studies by potentiodynamic polarization tests in 3.5% NaCl revealed that the electrolyte composition has an influence on the corrosion resistance of nano-crystalline oxide layer formed.

Thayananth, T.; Muthupandi, V. [Department of Metallurgical and Materials Engineering, National Institute of Technology, Tiruchirappalli-620015 (India); Rao, S. R. Koteswara [Principal, Tagore Engineering College, Chennai-600048 (India)

2010-10-04

405

Effect of Nano-crystalline Ceramic Coats Produced by Plasma Electrolytic Oxidation on Corrosion Behavior of AA5083 Aluminum Alloy  

NASA Astrophysics Data System (ADS)

High specific strength offered by aluminum and magnesium alloys makes them desirable in modern transportation industries. Often the restrictions imposed on the usage of these alloys are due to their poor tribological and corrosion properties. However, their corrosion properties can be further enhanced by synthesizing ceramic coating on the substrate through Plasma Electrolytic Oxidation (PEO) process. In this study, nano-crystalline alumina coatings were formed on the surface of AA5083 aluminum alloy test coupons using PEO process in aqueous alkali-silicate electrolyte with and without addition of sodium aluminate. X-ray diffraction (XRD) studies showed that the crystallite size varied between 38 and 46 nm and ?- and ?- alumina were the dominant phases present in the coatings. Corrosion studies by potentiodynamic polarization tests in 3.5% NaCl revealed that the electrolyte composition has an influence on the corrosion resistance of nano-crystalline oxide layer formed.

Thayananth, T.; Muthupandi, V.; Rao, S. R. Koteswara

2010-10-01

406

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

407

What Laboratory-Produced Plasma Structures Can Contribute to the Understanding of Cosmic Structures Both Large and Small  

Microsoft Academic Search

The tradition of the classical 1901 work by Birkeland [1] on aurora phenomena by laboratory terrella experiments was resumed by Alfvén [2], Cowling [3], Ferraro et al. [4], and by Bennett [5] in his terrella experiments. In 1954 [6] when experimenters accidentally produced in the laboratory structures later identified as diamagnetic vortex filaments, and in 1961 [7] when filaments, later

W. H. Bostick

1986-01-01

408

Long-distance directed transfer of microwaves in tubular sliding-mode plasma waveguides produced by KrF laser in atmospheric air  

NASA Astrophysics Data System (ADS)

A new regime of the sliding-mode propagation of microwave radiation in plasma waveguides in atmospheric air is studied both experimentally and theoretically. The mechanisms of air photoionization and relaxation under propagation of 25-ns pulses of KrF laser are investigated. It is shown that a tubular plasma waveguide of large radius (much larger than wavelength of the microwave signal) can be produced in the photoionization of air molecules by 248-nm radiation of KrF-laser. We experimentally demonstrate the laser-enhanced transfer of 38-GHz microwave signal to a distance of at least 60 m. The mechanism of the transfer is determined by total internal reflection of the signal on the optically less dense wall of the plasma waveguide. Analytical and numerical simulations performed for various waveguide radii and microwave radiation wavelengths show that the propagation length increases with decrease in the wavelength reaching a few kilometers for submillimeter waves. Medium-size KrF laser facility with about 400-J energy in a train of picosecond pulses is suggested for the directed transfer of microwave radiation to 1-km distance.

Zvorykin, V. D.; Levchenko, A. O.; Shutov, A. V.; Solomina, E. V.; Ustinovskii, N. N.; Smetanin, I. V.

2012-03-01

409

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

410

Autoresonant Excitation of Antiproton Plasmas  

SciTech Connect

We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination.

Andresen, G. B.; Bowe, P. D.; Hangst, J. S. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Ashkezari, M. D.; Hayden, M. E. [Department of Physics, Simon Fraser University, Burnaby British Columbia, V5A 1S6 (Canada); Baquero-Ruiz, M.; Chapman, S.; Fajans, J.; Povilus, A.; So, C. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A. J.; Madsen, N.; Werf, D. P. van der [Department of Physics, Swansea University, Swansea SA2 8PP (United Kingdom); Carpenter, P. T.; Hurt, J. L.; Robicheaux, F. [Department of Physics, Auburn University, Auburn, Alabama 36849-5311 (United States); Cesar, C. L. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-972 (Brazil)

2011-01-14

411

Using a dual plasma process to produce cobalt--polypyrrole catalysts for the oxygen reduction reaction in fuel cells -- part I: characterisation of the catalytic activity and surface structure  

E-print Network

A new dual plasma coating process to produce platinum-free catalysts for the oxygen reduction reaction in a fuel cell is introduced. The catalysts thus produced were analysed with various methods. Electrochemical characterisation was carried out by cyclic voltammetry, rotating ring- and rotating ring-disk electrode. The surface porosity of the different catalysts thus obtained was characterised with the nitrogen gas adsorption technique and scanning electron microscopy was used to determine the growth mechanisms of the films. It is shown that catalytically active compounds can be produced with this dual plasma process. Furthermore, the catalytic activity can be varied significantly by changing the plasma process parameters. The amount of H$_2$O$_2$ produced was calculated and shows that a 2 electron mechanism is predominant. The plasma coating mechanism does not significantly change the surface BET area and pore size distribution of the carbon support used. Furthermore, scanning electron microscopy pictures o...

Walter, Christian; Vyalikh, Denis; Brüser, Volker; Quade, Antje; Weltmann, Klaus-Dieter; 10.1149/2.078208jes

2012-01-01

412

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

413

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

414

Atmospheric Pressure Plasma-Initiated Chemical Vapor Deposition (AP-PiCVD) of Poly(diethylallylphosphate) Coating: A Char-Forming Protective Coating for Cellulosic Textile.  

PubMed

An innovative atmospheric pressure chemical vapor deposition method toward the deposition of polymeric layers has been developed. This latter involves the use of a nanopulsed plasma discharge to initiate the free-radical polymerization of an allyl monomer containing phosphorus (diethylallylphosphate, DEAP) at atmospheric pressure. The polymeric structure of the film is evidence by mass spectrometry. The method, highly suitable for the treatment of natural biopolymer substrate, has been carried out on cotton textile to perform the deposition of an efficient and conformal protective coating. PMID:25362895

Hilt, Florian; Boscher, Nicolas D; Duday, David; Desbenoit, Nicolas; Levalois-Grützmacher, Joëlle; Choquet, Patrick

2014-11-12

415

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

416

X-ray spectroscopic diagnostics of a copper plasma produced by a laser line focused onto a thin foil  

SciTech Connect

A 500-J, 2--6-ns, Nd laser was focused to a 100-..mu..m-wide line on a thin (375--1500 A-circle) copper film of 4--23 mm length, supported by a 1500-A-circle thick Formvar substrate. Space-resolved 8--16-A-circle wavelength x-ray spectroscopy and pinhole photography were utilized. The main spectral features include intense neon-like Cu XX lines, and somewhat less intense Cu XIX and XXI lines. Two types of axial structure are observed, one characterized by a finely (approx. <100 ..mu..m) corrugated structure, and the other by a mm scale irregular nonuniformity. The former could well be due to breakups caused by a filamentation instability. The latter appears to be associated with a mismatch between the laser pulse rise time and a characteristic (thickness-dependent) foil heating time, which makes it very sensitive to both laser-beam and copper-coating nonuniformities. The electron temperature in the Cu XX plasma, as estimated from intensity ratios of the 2p-italic-n-italicd-italic (n-italic> or =4) transition lines, increases with copper thickness.

Lee, T.N.; Molander, W.A.; Ford, J.L.; Elton, R.C.

1986-08-01

417

Atomic physics of relativistic high contrast laser-produced plasmas in experiments on Leopard laser facility at UNR  

NASA Astrophysics Data System (ADS)

The results of the recent experiments focused on study of x-ray radiation from multicharged plasmas irradiated by relativistic (I > 1019 W/cm2) sub-ps laser pulses on Leopard laser facility at NTF/UNR are presented. These shots were done under different experimental conditions related to laser pulse and contrast. In particular, the duration of the laser pulse was 350 fs or 0.8 ns and the contrast was varied from high (10-7) to moderate (10-5). The thin laser targets (from 4 to 750 ?m) made of a broad range of materials (from Teflon to iron and molybden to tungsten and gold) were utilized. Using the x-ray diagnostics including the high-precision spectrometer with resolution R ˜ 3000 and a survey spectrometer, we have observed unique spectral features that are illustrated in this paper. Specifically, the observed L-shell spectra for Fe targets subject to high intensity lasers (˜1019 W/cm2) indicate electron beams, while at lower intensities (˜1016 W/cm2) or for Cu targets there is much less evidence for an electron beam. In addition, K-shell Mg features with dielectronic satellites from high-Rydberg states, and the new K-shell F features with dielectronic satellites including exotic transitions from hollow ions are highlighted.

Safronova, A. S.; Kantsyrev, V. L.; Faenov, A. Y.; Safronova, U. I.; Wiewior, P.; Renard-Le Galloudec, N.; Esaulov, A. A.; Weller, M. E.; Stafford, A.; Wilcox, P.; Shrestha, I.; Ouart, N. D.; Shlyaptseva, V.; Osborne, G. C.; Chalyy, O.; Paudel, Y.

2012-06-01

418

Influence Of Secondary Electrons Produced From Plasma Material Interaction In Presence Of Crossed Electric And Magnetic Fields  

NASA Astrophysics Data System (ADS)

The electron energy distribution function (EEDF) plays a very important role in determining thruster efficiency as it determines various gas phase reaction rates. In Hall thrusters, secondary electron emission derived from the interaction of energetic electrons with ceramic channel surfaces influence the overall shape of the EEDF as well as determine the potential difference between the plasma and wall. The role of secondary electrons on the discharge operation of Hall thrusters is poorly understood. Experimentally, determining this effect is even more taxing as the secondary electron yield (SEY) varies drastically based on many parameters such as incident electron energies, flux and impact angle, and also on the surface properties such as temperature and roughness. The electron transport is also affected by the profile of the magnetic field, which is not uniform across the length of the accelerating channel. The goal of this work is to map out the variation of the EEDF and potential profile in response to the controlled introduction of secondary electrons. This data is expected to serve as a tool to validate and improve existing numerical models by providing boundary conditions and SEY for various situations that are encountered in Hall thrusters.

Sawlani, Kapil; Herzog, Joshua M.; Kwak, Joowon; Foster, John

2012-10-01

419

A numerical relativity approach to the initial value problem in asymptotically Anti-de Sitter spacetime for plasma thermalization - an ADM formulation  

E-print Network

This article studies a numerical relativity approach to the initial value problem in Anti-de Sitter spacetime relevant for dual non-equilibrium evolution of strongly coupled non-Abelian plasma undergoing Bjorken expansion. In order to use initial conditions for the metric obtained in arXiv:0906.4423 we introduce new, ADM formalism-based scheme for numerical integration of Einstein's equations with negative cosmological constant. The key novel element of this approach is the choice of lapse function vanishing at fixed radial position, enabling, if needed, efficient horizon excision. Various physical aspects of the gauge theory thermalization process in this setup have been outlined in our companion article arXiv:1103.3452. In this work we focus on the gravitational side of the problem and present full technical details of our setup. We discuss in particular the ADM formalism, the explicit form of initial states, the boundary conditions for the metric on the inner and outer edges of the simulation domain, the relation between boundary and bulk notions of time, the procedure to extract the gauge theory energy-momentum tensor and non-equilibrium apparent horizon entropy, as well as the choice of point for freezing the lapse. Finally, we comment on various features of the initial profiles we consider.

Michal P. Heller; Romuald A. Janik; Przemyslaw Witaszczyk

2012-03-04

420

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

421

Virus-Like Particle Vaccine Activates Conventional B2 Cells and Promotes B Cell Differentiation to IgG2a Producing Plasma Cells  

PubMed Central

We have previously shown that immunization with SIV-, SHIV-, or HA (influenza hemagglutinin)-virus-like particles (VLPs) elicits a strong humoral immune response in mice. However, little is known about the action VLPs exert on immune effector cells, including B cells. In this study, we found that all three types of VLPs could directly bind and activate B cells in vitro. VLPs stimulated the proliferation of B220+IgM+CD43?CD5? B2 cells and their differentiation to plasma cells that preferentially produce IgG2a antibodies. Up-regulation of Blimp-1, XBP-1, IRF4, and AID genes, which are responsible for class switch recombination and somatic hypermutation, was observed in VLPs-activated B2 cells. Stimulation of naïve splenocytes with VLPs led to high expression of IL-12, RANTES and MIP, the cytokine milieu that favors B cell differentiation into IgG2a secreting cells. VLP immunization of C57BL/6 mice corroborated our in vitro data showing enlarged germinal centers and expanded conventional B2 cells, but no enlarged marginal zone B1 cells, in the spleen. Enhanced antigen-specific plasma cell formation, antibody production, and IgG2a class switching were found in VLPs-immunized groups. The current study details the VLPs and B cell interactions which result in preferential IgG2a antibody production following VLP vaccination. PMID:19376580

Zhang, Sheng; Cubas, Rafael; Li, Min; Chen, Changyi; Yao, Qizhi

2009-01-01

422

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 <