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1

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

SciTech Connect

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

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

2006-06-19

2

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

3

Double layers in laser-produced plasmas  

Microsoft Academic Search

Double layers (DLs) are defined as discontinuities in the plasma potential and are related to regions of plasma without space charge neutrality. In this review the knowledge of double layers in laser-produced plasmas is summarized. It has been shown that DLs are generated in the coronal or outer region of the laser-plasma system. The space charges there were detected experimentally.

S. Eliezer; H. Hora

1989-01-01

4

Results of magnetoactive laser produced plasma investigations  

Microsoft Academic Search

Lifetime of the magnetic field generated in laser plasma is demonstrated to far exceed the laser-producing pulse duration. The theory of the pinch effect in laser plasma gains its development. The increase in density and temperature at pinching, as well as the long life of the magnetic field confining the hot plasma, are demonstrated to provide a possibility for the

Vadim Belyaev

2006-01-01

5

Initial plasma parameters for short-wave emission  

NASA Astrophysics Data System (ADS)

The paper examines the possibility of producing a plasma with the parameters required for gain at the transition n = 4 to n = 3 of a large number of hydrogen like ions. A calculation was made which relates the initial parameters of the expanding laser-produced plasma to the parameters required for lasing; the results indicate that the direct use of solid-state targets requires unrealistically high pump energies. It is suggested that the energy be pumped into a hydrogen matrix with a small admixture of the working element A or into a plasma with a density much lower than that of a solid-state plasma. The logic diagram is presented for calculating the plasma parameters and input energy for a solid-state working element A plasma, for a solid-state H + A matrix, and for an A plasma with adjustable initial density.

Gudzenko, L. I.; Derzhiev, V. I.; Evstigneev, V. V.; Iakovlenko, S. I.

1979-11-01

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

Z-Pinch Discharge in Laser Produced Plasma  

SciTech Connect

A fast coaxial electrical discharge, with relatively low current, was used to produce a Z-pinch effect in a laser produced aluminum plasma. The ion flux in the laser plasma was monitored with a Langmuir ion probe. The line density in the plasma column was controlled by using an aperture to select the portion of the laser plasma which enters the discharge cell. The Z-pinch dynamics were recorded using time-resolved imaging of the visible self-emission; the plasma was pinched to about one-third of the initial radius. Both the laser and Z-pinch plasmas were diagnosed using time-and space-resolved spectroscopy; substantial heating was observed. The measured behaviour of the pinch was compared with predictions of the slug model.

Sterling, E.; Lunney, J. G. [School of Physics, Trinity College Dublin (Ireland)

2010-10-08

8

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

9

MICROWAVE REFLECTION FROM SHOCK-PRODUCED PLASMAS  

Microsoft Academic Search

Reflection measurements were made of very low power X-band microwaves ; axially incident on shock-produced xenon and krypton plasmas. The electron ; density profile at the advancing shock front was measured with a special high ; resolution transverse 60 kMc interferometric probe. On comparison with free ; space exponential plasma-microwave interaction theory, the measured reflection ; coeificients were always very

G. W. Bethke; A. D. Ruess

1963-01-01

10

ECRH Produced Plasma for Materials Processing  

NASA Astrophysics Data System (ADS)

A device is being constructed to produce high density quiet plasmas for materials processing. The device consists of a solenoid magnetic field of strength up to 10 kG, and a 1.2 m long vacuum system. The plasma is produced by ECRH at either 10 GHz, or 18 GHz, with the resonance zone located on one end of the device. Plasma can be made from any gas simply by flowing the gas though the resonant zone, however, an alternative plasma production method is to sputter source material from a plate. This can be done by placing a biased plate near the ECRH resonant zone and accelerating ions from the resonant zone that will in tern impact the sputter plate and release more neutrals that will become ionized. Using this technique it is possible to produce purely metallic plasmas from several different materials. These plasmas can be used for materials processing, and have applications in the semi-conductor industry. Diagnostics include electrostatic probes, energy analyzers, LIF, and deposition measurements. The device is also equipped with an ICRH drive that can be used to change the pitch-angle of the plasma ions.

Rosenthal, Glenn; Cheung, P.; Wuerker, R. F.; Wong, A. Y.

1999-11-01

11

Microwave Reflection from Shock-Produced Plasmas  

Microsoft Academic Search

Reflection measurements have been made of very low power X-band microwaves, axially incident on shock-produced xenon and krypton plasmas. The electron density profile at the advancing shock front was measured with a special high-resolution transverse 60-kMcps interferometric probe. On comparison with free space exponential plasma-microwave interaction theory, the measured reflection coefficients were always found to be very significantly lower than

George W. Bethke; Allen D. Ruess

1964-01-01

12

Laser Discharge Initiation for Gas-fed Pulsed Plasma Thrusters J.W. Berkery  

E-print Network

Laser Discharge Initiation for Gas-fed Pulsed Plasma Thrusters J.W. Berkery and E.Y. Choueiri is to produce spatially uniform current sheet initiation in gas-fed pulsed plasma thrusters. The effect is ex is the initiation of the discharge in a pulsed plasma thruster through laser stimulation of the cathode

Choueiri, Edgar

13

Focused Laser Initiated RF Sustained High Pressure Air Plasmas  

NASA Astrophysics Data System (ADS)

Measurements and analysis of air breakdown processes and plasma production were done by focusing 193 nm, 300 mJ, 15 MW high power laser radiation inside a helical RF coil. We observe quantum resonant multi-photon and collisional cascade laser ionization processes that produce high density (ne˜5*10^15/cm^3) cylindrical seed plasmas. We installed an improved capacitive system that better matches the antenna impedance before plasma is produced, which increases the breakdown pressure from 20 to 60 torr with 5 kW incident RF power only. The focused laser and associated shock wave produces a plasma seed for sustaining by the RF (1-10 kW, 0.5-1.8 s) pulse. We find that triggering 20 ns multi-laser pulses at 20 Hz during one RF pulse increases the breakdown pressure from 70 to 85 torr single laser pulse. Measurements of the helical RF antenna plasma-loaded impedance are obtained by measuring the complex reflection coefficient with and without the laser pulse. Additional diagnostics are obtained with a 105 GHz interferometer to measure plasma density, collision frequency and electron temperature. Spectroscopic measurements of the plasma and comparison with the SPECAIR code are made to determine rotational and vibrational neutral gas temperatures. The results demonstrate that the laser formed seed plasma allows RF sustainment at higher initial air pressures than with RF only initiation.

Li, Yan; Scharer, John

2012-10-01

14

Tholins produced by a RF plasma  

NASA Astrophysics Data System (ADS)

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

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

2007-08-01

15

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.

16

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

17

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, 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. 63 refs.

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

1990-01-01

18

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

19

The diagnostics of plasmas produced by a high power excimer laser system  

NASA Astrophysics Data System (ADS)

A special designed long pulse XeCl MOPA laser system and its initial laser-target experiments are introduced. Laser produced plasmas of carbon, aluminum and copper are concerned. Based on measured results of plasma spectra and framing pictures of ejected plume, Plasma temperature and expanded speed of plasma flume are obtained.

Zhao, Xueqing; Liu, Jingru; Yi, Aiping; Hua, Hengqi; Zheng, Guoxin; Xue, Quanxi; Qian, Hang; Huang, Chao; Xiao, Weiwei; Huang, Xin; Ye, Xisheng; Wang, Lijun

2007-05-01

20

Parametric instabilities in helicon-produced plasmas  

SciTech Connect

Parametric instabilities arising in the pump field of a helicon wave are analyzed for typical parameters of helicon-produced plasmas. The pump wavenumber parallel to the magnetic field is assumed to be finite according to recent experimental findings obtained on a high-density helicon discharge. The parametric decay of the helicon pump wave into ion-sound and Trivelpiece-Gould waves is investigated. The approach takes into account that the damping rate of the Trivelpiece-Gould wave is generally much higher than the ion-sound frequency. The theoretical results are in agreement with the growth rates and thresholds of this instability, as well as the dispersion properties of the decay waves observed in helicon experiments. Estimates of the level of the decay parametric turbulence turn out to be sufficiently high to account for the strong absorption observed in helicon-produced plasmas.

Aliev, Yu.M.; Kraemer, M. [Lebedev Physical Institute of Russian Academy of Sciences, 119991, Moscow (Russian Federation); Experimentalphysik II, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

2005-07-15

21

Adventures in Laser Produced Plasma Research  

SciTech Connect

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

Key, M

2006-01-13

22

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

23

Plasma treatment for producing electron emitters  

DOEpatents

Plasma treatment for producing carbonaceous field emission electron emitters is disclosed. A plasma of ions is generated in a closed chamber and used to surround the exposed surface of a carbonaceous material. A voltage is applied to an electrode that is in contact with the carbonaceous material. This voltage has a negative potential relative to a second electrode in the chamber and serves to accelerate the ions toward the carbonaceous material and provide an ion energy sufficient to etch the exposed surface of the carbonaceous material but not sufficient to result in the implantation of the ions within the carbonaceous material. Preferably, the ions used are those of an inert gas or an inert gas with a small amount of added nitrogen.

Coates, Don Mayo (Santa Fe, NM); Walter, Kevin Carl (Los Alamos, NM)

2001-01-01

24

Arc initiation in cathodic arc plasma sources  

DOEpatents

A "triggerless" arc initiation method and apparatus is based on simply switching the arc supply voltage to the electrodes (anode and cathode). Neither a mechanical trigger electrode nor a high voltage flashover from a trigger electrode is required. A conducting path between the anode and cathode is provided, which allows a hot spot to form at a location where the path connects to the cathode. While the conductive path is eroded by the cathode spot action, plasma deposition ensures the ongoing repair of the conducting path. Arc initiation is achieved by simply applying the relatively low voltage of the arc power supply, e.g. 500 V-1 kV, with the insulator between the anode and cathode coated with a conducting layer and the current at the layer-cathode interface concentrated at one or a few contact points. The local power density at these contact points is sufficient for plasma production and thus arc initiation. A conductive surface layer, such as graphite or the material being deposited, is formed on the surface of the insulator which separates the cathode from the anode. The mechanism of plasma production (and arc initiation) is based on explosive destruction of the layer-cathode interface caused by joule heating. The current flow between the thin insulator coating and cathode occurs at only a few contact points so the current density is high.

Anders, Andre (Albany, CA)

2002-01-01

25

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

26

Plasma dynamics in a discharge produced by a pulsed dual frequency inductively coupled plasma source  

SciTech Connect

Using a Langmuir probe, time resolved measurements of plasma parameters were carried out in a discharge produced by a pulsed dual frequency inductively coupled plasma source. The discharge was sustained in an argon gas environment at a pressure of 10 mTorr. The low frequency (P{sub 2} {sub MHz}) was pulsed at 1 kHz and a duty ratio of 50%, while high frequency (P{sub 13.56} {sub MHz}) was maintained in the CW mode. All measurements were carried out at the center of the discharge and 20?mm above the substrate. The results show that, at a particular condition (P{sub 2} {sub MHz}?=?200 W and P{sub 13.56} {sub MHz?}=?600 W), plasma density increases with time and stabilizes at up to ?200 ?s after the initiation of P{sub 2} {sub MHz} pulse at a plasma density of (2?×?10{sup 17} m{sup ?3}) for the remaining duration of pulse “on.” This stabilization time for plasma density increases with increasing P{sub 2} {sub MHz} and becomes ?300 ?s when P{sub 2} {sub MHz} is 600 W; however, the growth rate of plasma density is almost independent of P{sub 2} {sub MHz}. Interestingly, the plasma density sharply increases as the pulse is switched off and reaches a peak value in ?10 ?s, then decreases for the remaining pulse “off-time.” This phenomenon is thought to be due to the sheath modulation during the transition from “pulse on” to “pulse off” and partly due to RF noise during the transition period. The magnitude of peak plasma density in off time increases with increasing P{sub 2} {sub MHz}. The plasma potential and electron temperature decrease as the pulse develops and shows similar behavior to that of the plasma density when the pulse is switched off.

Mishra, Anurag; Lee, Sehan [Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); Yeom, Geun Y., E-mail: gyyeom@skku.edu [Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746, South Korea and SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of)

2014-11-01

27

Microwave reflections from a vacuum ultraviolet laser produced plasma sheet  

E-print Network

) is the plasma frequency, m is the mass of the electron, is the permittivity of free space, is the microwaveMicrowave reflections from a vacuum ultraviolet laser produced plasma sheet K. L. Kelly, J. E and two-body recombination coefficient are measured by means of microwave backscatter plasma reflectivity

Scharer, John E.

28

Oxide cathodes produced by plasma deposition  

SciTech Connect

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

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

1997-12-31

29

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

SciTech Connect

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

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

2011-03-15

30

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

31

Plasma kallikrein: the bradykinin-producing enzyme.  

PubMed

Plasma prekallikrein is the liver-derived precursor of the trypsin-like serine protease plasma kallikrein (PK) and circulates in plasma bound to high molecular weight kininogen. The zymogen is converted to PK by activated factor XII. PK drives multiple proteolytic reaction cascades in the cardiovascular system such as the intrinsic pathway of coagulation, the kallikrein-kinin system, the fibrinolytic system, the renin-angiotensin system and the alternative complement pathway. Here, we review the biochemistry and cell biology of PK and focus on recent in vivo studies that have established important functions of the protease in procoagulant and proinflammatory disease states. Targeting PK offers novel strategies not previously appreciated to interfere with thrombosis and vascular inflammation in a broad variety of diseases. PMID:23846131

Björkqvist, J; Jämsä, A; Renné, T

2013-09-01

32

Thomson-Scattering from electron plasma waves in a magnetized laser-produced plasma  

NASA Astrophysics Data System (ADS)

We present temporally resolved Thomson-scattering measurements of the electron temperature and density of a magnetized laser-produced plasma. Our experiment demonstrates that by applying a 25T external magnetic field parallel to a laser beam in the plasma the electron temperature increases by nearly a factor of 2. Comparison with hydrodynamic modeling indicates the formation of a plasma channel suitable for guiding ultra-short pulse laser beams at conditions for GeV laser wakefield acceleration. This experiment was performed at the Jupiter Laser Facility, Lawrence Livermore National Laboratory, using a 527 nm, 5-ns long, 420 J laser beam focused with a random phase plate to an intensity of 1x 10^15 W/cm^2. He gas from a 1.5 mm gas jet is ionized to produce a plasma with an initial electron density of 3x10^18 cm-3. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and was partially funded by the Laboratory Directed Research and Development Program under project tracking code 06-ERD-056.

Pollock, Bradley; Divol, Laurent; Glenzer, Siegfried; Palastro, John; Ross, James; Tynan, George; Froula, Dustin

2009-11-01

33

Laser produced plasma for efficient extreme ultraviolet light sources  

SciTech Connect

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

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

2012-05-25

34

Fast Langmuir Probe Measurements in a Laser Produced Plasma  

Microsoft Academic Search

Sheath motion has been found to be an important influence on Langmuir probe measurements for a rapidly decaying plasma. The plasma is created when an organic molecule, tetrakis(dimethyl-amino)ethylene (TMAE), is ionized by a 193 nm pulsed excimer laser. The laser beam is expanded by a series of lenses to produce a plasma sheet with dimensions 0.7 - 1.5 cm ×

G. Ding; J. E. Scharer; K. L. Kelly

1997-01-01

35

Structure of an Exploding Laser-Produced Plasma  

NASA Astrophysics Data System (ADS)

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 plasma. Expansion perpendicular to B causes a wide range of effects, including a ``diamagnetic bubble'' or localized reduction of the background field, as well as visible periodic structures on the expanding plasma surface. A recent series of experiments at the UCLA Large Plasma Device (LaPD) studied these phenomena via a laser-produced plasma immersed in a large magnetized background plasma. The structure of the expanding plasma is diagnosed in three dimensions via a high-resolution (?L/Lplasma ˜0.03) in-plasma probe drive. Currents within the expanding plasma are found to have complex structure in three dimensions; in particular, an unexpected current system along the background field was discovered at the cavity surface. In addition to measurement of the plasma structure, the time behavior of large-scale (L ˜Lplasma) periodic structures on the plasma surface was investigated via two-probe correlation analysis, revealing that the structures are static and translate with the bubble across the background field.

Collette, Andrew

2010-11-01

36

Enhanced line emission from laser-produced plasmas  

NASA Technical Reports Server (NTRS)

This communication reports the first systematic study on background gas-induced spectral-line-emission enhancement from laser-produced plasmas. Line emission from aluminum plasmas was enhanced by factors of up to 35 by the introduction of He, Ne, Xe, or N2. The enhancement has been attributed to three-body recombination.

Timmer, C.; Srivastava, S. K.; Hall, T. E.; Fucaloro, A. F.

1991-01-01

37

Vacuum Arc Plasma Beam Produced From an Erbium Cathode  

Microsoft Academic Search

Er plasma was produced by a vacuum arc source with a truncated cone-shaped Er cathode and an annular copper anode. The plasma beam propagated into a cylindrical duct through the annular anode aperture and flowed in vacuum or in a low-pressure oxygen background along an axial magnetic field toward a substrate or an electrostatic ion current probe positioned on the

Vladimir N. Zhitomirsky; Avi Raveh; Raymond L. Boxman; Samuel Goldsmith

2009-01-01

38

Plasma opening switch using plasmas produced by a pulsed CO2 laser  

Microsoft Academic Search

Plasma opening switches have been studied by using laser-produced plasmas. In this paper, a CO2 laser (5 J\\/pulse, 5.5 MW peak power and 10.6 ?m wavelength) was used as a plasma source of the plasma opening switch (POS). The plasma parameters were measured by Faraday cup, Langmuir probe and a monochromator. It was found that ions with a fast flow

S. Ihara; S. Mori; M. Ishimine; S. Satoh; C. Yamabe; H. Akiyama

1997-01-01

39

Research of pulse CO2 laser produced tin plasma  

NASA Astrophysics Data System (ADS)

Experiments of pulse CO2 laser produced tin plasma had been carried out. Plasma parameters of electron temperature and density measurements both in axial and radial direction had been performed from a two-dimensional time and space resolved image spectra analysis. Debris speed of laser produced plasma in various buffer gas was quantitatively estimated by means of a fast gated intensified charge coupled device imaging system. The stopping power of the hydrogen buffer gas was assessed under ambient pressure ranging from 30 to 104 Pa.

Wu, Tao; Wang, Xing Bing; Zuo, Douluo; Lu, Peixiang

2013-02-01

40

Simulation of radiation in laser produced plasmas  

NASA Astrophysics Data System (ADS)

The radiation hydrodynamics code FAST1D(J.H.Gardner,A.J.Schmitt,J.P.Dahlburg,C.J.Pawley,S.E.Bodner,S.P.Obenschain,V.Serlin and Y.Aglitskiy,Phys. Plasmas,5,1935(1998)) was used directly (i.e. without postprocessor) to simulate radiation emitted from flat targets irradiated by the Nike laser, from 10^12 W/cm^2 to 10^13W/cm^2. We use enough photon groups to resolve spectral lines. Opacities are obtained from the STA code(A.Bar-Shalom,J.Oreg,M.Klapisch and T.Lehecka,Phys.Rev.E,59,3512(1999)), and non LTE effects are described with the Busquet model(M.Busquet,Phys.Fluids B,5,4191(1993)). Results are compared to transmission grating spectra in the range 100-600eV, and to time-resolved calibrated filtered diodes (spectral windows around 100, 180, 280 and 450 eV).

Colombant, D. G.; Klapisch, M.; Deniz, A. V.; Weaver, J.; Schmitt, A.

1999-11-01

41

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

42

Laser initiation and radiofrequency sustainment of seeded air plasmas  

Microsoft Academic Search

Summary form only given. Seeded gas plasmas and air constituents have been created by a 193 nm laser and radiofrequency sources. We have obtained 1014\\/cm3 plasma densities with initial electron temperatures of 0.3 eV in TMAE (tetrakis (dimethylamino) ethylene) by laser photoionization. We developed a fast Langmuir probe analysis of plasma decay independent of ion species mix. Langmuir probe and

J. Scharer; R. Cao; H. Gui; K. Kelly; E. Paller; R. Sund

2000-01-01

43

Laser Initiation and Radiofrequency Sustainment of Seeded Air Plasmas  

Microsoft Academic Search

Seeded gas plasmas and air constituents have been created by a 193 nm laser and radiofrequency sources. We have obtained 10^14\\/cm^3 plasma densities with initial electron temperatures of 0.3 eV in TMAE (tetrakis (dimethylamino) ethylene) by laser photoionization. We developed a fast Langmuir probe analysis of plasma decay independent of ion species mix. Langmuir probe and optical emission data illustrating

J. Scharer; G. Ding; H. Gui; K. Kelly; E. Paller

1999-01-01

44

Plasma waves near Saturn: initial results from Voyager 1  

Microsoft Academic Search

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

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

1981-01-01

45

Development of a laser-produced plasma target for beam–plasma interaction researches  

Microsoft Academic Search

A laser-produced plasma target system was developed for beam–plasma interaction experiments concerning heavy-ion inertial fusion. Irradiating a small particle of lithium hydride (LiH) with a pulsed laser, transformed the particle into a plasma. The isotropy of the plasma expansion was monitored by charge collectors. The electron density distribution was measured by interferometry. For particle sizes below and irradiation energies above

Y. Oguri; S. Abe; A. Sakumi; H. Okazaki; T. Watanabe; K. Shibata; K. Nishigori; M. Ogawa

1998-01-01

46

Diagnostics and analyses of a laser produced organic vapor plasma  

Microsoft Academic Search

Summary form only given. A fast Langmuir probe technique is developed for diagnosing a plasma produced by a 193 nm laser ionizing an organic vapor, tetrakis(dimethyl-amino)ethylene (TMAE). The plasma is characterized as high electron density (1013-1012 cm-3), low electron temperature (~0.1 eV). A probe theory on correction of sheath motion effects on ion saturation currents in Langmuir probe measurements is

G. Ding; J. E. Scharer; R. Cao; K. L. Kelly

2000-01-01

47

Laser produced plasma diagnostics by cavity ringdown spectroscopy and applications  

SciTech Connect

Laser-produced plasmas have many applications for which detailed characterization of the plume is requested. Cavity ring-down spectroscopy is a versatile absorption method which provides data on the plume and its surroundings, with spatial and temporal resolution. The measured absorption line shapes contain information about angular and velocity distributions within the plume. In various plasmas we have observed molecules or metastable atoms which were not present in the emission spectra.

Milosevic, S. [Institute of Physics, Zagreb (Croatia)

2012-05-25

48

Ramp-up of CHI Initiated Plasmas on NSTX  

SciTech Connect

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

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

2009-10-29

49

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

50

Towards laboratory produced relativistic electron-positron pair plasmas  

NASA Astrophysics Data System (ADS)

We review recent experimental results on the path to producing electron-positron pair plasmas using lasers. Relativistic pair-plasmas and jets are believed to exist in many astrophysical objects and are often invoked to explain energetic phenomena related to Gamma Ray Bursts and Black Holes. On earth, positrons from radioactive isotopes or accelerators are used extensively at low energies (sub-MeV) in areas related to surface science positron emission tomography and basic antimatter science. Experimental platforms capable of producing the high-temperature pair-plasma and high-flux jets required to simulate astrophysical positron conditions have so far been absent. In the past few years, we performed extensive experiments generating positrons with intense lasers where we found that relativistic electron and positron jets are produced by irradiating a solid gold target with an intense picosecond laser pulse. The positron temperatures in directions parallel and transverse to the beam both exceeded 0.5 MeV, and the density of electrons and positrons in these jets are of order 10 16 cm -3 and 10 13 cm -3, respectively. With the increasing performance of high-energy ultra-short laser pulses, we expect that a high-density, up to 10 18 cm -3, relativistic pair-plasma is achievable, a novel regime of laboratory-produced hot dense matter.

Chen, Hui; Meyerhofer, D. D.; Wilks, S. C.; Cauble, R.; Dollar, F.; Falk, K.; Gregori, G.; Hazi, A.; Moses, E. I.; Murphy, C. D.; Myatt, J.; Park, J.; Seely, J.; Shepherd, R.; Spitkovsky, A.; Stoeckl, C.; Szabo, C. I.; Tommasini, R.; Zulick, C.; Beiersdorfer, P.

2011-12-01

51

A mechanism to produce a dawn-dusk component of plasma flow during magnetic reconnection in the magnetotail  

NASA Technical Reports Server (NTRS)

Magnetic reconnection between antiparallel field lines in the magnetotail is generally thought to produce plasma acceleration in the earthward-tailward direction. However, measurements of the plasma velocity in the magnetotail during substorm activity sometimes reveal a dawn-dusk component of plasma flow. In this paper, we show that a dawn-dusk component of plasma acceleration may be produced during reconnection if the neutral line is not perpendicular to the magnetic field. In this case, Magnetohydrodynamic (MHD) simulations show that reconnection between antiparallel field lines will initially produce plasma acceleration that is nearly parallel to the neutral line because the magnetic tension force is not opposed by a pressure gradient force in this direction. As the magnetic field topology evolves to a steady state, the plasma flow direction rotates until it is nearly parallel to the plane that initially contained the antiparallel magnetic field lines before reconnection (hereafter referred to as the initial field plane). However, the time required to reach a steady state (typically several hundred seconds in the magnetotail region) may be greater than the time during which the reconnection process is active. Consequently, bursts of plasma flow with a dawn-dusk component may occur in the magnetotail. The initial acceleration along the neutral line depends on the angle theta (sub B) between the neutral line and the initial field plane, with the largest burst of plasma flow along the neutral line occuring when theta (s ub B) = 45 degs.

Hawkins, J. G.; Lee, L. C.; Yan, M.; Lin, Y.; Perkins, F. W.; Yamada, M.

1994-01-01

52

CHANGES PRODUCED IN MOUSE PLASMA PROTEINS BY ACUTE BACTERIAL INFECTIONS  

PubMed Central

The immunoelectrophoretic patterns of plasma proteins from mice are altered significantly by acute infections. Some proteins are dissociated into two or more components, some showed striking increase in plasma concentration, others are depleted, and certain ones appear which are undetectable in normal samples. ?1-C dissociated into two electrophoretic components under a variety of conditions in addition to infections. Endotoxins and killed organisms in vivo, and specific precipitate absorption, heat and aging in vitro produced this change. Endotoxins injected into mice also induced a rise in haptoglobin though not as sharply or predictably as acute infection. Preliminary results with samples from hospital patients with acute diseases are discussed. It was concluded that study of experimental diseases in laboratory animals by these techniques could provide a fruitful basis for the investigation of the plasma protein changes in similar human diseases. PMID:13785397

Williams, Curtis A.; Wemyss, Courtney T.

1961-01-01

53

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

54

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

55

Plasma-puff initiation of high Coulomb transfer switches  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

56

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.

57

Initial Plasmas in the Electric Tokamak (ET) At UCLA  

NASA Astrophysics Data System (ADS)

ET is scheduled to have an RF plasma at zero toroidal field in Aug. 1998. A short ohmic plasma will be attempted by the APS meeting at 1 kG. The new facility is expected to be completed by the year 2000. With R/a/b = 5/1/1.5 m ET is the largest tokamak by volume and at 1 T fields it is expected to produce ignition ready plasmas, if near classical confinement at near unit beta can be achieved. The most uncertain element of the project is plasma stability in achieving a magnetic well with reverse magnetic shear. We are planning on applying a variety of ICRF for heating, rotation and current drive. At present the NIMROD code is used to prepare us for dealing with stability and control issues under non ideal MHD conditions with biforcated poloidal rotation. Code results will be presented.

Taylor, R. J.; Gauvreau, J. L.; Gourdain, P. A.; Kissick, M. W.; Schmitz, L. W.; Tarditi, A.

1998-11-01

58

Scaling mechanisms of vapour/plasma shielding from laser-produced plasmas to magnetic fusion regimes  

NASA Astrophysics Data System (ADS)

The plasma shielding effect is a well-known mechanism in laser-produced plasmas (LPPs) reducing laser photon transmission to the target and, as a result, significantly reducing target heating and erosion. The shielding effect is less pronounced at low laser intensities, when low evaporation rate together with vapour/plasma expansion processes prevent establishment of a dense plasma layer above the surface. Plasma shielding also loses its effectiveness at high laser intensities when the formed hot dense plasma plume causes extensive target erosion due to radiation fluxes back to the surface. The magnitude of emitted radiation fluxes from such a plasma is similar to or slightly higher than the laser photon flux in the low shielding regime. Thus, shielding efficiency in LPPs has a peak that depends on the laser beam parameters and the target material. A similar tendency is also expected in other plasma-operating devices such as tokamaks of magnetic fusion energy (MFE) reactors during transient plasma operation and disruptions on chamber walls when deposition of the high-energy transient plasma can cause severe erosion and damage to the plasma-facing and nearby components. A detailed analysis of these abnormal events and their consequences in future power reactors is limited in current tokamak reactors. Predictions for high-power future tokamaks are possible only through comprehensive, time-consuming and rigorous modelling. We developed scaling mechanisms, based on modelling of LPP devices with their typical temporal and spatial scales, to simulate tokamak abnormal operating regimes to study wall erosion, plasma shielding and radiation under MFE reactor conditions. We found an analogy in regimes and results of carbon and tungsten erosion of the divertor surface in ITER-like reactors with erosion due to laser irradiation. Such an approach will allow utilizing validated modelling combined with well-designed and well-diagnosed LPP experimental studies for predicting consequences of plasma instabilities in complex fusion environment, which are of serious concern for successful energy production.

Sizyuk, Tatyana; Hassanein, Ahmed

2014-02-01

59

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

E-print Network

Design of a Microwave-Initiated Pulsed Plasma Thruster (MiPPT) Jian F. Li, Class of 2006 Submitted of a Microwave-Initiated Pulsed Plasma Thruster (MiPPT) i ABSTRACT The performance of gas-fed pulsed plasma a microwave-initiated pulsed plasma thruster (MiPPT) and perform all detailed simulations, prototyping

Choueiri, Edgar

60

RESEARCH NOTE: Parameters of plasma produced by an electron cyclotron resonance heating plasma gun  

Microsoft Academic Search

Plasma parameters of a plasma produced by a slotted cylindrical microwave cavity are investigated experimentally, and two components of electron temperature are observed. When the neutral gas pressure is decreased, both the temperature of the hot component and the energy density increase. The electron temperature rises at a rate of approximately 2 to 4·5 MeV s?1. This suggests that the

Masataka Masuda; Yuji Tanaka; Takayoshi Okuda

1972-01-01

61

Hydrolysis of hemicellulose to produce fermentable monosaccharides by plasma acid.  

PubMed

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

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

2013-09-12

62

On a characteristic initial value problem in Plasma physics  

E-print Network

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

Simone Calogero

2005-06-01

63

INITIATION AND PROLIFERATION OF GOSSYPOL-PRODUCING COTTON HAIRY ROOTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Hairy roots are masses of differentiated, transformed cells resulting from infection with Rhizobium rhizogenes (ATCC 15834) (Agrobacterium rhizogenes). Hairy root cultures derived from many plant species have been valuable research tools for producing secondary plant metabolites and for examining ne...

64

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

SciTech Connect

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

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

2012-05-01

65

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

66

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

67

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

68

Numerical analysis of the plasma-produced region in a plasma spraying system  

SciTech Connect

For this study, the Arcjet Plasmodynamic Analysis Code (APAC) developed by Fujita has been significantly modified in order to investigate the physical phenomena of the plasma-produced region in a plasma spraying system. For self-consistent determination of the heating process of working gas, plasma flow, which contains complicated physical phenomena, is obtained by interconnecting flow field analysis with electric field analysis. The main conclusions obtained are summarized as follows: (1) Discharge voltage decreased with discharge current significantly. On the other hand, it increases slightly with hydrogen flow rate. (2) Current density distribution governs physical phenomena in plasma flow. (3) Temperature and velocity distribution at the nozzle exit depend on the discharge current.

Matsuo, T.; Sakata, N.; Kato, S.; Nagayama, T.; Fujita, K.

1999-07-01

69

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

70

Strongly Polarized Plasma Emission Produced by Laser Ablation of Aluminum  

NASA Astrophysics Data System (ADS)

We have found that continuum emission produced in the laser ablation of a material may be strongly polarized, whereas as discrete atomic or ionic emission lines appear as minima in the plasma polarization spectrum [1]. This effect is indicative of strong directionality of electrons recombining in the plasma. By placing a polarizer before the detector, it is possible to suppress the continuum background, thereby greatly increasing the resolution and detection sensitivity. Previously this technique used double pulses of femtosecond Ti:Sapphire radiation to achieve maximum polarization [2]. Here we show that single pulses on both the fs and ns time scales produce strongly polarized spectra of Al. The effects of laser intensity, focal position, angle of incidence, and polarization state of the laser are explored. [4pt] [1] Y. Liu, S. Singha, T. E. Witt, and R. J. Gordon, Appl. Phys. Lett. 93, 161502 (2008).[0pt] [2] Y. Zhao, S. Singha, Y. Liu, and R. J. Gordon, Opt. Lett. 34 (in press).

Gordon, Robert; Liu, Yaoming; Penczak, John; Zhao, Youbo

2009-05-01

71

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

72

Laser-produced plasma light source for EUVL  

NASA Astrophysics Data System (ADS)

This paper is devoted to the development of laser produced plasma (LPP) EUV source architecture for advanced lithography applications in high volume manufacturing of integrated circuits. The paper describes the development status of subsystems most critical to the performance to meet scanner manufacturer requirements for power and debris mitigation. Spatial and temporal distributions of the radiation delivered to the illuminator of the scanner are important parameters of the production EUV tool, this paper reports on these parameters measured at the nominal repetition rate of the EUV source. The lifetime of the collector mirror is a critical parameter in the development of extreme ultra-violet LPP lithography sources. Deposition of target material and contaminants as well as sputtering and implantation of incident particles can reduce the reflectivity of the mirror coating substantially over time during exposure even though debris mitigation schemes are being employed. We report on progress of life-test experiments of exposed 1.6sr collectors using a Sn LPP EUV light source. The erosion of MLM coating is caused mostly by the high-energy ions generated from the plasma. In this manuscript the ion distribution measured at small (14 degree) and medium (45 degree) angles to the laser beam are presented. The measurements show that the chosen combination of the CO2 laser and Sn droplet targets is characterized by fairly uniform angular ion energy distribution. The maximum ion energy generated from the plasma is in the range of 3-3.5 keV for all incident angles of the collector. The measured maximum energy of the ions is significantly less than that measured and simulated for plasmas generated by short wavelength lasers (1 ?m). The separation of ions with different charge states was observed when a retarding potential was applied to the Faraday Cup detector.

Fomenkov, Igor V.; Brandt, David C.; Bykanov, Alexander N.; Ershov, Alex I.; Partlo, William N.; Myers, Dave W.; Böwering, Norbert R.; Farrar, Nigel R.; Vaschenko, Georgiy O.; Khodykin, Oleh V.; Hoffman, Jerzy R.; Chrobak, Christopher P.; Srivastava, Shailendra N.; Golich, Daniel J.; Vidusek, David A.; De Dea, Silvia; Hou, Richard R.

2009-03-01

73

Numerical study on the Z pinch dynamics of gas jet type discharge produced plasma (DPP) source  

NASA Astrophysics Data System (ADS)

Z pinch DPP source is often used as an Extreme Ultra-Violet (EUV) source. It is convenient to produce high temperature and high density plasma. There are several analytical models to describe the dynamics of the plasma. The snowplow model is a simple and widely used model to analyze the motion of the plasma shell and predict the pinch time; however, it is incapable of analyzing the plasma behavior after the maximum pinch and providing detailed information of concerned plasma parameters, such as electron density and electron temperature. In this study, we present the simulation results of the Z pinch DPP dynamics obtained by a 2D MHD code. This code solves the problem based on the assumption of single fluid, two temperature approximations in the cylindrical geometry. The numerical scheme for this MHD code is Total-Variation-Diminishing scheme in Lax Friedrich formulation (TVD-LF). The evolution of electron density, electron temperature, current density, magnetic flux and some other important parameters in Z pinch dynamics are investigated with this code. The simulation results show that the maximum pinch electron density is on the order of 10^19 cm-3, with a pinch plasma radius of about 0.1 mm. In order to optimize the radiation output, the influences of initial gas distribution and the current waveform on the Z pinch dynamics are also investigated. They affect the electron density at pinch stagnation obviously; while in term of electron temperature, the effect is slight.

Huang, Bin; Xie, Bin; Tomizuka, Taku; Watanabe, Masato; Xiao, Feng; Hotta, Eiki

2012-10-01

74

Plasma waves near Saturn: Initial results from Voyager 1  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

75

What produces the high densities observed in solar flare plasmas  

NASA Technical Reports Server (NTRS)

Attention is drawn to the implications of the high densities observed in flare plasmas in the wide temperature range from 10 to the 4th K to more than 10 to the 7th K. The chromospheric evaporation theory for the decay phase is discussed, and it is found that it is not consistent with the observations. It is pointed out that all the flare mechanisms proposed so far, e.g., magnetic field reconnection in various geometries, have entirely ignored the fundamental problem of how the high densities arise in the first place, and, in fact, they are unable to answer this question. It is suggested that compressional heatings of a flaring loop might be responsible for the density and emission measure (EM) increases observed in flare plasmas. Chromospheric evaporation associated with local heating in the initial rising phase of the flare, in distinction to the existing evaporation theory which assumes a coronal heating source, is also discussed. Possible observational tests, utilizing the newly launched Solar Maximum Mission (SMM) satellite, are presented.

Cheng, C.-C.; Feldman, U.; Doschek, G. A.

1981-01-01

76

Plasma processes for producing silanes and derivatives thereof  

DOEpatents

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

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

2014-03-25

77

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

SciTech Connect

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

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

2011-10-15

78

Initiation of nuclear reactions in femtosecond laser plasma  

SciTech Connect

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 {sup 235}U, {sup 236}U, {sup 238}U, and {sup 232}Th fission in a laser field of intensity 10{sup 20} to 10{sup 22} W/cm{sup 2}.

Golovinski, P. A., E-mail: golovinski@bk.ru [Moscow Institute of Physics and Technology (Russian Federation); Mikhin, E. A. [Voronezh State University of Architecture and Civil Engineering (Russian Federation)] [Voronezh State University of Architecture and Civil Engineering (Russian Federation)

2013-01-15

79

Atmospheric plasma inactivation of foodborne pathogens on fresh produce surfaces.  

PubMed

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

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

2007-10-01

80

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

81

Evidence of plasma polarization shift of Ti He-? resonance line in high density laser produced plasmas  

NASA Astrophysics Data System (ADS)

A spectroscopic study of the He-? (1s2 1s0 - ls2p 1p1) line emission (4749.73 eV) from high density plasma was conducted. The plasma was produced by irradiating Ti targets with intense (I ? l×l019 W/cm2), 400nm wavelength high contrast, short (45fs) p-polarized laser pulses at an angle of 45°. A line shift up to 3.4+1.0 eV (1.9±0.55 mÅ) was observed in the He-? line. The line width of the resonance line at FWHM was measured to be 12.1±0.6 eV (6.7±0.35 mÅ). For comparison, we looked into the emission of the same spectral line from plasma produced by irradiating the same target with laser pulses of reduced intensities (?1017 W/cm2): we observed a spectral shift of only 1.8+1.0 eV (0.9+0.55mÅ) and the line-width measures up to 5.8+0.25 eV (2.7+0.35 mÅ). These data provide evidence of plasma polarization shift of the Ti He-? line.

Khattak, F. Y.; Percie du Sert, O. A. M. B.; Rosmej, F. B.; Riley, D.

2012-12-01

82

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

NASA Astrophysics Data System (ADS)

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

Giar, Ryan; Scharer, John

2011-11-01

83

Dynamics of quark-gluon plasma produced in heavy ion collisions  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

84

ccsd00001731, Study on high pressure plasma produced by ArF  

E-print Network

ccsd­00001731, version 2 ­ 7 Nov 2004 Study on high pressure plasma produced by ArF laser Norio in a high pressure argon gas from 50 to 130 atm, the plasma development is observed by streak camera from side window of chamber. The high pressure ArF laser plasma develops symmetrically and the plasma

85

Superposition of two plasma beams produced in a vacuum arc deposition apparatus  

Microsoft Academic Search

Two plasma beams of different materials were produced from Ti, Zr, or Nb cathodes in a triple-cathode vacuum arc deposition apparatus. The cathodes were arranged in a circle centered on the system axis. The plasma produced by the cathode spots was transported through a straight plasma duct with an axial magnetic field, into a sample chamber, in which a single

Vladimir N. Zhitomirsky; Raymond L. Boxman; Samuel Goldsmith; Ilana Grimberg; Ben-Zion Weiss

1999-01-01

86

Superposition of two plasma beams produced in a vacuum arc deposition apparatus  

Microsoft Academic Search

Two plasma beams of different materials were produced from Ti, Zr or Nb cathodes in a triple-cathode vacuum arc deposition apparatus. The cathodes were arranged in a circle centered on the system axis. The plasma produced was transported through a straight plasma duct with an axial magnetic field, into a deposition chamber, in which a single Langmuir probe, an array

V. N. Zhitomirsky; R. L. Boxman; S. Goldsmith; I. Grimberg; B. Z. Weiss

1998-01-01

87

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

88

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

89

Analysis of spectra from laser produced plasmas using a neural network  

SciTech Connect

A backpropagation artificial neural network algorithm is applied to the analysis of [ital K]-shell x-ray line spectra from a well characterized laser produced plasma. After training on synthetic spectra produced by appropriate collisional radiative plasma emission models, the network correctly determines the electron temperature as a function of distance into the plasma. The results demonstrate the potential utility of neural networks for interpreting spectral data from plasma devices and sources.

Osterheld, A.L.; Morgan, W.L.; Larsen, J.T.; Young, B.K.F.; Goldstein, W.H. (Lawrence Livermore National Laboratory, University of California, P.O. Box 808, Livermore, California 94550 (United States) Kinema Research, P.O. Box 1147, Monument, Colorado 80132 (United States) Cascade Applied Sciences, Inc., P.O. Box 4477, Boulder, Colorado 80306 (United States))

1994-09-12

90

Laser produced plasma EUV sources for device development and HVM  

NASA Astrophysics Data System (ADS)

Laser produced plasma (LPP) systems have been developed as the primary approach for the EUV scanner light source for optical imaging of circuit features at sub-22nm and beyond nodes on the ITRS roadmap. This paper provides a review of development progress and productization status for LPP extreme-ultra-violet (EUV) sources with performance goals targeted to meet specific requirements from leading scanner manufacturers. We present the latest results on exposure power generation, collection, and clean transmission of EUV through the intermediate focus. Semiconductor industry standards for reliability and source availability data are provided. We report on measurements taken using a 5sr normal incidence collector on a production system. The lifetime of the collector mirror is a critical parameter in the development of extreme ultra-violet LPP lithography sources. Deposition of target material as well as sputtering or implantation of incident particles can reduce the reflectivity of the mirror coating during exposure. Debris mitigation techniques are used to inhibit damage from occuring, the protection results of these techniques will be shown over multi-100's of hours.

Brandt, David C.; Fomenkov, Igor V.; Lercel, Michael J.; La Fontaine, Bruno M.; Myers, David W.; Brown, Daniel J.; Ershov, Alex I.; Sandstrom, Richard L.; Bykanov, Alexander N.; Vaschenko, Georgiy O.; Böwering, Norbert R.; Das, Palash; Fleurov, Vladimir B.; Zhang, Kevin; Srivastava, Shailendra N.; Ahmad, Imtiaz; Rajyaguru, Chirag; De Dea, Silvia; Dunstan, Wayne J.; Baumgart, Peter; Ishihara, Toshi; Simmons, Rod D.; Jacques, Robert N.; Bergstedt, Robert A.; Porshnev, Peter I.; Wittak, Christian J.; Woolston, Michael R.; Rafac, Robert J.; Grava, Jonathan; Schafgans, Alexander A.; Tao, Yezheng

2012-03-01

91

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

SciTech Connect

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

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

2009-04-15

92

Measurement of the expansion of picosecond laser-produced plasmas using resonance absorption profile spectroscopy  

Microsoft Academic Search

Time-resolved, submicron density scale lengths in picosecond laser-produced plasmas are measured using resonance absorption profile spectroscopy. The density scale length at critical density is inferred from the angle and polarization dependence of the absorption of a picosecond laser pulse in a performed plasma. The early expansion of picosecond laser-produced plasmas produced from an Au target is studied, with measured scale

O. L. Landen; D. G. Stearns; E. M. Campbell

1989-01-01

93

Structure of magnetic fields generated in laser produced plasmas  

NASA Astrophysics Data System (ADS)

A numerical model is used in interpreting recent results on magnetic fields generated in laser plasma experiments. Satisfactory agreement is found between model predictions and experimental observations of the field morphology. The main features of the measured density profile are also reproduced. There is agreement between theory and experiment that peak fields occur far out in the coronal plasma. This is seen as suggesting that magnetic effects may have important consequences for laser-plasma interactions away from the critical density.

Boyd, T. J. M.; Humphreys-Jones, G. J.; Cooke, D.

1982-03-01

94

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

95

Transport of a vacuum arc produced plasma beam in a magnetized cylindrical duct  

Microsoft Academic Search

The transport of a vacuum arc produced plasma beam along a magnetized cylindrical duct was studied experimentally. The plasma source consisted of a Sn or an Al cathode and a 17 mm i.d. annular copper anode through which the plasma beam entered into the 160 mm diameter and 500 mm length cylindrical duct. Arc current, I.,,, was in the range

V. N. Zhitomirsky; O. Zarchin; R. L. Boxman; S. Goldsmith

2002-01-01

96

Persistence of uranium emission in laser-produced plasmas  

SciTech Connect

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., E-mail: hari@purdue.edu; Diwakar, P. K.; Hassanein, A. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

2014-04-28

97

Kilovolt radiation from a laser-produced Al plasma  

Microsoft Academic Search

We have characterized kilo-electron-volt (keV) emission from Al plasmas for various laser illuminations at the OMEGA laser with the goal of optimizing the ability to backlight low-atomic-number materials such as beryllium for fusion ignition studies. The plasma is diagnosed by spectral-measurement comparisons to detailed theoretical atomic physics models. It is found that a significant fraction of the radiation is due

J. A. Cobble; T. E. Tierney; J. Abdallah

2007-01-01

98

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

99

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

E-print Network

Pressure-driven, resistive magnetohydrodynamic interchange instabilities in laser-produced high magnetized plasma instabilities in laser-produced high-energy-density plasmas. Time-gated proton radiograph- quence of pressure-driven, resistive magnetohydrodynamic MHD interchange instabilities. In contrast

100

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

E-print Network

Observation of laser satellites in a plasma produced by a femtosecond laser pulse S. A. Pikuz P. N­459 10 October 1997 Laser satellites are detected in the emission spectra of magnesium and aluminum plasmas produced by femtosecond laser pulses. This is made possible by the realization of picosecond time

Umstadter, Donald

101

Dynamics of C2 formation in laser-produced carbon plasma in helium environment  

E-print Network

Dynamics of C2 formation in laser-produced carbon plasma in helium environment K. F. Al-Shboul, S the role of helium ambient gas on the dynamics of C2 species formation in laser-produced carbon plasma from the C2 species was studied using optical emission spectroscopy, and spectrally resolved

Harilal, S. S.

102

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

103

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

104

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

105

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

106

Experimental Results from Initial Operation of Plasma Injector 1  

Microsoft Academic Search

General Fusion has begun operation of its first full-scale plasma injector, designed to accelerate high density spheromak plasmas into the compression chamber of a proposed MTF reactor. The geometry of Plasma Injector 1 (PI-1) is that of a two stage coaxial Marshal gun with a conical converging accelerator electrodes, similar in shape to the MARAUDER device, while pulsed power is

Stephen Howard

2010-01-01

107

A comparison of plasma waves produced by ion accelerators in the F-region ionosphere  

NASA Technical Reports Server (NTRS)

Ion beams injected into the ionosphere are known to produce waves related to the normal modes of the plasma. The spectra of plasma waves produced during four sounding rocket experiments are examined. The experimental conditions were somewhat different during each experiment. The accelerated ion was either Xe(+) or Ar(+) and the experimental geometry, described by the separation vector between the plasma wave receiver and the ion accelerator, was either parallel or perpendicular to the geomagnetic field.

Kintner, P. M.; Labelle, J.; Scales, W.; Erlandson, R.; Cahill, L. J., Jr.

1986-01-01

108

Plasma choline metabolites and colorectal cancer risk in the Women's Health Initiative Observational Study.  

PubMed

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

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

2014-12-15

109

Fundamentals of Discharge Initiation in Gas-Fed Pulsed Plasma Thrusters  

E-print Network

Fundamentals of Discharge Initiation in Gas-Fed Pulsed Plasma Thrusters IEPC-2005-153 Presented discharges in gas-fed pulsed plasma thrusters (GFPPTs) is conducted. It is argued that undervoltage breakdown standing in the way of the gas-fed pulsed plasma thruster (GFPPT) becoming flight-ready hardware

Choueiri, Edgar

110

Ion current produced by a vacuum arc carbon plasma source  

Microsoft Academic Search

A vacuum arc carbon plasma source is described, in which an arc was ignited between a cathode and an anode having In aperture, by bringing the two electrodes into contact, and parting them while current was flowing. The inter-electrode gap length was varied. A focusing magnetic field was applied in the inter-electrode gap, and a toroidal magnetic field was applied

Vladimir N. Zhitomirsky; Oren Zarchin; She-Guan Wang; Raymond L. Boxman; Samuel Goldsmith

2001-01-01

111

Radiation cooling in laser-produced plasmas due to high-Z layers  

Microsoft Academic Search

Radiation cooling of laser-produced aluminum plasmas by highly ionized gold atoms was studied experimentally. The plasma was produced by irradiating 500-mum-diam glass spheres coated with two layers of aluminum and an intermediate gold layer of varying thickness. The 24-beam Omega laser system at a laser wavelength of 351 nm and intensity in the range (2-3)×1014 W\\/cm2 was used to produce

J. C. Moreno; S. Goldsmith; H. R. Griem; Leonard Cohen; R. Epstein; D. Bradley; P. A. Jaanimagi; J. Knauer

1989-01-01

112

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

SciTech Connect

We investigated the angular distribution of ions and atoms emanating from femto- and nanosecond laser-produced metal plasmas under similar laser fluence conditions. For producing plasmas, aluminum targets are ablated in vacuum employing pulses from a Ti:Sapphire ultrafast laser (40 fs, 800 nm) and an Nd:YAG laser (6 ns, 1064 nm). The angular distribution of ion emission as well as the kinetic energy distribution is characterized by a Faraday cup, while a quartz microbalance is used for evaluating deposited mass. The ion and deposited mass features showed that fs laser ablated plasmas produced higher kinetic energy and more mass per pulse than ns plumes over all angles. The ion flux and kinetic energy studies show fs laser plasmas produce narrower angular distribution while ns laser plasmas provide narrower energy distribution.

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

2012-06-15

113

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

114

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

115

Plasma observations near Saturn - Initial results from Voyager 1  

Microsoft Academic Search

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

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

1981-01-01

116

Plasma observations near Neptune - Initial results from Voyager 2  

Microsoft Academic Search

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

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

1989-01-01

117

Seminal Plasma Initiates a Neisseria gonorrhoeae Transmission State  

PubMed Central

ABSTRACT Niche-restricted pathogens are evolutionarily linked with the specific biological fluids that are encountered during infection. Neisseria gonorrhoeae causes the genital infection gonorrhea and is exposed to seminal fluid during sexual transmission. Treatment of N. gonorrhoeae with seminal plasma or purified semen proteins lactoferrin, serum albumin, and prostate-specific antigen each facilitated type IV pilus-mediated twitching motility of the bacterium. Motility in the presence of seminal plasma was characterized by high velocity and low directional persistence. In addition, infection of epithelial cells with N. gonorrhoeae in the presence of seminal plasma resulted in enhanced microcolony formation. Close association of multiple pili in the form of bundles was also disrupted after seminal plasma treatment leading to an increase in the number of single pilus filaments on the bacterial surface. Thus, exposure of N. gonorrhoeae to seminal plasma is proposed to alter bacterial motility and aggregation characteristics to influence the processes of transmission and colonization. PMID:24595372

Anderson, Mark T.; Dewenter, Lena; Maier, Berenike; Seifert, H. Steven

2014-01-01

118

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

119

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

120

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

121

Polarity effect on the behavior of gas puff z-pinch plasma produced by IPP system  

Microsoft Academic Search

Summary form only given, as follows. Hot spots produced by gas-puff z-pinch plasma which are high energy density plasma regions radiate intensive soft X-rays. A gas-puff z-pinch is expected in industrial applications such as soft X-ray lithography, microscopy and lasers. In these cases, the scattering of hot spots is important when the gas-puff z-pinch plasma is used as a point

K. Imasaka; K. Takahashi; J. Suehiro; M. Hara

2001-01-01

122

Laser-produced plasma: a new window for high pressure science  

Microsoft Academic Search

Summary form only given, as follows. High-energy-density laser-produced plasmas offer an unique window for the investigation of high pressure phenomena. From observations of the intensity of optical emission from and the reflectivity of a plasma generated by a laser-driven shock wave, one learns about not only the rate of thermal equilibriation between electrons and ions in a strongly coupled plasma

A. Ng

1999-01-01

123

Transport of a vacuum-arc produced plasma beam in a magnetized cylindrical duct  

Microsoft Academic Search

The transport of a vacuum-arc produced plasma beam along a magnetized cylindrical duct was studied experimentally. The plasma source consisted of a Sn or an Al cathode and a 17-mm internal diameter annular copper anode through which the plasma beam entered into the 160-mm diameter and 500-mm length cylindrical duct. The arc current Iarc was in the range of 30-100

Vladimir N. Zhitomirsky; Oren Zarchin; Raymond L. Boxman; Samuel Goldsmith

2003-01-01

124

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

125

Initial Plasma Startup Test on SUNIST Spherical Tokamak  

Microsoft Academic Search

The goal of the Sino-United Spherical Tokamak (SUNIST) at Tsinghua University is to extend the understanding of toroidal plasma physics at a low aspect ratio (R\\/a approx 1.3) and to demonstrate a maintainable target plasma by non-inductive startup. The SUNIST device is designed to operate with up to 13 kA of ohmic heating field current, and to 0.15 T of

Ying Wang; Li Zeng; Yexi He

2003-01-01

126

Laser initiation and decay processes in an organic vapor plasma  

Microsoft Academic Search

A large volume organic molecular plasma (hundreds of cm3) is created by a 193 nm laser ionizing an organic molecule, Tetrakis-(dimethylamino)-ethylene (TMAE). The plasma is found to be characterized by high electron density (10 13-1011cm-3), low electron temperature (~0.1 eV), fast creation (~10 ns) and rapid decaying (electron-ion recombination coefficient ~10-6 cm3\\/s). Fast Langmuir probe (LP) techniques are developed for

Guowen Ding

1999-01-01

127

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

128

Ion beam and plasma methods of producing diamondlike carbon films  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

129

Tritium Containment in the Dust and Debris of Plasma-Facing Materials Produced During Operations  

E-print Network

' . . , . Tritium Containment in the Dust and Debris of Plasma-Facing Materials Produced During avaihble original document. #12;Tritium Containment in the Dust and Debris of Plasma-Facing hlaterials important parameter that influence tritium build-up and release in the generated dust of PFMs is the effect

Harilal, S. S.

130

Space-dependent shift of spectral lines in laser-produced plasmas  

E-print Network

Space-dependent shift of spectral lines in laser-produced plasmas P. Jaeglé, A. Carillon, G. Jamelot and C. Wehenkel GRECO du CNRS « Interaction Laser-Matière », Ecole Polytechnique, 91120 Palaiseau ultraviolet extrême provenant d'un plasma produit par laser, le spectre étant obtenu en un seul tir sur cible

Boyer, Edmond

131

Influence of ambient gas on the temperature and density of laser produced carbon plasma  

E-print Network

Influence of ambient gas on the temperature and density of laser produced carbon plasma S. S; accepted for publication 11 November 1997 The effect of ambient gas on the dynamics of the plasma generated than in helium or air as an ambient. © 1998 American Institute of Physics. S0003-6951 98 04102

Harilal, S. S.

132

Characteristics of Very High Frequency Plasma Produced with Ladder-Shaped Electrode at High Pressure  

Microsoft Academic Search

A very high frequency (VHF) plasma was produced with a ladder-shaped electrode at high pressure and plasma parameters such as the density and temperature of electrons were measured as a function of pressure using a Langmuir probe. A VHF power source with a frequency of 60 MHz was used and the power was up to 450 W. When the pressure

Hiromu Takatsuka; Yasuhiro Yamauchi; Yoshiaki Takeuchi; Hiroshi Mashima; Hideaki Yamashita; Yoshinobu Kawai

2005-01-01

133

Quasielectrostatic whistler wave radiation from the hot electron emission of a laser-produced plasma  

Microsoft Academic Search

Measurements are presented of radiated wave electric fields which result from the creation of a dense, laser-produced plasma within a large, uniform background magnetoplasma. The radiated field patterns are consistent for waves propagating along the quasielectrostatic branch of the whistler wave dispersion curve calculated from the background plasma parameters. The energy source of these waves coincides with an observed energetic

Stephen Vincena; Walter Gekelman; M. A. van Zeeland; James Maggs; Andrew Collette

2008-01-01

134

Numerical Simulation of Laser-Produced Plasma Devices for EUV Lithography Using the Heights Integrated Model  

Microsoft Academic Search

Laser-produced plasma (LPP) devices have been modeled as the light source for extreme ultraviolet (EUV) lithography. A key challenge for LPP is achieving sufficient brightness to support the throughput requirements of high-volume manufacturing. An integrated model (HEIGHTS) was applied to simulate the environment of EUV sources and optimize their output. The model includes plasma evolution and magnetohydrodynamic processes in a

V. Sizyuk; A. Hassanein; V. Morozov; V. Tolkach; T. Sizyuk; B. Rice

2006-01-01

135

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

Microsoft Academic Search

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

Edgar P. Spalding; Mary Helen; M. Goldsmith

1993-01-01

136

Soft x-ray lithography using radiation from laser-produced plasmas  

Microsoft Academic Search

Plasmas formed by focusing 0.6-J pulses from a 10-Hz Nd:YAG laser onto solid targets were used as soft x-ray sources for lithographic studies. Results of exposing masked photoresists to plasma radiation produced using steel, copper, and tungsten as targets are presented.

T. J. McIlrath; M. L. Ginter; M. C. Pekerar

1985-01-01

137

Soft x-ray lithography using radiation from laser-produced plasmas  

SciTech Connect

Plasmas formed by focusing 0.6-J pulses from a 10-Hz Nd:YAG laser onto solid targets were used as soft x-ray sources for lithographic studies. Results of exposing masked photoresists to plasma radiation produced using steel, copper, and tungsten as targets are presented.

McIlrath, T.J.; Ginter, M.L.; Pekerar, M.C.; Ma, D.; Gohil, P.; Kapoor, H.

1985-07-01

138

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

Microsoft Academic Search

The formation of nanoparticles in a plasma produced by the interaction of ultrashort laser pulses with gold has been investigated. Three different experimental techniques were employed. (i) The plume expansion was characterized using fast imaging with the aid of an intensified charge-coupled device. (ii) The plasma composition was analyzed using time- and space-resolved optical emission spectroscopy. (iii) The ablated material

P. Spiga; J. Hermann; T. Itina; D. Grojo; D. Neamtu; D. Pailharey; W. Marine

2005-01-01

139

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

SciTech Connect

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

Grun, J.; Ripin, B.H.

1982-09-17

140

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

SciTech Connect

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

Grun, J.; Ripin, B.H.

1982-12-01

141

Identification of new heliumlike Al XII transitions emitted by laser-produced plasmas  

Microsoft Academic Search

New spectral lines of Al XII, emitted by aluminum laser-produced plasmas, have been identified in the extreme-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 aluminum-coated flat targets to produce linear plasma radiation sources from 3 to 6

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

1989-01-01

142

Spectroscopic study of plasmas produced by a laser equipped with distribution phase plates  

Microsoft Academic Search

The spectra emitted by Al and Si laser-produced plasmas were recorded in the region of 18--350 A. The bandlike structures observed near the Al XI and Si XII 2[ital p]--3[ital d] transitions at 52 and 44 A, respectively, are identified as Be-like dielectronic satellite transitions in Al and Si. The plasmas were produced with the Omega laser system at the

Samuel Goldsmith; J. C. Moreno; H. R. Griem; Leonard Cohen; J. P. Knauer

1993-01-01

143

Ion turbulence and thermal transport in laser-produced plasmas  

NASA Astrophysics Data System (ADS)

It is noted that ion-acoustic turbulence, self-generated magnetic fields and the inadequacy of classical transport theory have all been adduced in order to explain the observations showing thermal transport much below what would be expected from conventional arguments. The role of ion turbulence as a flux limiter is addressed, with particular regard to recent experiments in which target plasmas were irradiated by 1.06-micron neodymium laser light at irradiances of 10 to the 15 W/sq cm and greater. Saturation levels of the ion-acoustic turbulence driven by a combination of a suprathermal electron current and a heat flux are calculated on the basis of perturbed orbit theory. The levels of turbulence are found to be significantly lower than those commonly estimated from simple trapping arguments and too low to explain the thermal flux inhibition observed in the experiments used as a basis for the model.

Barr, H. C.; Boyd, T. J. M.

1982-06-01

144

Multiply charged ion spectra of a laser plasma produced on both sides of the target  

SciTech Connect

Multiply charged ion spectra in plasmas produced on both sides of Al and W targets by laser radiation with an intensity of 0.1 - 500 GW cm{sup -2} were investigated simultaneously. The charge-state and energy ion spectra of the laser plasmas were studied on both sides of the target with the aid of a double-channel mass spectrometer. The maximum ion multiplicity and energy on the rear side of the target were found to lower relative to the front side owing to a variation in the ionisation kinetics in the plasma. (interaction of laser radiation with matter. laser plasma)

Bedilov, M R; Davletov, I Yu; Sabitov, M S; Berdierov, G R; Tsoi, T G [Scientific-Research Institute of Applied Physics, M Ulughbek National University of Uzbekistan, Tashkent (Uzbekistan)

2001-05-31

145

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

SciTech Connect

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

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

2013-09-15

146

Conditions for producing and maintaining plasma ball lightning in the atmosphere  

Microsoft Academic Search

Based on the results of plasma experiments and research work done by Dawson and Jones, Trubnikov, Endean, and other researchers,\\u000a three requirements for producing and maintaining plasma ball lightning have been found: 1) rotation of plasma, 2) the density\\u000a of charged particlesn\\u000a \\u000a e\\u000a >3.15 x 10?10?2, 3) a stable confinement of plasma. In this model, the energy density of ball

Yousuo Zou

1989-01-01

147

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

148

Spectroscopic study of laser-produced plasmas in hydrogen  

SciTech Connect

A 300-mJ, 7-ns, 1064-nm pulse from a {ital Q}-switched neodymium-doped yttrium aluminum garnet laser was tightly focused into H{sub 2} at pressures of the order of 1 atm or less. Charge-coupled-device images, time-resolved schlieren, and time-resolved spectra from the vacuum ultraviolet through the visible distinguish the prompt centrally localized emission during the initial breakdown from the subsequent blast wave and shock dissociation of the gas. Schlieren images show that the shock wave expands from the center with a velocity in excess of 13 km/s, and then slows to close to sound wave speed within 1.5 {mu}s. Inside the shock front, starting with an initial electron density greater than 4{times}10{sup 18} cm{sup {minus}3} and a temperature of 10{sup 5} K, the emitting atomic gas cools and leaves a low-density core surrounded by a cylindrical shell of slowly expanding excited H about 1.5 mm from the focal axis after 8 {mu}s. The regions responsible for visible and vacuum ultraviolet emission are in local thermodynamic equilibrium. The density, temperature, and flow agree quantitatively with the predictions of Saha ionization and excitation equilibrium in a cylindrical blast wave with counterpressure. These models characterize the postplasma gas close to the region of breakdown and permit the source to be used for quantitative spectroscopic studies of atomic and molecular processes.

Kielkopf, J.F. [Department of Physics, University of Louisville, Louisville, Kentucky 40292 (United States)] [Department of Physics, University of Louisville, Louisville, Kentucky 40292 (United States)

1995-08-01

149

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

150

New trends in femtosecond Pulsed Laser Deposition and femtosecond produced plasma diagnostics  

E-print Network

New trends in femtosecond Pulsed Laser Deposition and femtosecond produced plasma diagnostics F Laser Deposition (PLD) with ultra short laser pulses, with the aim of producing materials of high to reach high sp3 content. PLD with ultra short pulses was used recently to deposit several systems

Paris-Sud XI, Université de

151

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

SciTech Connect

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

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

2014-08-15

152

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

153

Experimental Results from Initial Operation of Plasma Injector 1  

NASA Astrophysics Data System (ADS)

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

Howard, Stephen

2010-11-01

154

Late-time particle emission from laser-produced graphite plasma  

SciTech Connect

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

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

2011-09-01

155

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

156

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

157

IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 32, NO. 2, APRIL 2004 813 Characterization of Laser Produced Tetrakis  

E-print Network

flash lamp or laser, the plasma can be sustained at a much lower RF power level. A seed plasma can alsoIEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 32, NO. 2, APRIL 2004 813 Characterization of Laser Produced Tetrakis (Dimethylamino) Ethylene Plasma in a High-Pressure Background Gas Kamran Akhtar, Member

Scharer, John E.

158

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

Microsoft Academic Search

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

Th. Hammer; Th. Kappes; M. Baldauf

2004-01-01

159

Instability of a plasma produced by laser-induced ionisation of a target  

SciTech Connect

The development of a longitudinal-transverse instability in a plasma with the anisotropic velocity distribution of electrons produced by the tunnelling ionisation of a target by a short laser pulse is studied. The dependences of the growth rate of this longitudinal-transverse instability on the wave number and the propagation angle of perturbations are investigated. It is shown that the increasing longitudinal electrostatic field in a rather broad angular region is comparable with the exciting magnetic field. It is pointed out that the longitudinal-transverse instability of the anisotropic plasma can lead to the additional absorption of laser radiation by the nonthermal fluctuations of the electron density. (laser plasma)

Andriyash, I A; Bychenkov, V Yu [P. N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2008-09-30

160

The impact of Hall physics on magnetized plasma jets produced by radial foil configurations  

NASA Astrophysics Data System (ADS)

Although no one argues that plasma resistivity is important to include in the astrophysical simulations, based upon experiments with magnetized jets on pulsed power machines in the laboratory, we believe it may also be important to include the Hall term in the generalized Ohm's law in astrophysics simulation codes. In this talk, experiments carried out at Cornell University and at Imperial College on 1 to 1.5 MA pulsed power generators feature a plasma disk and a collimated, axial plasma jet with large Re (10^5) and Rem (10^3). The plasma jet is generated by ablation from electrical currents, which flow in a thin aluminum foil and converge to a central multi-pin cathode located under the foil. A twist in the pins produce the axial magnetic field necessary to magnetized the jet. It was observed that changing the polarity of the current alters drastically the plasma dynamics, an indication of the importance of the Hall effect in plasmas produced by radial foils. The overall agreement between experimental results and numerical simulations indicates that PERSEUS accounts properly for Hall physics in this geometry and plasma parameter range. Scaling to astrophysical occurrences via numerical simulations should highlight how Hall physics affects the dynamics of larger accretion disks.

Gourdain, P.-A.; Greenly, J. B.; Hammer, D. A.; Kusse, B. R.; Schrafel, P. C.; Seyler, C. E.; Bland, S. N.; Hall, G. N.; Lebedev, S. V.; Suzuki-Vidal, F.

2012-10-01

161

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

162

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

163

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

164

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

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

165

Dynamics of neutrals and ions in an ultrafast laser produced Zn plasma  

NASA Astrophysics Data System (ADS)

Optical time of flight dynamics of neutrals and ions in an ultrafast laser produced zinc plasma generated by irradiating a solid zinc target using 100 fs laser pulses is investigated. An acceleration of ions is observed which arises from internal Coulomb forces acting between charged species in the plasma. Some of the fast ions recombine with electrons in the plasma and generate fast neutrals. Plasma plume imaging performed at various ambient pressures indicates adiabatic expansion at lower pressures and plume front deceleration at higher pressures: at lower pressures the plume front-time (R-t) plot displays a linear expansion, shock wave model fits to the data at 5 Torr and at higher pressures the data fits better to the drag model. Furthermore, around an intermediate pressure of 10 Torr, the R-t plot fits to the shock wave model at earlier stages of plasma expansion, while it fits to the drag model at the later stages. These investigations provide relevant information on the acceleration of ions and neutrals in an expanding zinc plasma plume produced by ultrafast laser pulses.

Smijesh, N.; Rao, Kavya H.; Philip, Reji

2015-03-01

166

Surface analysis of alumina ceramic exposed to shock waves produced by plasma expander  

NASA Astrophysics Data System (ADS)

Material surface treatment by plasma expander is relatively recent. Plasma expander is based on the inverse pinch effect. The shock waves produced by plasma expander may also promote modifications in ceramic materials exposed to the expander. These modifications are mainly made by ablation phenomenon. This work was intended to verify the shock wave effects on the ionic ceramic samples with high dielectric constant. The alumina ceramic samples were formed by both uniaxial and isostatic pressing methods and sintered at 1650 °C. They were also produced with addition 0.15 wt% of MgO in order to obtain a high densification. The ceramic samples were divided in groups and exposed to 700, 1000 and 1440 pulses during 20 min. These pulses were generated by nitrogen plasma expander at 13.0 Pa and 6 kV. After plasma exposure, there was an increase in roughness parameter values of Al2O3 ceramic surface. The treatment by plasma expander did not modify the hydrophilic characteristic of the alumina ceramic samples. The results of hardness test presented no significant changes on hardness mean values.

Mota, R. P.; Campos, E.; Santos, C. N.; Lucena, E. F.; Machida, M.; Melo, F. C. L.

2015-03-01

167

[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

168

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

Microsoft Academic Search

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

Samuel Goldsmith; J. F. Seely; U. Feldman; W. E. Behring; Leonard Cohen

1985-01-01

169

A physical mechanism producing suprathermal populations and initiating substorms in the Earth's magnetotail  

NASA Astrophysics Data System (ADS)

We suggest a candidate physical mechanism, combining there dimensional structure and temporal development, which is potentially able to produce suprathermal populations and cross-tail current disruptions in the Earth's plasma sheet. At the core of the proposed process is the "akis" structure; in a thin current sheet (TCS) the stretched (tail-like) magnetic field lines locally terminate into a sharp tip around the tail midplane. At this sharp tip of the TCS, ions become non-adiabatic, while a percentage of electrons are accumulated and trapped: The strong and transient electrostatic electric fields established along the magnetic field lines produce suprathermal populations. In parallel, the tip structure is associated with field aligned and mutually attracted parallel filamentary currents which progressively become more intense and inevitably the structure collapses, and so does the local TCS. The mechanism is observationally based on elementary, almost autonomous and spatiotemporal entities that correspond each to a local thinning/dipolarization pair having duration of ~1 min. Energetic proton and electron populations do not occur simultaneously, and we infer that they are separately accelerated at local thinnings and dipolarizations, respectively. In one example energetic particles are accelerated without any dB/dt variation and before the substorm expansion phase onset. A particular effort is undertaken demonstrating that the proposed acceleration mechanism may explain the plasma sheet ratio Ti/Te?7. All our inferences are checked by the highest resolution datasets obtained by the Geotail Energetic Particles and Ion Composition (EPIC) instrument. The energetic particles are used as the best diagnostics for the accelerating source. Near Earth (X?10 RE) selected events support our basic concept. The proposed mechanism seems to reveal a fundamental building block of the substorm phenomenon and may be the basic process/structure, which is now missing, that might help explain the persistent, outstanding deficiencies in our physical description of magnetospheric substorms. The mechanism is tested, checked, and found consistent with substorm associated observations performed ~30 and 60 RE away from Earth.

Sarafopoulos, D. V.

2008-06-01

170

Four-dimensional imaging of the initial stage of fast evolving plasmas Pengfei Zhu, Zhongchao Zhang, Long Chen, Jun Zheng, Runze Li et al.  

E-print Network

are all-optical pump-probe techniques, such as time-resolved optical shadowgraph,7 Faraday rotation,8 probe capable of four-dimensional diagnosis, the initial stage of fast evolving plasmas produced either focus or defocus the probe electron beam. The effects of this field on the probe electron beam can

Cao, Jianming

171

Ultrafast x-ray streak camera for use in ultrashort laser-produced plasma research  

Microsoft Academic Search

In recent years there has been growing interest in energetic (?100 eV), temporally short (<10 ps) x rays produced by ultrashort laser-produced plasmas. The detection and temporal dispersion of the x rays using x-ray streak cameras has been limited to a resolution of 2 ps, primarily due to the transit time dispersion of the electrons between the photocathode and the

Ronnie Shepherd; Rex Booth; Dwight Price; Mark Bowers; Don Swan; Jim Bonlie; Bruce Young; Jim Dunn; Bill White; Richard Stewart

1995-01-01

172

X-ray diagnostics for ultrashort laser produced plasma experiments (abstract)  

Microsoft Academic Search

The characterization of subpicosecond laser produced plasmas is currently being investigated by the Livermore ultrashort pulse laser group. A 800-nm, 150-fs, 35-mJ laser is focused to a 7-?m spot on solid aluminum targets, producing XUV (<1 keV), K shell (1.5–30 keV), and hard (?3.0 keV) x-ray emission. The K-shell emission is studied using a Von Hamos crystal spectrograph with a

R. Shepherd; D. Price; H. Nathel; W. White; D. Slaughter; R. Stewart

1992-01-01

173

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

174

Possibility of deexcitation of isomeric nuclei in plasmas produced by subpicosecond laser pulses  

SciTech Connect

Possible schemes of X-ray-activated deexcitation of isomers of rhodium, silver, tellurium, and bismuth are considered. It is shown that conditions necessary for deexcitation of rhodium isomer can, in principle, be achieved in a high-temperature solid-body-density plasma produced by an ultrashort laser pulse.

Afonin, V. I. [Russian Federal Nuclear Center, Zababakhin All-Russia Research Institute of Technical Physics (Russian Federation)

2009-02-15

175

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

E-print Network

-doped yttrium aluminum garnet laser pulses for producing plasmas. A suite of diagnostics were used to analyze:10.1063/1.3486209 I. INTRODUCTION The optical lithographic processes for semiconductor manufacturing manufacturing technique; extreme ultraviolet lithogra- phy EUVL is to be employed.3,4 The advent of multilay

Harilal, S. S.

176

Numerical simulation of spontaneous magnetic fields in laser produced plasma jets using MAG code  

Microsoft Academic Search

The results of numerical simulation of spontaneous magnetic field generation and influence of this field on laser produced plasma jet expansion in vacuum and low density gas are presented. The numerical simulation has been carried out using MAG code for the case of aluminum plate of 5 mum of thickness irradiated by Nd laser. The laser pulse duration was 0.5

O. V. Diyankov; I. V. Glazyrin; S. V. Koshelev; V. A. Lykov

1997-01-01

177

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.

178

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

E-print Network

,6 laser induced fluorescence LIF ,7,8 Langmuir probe,9,10 microwave and laser interferometry,11 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.

179

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

E-print Network

of collimated proton,6 elec- tron, neutron beam,7 etc. LPP also produce high intensity ion beams with various is absorbed most efficiently by the material surface and the lifetime of the laser pulse is usually too short significant plasma intensity at lower laser fluence levels.9 According to Ref. 9, the threshold fluence

Harilal, S. S.

180

Composite resistors based on powders produced in low-temperature plasma  

Microsoft Academic Search

Conclusions 1.Resistance layers made from very fine titanium and vanadium nitride powders produced in low-temperature plasma retain their good operating characteristics over a wide range of resistance.2.Use of a very finely divided mixed titanium-vanadium nitride of composition TixVyN makes it possible to control the sign and magnitude of the TCR of the resistance element.

V. N. Troitskii; B. M. Grebtsov; Yu. N. Nikulin; V. V. Volod'ko; T. P. Potashnikova; V. I. Berestenko

1977-01-01

181

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

182

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

183

Plasma reforming and partial oxidation of hydrocarbon fuel vapor to produce synthesis gas and/or hydrogen gas  

DOEpatents

Methods and systems 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.; Detering, Brent A.

2003-08-19

184

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

185

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

186

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

187

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

188

Effects of initial water content on steam reforming of aliphatic hydrocarbons with nonthermal plasma  

Microsoft Academic Search

The effects of initial water content on steam reforming of aliphatic hydrocarbons such as methane, propane, and neopentane with nonthermal plasma were analyzed in terms of substrate conversion, carbon recovery, and product selectivity. It was found that water addition increased CO2 yield despite a decrease in substrate conversion. The number of carbon atoms in the substrate hydrocarbon affected the additive

Masami Sugasawa; Tomoyuki Terasawa; Shigeru Futamura

2010-01-01

189

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

SciTech Connect

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

Hopper, E.B. Jr.

1984-02-28

190

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

191

X-ray spectra produced by a hot plasma containing cold clouds  

NASA Astrophysics Data System (ADS)

We compute the hard X-ray spectra from a hot plasma pervaded by small cold dense clouds. The main cooling mechanism of the plasma is Compton cooling by the soft thermal emission from the clouds. We compute numerically the equilibrium temperature of the plasma together with the escaping spectrum. The spectrum depends mainly on the amount of cold clouds filling the hot phase. The clouds covering factor is constrained to be low in order to produce spectra similar to those observed in Seyfert galaxies and X-ray binaries, implying that an external reflector is required in order to reproduce the full range of observed reflection amplitudes. We also derive analytical estimates for the X-ray spectral slope and reflection amplitude using an escape probability formalism.

Malzac, Julien; Celotti, Annalisa

2002-09-01

192

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

193

Characteristics and time evolution of a hollow cathode produced glow discharge plasma in air  

NASA Astrophysics Data System (ADS)

Current radar systems use mechanical directors and phased array technology for beam steering. Use of a sheet plasma as a microwave reflector promises several advantages over these methods. Operation is inherently broad-band, since all frequencies below the plasma frequency are reflected. The orientation and shape of the reflector may be changed directly through electronic control without resort to moving parts or expensive RF switches. The relatively fast plasma formation and extinction times ([/approx]10/ /mus) allow for rapid redirection of the microwave beam. An experimental system, dubbed the Agile Mirror, has been constructed using a cylindrical LexanTM vacuum chamber suspended within a water cooled Helmholtz coil pair capable of producing a uniform 500 Gauss field. Using this system we have created plasmas capable of reflecting 10 GHz microwaves with characteristics comparable to that of a plane metallic reflector. Most previous glow discharge work has concentrated either on the DC characteristics, or on the very early evolution (<1-2 ?s), of the discharge. To create a practical agile mirror direction, we must be able to produce a stable, flat, homogeneous plasma sheet with predictable characteristics timescales from 5 ?s to 1 ms-a regime where little pertinent quantitative data exists. This work concentrates on diagnosing the time resolved behavior of the agile mirror plasma during the mid-time, from t = 5-300 ?s, in a regime which accentuates observed changes in the discharge circuit characteristics. Measurements on an air discharge produced using VD/approx2.2 kV, p ? 208 mTorr, and B ? 250 G reveal an ne=1011/ cm-3,/ Te=1[-]3 eV plasma with distinct negative glow, Faraday dark space, and positive column regions. Analysis of time resolved potential, temperature, and spectroscopic data reveal that this discharge transitions-on time scales of [/approx]100/ /mus-into a pure negative glow discharge. The characteristics and evolution of the discharge are highly reproducible. A computer model of the discharge reveals that heating of the background gas is responsible for the transition. Implications for operation of the agile mirror discharge as a plasma mirror are discussed.

Gregor, Joseph Atilla

194

Combined effects of pre-pulsing and target geometry on efficient EUV production from laser produced plasma experiments and modeling  

E-print Network

Combined effects of pre-pulsing and target geometry on efficient EUV production from laser produced plasma experiments and modeling A. Hassanein, T. Sizyuk, V. Sizyuk, and S. S. Harilal Center, USA ABSTRACT Laser produced plasmas (LPP) is currently a promising source of an efficient extreme

Harilal, S. S.

195

Characteristics of Helicon-Plasma Produced Using a Segmented Multi-Loop Antenna II  

NASA Astrophysics Data System (ADS)

It has been demonstrated that a large-diameter (up to 74 cm), large-volume (up to 2.1 m^3) helicon plasma can be produced very efficiently (production of ˜10^15 ion-electron pairs per one-watt of rf power) by using a flat spiral antenna, which is installed just outside an insulator window at the end of a cylindrical vacuum vessel and is immersed in a non-uniform magnetic field [1,2]. The same principle has been applied to a smaller device (20 cm in diameter and 1 m in axial length), but using a somewhat different type of flat antenna, namely a segmented multi-loop antenna [3]. By changing the electrical connections among the antenna segments, it is possible to excite the azimuthal modes of higher than m = 0 as well as the m = 0 mode itself, where m is the azimuthal mode number. Under certain conditions, it is possible to produce a non-uniform plasma along the uniform magnetic field due probably to the neutral depletion in the main plasma production region. The discharge characteristics of the device will be presented. [1] S. Shinohara and T. Tanikawa, Rev. Sci. Instrum. 75, 1941 (2004); Phys. Plasmas 12, 044502 (2005). [2] T. Tanikawa and S. Shinohara, Thin Solid Films 506-507, 559 (2006). [3] T. Tanikawa et al., Bull. Ameri. Phys. Soc. 51 (7), 164 (2006).

Tanikawa, Takao; Shinohara, Shunjiro

2008-11-01

196

Evidence for a hot-electron flux limit in laser-produced plasma experiments  

SciTech Connect

It has been found that it is necessary to impose a flux limit on the thermal electron transport in diffusion calculations of laser-produced plasmas to explain the observed partition of energy into fast and slow ions and x-rays. The effect of such a limit is to retain the deposited energy in the corona of the target. This containment increases the energy loss to fast ions, reduces the x-ray emission, and reduces the hydrodynamic efficiency. Although calculations for plasmas produced by lasers having wavelengths of 1 ..mu..m or shorter agree with experiment when a flux limit which is 1/30 times the classical flux limit is applied to the electron thermal flux, I will show that such a flux limit cannot explain the results obtained for 10 ..mu..m lasers. In this case it will be shown necessary to invoke a flux limit on the hot or suprathermal electrons.

McCall, G.H.

1983-01-01

197

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

NASA Astrophysics Data System (ADS)

Generation of highly collimated (?div ˜10 mrad), quasi-monoenergetic electron beam with peak energy 12 MeV and charge ˜50 pC has been experimentally demonstrated from self-guided laser wake-field acceleration (LWFA) in a plasma plume produced by laser ablation of solid nylon (C12H22N2O2)n target. A 7 TW, 45 fs Ti:sapphire laser system was used for LWFA, and the plasma plume forming pulse was derived from the Nd:YAG pump laser of the same system. The results show that a reproducible, high quality electron beam could be produced from this scheme which is simple, low cost and has the capability for high repetition rate operation.

Sanyasi Rao, Bobbili; Moorti, Anand; Rathore, Ranjana; Ali Chakera, Juzer; Anant Naik, Prasad; Dass Gupta, Parshotam

2013-06-01

198

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

SciTech Connect

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

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

2013-06-10

199

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

Microsoft Academic Search

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

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

1977-01-01

200

Heavy-ion beams produced by high-voltage pulse-powered plasma focus  

NASA Astrophysics Data System (ADS)

The paper reports preliminary experimental studies of heavy-ion beams produced by a new type of plasma focus device which is powered by a fast high-voltage pulse of 500 kV, 20 kA, and 50 ns. A variety of ion species, either from solid materials or gases, were obtained and their beam characteristics, including charge states, energy spectrum, and emittance, were measured.

Rhee, M. J.

1980-11-01

201

Overdense Plasmas Produced by Electron Cyclotron Heating in a Linear Multipole  

Microsoft Academic Search

A report is given of characteristics of a plasma produced by electron cyclotron heating (ECH) in a linear multipole (LMP) field configuration. The electron density measured by a 6 mm microwave interferometer reached 2×1012 cm-3, which corresponds to 30 times the cutoff density for the 2.45 GHz RF source. On the basis of the spatial distributions of electron density, electron

Masayuki Fukao; Ken-ichi Matsuura

1994-01-01

202

New Estimates for Absorption Coefficient in Weakly Nonideal Laser-Produced Plasmas  

Microsoft Academic Search

The early-time spectral emissions from weakly nonideal laser-produced plasma (LPP) plumes in a vacuum are essentially a continuum. This is exploited in a newly developed diagnostic technique to construct the 3-D profile of the LPP plume from time-resolved 2-D luminosity profiles.[1] Two power-law scaling relations are first invoked linking the time- and position-resolved specific continuum intensity to the local temperature

Yong W. Kim; Conrad Lloyd-Kinght

2000-01-01

203

7A8Spectroscopic studies of laser-produced hydrogen plasma  

Microsoft Academic Search

Time-resolved spectroscopic measurements were made of the decay of a laser-produced discharge in hydrogen over a range of pressures from one to 70 atmospheres. The plasma temperature, which ranged from about 105to10^{4}degK during theQ-switched laser pulse to several microseconds afterward, was obtained from the ratio of the intensity of H?to that of nearby continuum radiation. The electron density, which ranged

M. Litvak; D. Edwards

1966-01-01

204

Electron kinetics in a discharge plasma produced by a focused microwave beam in free space  

Microsoft Academic Search

A study is made of the electron kinetics in a discharge plasma produced by a high-power beam of electromagnetic radiation\\u000a in the centimeter-wave region under conditions approaching free space, when the dimensions of the chamber are much greater\\u000a than the wavelength of the microwave radiation. Two regimes of discharge production are investigated: the regime of short\\u000a microsecond pulses at a

A. A. Kuzovnikov; V. M. Shibkov; L. V. Shibkova

1997-01-01

205

Recent experiments on the hydrodynamics of laser-produced plasmas conducted at the PALS laboratory  

Microsoft Academic Search

We present a series of experimental results, and their interpretation, connected to various aspects of the hydrodynamics of laser produced plasmas. Experiments were performed using the Prague PALS iodine laser working at 0.44 mm wavelength and irradiances up to a few 1014 W0cm2. By adopting large focal spots and smoothed laser beams, the lateral energy transport and lateral expansion have

D. Batani; R. Dezulian; R. Redaelli; R. Benocci; H. Stabile; F. Canova; T. Desai; G. Lucchini; E. Krousky; K. Masek; M. Pfeifer; J. Skala; R. Dudzak; B. Rus; J. Ullschmied; V. Malka; J. Faure; M. Koenig; J. Limpouch; W. Nazarov; D. Pepler; K. Nagai; T. Norimatsu; H. Nishimura

2007-01-01

206

Sub-keV, subnanosecond measurements of X-ray spectra from laser-produced plasmas  

Microsoft Academic Search

X-ray spectral measurements of laser-produced plasmas were made for photon energies down to 100 eV with a time response of 0.5 nsec. Fast, windowless X-ray diodes were used in conjunction with critical angle reflecting mirrors and thin filters for energy definition for two channels 300 to 600 eV and 800 to 1300 eV. A third channel, using only an X-ray

H. N. Kornblum; L. N. Koppel; V. W. Livinsky; S. S. Glaros; H. G. Ahlstrom; J. T. Larsen

1977-01-01

207

Colliding laser-produced plasmas as targets for laser-generated extreme ultraviolet sources  

NASA Astrophysics Data System (ADS)

Colliding plasmas produced by neodymium-doped yttrium aluminium garnet (Nd:YAG) laser illumination of tin wedge targets form stagnation layers, the physical parameters of which can be controlled to optimise coupling with a carbon dioxide (CO2) heating laser pulse and subsequent extreme ultraviolet (EUV) production. The conversion efficiency (CE) of total laser energy into EUV emission at 13.5 nm ± 1% was 3.6%. Neglecting both the energy required to form the stagnation layer and the EUV light produced before the CO2 laser pulse is incident results in a CE of 5.1% of the CO2 laser energy into EUV light.

Cummins, T.; O'Gorman, C.; Dunne, P.; Sokell, E.; O'Sullivan, G.; Hayden, P.

2014-07-01

208

Nonthermal Biological Treatments Using Discharge Plasma Produced by Pulsed Power 4. Cleaning of Lakes and Marshes by Pulsed Power Produced Streamer Discharges in Water  

Microsoft Academic Search

Pulsed power has been used to produce non-thermal plasmas in atmospheric pressure gases that generate a high electric field at the tips of streamer discharges, where high energy electrons, free radicals, ultraviolet rays, and ozone are produced. These manifestations of streamer discharges have been used in the treatment of exhaust gases, removal of volatile and toxic compounds such as dioxin,

Hidenori Akiyama; Sunao Katsuki; Takao Namihira; Kazuo Ishibashi; Noriaki Kiyosaki

2003-01-01

209

Modeling of laser produced plasma and z-pinch x-ray lasers  

SciTech Connect

In this work we describe our theoretical activities in two directions of interest. First, we discuss progress in modeling laser produced plasmas mostly related to transient collisional excitation scheme experiments with Ne- and recently with Ni-like ions. Calculations related to the delay between laser pulses, transient gain duration and hybrid laser/capillary approach are described in more detail. Second, the capillary discharge plasma research, extended to wider range of currents and rise-times has been outlined. We have systematically evaluated the major plasma and atomic kinetic properties by comparing near- and far-field X-ray laser output with that for the capillary Argon X-ray laser operating under typical current values. Consistent with the experiment insight was obtained for the 469{angstrom} X-ray laser shadowgraphy experiments with very small kiloamp currents. At higher currents, as much as {approximately}200 kA we evaluated plasma temperature, density and compared x-ray source size and emitted spectra.

Dunn, J; Frati, M; Gonzales, J J; Kalashnikov, M P; Marconi, M C; Moreno, C H; Nickels, P V; Osterheld, A L; Rocca, J J; Sandner, W; Shlyaptsev, V N

1999-02-07

210

Time-resolved visible and extreme ultraviolet spectroscopy of laser-produced tin plasma  

NASA Astrophysics Data System (ADS)

Previous experimental studies of laser-matter interactions have often been conducted without sufficient accuracy or attention to critical laser parameters. Moreover, much of the work published in the open literature lacks the essential theoretical underpinnings necessary to explain observations and provide predictive capability for future experiments. In this study, we use nanosecond-resolved spectroscopic techniques to investigate fundamental physics in laser-produced tin plasma, and overcome these shortcomings by implementing several metrological innovations to ensure the accuracy of experimental data. Furthermore, we present a side-by-side comparison of experimental results with computational modeling to advance our understanding of the many nonlinear, interrelated processes that occur within transient tin plasma. This dissertation is divided into three primary sections. In the first section, we study the physics governing the generation and early-time evolution of tin plasma in the low-irradiance regime: IL ˜ 4 x 1011 - 1 x 1012W/cm2 . A two-channel XUV photodiode spectrometer has been developed to measure tin plasma temperature, as well as diagnose radiation transport processes during the laser irradiation phase. During laser heating, the radiation spectrum from semi-infinite tin targets was found to approach the blackbody limit in the 10--80 nm spectral range. Through one-dimensional numerical modeling, this is shown to be due to the penetration of a radiative diffusion wave beyond the critical depth. Analysis of the time-dependent tin emission spectrum has shown that nearly 30% of the incident laser energy is converted to energetic photons in the spectral range of 15 < hv < 120 eV. The equilibrium radiation temperature, characteristic of the optically thick ablation front, has shown reasonable agreement with numerical predictions despite the model's limited dimensionality. The second part of this work examines the late-time hydrodynamics associated with the radiative plasma phase studied in the preceding section. Nanosecond-gated optical emission spectroscopy is employed to diagnose electron temperature, electron density, and propagation velocity of the ablation plume. In contrast to the large change in radiation temperature observed for a factor of three increase in laser intensity, it is found that the post-pulse plume hydrodynamics is not significantly affected for the same variation in irradiation conditions. At late times, the ion kinetic energy is found to exceed electron thermal energy by more than 100 times, which serves as a lower bound on the ratio to the ion thermal counterpart. The expanding laser-produced tin plasma is well described by a cylindrical hydrodynamic transport model; a comparison between time-integrated experimental and numerical plasma energy density has shown convergence to within a factor of two. At distances > 3 mm from the target, it was found that the heavy ion tin plasma transitions from Boltzmann to coronal equilibrium, rendering LTE assumptions in the spectral deconvolution procedure invalid. In the final section of this study, we investigate the radiative properties of tin ablation plasma as the laser irradiance is varied by more than an order of magnitude. The effect of increased focused laser energy is manifested in a weak scaling of radiation temperature, and a significant broadening of the emission lifetime at the highest laser intensities. It is found that the resulting radiation conversion efficiency is not a strong function of laser intensity within the parameter regime of this work. It is shown that agreement between experimental and simulated plasma conditions becomes progressively worse in the high-irradiance regime as the ionization and radiative transfer models play increasingly dominant roles in the plasma energetics.

O'Shay, Joseph Fred

211

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

PubMed

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

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

2014-11-01

212

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

NASA Astrophysics Data System (ADS)

The x-ray laser-matter interaction for a low-Z material, carbon, is studied with a particle-in-cell code that solves the photoionization and x-ray transport self-consistently. Photoionization is the dominant absorption mechanism and nonthermal photoelectrons are produced with energy near the x-ray photon energy. The photoelectrons ionize the target rapidly via collisional impact ionization and field ionization, producing a hot plasma column behind the laser pulse. The radial size of the heated region becomes larger than the laser spot size due to the kinetic nature of the photoelectrons. The plasma can have a temperature of more than 10 000 K (>1 eV ), an energy density greater than 104 J /cm3 , an ion-ion Coulomb coupling parameter ? ?1 , and electron degeneracy ? ?1 , i.e., strongly coupled warm dense matter. By increasing the laser intensity, the plasma temperature rises nonlinearly from tens of eV to hundreds of eV, bringing it into the high energy density matter regime. The heating depth and temperature are also controllable by changing the photon energy of the incident laser light.

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

2014-11-01

213

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

214

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

215

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

216

Filamentation effects and second-harmonic spectra in laser-produced plasmas  

SciTech Connect

Sideway scattered second-harmonic spectra emitted from a 1064-nm-laser-produced plasma have been observed to originate from nonlinear coupling near the critical surface. The time evolution of the second-harmonic optical density confirmed the possibility that a plasmon issued from the resonant absorption of the incident beam can recombine with a photon ([omega][sub 0]) to give a transverse wave of frequency 2[omega][sub 0]. A plasmon issued from a parametric decay instability may also, by coalescence with an incident photon, give a transverse wave at a shifted second-harmonic frequency. The threshold of such a combination is determined. Moreover, irregular plasma-parameter variations and the perturbed spatial uniformity of the incident beam appear to alter the second-harmonic spectra. An oscillatory structure of the optical density of the observed second harmonic is interpreted as a result of the coupling physics involved and of laser-beam filamentation.

Khalfaoui, A.H.; Abdelli, S.; Kerdja, T.; Ghobrini, D. (MDRTE, Centre de Developpement des Technologies Avancees 2, boulevard Frantz Fanon, Alger-gare, Boite Postale 1017, Alger 16000 (Algeria))

1993-08-01

217

Spectroscopic study of emission coal mineral plasma produced by laser ablation  

NASA Astrophysics Data System (ADS)

Spectroscopic analysis of plasma produced by laser ablation of coal samples using 1064 nm radiation pulses from a Q-switched Nd:YAG on different target under air ambient, was performed. The emission of molecular band systems such as C2 Swan System (d3?g?a3?u), the First Negative System N2 (Band head at 501,53 nm) and emission lines of the C I, C II, were investigated using the optical emission spectroscopy technique. The C2 molecular spectra (Swan band) were analyzed to determine vibrational temperature (0,62 eV); the density and electron temperature of the plasma have been evaluated using Stark broadening and the intensity of the nitrogen emission lines N II, the found values of 1,2 eV and 2,2 x1018 cm-3 respectively.

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

2014-05-01

218

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

219

X-ray imaging diagnostics for magnetically confined and laser-produced fusion plasmas  

NASA Astrophysics Data System (ADS)

Recent advances in x-ray detection technology and diagnostic design have dramatically improved the ability of using x-ray imaging and spectroscopic diagnostics to accurately measure important parameters in magnetically confined and laser produced fusion plasmas. With these advancements, the detailed characterization of the diagnostic system properties has become ever more important. We present an overview of current and future x-ray diagnostic requirements for fusion plasmas and describe, in particular, diagnostic systems employing spherically bent crystals to resolving characteristic x-ray lines from trace impurities with energies in the range 1-20keV. The requirements and challenges for the simulation of existing and planned diagnostic installations and are discussed.

Pablant, N. A.; Bitter, M.; Delgado-Aparicio, L. F.; Hill, K. W.; Sanchez del Rio, M.

2011-09-01

220

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

SciTech Connect

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

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

2013-09-21

221

A novel technique for measurement of self-generated magnetic fields and the plasma density in laser produced plasmas from the Faraday rotation using two color probes  

Microsoft Academic Search

Diagnostic information about the self-generated magnetic fields (SGMF) generated in laser produced plasmas is normally obtained by measuring the Faraday rotation angle (FRA) of a linearly polarized laser probe beam passing through the plasma. Simultaneous recording of the corresponding interferogram is required to get the density information necessary for estimating the magnetic field. The problem with this method is that

A. S. Joshi; P. A. Naik; S. Barnwal; Y. B. S. R. Prasad; P. D. Gupta

2010-01-01

222

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

223

Comparison of glassy slag waste forms produced in laboratory crucibles and in a bench-scale plasma furnace  

SciTech Connect

Vitrification is currently the best demonstrated available technology for the disposal of high-level radioactive wastes. An innovative vitrification approach known as minimum additive waste stabilization (MAWS) is being developed. Both homogeneous glass and glassy slags have been used in implementing MAWS. Glassy slags (vitro-ceramics) are glass-crystal composites, and they are composed of various metal oxide crystalline phases embedded in an aluminosilicate glass matrix. Glassy slags with compositions developed in crucible melts at Argonne National Laboratory (ANL) were successfully produced in a bench-scale Retech plasma centrifugal furnace (PCF) by MSE, Inc. Detailed examinations of these materials showed that the crucible melts and the PCF produced similar glass and crystalline phases. The two sets of glassy slags exhibited similar chemical durability in terms of normalized releases of their major components. The slags produced in the PCF furnace using metals were usually less oxidized, although this had no effect on the corrosion behavior of the major components of the slags. However, the normalized release rate of cerium was initially lower for the PCF slags. This difference diminished with time as the redox sates of the metal oxides in slags began to be controlled by exposure to air in the tests. Thus, the deference in cerium release due to the differences in slag redox state may be transitory. The cerium solubility is a complex function of redox state and solution pH and Eh.

Feng, X.; Wronkiewicz, D.J.; Brown, N.R.; Gong, M. [Argonne National Lab., IL (United States); Whitworth, C.; Filius, K.; Battleson, D. [MSE, Inc., Butte, MT (United States)

1994-10-01

224

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

225

Survey of nuclei for low-energy nuclear excitation in laser-produced plasma  

NASA Astrophysics Data System (ADS)

We present a survey of stable and long-lived nuclei as well as nuclear isomers looking for candidates of studies of low-energy (1-30 keV) nuclear excitation by laser-produced plasma radiation. We concentrate on medium-size high-power lasers with pulse duration of hundreds of ps providing energy up to 1000 J and subrelativistic intensity of 10-10 W cm. Screening criteria are primarily the transition energy and the half-life, spin and parity of nuclear levels. Ta181 is suggested as first candidate for which an estimation of reaction efficiency is included.

Granja, C.; Kuba, J.; Haiduk, A.; Renner, O.

2007-03-01

226

Non-fouling microfluidic chip produced by radio frequency tetraglyme plasma deposition.  

PubMed

This Technical Note presents the direct surface modification of a glass/PTFE hybrid microfluidic chip, via radio frequency glow discharge plasma polymerisation of tetraethlylene glycol dimethylether (tetraglyme), to produce hydrophilic, non-fouling, PEO-like surfaces. We use several techniques including X-ray photoelectron spectroscopy (XPS), direct enzyme-linked immunosorbent assays (ELISA) and immunofluorescent imaging to investigate the channel coatings. Our results indicate the successful deposition of a PEO-like coating onto microchannel surfaces that has both solution and shelf stability (>3 months) and is capable of preventing fibrinogen adsorption to the microchannel surfaces. PMID:17389972

Salim, Malinda; Mishra, Gautam; Fowler, Gregory J S; O'sullivan, Brian; Wright, Phillip C; McArthur, Sally L

2007-04-01

227

Polarity effect on the behavior of gas-puff z-pinch plasma produced by IPP system  

Microsoft Academic Search

Hot spots produced by gas-puff z-pinch plasma which are high energy density plasma regions radiate intensive soft X-rays. The gas-puff z-pinch is expected to have industrial applications such as soft X-ray lithography, microscopy and in lasers. In these cases, the scattering of hot spots is important when the gas-puff z-pinch plasma is used as a point source of soft X-rays.

K. Imasaka; K. Takahashi; J. Suehiro; M. Hara

2001-01-01

228

Numerical and experimental study of behavior of gas-puff z-pinch plasma produced by inductive pulsed power generator  

Microsoft Academic Search

Magnetohydrodynamic (MHD) instabilities, such as kink and sausage instabilities, appeared on the gas-puff z-pinch plasma during the pinching process prevent spatial stability of hot spots, which are high energy density plasma regions produced by those instabilities on the z-pinch plasma column locally. Spatial stabilization of hot spots in the axial direction is very important to have practical applications. In this

K. Imasaka; Y. Kawauchi; K. Kawazoe; J. Suehiro; M. Hara

1998-01-01

229

On the plasma-focus-produced spheromak for the D-3He-fusion-based jet propulsion  

Microsoft Academic Search

Experimental results are presented which suggest the possibility of constructing a D-3He-based thruster on the basis of a Filippov-type plasma focus facility operating in the high-current gaseous discharge regime characterized by the following features: (i) cyclical self-production of a target pre-fusion plasma-in the central part of the plasma focus produced a closed, spheromak-like magnetic configuration (SLMC), (ii) the residual magnetic

A. B. Kukushkin; V. A. Rantsev-Kartinov

1995-01-01

230

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

231

Laser-imaging diagnostics of debris behavior from laser-produced tin plasma for EUV-light sources  

Microsoft Academic Search

In the development of extreme ultraviolet (EUV) light source for EUV lithography systems by laser-produced plasma (LPP), reduction of debris emitted from the plasma such as ions, droplets and neutral atoms is one of the most important factors. In our study, we developed a two-dimensional (2D) laser-induced fluorescence (LIF) imaging system for neutral atoms from the plasma and investigated neutral

D. Nakamura; H. Tanaka; Y. Hashimoto; K. Tamaru; A. Takahashi; T. Okada

2007-01-01

232

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

233

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.

234

Radiofrequency plasma assisted exfoliation and reduction of large-area graphene oxide platelets produced by a mechanical transfer process  

Microsoft Academic Search

We present a method to produce extended few layer flakes of reduced graphene oxide starting from bulk graphene oxide platelets using Ar plasma treatment at room temperature of mechanically exfoliated platelets. Multilayer graphene oxide platelets transferred to a silicon wafer by micromechanical cleavage were thinned in a controllable and reproducible way by plasma treatment to achieve few-layer reduced graphene sheets

Marta Cardinali; Luca Valentini; Paola Fabbri; Josè M. Kenny

2011-01-01

235

Lifetime of a depression in the plasma density over Jicamarca produced by space shuttle exhaust in the ionosphere  

Microsoft Academic Search

When the space shuttle orbiting maneuver subsystem (OMS) engines burn in the ionosphere, a plasma density depression, or ``hole,'' is produced. Charge exchange between the exhaust molecules and the ambient O+ ions yields molecular ion beams that eventually recombine with electrons. The resulting plasma hole in the ionosphere can be studied with ground-based, incoherent scatter radars (ISRs). This type of

E. Kudeki; L. Condori; F. Villanueva

2001-01-01

236

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

237

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

SciTech Connect

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 H{sub 2} 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 of 1 atm, T needs to be higher than about 450 deg. C in order to successfully produce washers of titanium hydride. Results on compressive strength of the loaded washers suggest that an appropriate ratio of atoms of hydrogen to titanium is less than H:Ti{approx}0.85:1.

Himura, H.; Saito, Y.; Sanpei, A.; Masamune, S.; Takeuchi, N.; Shiono, T. [Department of Electronics, Kyoto Institute of Technology, Matsugasaki, Sakyo Ward, Kyoto 606-8585 (Japan); Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo Ward, Kyoto 606-8585 (Japan)

2006-07-15

238

Colliding laser-produced plasmas as targets for laser-generated extreme ultraviolet sources  

SciTech Connect

Colliding plasmas produced by neodymium-doped yttrium aluminium garnet (Nd:YAG) laser illumination of tin wedge targets form stagnation layers, the physical parameters of which can be controlled to optimise coupling with a carbon dioxide (CO{sub 2}) heating laser pulse and subsequent extreme ultraviolet (EUV) production. The conversion efficiency (CE) of total laser energy into EUV emission at 13.5?nm?±?1% was 3.6%. Neglecting both the energy required to form the stagnation layer and the EUV light produced before the CO{sub 2} laser pulse is incident results in a CE of 5.1% of the CO{sub 2} laser energy into EUV light.

Cummins, T.; O'Gorman, C.; Dunne, P.; Sokell, E.; O'Sullivan, G. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Hayden, P., E-mail: patrick.hayden@physics.org [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); School of Physical Sciences and National Centre for Plasma Science and Technology, Dublin City University, Glasnevin, Dublin 9 (Ireland)

2014-07-28

239

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

240

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

SciTech Connect

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., E-mail: subhash.laserlab@gmail.com; Fallon, C.; Hayden, P.; Yeates, P.; Costello, J. T. [National Centre for Plasma Science and Technology and School of Physical Sciences, Dublin City University, Dublin 9 (Ireland); Mujawar, M. [School of Physics, Trinity College, Dublin 2 (Ireland)

2014-09-15

241

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

242

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

243

Alcohol produces dose-dependent antiatherogenic and atherogenic plasma lipoprotein responses.  

PubMed

A comprehensive assessment of lipoprotein compositional/metabolic response to incremental caloric ethanol (EtOH) doses ranging from low to moderate to high was undertaken using male squirrel monkeys. Control monkeys were maintained on a chemically defined, isocaloric liquid diet, while experimental primates wee fed increasing doses of alcohol (6, 12, 18, 24, 30, and 36% of energy) substituted isocalorically for carbohydrate at 3-month intervals. Liver function tests and plasma triglyceride were normal for all animals. Plasma cholesterol showed a transient increase at the 12% caloric dose that was attributed solely to an increase in high density lipoprotein (HDL). A more pronounced increase in plasma sterol, beginning at 24% and continuing to 36% EtOH, was the result of increments in both HDL and low density lipoprotein (LDL) cholesterol, although the contribution by the latter was substantial primarily at the 36% dose. Plasma apolipoprotein elevations (HDL apolipoprotein A-I, LDL apolipoprotein B) generally accompanied the lipoprotein lipid increases, although the first atherogenic response for LDL became manifest as a significant increase in apolipoprotein B at 18% EtOH calories. Postheparin plasma lipoprotein lipase was not affected by dietary alcohol, whereas hepatic triglyceride lipase activity showed significant increases at higher (24 and 36%) EtOH doses. Plasma lecithin-cholesterol acyltransferase activity was normal at the 6 and 12% EtOH doses, but exhibited a significant reduction beginning at 18% and continuing to 36% EtOH. Alterations in these key lipoprotein regulatory enzymes may represent the underlying metabolic basis for the observed changes in lipoprotein levels and our earlier findings of HDL2/HDL3 subfraction modifications. Results from our study indicate that in squirrel monkeys, moderate (12%) EtOH caloric intake favors an antiatherogenic lipoprotein profile (increases HDL, normal LDL levels, and lecithin-cholesterol acyltransferase activity), whereas higher doses (24-36%) produce both coronary-protective (increases HDL) and atherogenic (increases LDL) responses. Moreover, the 18% EtOH level represents an important transition dose which signals early adverse alterations in lipoprotein composition (increases apolipoprotein B) and metabolism (decreases lecithin-cholesterol acyltransferase). PMID:1570359

Hojnacki, J L; Cluette-Brown, J E; Deschenes, R N; Mulligan, J J; Osmolski, T V; Rencricca, N J; Barboriak, J J

1992-05-01

244

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

245

An experimental study of recombination in a laser-produced plasma  

NASA Astrophysics Data System (ADS)

Ion kinetic energies up to approximately 40 keV measured at a large range of distances from the target for a laser-produced plasma created by a neodymium laser of pulse length 4 ns focussed to an intensity of approximately 10 to the 16th W/sq m onto a solid carbon slab are presented. With increasing distance from the target, an increase in average ion energy and a decrease in the number of ions detected for each ion species is observed up to a distance of 1.45 m from the target, while at longer distances the average ion energy and number of ions detected remain approximately constant with increasing distance from the target. The results show that recombination is important in determining the ion energy spectra observed in laser-produced plasma studies, but that there are also (higher energy) ions which are 'frozen' in high charge states and do not recombine even by the time they have travelled long distances from the target.

Tallents, G. J.

1980-07-01

246

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

247

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

248

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

249

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

SciTech Connect

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{sup ?6?}Torr to 10{sup 2?}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 (3d{sup 9}({sup 2}D) 4p ? 3d{sup 9}({sup 2}D) 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 (3p{sup 6}3d{sup 8}({sup 3}P) 4s? 3p{sup 6}3d{sup 9} 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. [Laser and Nonlinear Optics Laboratory, Department of Physics, National Institute of Technology Calicut, Calicut 673601 (India); Joshi, Jagdish C.; Philip, Reji, E-mail: reji@rri.res.in [Ultrafast and Nonlinear Optics Lab, Light and Matter Physics Group, Raman Research Institute, Bangalore 560080 (India)

2014-07-07

250

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

NASA Astrophysics Data System (ADS)

We report short-time variations in the plasma tail of C/2013 R1(Lovejoy). A series of short (2-3 minutes) exposure images with the 8.2 m Subaru telescope shows faint details of filaments and their motions over a 24 minute observing duration. We identified rapid movements of two knots in the plasma tail near the nucleus (˜ 3× {{10}5} km). Their speeds are 20 and 25 km s-1 along the tail and 3.8 and 2.2 km s-1 across it, respectively. These measurements set a constraint on an acceleration model of plasma tail and knots as they set the initial speed just after their formation. We also found a rapid narrowing of the tail. After correcting the motion along the tail, the narrowing speed is estimated to be ˜8 km s-1. These rapid motions suggest the need for high time-resolution studies of comet plasma tails with a large telescope.

Yagi, Masafumi; Koda, Jin; Furusho, Reiko; Terai, Tsuyoshi; Fujiwara, Hideaki; Watanabe, Jun-Ichi

2015-03-01

251

Characterization by emission spectrometry of a laser-produced plasma from a copper target in air at atmospheric pressure  

NASA Astrophysics Data System (ADS)

A laser-produced plasma is generated from a copper target using a nitrogen laser. The plasma is formed in air at atmospheric pressure. The temporal characteristics of the plasma are studied by atomic emission spectrometry. The features of the spectra such as the type of lines and the line broadening are described and compared to those obtained at reduced pressure or in other gases. As self-absorption is predominant when the plasma first forms, a time delay is required to obtain the best analytical performance. Limits of detection in the range of 1 - 10 ppm are obtained for copper.

Autin, M.; Briand, A.; Mauchien, P.; Mermet, J. M.

1993-06-01

252

A Langmuir Probe Diagnostic for Use in Inhomogeneous, Time-Varying Plasmas Produced by High-Energy Laser Ablation  

SciTech Connect

Langmuir probes (LP) are used extensively to characterize plasma environments produced by radio frequency, pulsed plasma thrusters, and laser ablation. We discuss here the development of a LP diagnostic to examine high-density, high-temperature inhomogeneous plasmas such as those that can be created at the University of Rochester's Laboratory for Laser Energetics OMEGA facility. We have configured our diagnostic to examine the velocity of the plasma expanding from the target. We observe velocities of approximately 16-17 cm/{micro}s, with individual LP currents displaying complex structures, perhaps due to the multiple atomic species and ionization states that exist.

Patterson, J R; Emig, J A; Fournier, K B; Jenkins, P P; Trautz, K M; Seiler, S W; Davis, J F

2012-05-01

253

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

254

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

255

Spectroscopic Measurements of Collision-less Coupling Between Laser-Produced, Super-Alfvénic Debris Plasmas and Magnetized, Ambient Plasmas  

NASA Astrophysics Data System (ADS)

Emission spectroscopy is currently being utilized in order to assess collision-less momentum and energy coupling between super-Alfvénic debris plasmas and magnetized, ambient plasmas of astrophysical relevance. In a recent campaign on the Large Plasma Device (LAPD) utilizing the Phoenix laboratory Raptor laser (130 J, 25 ns FWHM), laser-ablated carbon debris plasmas were generated within magnetized, ambient helium plasmas (nelec ? 3×1012 cm-3, Telec ? 5.5 eV, B0 = 200 G), and prominent spectral lines of carbon and helium ions were studied in high resolution (? 0.01 nm). Time-resolved Doppler shift and width measurements of a C V ion spectral line reveal significant deceleration as the ions stream through the background plasma, which may indirectly indicate momentum coupling. Spectral lines of He II ions are observed to intensify by orders of magnitude and broaden, indicating energy transfer from the debris plasma to the background plasma.

Bondarenko, Anton; Everson, E.; Schaeffer, D.; Constantin, C.; Vincena, S.; Van Compernolle, B.; Clark, S.; Niemann, C.

2013-06-01

256

7 CFR 1219.31 - Initial nomination and appointment of producer members and alternates.  

Code of Federal Regulations, 2013 CFR

...MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE HASS AVOCADO PROMOTION, RESEARCH, AND INFORMATION Hass Avocado Promotion, Research, and Information Order The Hass Avocado Board § 1219.31 Initial nomination and appointment...

2013-01-01

257

7 CFR 1219.31 - Initial nomination and appointment of producer members and alternates.  

Code of Federal Regulations, 2010 CFR

...MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE HASS AVOCADO PROMOTION, RESEARCH, AND INFORMATION Hass Avocado Promotion, Research, and Information Order The Hass Avocado Board § 1219.31 Initial nomination and appointment...

2010-01-01

258

7 CFR 1219.31 - Initial nomination and appointment of producer members and alternates.  

Code of Federal Regulations, 2011 CFR

...MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE HASS AVOCADO PROMOTION, RESEARCH, AND INFORMATION Hass Avocado Promotion, Research, and Information Order The Hass Avocado Board § 1219.31 Initial nomination and appointment...

2011-01-01

259

7 CFR 1219.31 - Initial nomination and appointment of producer members and alternates.  

Code of Federal Regulations, 2014 CFR

...MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE HASS AVOCADO PROMOTION, RESEARCH, AND INFORMATION Hass Avocado Promotion, Research, and Information Order The Hass Avocado Board § 1219.31 Initial nomination and appointment...

2014-01-01

260

7 CFR 1219.31 - Initial nomination and appointment of producer members and alternates.  

Code of Federal Regulations, 2012 CFR

...MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE HASS AVOCADO PROMOTION, RESEARCH, AND INFORMATION Hass Avocado Promotion, Research, and Information Order The Hass Avocado Board § 1219.31 Initial nomination and appointment...

2012-01-01

261

High pressure N2, O2 and air mixture plasmas produced by a radiofrequency Helicon plasma source  

Microsoft Academic Search

Summary form only given, as follows. High pressure (10-760 Torr) plasmas of N2, O2 and air gas mixture are investigated in this work by using a radiofrequency helicon plasma source. Langmuir probe theory and collisional helicon wave propagation characteristics at high pressure are utilized to obtain plasma density and electron temperature. The wave modelling results show that higher rf wave

J. E. Scharer; X. M. Guo; K. L. Kelly; H. Gui

1999-01-01

262

Optimization of laser-produced plasmas for nanolithography and materials detection  

NASA Astrophysics Data System (ADS)

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

Freeman, Justin R.

263

Initial operation of a 10 ms, quasi-steady multi-megawatt, coaxial plasma thruster  

SciTech Connect

The Los Alamos National Laboratory Coaxial Thruster Experiment (CTX) has been upgraded to enable the quasi-steady operation of MPD type thrusters at power levels from 1 to 40 MW for 10 ms. Initial diagnostics include an 8 position, 3 axis magnetic field probe to measure magnetic field fluctuations during the pulse, a triple Langmuir probe to measure ion density, electron temperature and plasma potential and a time-of-flight neutral particle spectrometer to measure specific impulse. Here we report on preliminary investigation of long-pulse quasi-steady coaxial thruster performance.

Scheuer, J.T.; Schoenberg, K.F.; Henins, I.; Gerwin, R.A.; Garcia, J.A.; Gribble, R.F. (Los Alamos National Laboratory, Mail Stop E526, Los Alamos, New Mexico 87545 (United States)); Mayo, R.M.; Black, D.C. (Department of Nuclear Engineering, Campus Box 7909, North Carolina State University, Raleigh, North Carolina 27695-7909 (United States)); Hoyt, R.P. (Aerospace and Energetics Research Program, FL-10, University of Washington, Seattle, Washington 98195 (United States))

1993-01-20

264

Effects of Ion Beam Waveform on Flyer Acceleration Produced by Pulsed Ion Beam Ablation Plasma  

NASA Astrophysics Data System (ADS)

The main objective of the current study is to clarify the influence of ion beam waveform and to investigate the momentum producing capability of flyer acceleration for propulsion applications, which is produced by irradiating target materials with pulsed ion beam. Al thin foil with a thickness of 50 ?m was used to form the high-pressure, high-temperature, and high-energy density ablation plasma when it interacts with pulsed ion beam. The analytical procedures are based on one-dimensional hydrodynamic equations together with a real gas equation of state. This paper presents not only the physical parameters of pulsed ion beam interaction with a target, but also shows the effects of ion beam waveform on momentum production. In addition, we describe the mechanism of ablation pressure formation and compare the results obtained for the rectangular and the parabolic waveform of ion beam irradiation. An ion beam with parabolic waveform produces ablation pressure more efficiently than a rectangular waveform. Propulsion performance is also estimated. An impulse bit of 50.7 mNs and a specific impulse of 5200 s are obtained at an electric power consumption of 1677 W.

Buttapeng, Chainarong; Yazawa, Masaru; Harada, Nobuhiro

265

Pilot Scale Test of a Produced Water-Treatment System for Initial Removal of Organic Compounds  

Microsoft Academic Search

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

Soondong Kwon; Enid Sullivan; Lynn Katz; Kerry Kinney; Robert Bowman

2008-01-01

266

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

SciTech Connect

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

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

2008-09-07

267

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

NASA Astrophysics Data System (ADS)

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

Hassanein, A.; Sizyuk, T.

2013-05-01

268

Thermophysical property measurement at high temperatures by laser-produced plasmas  

SciTech Connect

Excitation by a high-power laser pulse of a material surface generates a sequence of plasma, fluid flow, and acoustic events. These are well separated in time, and their detection and analysis can lead to determination of material properties of the condensed phase target. We have developed a new methodology for real-time determination of molten metal composition by time-resolved spectroscopy of laser-produced plasmas (LPP). If the laser pulse is shaped in such a way that the movement of the bulk surface due to evaporation is kept in pace with the thermal diffusion front advancing into the interior of the target, the LPP plume becomes representative of the bulk in elemental composition. In addition, the mass loss due to LPP ablation is very well correlated with the thermal diffusivity of the target matter. For several elemental solid specimens, we show that the product of the ablation thickness and heat of formation is proportional to the thermal diffusivity per unit molecular weight. Such measurements can be extended to molten metal specimens if the mass loss by ablation, density, heat of formation, and molecular weight can be determined simultaneously. The results from the solid specimen and the progress with a levitation-assisted molten metal experiment are presented.

Kim, Y.W. [Lehigh Univ., Bethehem, PA (United States)

1993-05-01

269

Magnetic reconnection in high-energy-density laser-produced plasmas  

SciTech Connect

Recently, novel experiments on magnetic reconnection have been conducted in laser-produced plasmas in a high-energy-density regime. Individual plasma bubbles self-generate toroidal, mega-gauss-scale magnetic fields through the Biermann battery effect. When multiple bubbles are created at small separation, they expand into one another, driving reconnection of this field. Reconnection in the experiments was reported to be much faster than allowed by both Sweet-Parker, and even Hall-MHD theories, when normalized to the nominal magnetic fields self-generated by single bubbles. Through particle-in-cell simulations (both with and without a binary collision operator), we model the bubble interaction at parameters and geometry relevant to the experiments. This paper discusses in detail the reconnection regime of the laser-driven experiments and reports the qualitative features of simulations. We find substantial flux-pileup effects, which boost the relevant magnetic field for reconnection in the current sheet. When this is accounted for, the normalized reconnection rates are much more in line with standard two-fluid theory of reconnection. At the largest system sizes, we additionally find that the current sheet is prone to breakup into plasmoids.

Fox, W.; Bhattacharjee, A.; Germaschewski, K. [Center for Integrated Computation and Analysis of Reconnection and Turbulence, and Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, University of New Hampshire, Durham, New Hampshire 03824 (United States)

2012-05-15

270

Anomalous helicon wave absorption and parametric excitation of electrostatic fluctuations in a helicon-produced plasma  

NASA Astrophysics Data System (ADS)

The nonlinear nature of the rf absorption in a helicon-produced plasma was recently evidenced by the observation that the helicon wave damping as well as the level of short-scale electrostatic fluctuations excited in the helicon plasma increases with rf power. Correlation methods using electrostatic probes as well as microwave back-scattering at the upper-hybrid resonance allow identifying the fluctuations as ion-sound and Trivelpiece-Gould waves satisfying the frequency and wavenumber matching conditions for the parametric decay instability of the helicon pump wave. Furthermore, the growth rates and thresholds deduced from their temporal growth are in good agreement with theoretical predictions for the parametric decay instability that takes into account realistic damping rates for the decay waves as well as a non-vanishing parallel wavenumber of the helicon pump. The close relationship between the rf absorption and the excitation of the fluctuations was investigated in more detail by performing time- and space-resolved measurements of the helicon wave field and the electrostatic fluctuations.

Krämer, M.; Aliev, Yu M.; Altukhov, A. B.; Gurchenko, A. D.; Gusakov, E. Z.; Niemi, K.

2007-05-01

271

Potential effects of Plasma on the Development of Laser Produced Craters  

SciTech Connect

Laser ablation and crater formation have been studied on a copper target using a 10 Hz, Nd:YAG laser system delivering pulses up to 100 mJ in 40 ps with a flux on target F{<=} 5000 J/cm2. Crater dimensions were measured using optical microscope or SEM (Scanning Electron Microscope). In order to understand the process of crater formation, we considered various theoretical models present in the literature and revised them taking into account the occurrence of plasma phenomena, which are important at the intensities used in this experiment. We also compared our experimental results with other results obtained at the PALS laboratory, using a 0.44 {mu}m wavelength laser and much higher laser intensities. Finally we explore the possibility of extending the information derived from laser produced craters to other types of craters.

Batani, Dimitri; Desai, Tara; Rossetti, Stefano; Lucchini, Gianni [Dipartimento di Fisica, 'G.Occhialini', Universita degli Studi Milano-Bicocca, Piazza della Scienza 3, 20126 Milan (Italy)

2006-04-07

272

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

273

Soft-x-ray generation in a helium environment using laser-produced plasmas.  

PubMed

Soft-x-ray radiation was generated by focusing the beam of a Q-switched Nd:glass laser on a steel target in a chamber filled with He at pressures of 10(-5)mbar produced plasma was reduced by less than 10% compared with the emission under high-vacuum conditions. The half-width tau(x-ray) of the soft-x-ray emission time was independent of p and of the same order as the laser pulse half-width tau(LASER) asymptotically equal to 17 nsec. PMID:19718221

Kühne, M; Petzold, H C

1984-01-01

274

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

SciTech Connect

Magnets of Co-Zr-B, one of the permanent magnetic compounds without rare-earth elements, were successfully produced by the spark plasma sintering method. The resultant Co-Zr-B magnets had high densities of 92%–96% and consisted mainly of the Co{sub x}Zr (x ? 5) phase. The coercivity of the Co-Zr-B magnets was highly dependent on the consolidation temperature and the boron content. The highest maximum energy product of 6.0 MGOe, with a remanence of 6.4 kG and the coercivity of 4.0 kOe, was achieved by the Co{sub 80}Zr{sub 18}B{sub 2} magnets consolidated at 873?K.

Saito, Tetsuji, E-mail: tetsuji.saito@it-chiba.ac.jp; Akiyama, Tomoya [Department of Mechanical Science and Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016 (Japan)

2014-05-07

275

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

276

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

SciTech Connect

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

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

2011-09-26

277

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

SciTech Connect

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.

Cone, K. V. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); University of California at Davis, Davis, California 95616 (United States); Baldis, H. A. [University of California at Davis, Davis, California 95616 (United States); Dunn, J.; May, M. J.; Schneider, M. B.; Scott, H. A. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Purvis, M. A. [Colorado State University, Fort Collins, Colorado 80521 (United States)

2012-10-15

278

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

SciTech Connect

The volumetric heating of a thin copper target has been studied with time resolved x-ray spectroscopy. The copper target was heated from a plasma produced using the Lawrence Livermore National Laboratory's Compact Multipulse Terrawatt (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 2-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.

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

2012-05-02

279

Interaction of a laser-produced plasma with a solid surface: soft X-ray spectroscopy of high-Z ions in a cool dense plasma  

Microsoft Academic Search

Experimental data and theoretical calculations are presented for X-ray spectra from a laser-produced plasma interacting with a solid surface and are compared with those obtained from the hot-burst core of the plasma. Intensities of the spectral lines of the principal series of the H-like and He-like magnesium ions were investigated. A close study of the resonance and intercombination lines was

I. L. Beigman; P. Y. Pirogovskiy; L. P. Presnyakov; A. P. Shevelko; D. B. Uskov

1989-01-01

280

Bragg Scattering of Electromagnetic Wave by Microwave Produced Periodic Plasma Layers  

Microsoft Academic Search

The feasibility of using artificial atmospheric plasma as a Bragg reflector in the upper atmosphere to relay electromagnetic wave is studied. The research includes three parts, (1) the generation of periodic plasma layers and their reflectivity; (2) the lifetime of plasma electrons; and (3) the propagation of high power microwave pulse in air breakdown environment. A set of parallel plasma

Yong-Shan Zhang

1991-01-01

281

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

NASA Astrophysics Data System (ADS)

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

Manuel, Mario J.-E.

282

Laser Produced Plasmas as a Source of Ions, Protons and X-rays  

NASA Astrophysics Data System (ADS)

The work presented in this thesis is primarily focused on the use of a laser produced plasma as a source of protons, ions and X-rays. It explores high impact applications of both high power ultrafast lasers and nanosecond lasers. Section 1 gives a general introduction to the physics governing the experiments and the lasers in the following sections. Section 2 describes all the laser systems used in this thesis. Section 3 is covers two different experiments involving the generation of X-rays from a laser produced plasma. Section 4 describes a laser accelerated proton experiment conducted in the Center for Plasma Research in Queens University Belfast, using the TARANIS laser system. In this experiment 13 MeV protons were accelerated from10 ?m gold foil targets into a sample of BK-7 glass. The interaction of the protons with the glass were observed by taking spatially resolved images of the transient opacity induced by the protons interacting with the BK-7 Glass and an optical probe beam. These spatially resolved images are presented in Section 4.3. Section 5 describes the refurbishment of the 1-m normal incidence VUV spectrometer. It describes the replacement of a photographic plate based detection system with a linear CCD array. The CCD array can detect the VUV radiation through a sodium salicylate phosphor coating which emits at 410 nm on interacting with VUV radiation. Different phosphors are compared in terms of sensitivity and ease of coating and the grounds for choosing sodium salicylate are explained. The adaptations to the spectrometer to use the linear CCD array are described and the details on calibrating the spectrometer are explained. Finally, Section 6 describes a set of spectroscopic experiments which use the refurbished 1-m normal incidence spectrometer. First Section 6.2 describes a repeat of the photoabsorption of indium and indium plus which was conducted previously on the spectrometer. This was designed as a proof of principle of the working of the new phosphor based linear CCD array system. (Abstract shortened by UMI.).

Stefanuik, Robert

283

Initial design for an experimental investigation of strongly coupled plasma behavior in the Atlas facility  

SciTech Connect

Atlas is a high current ({approximately} 30 MA peak, with a current risetime {approximately} 4.5 {micro}sec), high energy (E{sub stored} = 24 MJ, E{sub load} = 3--6 MJ), pulsed power facility which is being constructed at Los Alamos National Laboratory with a scheduled completion date in the year 2000. When operational, this facility will provide a platform for experiments in high pressure shocks (> 20 Mbar), adiabatic compression ({rho}/{rho}{sub 0} > 5, P > 10 Mbar), high magnetic fields ({approximately} 2,000 T), high strain and strain rates ({var_epsilon} > 200%, d{var_epsilon}/dt {approximately} 10{sup 4} to 10{sup 6} s{sup {minus}1}), hydrodynamic instabilities of materials in turbulent regimes, magnetized target fusion, equation of state, and strongly coupled plasmas. For the strongly coupled plasma experiments, an auxiliary capacitor bank will be used to generate a moderate density (< 0.1 solid), relatively cold ({approximately} 1 eV) plasma by ohmic heating of a conducting material of interest such as titanium. This stargate plasma will be compressed against a central column containing diagnostic instrumentation by a cylindrical conducting liner that is driven radially inward by current from the main Atlas capacitor bank. The plasma is predicted to reach densities of {approximately} 1.1 times solid, achieve ion and electron temperatures of {approximately} 10 eV, and pressures of {approximately} 4--5 Mbar. This is a density/temperature regime which is expected to experience strong coupling, but only partial degeneracy. X-ray radiography is planned for measurements of the material density at discrete times during the experiments; diamond Raman measurements are anticipated for determination of the pressure. In addition, a neutron resonance spectroscopic technique is being evaluated for possible determination of the temperature (through low percentage doping of the titanium with a suitable resonant material). Initial target plasma formation experiments are being planned on an existing pulsed power facility at LANL and will be completed before the start of operation of Atlas.

Munson, C.P.; Benage, J.F. Jr.; Taylor, A.J.; Trainor, R.J. Jr.; Wood, B.P.; Wysocki, F.J.

1999-07-01

284

X-ray diagnostics for ultrashort laser produced plasma experiments (abstract)  

SciTech Connect

The characterization of subpicosecond laser produced plasmas is currently being investigated by the Livermore ultrashort pulse laser group. A 800-nm, 150-fs, 35-mJ laser is focused to a 7-{mu}m spot on solid aluminum targets, producing XUV ({lt}1 keV), {ital K} shell (1.5--30 keV), and hard ({ge}3.0 keV) x-ray emission. The {ital K}-shell emission is studied using a Von Hamos crystal spectrograph with a KAP crystal curved to an 80-mm radius, resulting in a calculated resolution of {ital E}/{Delta}{ital E}{approx}400. The dispersed x rays are detected with a microchannel plate intensified reticon detector which relays the images out of the chamber and displayed on a computer monitor. The hard x rays are monitored with an array of filter x-ray diodes, covering energies from 3 to 75 keV. The XUV emission is monitored with a variably spaced line grating, flat field spectrometer, and a grazing incidence spectragraph. The diagnostics will be presented along with current data from experiments. This work was performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48.

Shepherd, R.; Price, D.; Nathel, H.; White, W.; Slaughter, D.; Stewart, R. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))

1992-10-01

285

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

Muñoz, M.; Uyar, A.; Correia, E.; Díez, C.; Fernandez-Gonzalez, A.; Caamaño, J. N.; Martínez-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

286

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

DOEpatents

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

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

1999-08-24

287

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

288

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

DOEpatents

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

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

1997-07-08

289

High$beta$ capture and mirror confinement of laser-produced plasmas. Semiannual report, February 1July 31, 1973  

Microsoft Academic Search

The United Aircraft Research Laboratories are engaged in a program to ; investigate the use of a dense, mirror-confined, laser-produced plasma as the ; target for a neutral-injection beam and to examine this technique for ; establishing and maintaining a high-temperature, high-density, steady-state, ; mirrorconfined fusion plasma. The program is a direct extension of the current ; UARL investigations of

A. F. Haught; D. H. Polk; J. T. Woo; W. J. Fader; R. G. Tomlinson; R. A. Jong; W. B. Ard

1973-01-01

290

Time-resolved absorption spectroscopy using ultrashort soft x-ray pulse from femtosecond laser-produced plasma  

Microsoft Academic Search

High-density plasma created near a solid surface by an intense femtosecond laser pulse emits ultrashort x-ray pulses that are synchronized with the laser pulse. We show the spectral and temporal properties of broadband soft x-rays emitted from a femtosecond laser-produced plasma on a metal surface. The soft x-ray emission was increased about 20-fold by fabricating an array of nanocylinders on

Hidetoshi Nakano; Tadashi Nishikawa; Katsuya Oguri

2004-01-01

291

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

292

Mechanism of forward development of a plasma produced by an excimer laser in high-pressure argon gases  

NASA Astrophysics Data System (ADS)

In high-pressure argon gases up to 150 atm, the plasma produced by a XeCl excimer laser developed not only backward but also forward. The model for the forward development, called a forward breakdown wave, could not predict the developmental behavior in the latter stage. The development model was modified, newly taking into account the laser absorption by the plasma when the laser light was transmitted through the backward plasma. The time variation of the absorption coefficient at each distance was calculated using the inverse bremsstrahlung by the electron-ion impact. This modified model could better predict the forward development behavior than the previous model.

Tsuda, Norio; Yamada, Jun

2000-03-01

293

Plasma puff initiation of high Coulomb transfer switches. Annual progress report, 1 October 1989-30 September 1990  

SciTech Connect

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.

1990-09-01

294

Direct structuring of solids by EUV radiation from a table-top laser produced plasma source  

NASA Astrophysics Data System (ADS)

In recent years, technological developments in the area of extreme ultraviolet lithography (EUVL) have experienced great improvements. Currently, the application of EUV radiation apart from microlithography comes more and more into focus. Main goal of our research is to utilize the unique interaction between soft x-ray radiation and matter for probing, modifying, and structuring solid surfaces. In this contribution we present a setup capable of generating and focusing EUV radiation. It consists of a table-top laser-produced plasma source. In order to obtain a small focal spot resulting in high EUV fluence, a modified Schwarzschild objective consisting of two spherical mirrors with Mo/Si multilayer coatings is adapted to this source, simultaneously blocking unwanted out-of-band radiation. By demagnified (10x) imaging of the plasma an EUV spot of 5 ?m diameter with a maximum energy density of ~0.72 J/cm² is generated (pulse length 8.8 ns). We present first applications of this integrated source and optics system, demonstrating its potential for high-resolution modification and structuring of solid surfaces. As an example, etch rates for PMMA, PC and PTFE depending on EUV fluences were determined, indicating a linear etch behavior for lower energy densities. In order to investigate changes of the chemical composition of PMMA induced by EUV radiation we present FTIR and NEXAFS measurements on irradiated samples. The latter were performed using the laboratory source tuned to the XUV spectral range around the carbon K-edge (? ~ 4.4 nm) and a flat-field spectrometer. For showing the potential of this setup, first damage tests were performed on grazing incidence gold mirrors. For these thin Gold films, threshold energy densities could be determined, scaling linear with the film thickness.

Barkusky, Frank; Bayer, Armin; Peth, Christian; Mann, Klaus

2009-05-01

295

Study of ultra-intense laser produced plasmas via computer simulation  

NASA Astrophysics Data System (ADS)

Recent advances in the development of intense short pulse lasers have led to exciting progress in high energy density physics (HEDP). As an example, a several mum thin foil that is irradiated by a 100 TW, sub-picosecond laser pulse reaches keV (1 keV ˜ 11,000,000 C) temperatures at solid density. The resultant electron distribution is temporarily far out of equilibrium, featuring two or more widely distinct temperatures. In modeling such extreme plasmas, both kinetic and collisional effects on the energy transport are essential. Of particular difficulty are the large density gradients between the critical density (the density at which the laser is absorbed), and solid densities exceeding several hundred times the critical density. For a 1 mum wavelength laser pulse, the critical density, nc, is 1021 cm --3. This means that a numerical model needs to describe the laser-plasma interaction in the low density region, as well as fast particle transport in the extremely dense target region where Coulomb collision processes are important for energy transfer. In cone-guided fast ignition inertial confinement fusion experiments, fuel previously compressed by an ablative implosion is ignited by the injection of an intense short laser pulse via a cone embedded within the fuel target. The implosion precondition creates density scales which range over five orders of magnitude from the cone interior to the highly compressed core. A critical issue for this process is whether the hot electrons produced in the interaction are in an energy range conducive to efficient heating of the core. In this work, Particle-in-Cell simulations evaluate the entire cone-guided fast ignition experiment for the first time, including hot electron generation at the cone tip, energy transport to the compressed fuel core, and subsequent collisional core heating. The laser-plasma interaction within the cone target is particularly important, as temperatures of hot electrons generated here are found to be lower than previously expected while overall absorption is influenced by non-linear electrodynamic processes.

Chrisman, Brian R.

296

Microwave emission from plasmas produced by magnetically confined-electron beams  

Microsoft Academic Search

Microwave emission, in the x-band frequency range (8.2-12.4 GHz), from a thin, large, rectangular sheet plasma has been measured. The plasma electron density was such that the plasma frequency was within or just above this frequency range. The plasma was immersed in an external magnetic field from a set of Helmholz coils. The magnetic field was oriented parallel to the

Donald P. Murphy; Richard F. Fernsler; Robert E. Pechacek; Robert A. Meger

2002-01-01

297

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

Microsoft Academic Search

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

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

1997-01-01

298

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

299

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

300

Optical transmission and reflection of a plasma produced in nanosecond laser induced air breakdown  

NASA Astrophysics Data System (ADS)

In this paper, we investigate dynamics of optical breakdown in air induced by a pump- probe laser beam technique. The optical breakdown was generated by an Nd:YAG laser beam (operating at 10 ns pulse duration and 1064 nm wavelength). A small part of the beam was separated from the main beam by an optical splitter and was aligned to probe the breakdown plasma transversely. Monitoring the time resolved reflectivity from the breakdown plasma may give information on critical density and together with its transmittivity through the plasma provides information on plasma absorptivity. The results of this experiment can be also used to describe dynamics of breakdown plasma evolution.

Mahdieh, M. H.; Akbari J., M.; Bababei, Z.

2015-02-01

301

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

PubMed Central

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

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

2014-01-01

302

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

SciTech Connect

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

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

2013-10-15

303

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

304

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

NASA Astrophysics Data System (ADS)

Laser target energy coupling mechanism is crucial in the shock ignition (SI) scheme, and x-ray radiation energy is a non-negligible portion of the laser produced plasma energy. To evaluate the x-ray radiation energy amount at conditions relevant to SI scheme, instantaneous x-ray radiation energy is investigated experimentally with continuum phase plates smoothed lasers irradiating layer polystyrene targets. Comparative laser pulses without and with shock spike are employed. With the measured x-ray angular distribution, full space x-ray radiation energy and conversion efficiency are observed. Instantaneous scaling law of x-ray conversion efficiency is obtained as a function of laser intensity and time. It should be pointed out that the scaling law is available for any laser pulse shape and intensity, with which irradiates polystyrene planar target with intensity from 2 × 1014 to 1.8 × 1015 W/cm2. Numerical analysis of the laser energy transformation is performed, and the simulation results agree with the experimental data.

Shang, Wanli; Wei, Huiyue; Li, Zhichao; Yi, Rongqing; Zhu, Tuo; Song, Tianmin; Huang, Chengwu; Yang, Jiamin

2013-10-01

305

Intense electron emission due to picosecond laser-produced plasmas in high gradient electric fields  

SciTech Connect

Picosecond laser pulses at a wavelength of 266 nm have been focused onto a solid metal cathode in coincidence with high gradient electric fields to produce high brightness electron beams. At power densities exceeding 10{sup 9} W/cm{sup 2}, a solid density plasma is formed and intense bursts of electrons are emitted from the target accompanied by macroscopic surface damage. An inferred {similar to}1 {mu}C of integrated charge with an average current of {similar to}20 A is emitted from a radio-frequency cavity driven at electric field gradients of {similar to}80 MV/m. In another experiment, where a dc extraction field of {similar to}6 MV/m is used, we observed an electron charge of {similar to}0.17 {mu}C. Both results are compared with the Schottky effect and the Fowler--Nordheim field emission. We found that this laser-induced intense electron emission shares many features with the explosive electron emission processes. No selective wavelength dependence is observed in the production of the intense electron emission in the dc extraction field. The integrated electrons give an apparent quantum efficiency of {similar to}1.2%, which is one of the highest reported to date from metal photocathodes at these photon energies.

Wang, X.J.; Tsang, T.; Kirk, H.; Srinivasan-Rao, T.; Fischer, J.; Batchelor, K.; Russell, P.; Fernow, R.C. (Brookhaven National Laboratory, Upton, New York 11973 (United States))

1992-08-01

306

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

307

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

308

Pump-probe imaging of nanosecond laser-induced bubbles in distilled water solutions: Observations of laser-produced-plasma  

NASA Astrophysics Data System (ADS)

This article presents the analysis of the laser-produced-plasma (LPP) formed by the focusing of a 9 ns laser pulse, ? =532 nm, with a NA=0.6 aspherical lens using energies between 100-1500 ?J, into distilled water with varying solutions of table salt. Observations of the filamentation plasma were made, which are explained by self-focusing of the laser pulse by the LPP through ponderomotive cavitation of the electron plasma in the center of the beam. The filamentation of the beam through a low density plasma wave guide explains why the transmission of the pump laser through the interaction region was notably higher on previous experiments that we performed [R. Evans et al., Opt. Express 16, 7481 (2008)], than a very similar set of experiments performed by Noack and Vogel [IEEE J. Quantum Electron. 35, 1156 (1999)].

Evans, R.; Camacho-López, S.

2010-11-01

309

Time-resolved vibrational and rotational emission analysis of laser-produced plasma of carbon and polymers  

E-print Network

Time-resolved vibrational and rotational emission analysis of laser-produced plasma of carbon University, Krako´w, PL-30-059, Krako´w, ul. Reymonta 4, Poland Received 25 October 1998; received in revised reserved. Keywords: Nd:YAG laser ablation; Time-resolution; Carbon molecules; Vibrational and rotational

310

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

E-print Network

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

Harilal, S. S.

311

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

312

Development of Visualization System of Neutral Particles Generated from Laser-Produced Plasma for an EUV Light Source  

Microsoft Academic Search

In the development of extreme ultraviolet (EUV) sources for practical optical lithography systems, one of the most important subjects is debris mitigation. In, particularly mitigation of fast neutral atoms is very difficult compared with other particles such as ions and droplets. Thus, in our study, we developed a visualization system for neutral atoms emitted from laser-produced plasma (LPP) based EUV

Hiroki Tanaka; Atsushi Matsumoto; Akihiko Takahashi; Tatsuo Okada

2007-01-01

313

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

E-print Network

1316 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 36, NO. 4, AUGUST 2008 Schlieren Imaging of Flow, and Laxminarayan L. Raja Abstract--Schlieren imaging of flow field structure produced by direct-current surface of a 30 wedge. Schlieren imaging reveals that for cathodes located upstream of the anodes, the discharge

Raja, Laxminarayan L.

314

Initial carrier-envelope phase of few-cycle pulses determined by THz emission from air plasma  

E-print Network

The evolution of THz waveform generated in air plasma provides a sensitive probe to the variation of the carrier envelope phase (CEP) of propagating intense few-cycle pulses. Our experimental observation and calculation reveal that the number and positions of the inversion of THz waveform are dependent on the initial CEP, which is near 0.5{\\pi} constantly under varied input pulse energies when two inversions of THz waveform in air plasma become one. This provides a method of measuring the initial CEP in an accuracy that is only limited by the stability of the driving few-cycle pulses.

Xu, Rongjie; Song, Liwei; Liu, Peng; Li, Ruxin; Xu, Zhizhan

2013-01-01

315

Transient plasma ignition  

Microsoft Academic Search

This paper presents images of transient plasma applied in varied circumstances to fuel ignition and subsequent combustion. The transient plasma occurs during the formative phase of an arc discharge, and persists for ?50 ns. The results demonstrate that transient plasma ignition initiates combustion efficiently, produces excited species distinct from traditional spark ignition, and that for some applications, including reduced delays

Jianbang Liu; Fei Wang; Guoqiang Li; Andras Kuthi; Ephraim J. Gutmark; Paul D. Ronney; Martin A. Gundersen

2005-01-01

316

Chemical characterization of PAN based carbon fibers produced by microwave assisted plasma (MAP) technology and effect of plasma treatment on carbon fiber surface and interphase with polymer matrix  

NASA Astrophysics Data System (ADS)

The first objective of this research was to chemically characterize the surface of conventional carbon fiber and carbon fiber produced by microwave assisted plasma (MAP) manufacturing process. The chemical composition and functional groups on the surface of the fibers were determined by X-ray photoelectron spectroscopy (XPS). The untreated unsized MAP carbon fibers were compared to untreated unsized conventional carbon fibers and showed a significant amount of oxygen. Comparison between treated unsized MAP carbon fiber and treated unsized conventional carbon fiber reveal a 100% enhancement of oxygen elemental concentration. Two plasma systems, remote applicator and atmospheric plasma were used to treat untreated unsized conventional carbon fiber. XPS results indicated that both systems have changed the chemical composition of carbon fiber surface. Oxygen-containing functional groups were found on carbon fiber surface after plasma treatment. Auger electron spectroscopy combining with chemical deritivazation was used to investigate the effect of morphological structure of carbon fiber surface on the placement of carboxyl groups. It was found that carboxyl groups were located preferentially in the valleys. A model of surface morphological structure of carbon fibers treated with plasma was proposed. Chemical bonding formed in the interphase between plasma treated carbon fiber and urethane was investigated using FTIR imaging. Directed evidence of formation of hydrogen bonding between carbon fiber and urethane was observed.

Luo, Xiaoyu

317

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

318

Diagnostics and analyses of decay process in laser produced tetrakis(dimethyl-amino)ethylene plasma  

Microsoft Academic Search

A large volume (hundreds of cm3) plasma is created by a 193 nm laser ionizing an organic vapor, tetrakis(dimethyl-amino)ethylene (TMAE). The plasma is characterized as high electron density (1013-1012 cm-3) and low electron temperature (~0.1 eV). To investigate the plasma decay processes, a fast Langmuir probe technique is developed, including detailed considerations of probe structure, probe surface cleaning, shielding, frequency

Guowen Ding; John E. Scharer; Kurt L. Kelly

2001-01-01

319

Diagnostics and analyses of decay process in laser produced tetrakis(dimethyl-amino)ethylene plasma  

Microsoft Academic Search

A large volume (hundreds of cm3) plasma is created by a 193 nm laser ionizing an organic vapor, tetrakis(dimethyl-amino)ethylene (TMAE). The plasma is characterized as high electron density (1013–1012 cm?3) and low electron temperature (?0.1 eV). To investigate the plasma decay processes, a fast Langmuir probe technique is developed, including detailed considerations of probe structure, probe surface cleaning, shielding, frequency

Guowen Ding; John E. Scharer; Kurt L. Kelly

2001-01-01

320

Spectroscopic Diagnostics for Plasma Produced by Exposure of a Target in Liquid to Dual Laser Pulses  

NASA Astrophysics Data System (ADS)

We have studied the optical emission spectra of a laser plasma formed when targets made from zinc alloys and positioned in a liquid are exposed to dual laser pulses, for different delays between pulses. We give estimates of the electron temperature and electron concentration for the plasma in the liquid from the Boltzmann and Saha-Boltzmann equations and the Stark line broadening. We have established that as the interpulse interval increases, fractionation of the alloying elements entering the plasma is enhanced.

Burakov, V. S.; Butsen?, A. V.; Kiris, V. V.; Tarasenko, N. V.

2013-09-01

321

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

322

Atmospheric-pressure CO{sub 2} laser with an electron-beam-initiated discharge produced in a working mixture  

SciTech Connect

An atmospheric-pressure CO{sub 2} laser with an electron-beam-initiated discharge produced in a working mixture is developed. The laser output energy of 18 mJ from a {approx}6-cm{sup 3} active volume is achieved. The laser operation with a pulse repetition rate of up to 5 Hz is demonstrated. The specific energy deposit of {approx}0.1 J cm{sup -3} is obtained in the CO{sub 2}:N{sub 2}:He = 1:1:4 gas mixture at the atmospheric pressure during a pulsed nonself-sustained discharge with ionisation amplification. (lasers)

Alekseev, S B; Orlovskii, Viktor M; Tarasenko, Viktor F [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation)

2003-12-31

323

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

324

Responses of organic and inorganic materials to intense EUV radiation from laser-produced plasmas  

NASA Astrophysics Data System (ADS)

We have investigated responses of polymers to EUV radiation from laser-produced plasmas beyond ablation thresholds and micromachining. We concentrated on fabricate precise 3D micro-structures of PDMS, PMMA, acrylic block copolymers (BCP), and silica. The micromachining technique can be applied to three-dimensional micro-fluidic and bio-medical devices. The EUV processing is a promising to realize a practical micromachining technique. In the present work, we used two EUV radiation sources; (a) Wide band EUV light in a range of 10{300 eV was generated by irradiation of Ta targets with Nd:YAG laser light at 500 mJ/pulse. (b) Narrow band EUV light at 11 and 13 nm was generated by irradiation of solid Xe and Sn targets, respectively, with pulsed TEA CO2 laser light. The generated EUV light was condensed onto the materials at high power density beyond the ablation thresholds, using ellipsoidal mirrors. We found that through-holes with a diameter of one micrometer an be fabricated in PMMA and PDMS sheets with thicknesses of 4-10 micrometers, at 250 and 230 nm/shot, respectively. The effective ablation of PMMA sheets can be applied to a LIGA-like process for fabricating micro-structures of metals for micro- and nano-molds. PDMS sheets are ablated if it is irradiated with EUV light beyond a distinct threshold power density, while PDMS surfaces were modified at lower power densities. Furthermore, BCP sheets were ablated to have 1-micrometer structures. Thus, we have developed a practical technique for micromachining of PMMA, PDMS and BCP sheets in a micrometer scale.

Makimura, Tetsuya; Torii, Shuichi; Nakamura, Daisuke; Takahashi, Akihiko; Okada, Tatsuo; Niino, Hiroyuki; Murakami, Kouichi

2013-05-01

325

Novel Giant-Size Plasmas Produced by Microwave Discharge with Slot Antenna Array  

NASA Astrophysics Data System (ADS)

There is a growing need for giant-scale high-density plasma sources for manufacturing a meter-size flat panel display and for surface modification of large-area various materials. Capacitive discharges at frequencies in VHF range have been studied to meet this demand, however standing wave effect and edge effect significantly degrade the plasma uniformity. Here, we present a new technology for generation of large-area flat high-density plasma based on surface wave excitation at 2.45 GHz. A critical challenge to avoid huge atmospheric pressure acting on a microwave window was dodged by fully filling a waveguide, which is directly inserted in a low-pressure discharge vessel. The second challenge is a discharge antenna construction to attain the plasma uniformity over meter-scale. This issue was solved by a careful design of slot antenna array. Surface waves propagating along the dielectric-plasma interface were investigated in FDT simulation. A surface wave mode was observed in plasma by a movable antenna, indicating the mode number predicted in the simulation. In a discharge vessel, 1 m long and 0.3 m wide, we obtained the plasma density of 5x10@super11@ cm@super-3@ with 10 and 50 mTorr Ar. Three-dimensional profiles of plasma density in different conditions measured by a Langmuir probe will be presented.

Sugai, H.; Nojiri, Y.; Takasu, K.; Ishijima, T.; Stamate, E.

2004-09-01

326

Cold plasma technologies for the inactivation of human pathogens on fresh and fresh-cut produce  

Technology Transfer Automated Retrieval System (TEKTRAN)

Research in cold plasma processing at the USDA’s Eastern Regional Research Center is focused on developing this technology into an effective tool to improve the safety of a variety of foods. Cold plasma applied to outbreak strains of Escherichia coli O157:H7 and Salmonella Stanley inoculated on the ...

327

Comparison of EUV spectral and ion emission features from laser-produced Sn and Li plasmas  

Microsoft Academic Search

Planar slabs of pure Sn and Li were irradiated with 1064 nm, 9 ns Nd:YAG laser pulses. The resulting plasmas were evaluated with an absolutely calibrated extreme ultraviolet (EUV) power tool, a transmission grating spectrograph, a pinhole camera, and a Faraday cup. These diagnostic tools have allowed us to determine EUV conversion efficiency (CE), EUV spectral emission features, EUV-emitting plasma

R. W. Coons; D. Campos; M. Crank; S. S. Harilal; A. Hassanein

2010-01-01

328

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

329

Structure of an Exploding Laser-Produced Plasma A. Collette* and W. Gekelman  

E-print Network

in a predetermined pattern. We use both fast (fmax > 50 MHz) three-axis magnetic coil probes ( dBx;y;z dt ) and Langmuir probes configured to measure ac floating potential. The magnetic probes are 1 mm in size (compared with a moving probe within an expanding dense plasma, embedded in a background magnetized plasma. High

California at Los Angles, University of

330

Diagnostics and analyses of decay process in laser produced tetrakis,,dimethyl-amino...ethylene plasma  

E-print Network

) and low electron temperature 0.1 eV . To investigate the plasma decay processes, a fast Langmuir probe system and 3 probe contami- nation by TMAE vapor. The techniques of the fast Langmuir probe measurements,5 In this manuscript, the plasma parameters are primarily detected by a single Langmuir probe. However, difficulties

Scharer, John E.

331

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

332

Spectroscopic characterization of a titan plasma produced by a continuous-high-power CO2 laser  

Microsoft Academic Search

It is well known, metallic plasmas created during welding with high power lasers are very important for the welding process. During recent years, we have been trying to characterize these kinds of plasmas, in order to get a better comprehension of the absorption of laser light by a steel target during welding with a CO2 laser. A complete spectroscopic characterization

Angel M. de Frutos Baraja; Anne Poueyo-Verwaerde; G. Deshors; Remy Fabbro; Jose M. Orza

1993-01-01

333

Propagation of charge-exchange plasma produced by an ion thruster  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

334

Visualizing electromagnetic fields in laser-produced counter-streaming plasma experiments for collisionless shock laboratory astrophysics  

SciTech Connect

Collisionless shocks are often observed in fast-moving astrophysical plasmas, formed by non-classical viscosity that is believed to originate from collective electromagnetic fields driven by kinetic plasma instabilities. However, the development of small-scale plasma processes into large-scale structures, such as a collisionless shock, is not well understood. It is also unknown to what extent collisionless shocks contain macroscopic fields with a long coherence length. For these reasons, it is valuable to explore collisionless shock formation, including the growth and self-organization of fields, in laboratory plasmas. The experimental results presented here show at a glance with proton imaging how macroscopic fields can emerge from a system of supersonic counter-streaming plasmas produced at the OMEGA EP laser. Interpretation of these results, plans for additional measurements, and the difficulty of achieving truly collisionless conditions are discussed. Future experiments at the National Ignition Facility are expected to create fully formed collisionless shocks in plasmas with no pre-imposed magnetic field.

Kugland, N. L.; Ross, J. S.; Glenzer, S. H.; Huntington, C.; Martinez, D.; Plechaty, C.; Remington, B. A.; Ryutov, D. D.; Park, H.-S. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Chang, P.-Y.; Fiksel, G.; Froula, D. H. [Laboratory for Laser Energetics, University of Rochester, 250 E. River Road, Rochester, New York 14636 (United States)] [Laboratory for Laser Energetics, University of Rochester, 250 E. River Road, Rochester, New York 14636 (United States); Drake, R. P.; Grosskopf, M.; Kuranz, C. [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States)] [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Gregori, G.; Meinecke, J.; Reville, B. [Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom)] [Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Koenig, M.; Pelka, A. [Laboratoire pour l'Utilisation des Lasers Intenses (LULI), École Polytechnique-Univ, Paris VI, 91128 Palaiseau (France)] [Laboratoire pour l'Utilisation des Lasers Intenses (LULI), École Polytechnique-Univ, Paris VI, 91128 Palaiseau (France); and others

2013-05-15

335

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

SciTech Connect

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

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

2013-06-28

336

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

SciTech Connect

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

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

2009-10-31

337

Probes of the quark-gluon plasma as it might be produced in ultra-relativistic nuclear collisions  

SciTech Connect

The energy densities which might be achieved in ultra-relativistic nuclear collisions are discussed. Using these estimates, promising probes of a quark-gluon plasma as it might be produced in such collisions are reviewed. I discuss in detail the emission of photons and di-leptons. The consequences of hydrodynamic expansion and a first order phase transition are explored for the transverse momentum spectrum of hadrons. Fluctuations in the rapidity distribution of hadrons are also discussed as a possible signal for a first order phase transition. The possibility that copious production of strange particles may signal the production of a quark-gluon plasma is also critically assessed. 24 references.

McLerran, L.

1984-01-01

338

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

339

Potential formation in a collisionless plasma produced in an open magnetic field in presence of volume negative ion source  

SciTech Connect

The electric potential near a wall for a multi-species plasma with volume produced negative ions in presence of axially varying magnetic field is studied following an analytical-numerical approach. A constant negative ion source is assumed throughout the plasma volume, along with finite temperature positive ions and Boltzmann electrons. The particles are assumed to be guided by an open magnetic field that has its maximum at the centre, and field strength decreasing towards the walls. The one dimensional (1D) Poisson equation is derived using an analytical approach, and then solved numerically to study the potential profiles. Effect of (a) negative ion production rate, (b) magnetic field profile, and (c) negative ion temperature on the potential profile has been investigated. A potential peak appears near the wall when the negative ion temperature and density are sufficiently high. Also, the presence of negative ions further decreases the potential in the plasma region for a finite Debye Length (?{sub D})

Phukan, Ananya, E-mail: ananya.phukan26@gmail.com; Goswami, K. S.; Bhuyan, P. J. [Centre of Plasma Physics, Institute for Plasma Research Sonapur, Kamrup (M), Assam 782402 (India)

2014-08-15

340

Refraction-Enhanced X-ray Radiography for Inertial Confinement Fusion and Laser-Produced Plasma Applications  

SciTech Connect

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

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

2008-08-26

341

Potential formation in a collisionless plasma produced in an open magnetic field in presence of volume negative ion source  

NASA Astrophysics Data System (ADS)

The electric potential near a wall for a multi-species plasma with volume produced negative ions in presence of axially varying magnetic field is studied following an analytical-numerical approach. A constant negative ion source is assumed throughout the plasma volume, along with finite temperature positive ions and Boltzmann electrons. The particles are assumed to be guided by an open magnetic field that has its maximum at the centre, and field strength decreasing towards the walls. The one dimensional (1D) Poisson equation is derived using an analytical approach, and then solved numerically to study the potential profiles. Effect of (a) negative ion production rate, (b) magnetic field profile, and (c) negative ion temperature on the potential profile has been investigated. A potential peak appears near the wall when the negative ion temperature and density are sufficiently high. Also, the presence of negative ions further decreases the potential in the plasma region for a finite Debye Length (?D).

Phukan, Ananya; Goswami, K. S.; Bhuyan, P. J.

2014-08-01

342

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

343

Diffusion-controlled regime of surface-wave-produced plasmas in helium gas  

Microsoft Academic Search

The study presents a numerical fluid-plasma model of diffusion-controlled surface-wave-sustained discharges in helium gas. The self-consistent behaviour of the discharge based on the interrelation between plasma density and Theta, the power absorbed on average by one electron, is described. The nonlinear process of step ionization in the charged particle balance equation is the main factor, which ensures the self-consistency. However,

J. Berndt; K. Makasheva; H. Schlüter; A. Shivarova

2002-01-01

344

Magnetic Compression of a Long Pulse Electron Beam Produced with an Arc Plasma Emitter1  

Microsoft Academic Search

This report presents the first experi- mental results on transportation and compression of long-pulse electron beam. Original electron beam source with a plasma emitter was used for beam generation. The source has a multi-aperture two-grid electron optical system (EOS); a plasma emitter was based on the hydrogen arc discharge. Electron beam of 26 keV, 50 A, 250 µs pulse length

Yu. A. Trunev; I. V. Kandaurov; A. V. Burdakov

345

Optimization of the neutron yield in fusion plasmas produced by Coulomb explosions of deuterium clusters irradiated by a petawatt laser.  

PubMed

The kinetic energy of hot (multi-keV) ions from the laser-driven Coulomb explosion of deuterium clusters and the resulting fusion yield in plasmas formed from these exploding clusters has been investigated under a variety of conditions using the Texas Petawatt laser. An optimum laser intensity was found for producing neutrons in these cluster fusion plasmas with corresponding average ion energies of 14 keV. The substantial volume (1-10 mm(3)) of the laser-cluster interaction produced by the petawatt peak power laser pulse led to a fusion yield of 1.6×10(7) neutrons in a single shot with a 120 J, 170 fs laser pulse. Possible effects of prepulses are discussed. PMID:23496630

Bang, W; Dyer, G; Quevedo, H J; Bernstein, A C; Gaul, E; Donovan, M; Ditmire, T

2013-02-01

346

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

SciTech Connect

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, E-mail: gambinon@ethz.ch; Brandstätter, Markus; Rollinger, Bob; Abhari, Reza [ETH Zürich, Laboratory for Energy Conversion, Sonneggstrasse 3, 8092 Zürich (Switzerland)

2014-09-15

347

Experimental study of the excitation of rhodium isomer in a plasma produced by a picosecond laser pulse  

SciTech Connect

Estimates and first experimental results on the excitation of a long-lived isomer state (E{sub m} = 39.756 keV, J{sup p} = 9/2{sup -}, and T{sub 1/2} = 56.114 min) of Rh{sup 103} nuclei under the action of X radiation in a hot solid-state-density rhodium plasma produced by a picosecond laser pulse in the SOKOL-P laser facility are presented.

Afonin, V. I.; Kakshin, A. G.; Mazunin, A. V. [Russian Federal Nuclear Center, Zababakhin All-Russia Research Institute of Technical Physics (Russian Federation)

2010-03-15

348

Elemental analysis using hard x-ray emission from a laser-produced plasma, induced by a femtosecond laser pulse  

NASA Astrophysics Data System (ADS)

A new approach for elemental analysis, which is based on the measurement of the hard x ray emitted from a laser-produced plasma is reported here. Since the K-shell emission is characteristic of the element in a sample, Cu, Zn, Fe, Co, and Ni were readily confirmed to be present in brass and kovar alloys by measuring the x-ray emission spectrum over an energy range from 2 to 30 keV.

Takeyasu, N.; Hirakawa, Y.; Imasaka, T.

2001-10-01

349

Investigation of plasmas produced by laser ablation using single and double pulses for food analysis demonstrated by probing potato skins  

Microsoft Academic Search

We report on investigations of plasmas produced by laser ablation of fresh potatoes using infrared nanosecond laser radiation.\\u000a A twin laser system consisting of two Nd:YAG oscillators was used to generate single or double pulses of adjustable interpulse\\u000a delay. The potatoes were irradiated under ambient air with moderate pulse energies of about 10 mJ. The expansion dynamics\\u000a of the ablation plume

S. Beldjilali; W. L. Yip; J. Hermann; T. Baba-Hamed; A. Belasri

2011-01-01

350

Plasma levels of intact and cleaved urokinase receptor decrease in HIV-1-infected patients initiating highly active antiretroviral therapy.  

PubMed

Elevated blood levels of soluble urokinase receptor (suPAR) measured by ELISA decrease in human immunodeficiency virus-1 (HIV-1)-infected patients initiating highly active antiretroviral therapy (HAART). As the suPAR ELISA measures both three- and two-domain suPAR [suPAR(I-III), suPAR(II-III)] and suPAR(I-III)-ligand complexes, the amount by which the individual suPAR forms (suPAR(I-III), suPAR(II-III) and one-domain suPAR [suPAR(I)]) decrease in plasma in HIV-1-infected patients initiating HAART is unknown. Consequently, the objective of this study was to investigate HAART-induced changes in the individual plasma suPAR forms in HIV-1-infected patients. Plasma suPAR was measured by three time-resolved fluorescence immunoassays detecting suPAR(I-III), suPAR(I-III) + suPAR(II-III) and suPAR(I) in 29 treatment-naïve HIV-1-infected patients followed annually for 5 years after initiation of HAART and in 20 age- and gender-matched healthy individuals. In addition, plasma levels of the following inflammatory markers were also investigated: soluble tumour necrosis factor receptor (sTNFr)-II, TNF-alpha, interleukins (IL)-10, IL-6, IL-4, IL-2 and interferon (IFN)-gamma. In HIV-1-infected patients, plasma suPAR(I-III), suPAR(II-III) and suPAR(I) decreased within the first treatment year (all P < 0.05) and suPAR(I-III) and suPAR(II-III) remained above normal throughout follow-up (both P < 0.05). Plasma sTNFrII, IL-6, IFN-gamma and IL-10 also decreased during HAART (all P < 0.05). In HIV-1-infected patients, sTNFrII correlated with all suPAR forms before (all P < 0.01) and after 5 years HAART (all P < 0.001), whereas sTNFrII and suPAR did not correlate in healthy individuals. Intact and cleaved plasma suPAR decreased in HIV-1-infected patients initiating HAART but remained above normal. The positive correlation with sTNFrII suggests that the individual plasma suPAR forms are linked to immune activation in HIV-1 infection. PMID:16764702

Ostrowski, S R; Katzenstein, T L; Pedersen, M; Høyer-Hansen, G; Gerstoft, J; Pedersen, B K; Ullum, H

2006-06-01

351

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

SciTech Connect

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

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

2013-04-22

352

Quality control material for plasma fibrinogen test produced from purified human fibrinogen  

PubMed Central

Plasma fibrinogen measurement is a routine laboratory procedure commonly performed on automated coagulation analysers. Its determination is quantitative, not quantitative. Yet, a lack of precision has been an issue for fibrinogen measurement. A control material derived from plasma comprises many proteins, inhibitors and fatty acids, any or all of which can interfere in the fibrinogen assay. This study has attempted to develop a quality control material using purified human fibrinogen and has compared measurement precision between both purified and plasma materials. Purified fibrinogen was prepared using Cohn fraction 1 and glycine precipitation. Purified fibrinogen clottability was greater than 95%, with no main plasma proteins, lipids or fibrinogen degradation products observed. Two purified control materials were lyophilized at normal (2.30 g lm1) and abnormal (1.20 g lm1) levels of fibrinogen concentration. Precision was evaluated using a liquid-type reagent, Thrombocheck Fib(L), on automated coagulation analysers. Coefficient of variation for within-run, intraday and between-day precision of the purified materials was 0.7-3.5%. In comparison, the coefficient of variation for plasma materials ranged from 1.2 to 5.3%. These results suggest that materials prepared from purified fibrinogen can be useful to laboratory quality control by improving overall precision of fibrinogen measurement and are applicable to automated coagulation analysers. PMID:18924717

Uemura, Yahiro; Tatsumi, Noriyuki

2003-01-01

353

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

354

ADVANCES IN APPLIED PLASMA SCIENCE, Vol.9, 2013 ISAPS '13, Istanbul Design and Optimization of Laser Produced Plasma Devices for  

E-print Network

, minimized debris production and mitigation, components lifetime, and source brightness for the high volume parameters to predict EUV photons emission, collection, source size and intensity, atomic and ionic debris producing, as well as effect of debris on LPP device components lifetime. We utilized HEIGHTS LPP package

Harilal, S. S.

355

Radiation environments produced by plasma Z-pinch stagnation on central targets  

SciTech Connect

A goal of modern pulsed-power technology is the development of an intense, megajoule level source of soft x-rays for use in high-energy density physics experiments. Since 1980 experimental facilities, theoretical concepts, computational tools, and diagnostics have been developed that place pulsed-power at the threshold of performing experiments of great interest to the applied physics community. In this paper the ``Flying Radiation Case`` approach will be presented and its predicted performance on Sandia National Laboratory`s Z-Machine [M.K. Matzen, Phys. Plasmas 4, 1519 (1997)] is described. The effects of instability growth in the plasma during the implosion, its reassembly on a central cushion, and the plasma interactions with shaped electrodes are considered.

Brownell, J.H.; Bowners, R.L.; McLenithan, K.D.; Peterson, D.L.

1997-11-01

356

Measurements of large scale-length plasmas produced from gas-filled targets  

SciTech Connect

Apart from their intrinsic interest, plasma physics processes are important because they affect the coupling of the laser energy into laser-irradiated targets. Recently, new gas-filled targets have been developed to create large mm-size plasmas for the study of stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS). We present x-ray images and x-ray spectra to characterize these targets, which show that the plasmas are homogeneous, have electron densities of {approximately}10{sup 21} cm{sup {minus}3}, and attain electron temperatures of {approximately}3 keV. We also present SBS measurements to demonstrate how systematic studies of physical phenomena can be performed using these targets.

Back, C.A.; Berger, R.L.; Estabrook, K. [and others

1995-06-30

357

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

SciTech Connect

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

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

2014-06-15

358

A promising plasmatron-produced highly ionized plasma source for research\\/industrial demand  

Microsoft Academic Search

Presents the design features and basic parameters of an industrially important plasma jets source developed from a high-current arc pasmatron (I<=3D500A, G=3D1-4g\\/s, jet diameter at a minimum-6mm). The system has been realized of to collect and process data on plasma radiation in the 200-950nm region (resolution=3D0.01nm) allowing securing of a great body of information on atomic\\/ionic line characteristics (radiation transition

A. A. Belevtsev; V. F. Chinnov; E. Kh. Isakaev; A. D. Iserov; V. I. Kalinin; V. K. Korolev; A. V. Markin; D. I. Ryazhsky; O. A. Sinkevich; S. A. Tereshkin; A. S. Tyuftyaev

1998-01-01

359

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

360

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

361

The WIND-HAARP experiment: Initial results of high power radiowave interactions with space plasmas  

Microsoft Academic Search

Results from the first science experiment with the new HF Active Auroral Research Program (HAARP) in Alaska are reported. The objective was to study the effects of space plasmas on high power radiowave transmission to high altitudes in the magnetosphere. Reception was done by the NASA\\/WIND satellite. The data suggest that structured space plasmas along the propagation path impose a

P. Rodriguez; E. J. Kennedy; M. J. Keskinen; C. L. Siefring; Sa. Basu; M. McCarrick; J. Preston; M. Engebretson; M. L. Kaiser; M. D. Desch; K. Goetz; J.-L. Bougeret; R. Manning

1998-01-01

362

The WIND-HAARP Experiment: Initial results of high power radiowave interactions with space plasmas  

Microsoft Academic Search

Results from the first science experiment with the new HF Active Auroral Research Program (HAARP) in Alaska are reported. The objective was to study the effects of space plasmas on high power radiowave transmission to high altitudes in the magnetosphere. Reception was done by the NASA\\/WIND satellite. The data suggest that structured space plasmas along the propagation path impose a

P. Rodriguez; E. J. Kennedy; M. J. Keskinen; C. L. Siefring; Sa. Basu; M. McCarrick; J. Preston; M. Engebretson; M. L. Kaiser; M. D. Desch; K. Goetz; J.-L. Bougeret; R. Manning

1998-01-01

363

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

364

Ion current distribution produced by a vacuum arc carbon plasma source  

Microsoft Academic Search

A vacuum arc carbon plasma source is described, in which an arc was ignited between a cathode and an anode having an aperture, by bringing the two electrodes into contact, and parting them while current was flowing. The inter-electrode gap length was varied. A focusing magnetic field was applied in the inter-electrode gap, and a toroidal magnetic field was applied

V. N. Zhitomirsky; O. Zarchin; S. G. Wang; R. L. Boxman; S. Goldsmith

2000-01-01

365

Bragg scattering of electromagnetic waves by microwave-produced plasma layers  

Microsoft Academic Search

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

S. P. Kuo; Y. S. Zhang

1990-01-01

366

Diagnostics of plasma produced by femtosecond laser pulse impact upon a target with an internal nanostructure  

SciTech Connect

X-ray diagnostics of the interaction of femtosecond laser pulses with intensities of 10{sup 16}-10{sup 18} W/cm{sup 2} with CO{sub 2} clusters and frozen nanosize water particles is carried out. The stage of cluster expansion and the formation of a plasma channel, which governs the parameters of the formed X-ray radiation source and accelerated ion flows, is studied. The measurements are based on recording spatially resolved X-ray spectra of H- and He-like oxygen ions. Utilization of Rydberg transitions for spectra diagnostics makes it possible to determine plasma parameters on a time scale of t {approx} 10 ps after the beginning of a femtosecond pulse. The role of the rear edge of the laser pulse in sustaining the plasma temperature at a level of {approx}100 eV in the stage of a nonadiabatic cluster expansion is shown. The analysis of the profiles and relative intensities of spectral lines allows one to determine the temperature and density of plasma electrons and distinguish the populations of 'thermal' ions and ions that are accelerated up to energies of a few tens of kiloelectronvolts. It is shown that the use of solid clusters made of frozen nanoscale water droplets as targets leads to a substantial increase in the number of fast He-like ions. In this case, however, the efficiency of acceleration of H-like ions does not increase, because the time of their ionization in plasma exceeds the time of cluster expansion.

Skobelev, I. Yu.; Faenov, A. Ya.; Gasilov, S. V.; Pikuz, T. A.; Pikuz, S. A. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Magunov, A. I. [Russian Academy of Sciences, Prokhorov Institute of General Physics (Russian Federation); Boldarev, A. S.; Gasilov, V. A. [Russian Academy of Sciences, Institute of Mathematical Modeling (Russian Federation)

2010-12-15

367

Surface initiated polymerization on pulsed plasma deposited polyallylamine: a polymer substrate-independent strategy to soft surfaces with polymer brushes.  

PubMed

The deposition of polyallylamine (PAA) adlayers by pulsed plasma polymerization on various types of polymeric substrates has been explored as a general route to amino functionalized polymeric surfaces. These amino groups are highly suitable for anchoring an atom transfer radical polymerization (ATRP) initiator via a robust amide linkage. Subsequent surface initiated ATRP (SI-ATRP) of monomethoxy oligo(ethylene glycol) methacrylate (MeOEGMA) resulted in polyMeOEGMA brush grafted polymer surfaces. This combined strategy of pulsed plasma polymerization with SI-ATRP was demonstrated for five different polymeric substrates namely polyether ether ketone (PEEK), polyethylene terephthalate (PET), polyimide (PI), polypropylene (PP), and polytetrafluoroethylene (PTFE). Analysis of brush layers by attenuated total reflection infrared (ATR-IR) spectroscopy as well as X-ray photoelectron spectroscopy (XPS) fully corroborated the success of the proposed strategy for all substrate types. PMID:21858892

Yameen, Basit; Khan, Hadayat Ullah; Knoll, Wolfgang; Förch, Renate; Jonas, Ulrich

2011-11-01

368

Change in the ionisation state of a near-surface laser-produced aluminium plasma in double-pulse ablation modes  

SciTech Connect

The near-surface plasma produced upon irradiation of an aluminium target by two successive laser pulses with nonresonance and resonance wavelengths is studied by the spectroscopic and probe-assisted methods. The feasibility of increasing the ion fraction in the laser-produced plasma in double-pulse ablation modes is demonstrated. The conditions are determined under which processes on the surface as well as selective excitation and ionisation in the plasma have a determining effect on the formation of its ionisation state. (interaction of laser radiation with matter. laser plasma)

Burakov, V S; Bokhonov, A F; Nedel'ko, M I; Tarasenko, N V [Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, Minsk (Belarus)

2003-12-31

369

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

370

Measurements of Hot Electrons Produced by Two-Plasmon Decay in Near Direct-Drive-Ignition Plasma Conditions  

NASA Astrophysics Data System (ADS)

Measurements of hot-electron generation by two-plasmon-decay instability have been made in plasmas relevant to direct-drive-ignition plasma conditions. Four 351-nm, 2-ns-long beams on the OMEGA EP Laser provided the high energy (10 kJ) necessary to produce overlap laser intensities from 1 to 7 x 10^14 W/cm^2 in large 1-mm-diam laser spots. These laser conditions produced coronal electron temperatures >2 keV with density scale lengths at ncr/4 greater than 400 ?m in CH plasmas. The total number of hot electrons increases exponentially over nearly four orders of magnitude and the hot-electron temperature increases from 30 keV to 110 keV. In this intensity range, changing the ablator material from CH to Al reduced the number of hot electrons by an order of magnitude over the entire range. Experiments to measure the angular dependence of the electrons and the coupling of these electrons to direct-drive implosions will be presented. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302.

Michel, D. T.; Yaakobi, B.; Hu, S. X.; Craxton, R. S.; Myatt, J. F.; Seka, W.; Edgell, D. H.; Goncharov, V. N.; Froula, D. H.

2011-11-01

371

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

SciTech Connect

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

Shepherd, R.; Price, D.; White, B.; Osterheld, A.; Walling, R.; Slaughter, D.; Stewart, R. [Lawrence Livermore National Lab., CA (United States); Gordan, S. [California Univ., Berkeley, CA (United States). Dept. of Physics

1992-06-05

372

Using Plasma-Activated High Performance Fibers with Nanocrystalline Structure in Producing New Reinforced Composite Materials  

Microsoft Academic Search

A wet-pull-out method for investigation of interaction between the high performance polyethylene (HPPE) fiber and polymer matrix is discussed. The paper concerns a cold plasma technique for improving the bond of the HPPE fibers to the matrices and the fibers impregnation with the matrix. Controlled parameters are pull-out force and the height of the matrix capillary lifting along the fiber

V. Kudinov; N. Korneeva

2008-01-01

373

Bragg scattering of EM waves by microwave produced periodic plasma layers  

Microsoft Academic Search

Uses of artificial plasma layers as Bragg reflectors for applications in telecommunication links and over-the-horizon (OTH) radars are currently being investigated in a large chamber of Plexiglas. Two microwave beams at right angles to each other are directed through the S-band horns into the chamber containing air at a pressure comparable to that of the upper atmosphere (~50 km). Inside

Y. S. Zhang; S. P. Kuo

1989-01-01

374

Analysis of two colliding laser-produced plasmas by emission spectroscopy and fast photography  

Microsoft Academic Search

In this work two colliding laser-induced plasmas (LIP) on Cu and C were studied by means of time resolved emission spectroscopy and fast photography. The experiments were performed using two opposing parallel targets of Cu and C in vacuum, ablated with two synchronized ns lasers. The results showed an increased emission intensity from copper ions Cu II (368.65, 490.97, 493.16,

C. Sánchez-Aké; D. Mustri-Trejo; T. García-Fernández; M. Villagrán-Muniz

2010-01-01

375

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

NASA Astrophysics Data System (ADS)

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° 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.; Hakel, P.; Mancini, R. C.; Abdallah, J.; Junkel-Vives, G. C.; Witte, K.

2004-10-01

376

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

SciTech Connect

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

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

2014-10-07

377

Polarisation dependences of harmonic generation in the plasma produced in the ionisation of excited-state hydrogen-like atoms  

SciTech Connect

An analytic theory of harmonic generation in the plasma produced from the gas of hydrogen-like atoms in excited states is considered for relatively intense radiation. The consideration of l-degeneracy of the electrons in these excited states allowed deriving the dependence of generation efficiency on the principal quantum number. In the context of the Bethe model of gas ionisation, we revealed the threshold nonlinear dependence of the maximum generation efficiency on the degree of circular polarisation of the pump field for its given intensity. Analytic calculations were performed for the fifth and seventh harmonics. The results of these calculations allowed generalising to the case of excited atoms the previously obtained results for the third harmonic in the plasma arising from hydrogen-like atoms in the ground state. (nonlinear optical phenomena)

Silin, Viktor P; Silin, Pavel V [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2005-02-28

378

Characteristics of sheath-driven tangential flow produced by a low-current DC surface glow discharge plasma actuator  

NASA Astrophysics Data System (ADS)

An experimental investigation of low-speed flow actuation at near-atmospheric pressure is presented. The flow actuation is achieved via low-current ( \\lesssim 1.0 mA) continuous or pulsed DC surface glow discharge plasma. The plasma actuator, consisting of two sharp-edged nickel electrodes, produces a tangential flow in a direction from anode to cathode, and is visualized using high-speed schlieren photography. The induced flow velocity estimated via the schlieren images reaches up to 5 m/s in test cases. The actuation capability increases with pressure and electrode gap distances, and the induced flow velocity increases logarithmically with the discharge power. Pulsed DC exhibits slightly improved actuation capability with better directionality. An analytic estimation of induced flow velocity obtained based on ion momentum in the cathode sheath and gas dynamics in one-dimensional flow yields values similar to those measured.

Shin, Jichul; Shajid Rahman, Mohammad

2014-08-01

379

Lifetime of a depression in the plasma density over Jicamarca produced by space shuttle exhaust in the ionosphere  

NASA Astrophysics Data System (ADS)

When the space shuttle orbiting maneuver subsystem (OMS) engines burn in the ionosphere, a plasma density depression, or "hole," is produced. Charge exchange between the exhaust molecules and the ambient O+ ions yields molecular ion beams that eventually recombine with electrons. The resulting plasma hole in the ionosphere can be studied with ground-based, incoherent scatter radars (ISRs). This type of ionospheric modification is being studied during the Shuttle Ionospheric Modification with Pulsed Localized Exhaust (SIMPLEX) series of experiments over ISR systems located around the globe. The SIMPLEX 1 experiment occurred over Jicamarca, Peru, in the afternoon on October 4, 1997, during shuttle mission STS 86. An electron density depression was produced at 359 km altitude at the midpoint of a magnetic field line. The experiment was scheduled when there were no zonal drifts of the plasma so the modified field line remained fixed over the 50 MHz Jicamarca radar. The density depression was filled in by plasma flowing along the magnetic field line with a time constant of 4.5 min. The density perturbation had completely vanished 20 min after the engine burn. The experimental measurements were compared with two models: (1) SAMI2, a fully numerical model of the F region, and (2) an analytic representation of field-aligned transport by ambipolar diffusion. The computed recovery time from each model is much longer than the observed recovery time. The theory of ambipolar diffusion currently used in ionospheric models seems to be inadequate to describe the SIMPLEX 1 observations. Several possible sources for this discrepancy are discussed. The SIMPLEX 1 active experiment is shown to have the potential for testing selected processes in ionospheric models.

Bernhardt, P. A.; Huba, J. D.; Kudeki, E.; Woodman, R. F.; Condori, L.; Villanueva, F.

2001-09-01

380

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

SciTech Connect

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

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

2002-06-01

381

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

382

Density and x-ray emission profile relationships in highly ionized high-Z laser-produced plasmas  

NASA Astrophysics Data System (ADS)

We present a benchmark measurement of the electron density profile in the region where the electron density is 1019 cm-3 and where the bulk of extreme ultraviolet (EUV) emission occurs from isotropically expanding spherical high-Z gadolinium plasmas. It was found that, due to opacity effects, the observed EUV emission is mostly produced from an underdense region. We have analyzed time-resolved emission spectra with the aid of atomic structure calculations and find the multiple ion charge states around 18+ during the laser pulse irradiation.

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

2015-03-01

383

Magnetic properties of Sm5Fe17/Fe composite magnets produced by spark plasma sintering method  

NASA Astrophysics Data System (ADS)

Mixtures of powdered Sm5Fe17 melt-spun ribbon and Fe powder were consolidated into bulk magnets by the spark plasma sintering (SPS) method. Although these bulk magnets consisted of the hard magnetic Sm5Fe17 and soft magnetic ?-Fe phases, they had a smooth hysteresis loop and exhibited coercivity. Among the magnets studied, the Sm5Fe17/Fe composite magnet with 30%Fe showed a remanence of 94 emu/g with a coercivity of 2.9 kOe.

Saito, Tetsuji; Miyoshi, Hiroya

2012-04-01

384

Ultrafast imaging of transient electronic plasmas produced in conditions of femtosecond waveguide writing in dielectrics  

SciTech Connect

Femtosecond laser-induced plasmas in bulk dielectrics are imaged under waveguide writing conditions, for different polarizations, pulse durations, and processing depths, and their temporal evolution is measured using ultrafast pump-probe microscopy. The irradiation beam profile is elliptically shaped yielding a disklike focal volume. We demonstrate for doped phosphate glass that increasing the pulse duration improves the spatial distribution of deposited energy by minimizing beam filamentation and prefocal depletion effects. As a consequence, energy deposition in the desired volume is greatly enhanced. Our results identify key parameters for optimizing femtosecond laser processing of dielectrics and different strategies to minimize energy loss channels.

Gawelda, W.; Puerto, D.; Siegel, J.; Ferrer, A.; Ruiz de la Cruz, A.; Fernandez, H.; Solis, J. [Laser Processing Group, Instituto de Optica, C.S.I.C., Serrano 121, 28006 Madrid (Spain)

2008-09-22

385

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

386

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

SciTech Connect

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

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

2014-03-28

387

Time-resolved Thomson scattering on high-intensity laser-produced hot dense helium plasmas  

NASA Astrophysics Data System (ADS)

The introduction of brilliant free-electron lasers enables new pump-probe experiments to characterize warm and hot dense matter states, i.e. systems at solid-like densities and temperatures of one to several hundred eV. Such extreme conditions are relevant for high-energy density studies such as, e.g., in planetary physics and inertial confinement fusion. We consider here a liquid helium jet pumped with a high-intensity optical short-pulse laser that is subsequently probed with brilliant soft x-ray radiation. The optical short-pulse laser generates a strongly inhomogeneous helium plasma which is characterized with particle-in-cell simulations. We derive the respective Thomson scattering spectrum based on the Born-Mermin approximation for the dynamic structure factor considering the full density and temperature-dependent Thomson scattering cross section throughout the target. We observe plasmon modes that are generated in the interior of the target and study their temporal evolution. Such pump-probe experiments are promising tools to measure the important plasma parameters density and temperature. The method described here can be applied to various pump-probe scenarios by combining optical lasers, soft x-rays and hard x-ray sources.

Sperling, P.; Liseykina, T.; Bauer, D.; Redmer, R.

2013-02-01

388

Analysis of two colliding laser-produced plasmas by emission spectroscopy and fast photography  

NASA Astrophysics Data System (ADS)

In this work two colliding laser-induced plasmas (LIP) on Cu and C were studied by means of time resolved emission spectroscopy and fast photography. The experiments were performed using two opposing parallel targets of Cu and C in vacuum, ablated with two synchronized ns lasers. The results showed an increased emission intensity from copper ions Cu II (368.65, 490.97, 493.16, 495.37 and 630.10 nm) and Cu III (374.47 and 379.08 nm) due to the ionization that occurs during collisions of Cu and C species. It was found that the optimum delay between pulses, which yields the maximum emission enhancement of Cu ions, depends on the sampling distance. On the other hand, the emission intensity of C lines, C II (426.70 nm), C III (406.99 and 464.74 nm) and C IV (465.83 nm), decreased and the formation of C 2 molecules was observed. A comparison between the temporal evolution of the individual plasmas and their collision performed by combining imaging and the time resolved emission diagnostics, revealed an increase of the electron temperature and electron density and the splitting of the plume into slow and fast components.

Sánchez-Aké, C.; Mustri-Trejo, D.; García-Fernández, T.; Villagrán-Muniz, M.

2010-05-01

389

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

390

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

391

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

Cancer.gov

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

392

Studies of ion kinetic effects in shock-driven inertial confinement fusion implosions at OMEGA and the NIF and magnetic reconnection using laser-produced plasmas at OMEGA  

E-print Network

Studies of ion kinetic effects during the shock-convergence phase of inertial confinement fusion (ICF) implosions and magnetic reconnection in strongly-driven, laser-produced plasmas have been facilitated by the use of ...

Rosenberg, Michael Jonathan

2014-01-01

393

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

394

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

395

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

396

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

397

Plasma composition in Jupiter's magnetosphere - Initial results from the Solar Wind Ion Composition Spectrometer  

NASA Technical Reports Server (NTRS)

The ion composition in the Jovian environment was investigated with the Solar Wind Ion Composition Spectrometer on board Ulysses. A hot tenuous plasma was observed throughout the outer and middle magnetosphere. In some regions two thermally different components were identified. Oxygen and sulfur ions with several different charge states, from the volcanic satellite Io, make the largest contribution to the mass density of the hot plasma, even at high latitude. Solar wind particles were observed in all regions investigated. Ions from Jupiter's ionosphere were abundant in the middle magnetosphere, particularly in the high-latitude region on the dusk side, which was traversed for the first time.

Geiss, J.; Gloeckler, G.; Balsiger, H.; Fisk, L. A.; Galvin, A. B.; Gliem, F.; Hamilton, D. C.; Ipavich, F. M.; Livi, S.; Mall, U.

1992-01-01

398

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

399

System to continuously produce carbon fiber via microwave assisted plasma processing  

DOEpatents

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

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

2014-03-25

400

Characteristics of Rf-Produced, High-Density Plasma with Very Small Diameter  

NASA Astrophysics Data System (ADS)

To investigate characteristics of helicon plasma with a very small diameter, we have developed the Small Helicon Device (SHD) and measured the electron density under various conditions over a wide range of radio frequencies. Using a tube with inner diameter of 20 mm, an electron density ne of ~1013 cm-3 near the antenna region was obtained with an excitation frequency f of 7 MHz, rf power Prf of ~1000 W, and axial magnetic field in the magnet coil region B of 560 G. In the case of an inner diameter of 5 (10) mm under conditions of f = 12 (7) MHz, Prf ~1000 W, and B = 280 G, ne of ~1011 cm-3 was succesfully achieved even away from the antenna region.

Nakagawa, Toshiki; Shinohara, Shunjiro; Kuwahara, Daisuke; Mishio, Akira; Fujitsuka, Hiroaki

401

Magnetic properties of Pr-Fe-Ti-B nanocomposite magnets produced by spark plasma sintering method  

NASA Astrophysics Data System (ADS)

Amorphous melt-spun ribbons of Pr8Fe86-xTixB6 (x = 0-10) alloys were successfully consolidated into bulk materials by the spark plasma sintering method. X-ray diffraction and transmission electron microscopic studies revealed that the resultant bulk materials consisted of nanosized grains of the ?-Fe and Pr2Fe14B phases. The coercivity of the Pr-Fe-Ti-B bulk nanocomposite magnets increased with increasing Ti content. The Pr8Fe80Ti6B6 bulk nanocomposite magnet exhibited a high remanence of 10.2 kG with a coercivity of 4.9 kOe, while the Pr8Fe76Ti10B6 bulk magnet exhibited a remanence of 6.5 kG with a high coercivity of 8.2 kOe.

Saito, Tetsuji; Ishikawa, Hiroyuki; Nishio-Hamane, Daisuke

2011-04-01

402

Microstructure and mechanical behavior of ODS and non-ODS Fe-14Cr model alloys produced by spark plasma sintering  

NASA Astrophysics Data System (ADS)

In this work the spark plasma sintering (SPS) technique has been explored as an alternative consolidation route for producing ultra-fine grained Fe-14Cr model alloys containing a dispersion of oxide nanoparticles. Elemental powders of Fe and Cr, and nanosized Y2O3 powder have been mechanically alloyed in a planetary ball mill and rapidly sintered in a spark plasma furnace. Two alloys, with nominal compositions Fe-14%Cr and Fe-14%Cr-0.3%Y2O3 (wt.%), have been fabricated and their microstructure and mechanical properties investigated. The results have been compared with those obtained for other powder metallurgy processed alloys of the same composition but consolidated by hot isostatic pressing. The SPS technique under the present conditions has produced Fe-14Cr materials that apparently exhibit different microstructures yielding inferior mechanical properties than the counterpart material consolidated by hot isostatic pressing. Although the presence of a dispersion of Y-rich particles is evident, the oxide dispersion strengthened (ODS) Fe-14Cr alloy consolidated by SPS exhibits poor tensile properties. The extensive decoration of the powder particle surfaces with Cr-rich precipitates and the residual porosity appear to be responsible for the impaired properties of this ODS alloy consolidated by SPS.

Auger, M. A.; de Castro, V.; Leguey, T.; Muñoz, A.; Pareja, R.

2013-05-01

403

Modulation of plant plasma membrane H+-ATPase by phytotoxic lipodepsipeptides produced by the plant pathogen Pseudomonas fuscovaginae.  

PubMed

Pseudomonas fuscovaginae produces the lipodepsipeptides syringotoxin, fuscopeptin A and fuscopeptin B concurrently. These phytotoxins inhibit acidification of the external medium by fusicoccin-treated rice leaf sheath discs. When tested in vitro on H+-ATPase of rice shoot plasma membranes, syringotoxin and its structural analogue syringomycin, produced by P. syringae pv. syringae, displayed a double effect. At low concentrations they stimulated the ATPase activity of native right-side-out membrane vesicles in a detergent-like manner. At higher concentrations, however, this stimulation was reversed. With membranes treated with the detergent Brij 58, inhibition of ATPase activity was observed at low concentrations of the nonapeptides. The latter effect required the presence of an intact lactone ring formed by the nonapeptide head of these molecules. In contrast, fuscopeptins A and B inhibited enzyme activity regardless of the orientation of the vesicles. These observations were confirmed using plasma membranes from a yeast strain whose own H+-ATPase had been replaced by a single plant H+-ATPase isoform, PMA2, from Nicotiana plumbaginifolia. The kinetics of inhibition induced by the most active compound fuscopeptin B, showed a non-competitive pattern, with a Ki of about 1 microM. The combination of syringotoxin (or syringomycin) with the more hydrophobic fuscopeptins, in amounts with little or no effect, resulted in strong inhibition of the enzyme activity of rice membranes, suggesting a synergistic effect for the two types of toxins. PMID:9675287

Batoko, H; de Kerchove d'Exaerde, A; Kinet, J M; Bouharmont, J; Gage, R A; Maraite, H; Boutry, M

1998-07-17

404

Optimization of extreme ultraviolet photons emission and collection in mass-limited laser produced plasmas for lithography application  

NASA Astrophysics Data System (ADS)

The progress in development of commercial system for next generation EUV lithography requires, among other factors, significant improvement in EUV photon sources such as discharge produced plasma (DPP) and laser produced plasma (LPP) devices. There are still many uncertainties in determining the optimum device since there are many parameters for the suitable and efficient energy source and target configuration and size. Complex devices with trigger lasers in DPP or with pre-pulsing in LPP provide wide area for optimization in regards to conversion efficiency (CE) and components lifetime. We considered in our analysis a promising LPP source configuration using 10-30 ?m tin droplet targets, and predicted conditions for the most efficient EUV radiation output and collection as well as calculating photons source location and size. We optimized several parameters of dual-beam lasers and their relationship to target size. We used our HEIGHTS comprehensive and integrated full 3D simulation package to study and optimize LPP processes with various target sizes to maximize the CE of the system.

Sizyuk, T.; Hassanein, A.

2012-08-01

405

Influence of magnetic field on laser-produced barium plasmas: Spectral and dynamic behaviour of neutral and ionic species  

SciTech Connect

The expansion dynamics and spectral behaviour of plasma produced by a Nd:YAG laser (??=?1.064??m, pulse width: 8?ns) from barium target and expanding in 0.45?T transverse magnetic field in vacuum (10{sup ?5?}Torr pressure) are investigated using time-of-flight optical emission spectroscopy. The experiments are carried out at various laser fluences from 12 to 31?J/cm{sup 2}. The temporal profiles of neutral (Ba I 553.5 and 577.7?nm) lines are temporally broadened, while that of ionic (Ba II 413.0 and 455.4?nm) lines show strong confinement in the presence of a magnetic field. In the absence of magnetic field, the temporal profile of Ba I 553.5?nm is exactly reproduced by fitting with two Shifted Maxwell Boltzmann (SMB) Distribution components, while in the presence of a magnetic field the profile could only be fitted with three components. The field enhanced and field induced SMB components of neutral profile are correlated with populations of ground state, metastable states, and long-lived Rydberg states present in the barium plasma, while SMB components of ionic lines are explained on the basis of the presence of super-elastic collisions among the excited species in the plasma. The spatial variation of electron temperature and temporal variation of electron density are deduced and correlated to the different collisional processes in the barium plasma. The ionic profiles show efficient confinement in the presence of a magnetic field at higher fluences.

Raju, Makaraju Srinivasa; Gopinath, Pramod, E-mail: pramod@iist.ac.in [Department of Physics, Indian Institute of Space Science and Technology, Thiruvananthapuram 695547 (India); Singh, R. K.; Kumar, Ajai [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

2014-10-21

406

Generation mechanism of hydroxyl radical species and its lifetime prediction during the plasma-initiated ultraviolet (UV) photolysis  

PubMed Central

Through this work, we have elucidated the mechanism of hydroxyl radicals (OH•) generation and its life time measurements in biosolution. We observed that plasma-initiated ultraviolet (UV) photolysis were responsible for the continues generation of OH• species, that resulted in OH• to be major reactive species (RS) in the solution. The density and lifetime of OH• species acted inversely proportional to each other with increasing depth inside the solution. The cause of increased lifetime of OH• inside the solution is predicted using theoretical and semiempirical calculations. Further, to predict the mechanism of conversion of hydroxide ion (OH?) to OH• or H2O2 (hydrogen peroxide) and electron, we determined the current inside the solution of different pH. Additionally, we have investigated the critical criterion for OH• interaction on cancer cell inducing apoptosis under effective OH• exposure time. These studies are innovative in the field of plasma chemistry and medicine. PMID:25790968

Attri, Pankaj; Kim, Yong Hee; Park, Dae Hoon; Park, Ji Hoon; Hong, Young J.; Uhm, Han Sup; Kim, Kyoung-Nam; Fridman, Alexander; Choi, Eun Ha

2015-01-01

407

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

408

IR-Assisted Discharge Initiation in Pulsed Plasma Thrusters James E. Cooley  

E-print Network

Electric Propulsion & Plasma Dynamics Lab (EPPDyL) Mechanical and Aerospace Engineering Department desorption. Mass spectro- scopic measurements and theoretical calculations implicate water desorption from Group. Associate Fellow AIAA. Presented at the 38th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

Choueiri, Edgar

409

Filamentary structure of plasma produced by compression of puffing deuterium by deuterium or neon plasma sheath on plasma-focus discharge  

NASA Astrophysics Data System (ADS)

The present experiments were performed on the PF-1000 plasma focus device at a current of 2 MA with the deuterium injected from the gas-puff placed in the axis of the anode face. The XUV frames showed, in contrast with the interferograms, the fine structure: filaments and spots up to 1 mm diameter. In the deuterium filling, the short filaments are registered mainly in the region of the internal plasmoidal structures and their number correlates with the intensity of neutron production. The longer filamentary structure was recorded close to the anode after the constriction decay. The long curve-like filaments with spots were registered in the big bubble formed after the pinch phase in the head of the umbrella shape of the plasma sheath. Filaments can indicate the filamentary structure of the current in the pinch. Together with the filaments, small compact balls a few mm in diameter were registered by both interferometry and XUV frame pictures. They emerge out of the dense column and their life-time can be greater than hundreds of ns.

Kubes, P.; Paduch, M.; Cikhardt, J.; Kortanek, J.; Cikhardtova, B.; Rezac, K.; Klir, D.; Kravarik, J.; Zielinska, E.

2014-12-01

410

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

411

Conformational Changes Produced by ATP Binding to the Plasma Membrane Calcium Pump*  

PubMed Central

The aim of this work was to study the plasma membrane calcium pump (PMCA) reaction cycle by characterizing conformational changes associated with calcium, ATP, and vanadate binding to purified PMCA. This was accomplished by studying the exposure of PMCA to surrounding phospholipids by measuring the incorporation of the photoactivatable phosphatidylcholine analog 1-O-hexadecanoyl-2-O-[9-[[[2-[125I]iodo-4-(trifluoromethyl-3H-diazirin-3-yl)benzyl]oxy]carbonyl]nonanoyl]-sn-glycero-3-phosphocholine to the protein. ATP could bind to the different vanadate-bound states of the enzyme either in the presence or in the absence of Ca2+ with high apparent affinity. Conformational movements of the ATP binding domain were determined using the fluorescent analog 2?(3?)-O-(2,4,6-trinitrophenyl)adenosine 5?-triphosphate. To assess the conformational behavior of the Ca2+ binding domain, we also studied the occlusion of Ca2+, both in the presence and in the absence of ATP and with or without vanadate. Results show the existence of occluded species in the presence of vanadate and/or ATP. This allowed the development of a model that describes the transport of Ca2+ and its relation with ATP hydrolysis. This is the first approach that uses a conformational study to describe the PMCA P-type ATPase reaction cycle, adding important features to the classical E1-E2 model devised using kinetics methodology only. PMID:24025327

Mangialavori, Irene C.; Ferreira-Gomes, Mariela S.; Saffioti, Nicolás A.; González-Lebrero, Rodolfo M.; Rossi, Rolando C.; Rossi, Juan Pablo F. C.

2013-01-01

412

Clonally expanded plasma cells in the cerebrospinal fluid of MS patients produce myelin-specific antibodies.  

PubMed

Clonally expanded plasma cells (cePC) and their presumed products, oligoclonal immunoglobulin G bands (OCB), are characteristic findings in the cerebrospinal fluid (CSF) of patients with multiple sclerosis (MS). While cePC and OCB strongly suggest an involvement of B cell-dependent immune mechanisms in the pathogenesis of MS, their actual pathological relevance and target antigens remain unknown. To further understand the potential role played by cePC, we generated a panel of monoclonal antibodies (MS-mAb) from CSF-derived cePC from four patients with early or definite MS. Single-cell RT-PCR of correctly paired heavy and light chain immunoglobulin genes from individual cePC ensured the subsequent resurrection of their original antigen specificity. Immunofluorescence stainings of MS lesion tissue with MS-mAb revealed myelin reactivity in the cePC repertoire of all four patients and intracellular filament reactivity in one patient. While myelin staining by MS-mAb was only rarely detectable in non-MS CNS white matter tissue, it was greatly enhanced at the edge of demyelinating lesions in MS brain tissue. Our findings provide conclusive evidence for the presence of an antigen-driven B cell response in the CSF of MS patients directed against epitopes present in areas of myelin degradation. PMID:18521957

von Büdingen, Hans-Christian; Harrer, Melanie D; Kuenzle, Sandra; Meier, Mirjam; Goebels, Norbert

2008-07-01

413

Fasting Plasma Glucose as Initial Screening for Diabetes and Prediabetes in Irish Adults: The Diabetes Mellitus and Vascular Health Initiative (DMVhi)  

PubMed Central

Objective Type 2 diabetes has a long pre clinical asymptomatic phase. Early detection may delay or arrest disease progression. The Diabetes Mellitus and Vascular health initiative (DMVhi) was initiated as a prospective longitudinal cohort study on the prevalence of undiagnosed Type 2 diabetes and prediabetes, diabetes risk and cardiovascular risk in a cohort of Irish adults aged 45-75 years. Research Design and Methods Members of the largest Irish private health insurance provider aged 45 to 75 years were invited to participate in the study. Exclusion criteria: already diagnosed with diabetes or taking oral hypoglycaemic agents. Participants completed a detailed medical questionnaire, had weight, height, waist and hip circumference and blood pressure measured. Fasting blood samples were taken for fasting plasma glucose (FPG). Those with FPG in the impaired fasting glucose (IFG) range had a 75gm oral glucose tolerance test performed. Results 122,531 subjects were invited to participate. 29,144 (24%) completed the study. The prevalence of undiagnosed diabetes was 1.8%, of impaired fasting glucose (IFG) was 7.1% and of impaired glucose tolerance (IGT) was 2.9%. Dysglycaemia increased among those aged 45-54, 55-64 and 65-75 years in both males (10.6%, 18.5%, 21.7% respectively) and females (4.3%, 8.6%, 10.9% respectively). Undiagnosed T2D, IFG and IGT were all associated with gender, age, blood pressure, BMI, abdominal obesity, family history of diabetes and triglyceride levels. Using FPG as initial screening may underestimate the prevalence of T2D in the study population. Conclusions This study is the largest screening study for diabetes and prediabetes in the Irish population. Follow up of this cohort will provide data on progression to diabetes and on cardiovascular outcomes. PMID:25874867

Sinnott, Margaret; Kinsley, Brendan T.; Jackson, Abaigeal D.; Walsh, Cathal; O’Grady, Tony; Nolan, John J.; Gaffney, Peter; Boran, Gerard; Kelleher, Cecily; Carr, Bernadette

2015-01-01

414

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

415

Plasma disposition and faecal excretion of netobimin metabolites and enantiospecific disposition of albendazole sulphoxide produced in ewes.  

PubMed

Netobimin (NTB) was administered orally to ewes at 20 mg/kg bodyweight. Blood and faecal samples were collected from 1 to 120 h post-treatment and analysed by high-performance liquid chromatography (HPLC). Using a chiral phase-based HPLC, plasma disposition of albendazole sulphoxide (ABZSO) enantiomers produced was also determined. Neither NTB nor albendazole (ABZ) was present and only ABZSO and albendazole sulphone (ABZSO(2)) metabolites were detected in the plasma samples. Maximum plasma concentrations (C(max)) of ABZSO (4.1 +/- 0.7 microg/ml) and ABZSO(2) (1.1 +/- 0.4 microg/ml) were detected at (t(max)) 14.7 and 23.8 h, respectively following oral administration of netobimin. The area under the curve (AUC) of ABZSO (103.8 +/- 22.8 (microg h)/ml) was significantly higher than that ABZSO(2)(26.3 +/- 10.1 (microg h)/ml) (p < 0.01). (-)-ABZSO and (+)-ABZSO enantiomers were never in racemate proportions in plasma. The AUC of (+)-ABZSO (87.8 +/- 20.3 (microg h)/ml) was almost 6 times larger than that of (-)-ABZSO (15.5 +/- 5.1 (microg h)/ml) (p < 0.001). Netobimin was not detected, and ABZ was predominant and its AUC was significantly higher than that of ABZSO and ABZSO(2), following NTB administration in faecal samples (p > 0.01). Unlike in the plasma samples, the proportions of the enantiomers of ABZSO were close to racemic and the ratio of the faecal AUC of (-)-ABZSO (172.22 +/- 57.6 (microg h)/g) and (+)-ABZSO (187.19 +/- 63.4 (microg h)/g) was 0.92. It is concluded that NTB is completely converted to ABZ by the gastrointestinal flora and absorbed ABZ is completely metabolized to its sulphoxide and sulphone metabolites by first-pass effects. The specific behaviour of the two enantiomers probably reflects different enantioselectivity of the enzymatic systems of the liver that are responsible for sulphoxidation and sulphonation of ABZ. PMID:17004041

Gokbulut, C; Cirak, V Y; Senlik, B

2006-10-01

416

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

SciTech Connect

The ionic dependence of the trout sperm plasma membrane potential was analysed by measuring the accumulation of the lipophilic ions {sup 3}H-tetraphenylphosphonium (TPP) and {sup 14}C-thiocyanate (SCN) following dilution in artificial media isotonic to the seminal fluid. Our data showed that the trout sperm plasma membrane has a mixed conductance: the plasma membrane potential is sensitive upon the transmembrane gradients of K+, Na+, and H+. This potential is negative (less than -40 mV) in a 125 mM choline chloride media (ChM) at pH 8.5. Replacement of choline by sodium has a small depolarizing effect. The membrane potential is about -15 mV in a 125 mM potassium chloride and falls near zero mV only if valinomycin is added. In ChM changing the external pH (pHe) greatly affects the membrane potential: its value rises from less than -40 mV at pHe 9.0 to -17 mV at pHe 5.0. This pH effect is observed also in presence of sodium or potassium. A decrease in the transmembrane proton gradient produced by increasing internal pH without changing pHe induces also a depolarisation of the plasma membrane. In the different media in which trout sperm remain immotile after dilution (media with (K+) greater than 20-40 mM or a pH less than 7.5) the plasma membrane is more depolarized than in media allowing motility, suggesting a relationship between the state of membrane polarization and the intracellular effectors of the axonemal movement.

Gatti, J.L.; Billard, R.; Christen, R. (Laboratoire de Physiologie de la Reproduction, Nouzilly (France))

1990-06-01

417

Observation of neutron spectrum produced by fast deuterons via ultraintense laser plasma interactions.  

PubMed

We report the first precise spectral measurement of fast neutrons produced in a deuterated plastic target irradiated by an ultraintense sub-picosecond laser pulse. The 500-fs, 50-J, 1054-nm laser pulse was focused on the deuterated polystyrene target with an intensity of 2 x 10(19) W/cm(2). The neutron spectra were observed at 55 degrees and 90 degrees to the rear target normal. The neutron emission was 7 x 10(4) per steradian for each detector. The observed neutron spectra prove the acceleration of deuterons and neutron production by d(d,n)3He reactions in the target. The neutron spectra were compared with Monte Carlo simulation results and the deuteron's directional anisotropy and energy spectrum were studied. We conclude that 2% of the laser energy was converted to deuterons, which has an energy range of 30 keV up to 3 MeV. PMID:11909268

Izumi, N; Sentoku, Y; Habara, H; Takahashi, K; Ohtani, F; Sonomoto, T; Kodama, R; Norimatsu, T; Fujita, H; Kitagawa, Y; Mima, K; Tanaka, K A; Yamanaka, T

2002-03-01

418

Initial growth, refractive index, and crystallinity of thermal and plasma-enhanced atomic layer deposition AlN films  

SciTech Connect

The authors have studied and compared the initial growth and properties of AlN films deposited on Si(111) by thermal and plasma-enhanced atomic layer deposition (ALD) using trimethylaluminum and either ammonia or a N{sub 2}-H{sub 2} mixture as precursors. In-situ spectroscopic ellipsometry was employed to monitor the growth and measure the refractive index of the films during the deposition. The authors found that an incubation stage only occurred for thermal ALD. The linear growth for plasma-enhanced ALD (PEALD) started instantly from the beginning due to the higher nuclei density provided by the presence of plasma. The authors observed the evolution of the refractive index of AlN during the growth, which showed a rapid increase up to a thickness of about 30?nm followed by a saturation. Below this thickness, higher refractive index values were obtained for AlN films grown by PEALD, whereas above that the refractive index was slightly higher for thermal ALD films. X-ray diffraction characterization showed a wurtzite crystalline structure with a (101{sup ¯}0) preferential orientation obtained for all the layers with a slightly better crystallinity for films grown by PEALD.

Van Bui, Hao, E-mail: H.VanBui@utwente.nl; Wiggers, Frank B.; Gupta, Anubha; Nguyen, Minh D.; Aarnink, Antonius A. I.; Jong, Michel P. de; Kovalgin, Alexey Y., E-mail: A.Y.Kovalgin@utwente.nl [MESA Institute for Nanotechnology, University of Twente, P. O. Box 217, 7500 AE Enschede (Netherlands)

2015-01-01

419

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

420

On a heating mechanism for cold hydrogen and deuterium atoms produced at the edge of a tokamak plasma  

NASA Astrophysics Data System (ADS)

Spectroscopic measurements of the Dicons/Journals/Common/alpha" ALT="alpha" ALIGN="MIDDLE"/> and Hicons/Journals/Common/alpha" ALT="alpha" ALIGN="MIDDLE"/> line profiles emitted within the edge region of a tokamak plasma, have revealed the existence of a cold central component, broadened mainly by the Zeeman effect arising from the confining magnetic field. Evaluation of the Doppler broadening suggests that the cold component is probably produced by electron impact-induced molecular dissociation, dissociative excitation being one of the few mechanisms which can explain the formation of atoms of kinetic energy around 0.2 eV against a background of comparatively hot electrons and ions. Further analysis of these line profiles, observed along different directions in the equatorial plane and under various tokamak discharge conditions, reveals, in addition to this effective `cold temperature', an effective `lukewarm temperature', which we explain in terms of an appreciable collisional heating mechanism. Estimates of the rates for ion-induced dipole and ion-induced quadrupole collisions with excited atoms, yield values of the correct order of magnitude for this observed `lukewarm temperature'. In addition, measurements of Balmer-icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> line profiles, radiated from a gas discharge in a magnetic field of similar magnitude, are analysed and their shapes compared with those from the tokamak plasma.

Hey, J. D.; Chu, C. C.; Hintz, E.

1999-07-01

421

Antibody-integrated and functionalized graphite-encapsulated magnetic beads, produced using ammonia gas plasma technology, for capturing Salmonella.  

PubMed

Salmonella spp. is the single and most important causative agent of foodborne infections, especially involving foods such as eggs, milk and meat. To prevent infection, a reliable surveillance system is required that can quickly and sensitively detect Salmonella. Here, we describe the development of antibody-integrated magnetic beads that are functionalized by a novel strategy using ammonia gas plasma. Ammonia plasma, produced by a radio frequency (RF) power supply, was allowed to react with the surface of graphite-encapsulated magnetic beads, resulting in the introduction of amino groups. An anti-Salmonella antibody was then anchored by sulfide groups present on the protein surface to the amino groups of the magnetic beads via N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP). The potential usefulness of these magnetic beads for capturing Salmonella was examined as follows. The beads were incubated with Salmonella in liquid medium and then separated from the supernatant by applying a magnetic field. After thorough washing, adsorption of Salmonella to the beads was confirmed by immunochromatography, polymerase chain reaction and a direct culture assay. Our findings indicate that the capture and concentration of Salmonella using the antibody-integrated magnetic beads was more efficient than commercial Dynabeads® anti-Salmonella, which are conventionally used for concentrating Salmonella from liquid cultures. We believe this novel bead technology will contribute to the enhanced detection of Salmonella. PMID:25660257

Sakudo, Akikazu; Chou, Han; Nagatsu, Masaaki

2015-03-01

422

Transitions of Zn XXII, Zn XXIII, Zn XXIV, Ge XXIV, and Ge XXV observed in laser-produced plasmas  

NASA Technical Reports Server (NTRS)

Wavelengths and wave numbers are presented for zinc lines in the F I, O I, and N I isoelectronic sequences as well as for germanium lines in the F I and O I sequences. The transitions are of the type 2s(2)2p(k)-2s2p(k+1), and the lines were observed near 100 A in the spectra of plasmas produced by focusing the pulse from a high-power glass laser on to solid targets of different elements and compounds. The results are compared with prediction based on extrapolations of semiempirical formulas derived by Edlen (1969). The wavelengths and wave numbers of some of the corresponding transitions in Cu XXI, Cu XXII, Cu XXIII, Ga XXIII, and Ga XXIV are interpolated with a probable wavelength accuracy of at least plus or minus 0.02 A.

Behring, W. E.; Cohen, L.; Doschek, G. A.; Feldman, U.

1976-01-01

423

Effects of the dynamics of droplet-based laser-produced plasma on angular extreme ultraviolet emission profile  

SciTech Connect

The emission distribution of extreme ultraviolet (EUV) radiation from droplet targets is dependent on the dynamics of the laser-produced plasma. The EUV emission is measured on a 2% bandwidth centered at 13.5?nm (in-band). The targets of the laser are small (sub-50 ?m) tin droplets, and the in-band emission distribution is measured for different laser irradiances and droplet sizes at various angular positions. Larger droplets lead to a faster decay of EUV emission at larger angles with respect to the laser axis. A decrease in laser irradiance has the opposite effect. The measurements are used together with an analytical model to estimate plume dynamics. Additionally, the model is used to estimate EUV emission distribution for a desired droplet diameter and laser irradiance.

Giovannini, Andrea Z.; Abhari, Reza S. [Laboratory for Energy Conversion, ETH Zurich, 8092 Zurich (Switzerland)

2014-05-12

424

Clonally expanded plasma cells in the cerebrospinal fluid of patients with central nervous system autoimmune demyelination produce "oligoclonal bands".  

PubMed

Clonally expanded plasma cells (cePC) and oligoclonal IgG (oligoclonal bands, OCB) in the cerebrospinal fluid (CSF) suggest an involvement of B cell mechanisms in autoimmune CNS demyelination. Due to their CSF-restricted occurrence, OCB are commonly believed to be the products of B cells inside the borders of the blood brain barrier. A comparison of CSF cell Ig transcriptomes and CSF-Ig proteomes recently demonstrated, that in multiple sclerosis patients CSF cells are the origin of CSF immunoglobulins. We expand these findings by applying anti-idiotypic antibodies to detect specific heavy chain CDR3 idiotopes of cePC-produced antibodies amongst OCB in the CSF of a patient each with MS and acute disseminated encephalomyelitis. PMID:19900722

von Büdingen, Hans-Christian; Gulati, Monica; Kuenzle, Sandra; Fischer, Katja; Rupprecht, Tobias A; Goebels, Norbert

2010-01-25

425

? secretase-dependent cleavage initiates Notch signaling from the plasma membrane  

PubMed Central

Notch signaling is critical to animal development, and its dysregulation leads to human maladies ranging from birth defects to cancer. Although endocytosis is currently thought to promote signal activation by delivering activated Notch to endosome-localized ? secretase, the data are controversial and the mechanisms that control Notch endocytosis remain poorly defined. Here, we investigated the relationship between Notch internalization and signaling. siRNA-mediated depletion studies reveal that Notch endocytosis is clathrin-dependent and requires epsin1, AP2, and Nedd4. Moreover, we show that epsin1 interaction with Notch is ubiquitin-dependent. Contrary to the current model, we demonstrate that internalization defects lead to elevated ? secretase-mediated Notch processing and downstream signaling. These results indicate that signal activation occurs independently of Notch endocytosis and that ? secretase cleaves Notch at the plasma membrane. These observations support a model where endocytosis serves to down-regulate Notch in signal receiving cells. PMID:20573067

Sorensen, Erika B.; Conner, Sean D.

2010-01-01

426

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

427

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

428

Plasma Channels for Electron Accelerators Using Discharges in Structured Gas Cells  

Microsoft Academic Search

We present a new scheme to produce preformed plasma waveguides to extend the acceleration length of laser-plasma accelerators. The plasma is produced in a hydrogen background by a high-voltage discharge between two hollow conic electrodes through a sequence of thin dielectric plates with apertures that fix the initial plasma diameter and position. The thickness of the dielectric plates is close

Rodolfo A. Bendoyro; Roxana I. Onofrei; João Sampaio; Rita Macedo; Gonçalo Figueira; Nelson C. Lopes

2008-01-01

429

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

430

Low-level Plasma HIVs in Patients on Prolonged Suppressive Highly Active Antiretroviral Therapy Are Produced Mostly by Cells Other Than CD4 T-cells  

PubMed Central

The cellular source(s) and the clinical significance of persistent low-level viremia, below 50 HIV-RNA copies per ml of plasma, achieved in many patients with high adherence to highly active antiretroviral therapy (HAART) remain unclear. Also, it is not clear if residual plasma HIVs during HAART can become predominant populations in the rebounding plasma viral loads after therapy interruption. Since, different HIV quasispecies tend to compartmentalize in various cell types and tissue locations in patients during chronic infection, the phylogenetic relationships between HIV sequences amplified from residual plasma viruses and CD4 T cells of five patients on long-term suppressive therapy were examined. Three of these patients stopped therapy voluntarily for three weeks, but only one of them demonstrated viral load rebound in plasma. In phylogenetic analyses, the residual plasma viruses were found to be distinct genetically from the majority of CD4 T cell-associated virus populations in 4 of 5 patients. The compartmental analyses revealed that in all patients, plasma- and CD4 T cell-derived viral sequences were compartmentalized separately. Interestingly, the plasma sequences obtained before and after HAART-off in two patients were produced apparently from the same compartment, which was different from the circulating CD4 T cell-compartment. These results suggest the possibility that residual plasma viruses in patients on long-term suppressive HAART may be produced persistently from a cellular source yet to be identified, and are capable of spreading quickly in vivo, accounting for the rapid rebound of viral loads in plasma after therapy interruption. PMID:19031450

Sahu, Gautam K.; Paar, David; Frost, Simon D. W.; Smith, Melissa M.; Weaver, Scott; Cloyd, Miles W.

2010-01-01

431

Space-resolved XUV spectra of CVI and BV lines from a 10 ps KrF laser-produced plasma  

SciTech Connect

We produced a plasma using highly focused {approx_equal}50 mJ, 10 ps pulses from a KrF laser on graphite and boron-carbide targets. We measured space-resolved (along the plasma axis) line profiles of Hydrogen-like and Helium-like Carbon and Boron resonance lines, using a crossed-slit, 1 m grazing-incidence spectrometer, with a spatial resolution {approx_equal}50 {mu}m. Synthetic spectra generated with the atomic postprocessor CRETIN provided preliminary estimates of the plasma electron temperature and density.

Iglesias, E. J.; Griem, H. R.; Elton, R. C. [Institute for Plasma Research, University of Maryland, College Park, Maryland 20742-3511 (United States); Scott, H. [Lawrence Livermore National Laboratory, P.O. Box 808, L-18, Livermore, California 94551 (United States)

1999-04-01

432

Numerical simulation of microwave amplification in a plasma channel produced in a gas via multiphoton ionisation by a femtosecond laser pulse  

NASA Astrophysics Data System (ADS)

This paper examines the evolution of a nonequilibrium plasma channel produced in xenon by a femtosecond KrF laser pulse. We demonstrate that such a channel can be used to amplify microwave pulses over times of the order of the relaxation time of the photoelectron energy spectrum in xenon. Using the slowly varying amplitude approximation, we analyse the propagation and amplification of an rf pulse in a plasma channel, in particular when the rf field influences the electron energy distribution function in the plasma.

Bogatskaya, A. V.; Volkova, E. A.; Popov, A. M.

2014-12-01

433

Ubiquitin initiates sorting of Golgi and plasma membrane proteins into the vacuolar degradation pathway  

PubMed Central

Background In yeast and mammals, many plasma membrane (PM) proteins destined for degradation are tagged with ubiquitin. These ubiquitinated proteins are internalized into clathrin-coated vesicles and are transported to early endosomal compartments. There, ubiquitinated proteins are sorted by the endosomal sorting complex required for transport (ESCRT) machinery into the intraluminal vesicles of multivesicular endosomes. Degradation of these proteins occurs after endosomes fuse with lysosomes/lytic vacuoles to release their content into the lumen. In plants, some PM proteins, which cycle between the PM and endosomal compartments, have been found to be ubiquitinated, but it is unclear whether ubiquitin is sufficient to mediate internalization and thus acts as a primary sorting signal for the endocytic pathway. To test whether plants use ubiquitin as a signal for the degradation of membrane proteins, we have translationally fused ubiquitin to different fluorescent reporters for the plasma membrane and analyzed their transport. Results Ubiquitin-tagged PM reporters localized to endosomes and to the lumen of the lytic vacuole in tobacco mesophyll protoplasts and in tobacco epidermal cells. The internalization of these reporters was significantly reduced if clathrin-mediated endocytosis was inhibited by the coexpression of a mutant of the clathrin heavy chain, the clathrin hub.?Surprisingly, a ubiquitin-tagged reporter for the Golgi was also transported into the lumen of the vacuole. Vacuolar delivery of the reporters was abolished upon inhibition of the ESCRT machinery, indicating that the vacuolar delivery of these reporters occurs via the endocytic transport route. Conclusions Ubiquitin acts as a sorting signal at different compartments in the endomembrane system to target membrane proteins into the vacuolar degradation pathway: If displayed at the PM, ubiquitin triggers internalization of PM reporters into the endocytic transport route, but it also mediates vacuolar delivery if displayed at the Golgi. In both cases, ubiquitin-tagged proteins travel via early endosomes and multivesicular bodies to the lytic vacuole. This suggests that vacuolar degradation of ubiquitinated proteins is not restricted to PM proteins but might also facilitate the turnover of membrane proteins in the early secretory pathway. PMID:22970698

2012-01-01

434

Laser-produced plasma x-ray diagnostics with an x-ray streak camera at the Iskra-4 plant  

NASA Astrophysics Data System (ADS)

An X.raj streak camera with an Xray streak tube used for laser-produced plasma soft Xrays measurement is described, and experimental results are given. In investigating short-Jived high temperature plasma, and inertial control of thermonuclear fusion in particular, measurement techniques based on registration of X-.rays emitted by the investigated object are of great value. They make it possible to get much information on the dynamics of plasma evolution, its form, dimensions, temperature, and density. The instrumentation used for these purposes must meet the following main requirements: it must provide measuring X-.rays time, intensity and spatial coordinate; its spectral range must be wide, from relatively hard to extremely soft X-rays (tens of keV to tens of eV quantum energy); its tiive resolution must be high (of the order of 10 s). At present the only type of an instrument satisfying the above requirements is a streak camera with an X-ray' streak tube (X'RST). The XRST operation principle has been known long ago: the photocathode converts the incident X-rays into an electron beam, which is accelerated and focused by the electric fields onto the output phosphor screen, where a visible image of the incident radiation cross-.section appears. The image travels very rapidly over the screen, resulting in a time sweep. The design and development of such kind of instrumentation was begun in our country more than 10 years ago. In 1986 the All-Union Research Institute of experimental Physics, in collaboration with the Research Institute of Pulse Technique, designed and built first instruments with satisfactory parameters. These instruments found use in laser thermonuclear fusion research. Mainly two types of X-.ray streak tubes are used for X-.ray spatial-temporal structure registration: special type X-ray streak tubes with X-ray sensitive photocathodes and transparent for X-ray input windows, and X-ray streak tubes with X-ray sensitive photocathodes and without an input win dow; these tubes are joined to a continuously pumped-out vacuum plant with an X-ray source inside it. The quantum energy lower limit of the registered X-rays depends on the input window thickness and. material, which determine its transparency for the radiation being investigated.

Berkovski, Arkadi G.; Gubanov, Yuri I.; Pryanishnikov, Ivan G.; Murugov, Vasili M.; Petrov, Sergej I.; Senik, Alexei V.

1991-04-01

435

The effect of shortening stability on commercially produced army ration biscuits. I. Initial data and results of accelerated stability tests  

Microsoft Academic Search

Summary  An experiment involving the commercial production and packaging of two types of Army ration biscuits prepared from common\\u000a ingredients with nine lots of vegetable oil shortening of increasing stability values and two lots of lard as the only ingredient\\u000a variables has been described, and the initial analytical data presented.\\u000a \\u000a Evaluation of accelerated stability tests on both shortenings and biscuit shows

L. W. Horne; H. H. Stevens; J. B. Thompson

1948-01-01

436

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

437

Some preliminary evaluations of black coating on aluminium AA2219 alloy produced by plasma electrolytic oxidation (PEO) process for space applications  

Microsoft Academic Search

This paper describes the results of a study of a black coating produced on aluminium AA2219 alloy using a process that involves creation of a hard ceramic oxide layer on the surface of the alloy by plasma electrolytic oxidation (PEO) known as the 'KERONITE®' process. Coating microstructure has been examined and the coating characteristics such as porosity, hardness, adhesion and

S. Shrestha; A. Merstallinger; D. Sickert; B. D. Dunn

2003-01-01

438

Patient-centered medical home initiative produced modest economic results for Veterans Health Administration, 2010-12.  

PubMed

In 2010 the Veterans Health Administration (VHA) began a nationwide initiative called Patient Aligned Care Teams (PACT) that reorganized care at all VHA primary care clinics in accordance with the patient-centered medical home model. We analyzed data for fiscal years 2003-12 to assess how trends in health care use and costs changed after the implementation of PACT. We found that PACT was associated with modest increases in primary care visits and with modest decreases in both hospitalizations for ambulatory care-sensitive conditions and outpatient visits with mental health specialists. We estimated that these changes avoided $596 million in costs, compared to the investment in PACT of $774 million, for a potential net loss of $178 million in the study period. Although PACT has not generated a positive return, it is still maturing, and trends in costs and use are favorable. Adopting patient-centered care does not appear to have been a major financial risk for the VHA. PMID:24889947

Hebert, Paul L; Liu, Chuan-Fen; Wong, Edwin S; Hernandez, Susan E; Batten, Adam; Lo, Sophie; Lemon, Jaclyn M; Conrad, Douglas A; Grembowski, David; Nelson, Karin; Fihn, Stephan D

2014-06-01

439

The use of neutral beam heating to produce high performance fusion plasmas, including the injection of tritium beams into the Joint European Torus (JET)  

SciTech Connect

The neutral beam injection (NBI) system of the Joint European Torus (JET) [[ital Plasma] [ital Physics] [ital and] [ital Controlled] [ital Nuclear] [ital Fusion] [ital Research] (International Atomic Energy Agency, Vienna, 1985), Vol. 1, p. 11] has proved to be an extremely effective and flexible heating method capable of producing high performance plasmas and performing a wide range of related physics experiments. High fusion performance deuterium plasmas have been obtained in the hot-ion (HI) H-mode regime, using the central particle fueling and ion heating capabilities of the NBI system in low target density plasmas, and in the pellet enhanced plasma (PEP) H-mode regime, where the good central confinement properties of pellet fueled plasmas are exploited by additional heating and fueling as well as the transition to H mode. The HI H-mode configuration was used for the First Tritium Experiment (FTE) in JET in which NBI was used to heat the plasma using 14 D[sup 0] beams and, for the first time, to inject T[sup 0] using the two remaining beams. These plasmas had a peak fusion power of 1.7 MW from deuterium--tritium (D--T) fusion reactions. The capability for injection of a variety of beam species (H[sup 0], D[sup 0], [sup 3]He[sup 0], and [sup 4]He[sup 0]) has allowed the study of confinement variation with atomic mass and the simulation of [alpha]-particle transport. Additionally, the use of the NBI system has permitted an investigation of the plasma behavior near the toroidal [beta] limit over a wide range of toroidal field strengths.

Thompson, E.; Stork, D.; de Esch, H.P.L. (JET Joint Undertaking, Abingdon, Oxon 0X14 3EA (United Kingdom)); the JET Team

1993-07-01

440

Experiments with Plasmas Produced by Potassium-Seeded Cyanogen Oxygen Flames for Study of Radio Transmission at Simulated Reentry Vehicle Plasma Conditions  

NASA Technical Reports Server (NTRS)

A method for the chemical production of an ionized gas stream for application to radio transmission studies is described. Involved is the combustion of gaseous cyanogen and oxygen with the addition of vaporized potassium in some cases to further increase the ionization. Experiments are described in which a 3-inch-diameter subsonic free jet at atmospheric pressure is used, and the results are presented. The plasma obtained by using this method is sufficient to simulate plasma conditions expected for reentering hypersonic vehicles. The unseeded plasma stream temperature is indicated to be about 4,200 K, with the degree of ionization indicated to be that expected from thermal equilibrium considerations. Measurements of radio-signal loss due to the unseeded flame plasma are presented for microwaves of 8 to 20 kmc transmitted through the stream and for a dipole transmitting model of 219.5 mc immersed in the stream. Favorable comparison of these results with the simple plane-wave signal-attenuation theory was obtained. In the case of a 9.4-kmc microwave signal of 30-kw peak power, the preliminary indication is that the plasma characteristics were not changed due to this strong signal. Comparison of a simplified concept of radio-signal attenuation due to plasmas is made with some hypersonic reentry vehicle signal-loss data. Other areas of plasma research using this method for the transmission problem are indicated.

Huber, Paul W.; Gooderum, Paul B.

1961-01-01

441

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

442

Analysis of laser-produced aerosols by inductively coupled plasma mass spectrometry: transport phenomena and elemental fractionation.  

PubMed

The transport phenomena of laser-produced aerosols prior to analysis by inductively coupled plasma mass spectrometry (ICPMS) were examined. Aerosol particles were visualized over the cross section of a transport tube attached to the outlet of a conventional ablation cell by light scattering using a pulsed laser source. Experiments were carried out under laminar or turbulent in-cell flow conditions applying throughputs of up to 2.0 L/min and reveal the nature of aerosol transportation to strongly depend on both flow rate and carrier gas chosen. For instance, laser ablation (LA) using laminar in-cell flow and helium as aerosol carrier resulted in stationary but inhomogeneous dispersion patterns. In addition, aerosols appear to be separated into two coexisting phases consisting of (i) dispersed particles that accumulate at the boundary layer of several vortex channel flows randomly arranged along the tube axis and (ii) larger fragments moving inside. The occurrence of these fragments was found to affect the accuracy of Si-, Zn-, and Cd-specific ICPMS analyses of aerosols released by LA of silicate glass (SRM NIST610). Accuracy drifts of more than 10% were observed for helium flow rates of >1 L/min, most probably, due to preferential evaporation and diffusion losses of volatile constituents inside the ICP. The utilization of turbulent in-cell flow made the vortex channels collapse and resulted in an almost complete aerosol homogenization. In contrast, LA using argon as aerosol carrier generally yielded a higher degree of dispersion, which was nearly independent of the flow conditions applied. To illustrate the differences among laminar and turbulent in-cell flow, furthermore, the velocity field inside the ablation cell was simulated by computational fluid dynamics. PMID:18205331

Koch, J; Wälle, M; Dietiker, R; Günther, D

2008-02-15

443

Controlling the length of plasma waveguide up to 5 mm, produced by femtosecond laser pulses in atomic clustered gas.  

PubMed

We report the observation of longitudinally uniform plasma waveguide with a controlled length of up to nearly 5 mm, in argon clustered gas jet. This self-channeling plasma is obtained using a 35 mJ, 30 fs FWHM pulse as a pump laser pulse to create the plasma channel. A 1 mJ pulse of the same laser is used for probing the plasma channels using interferometric diagnostics. The radial distribution of the electron density confirms the formation of a plasma waveguide. Clustered argon enhances the absorption efficiency of femtosecond pulses which enables the use of pump pulses of only 35 mJ, approximately 10 times less energy than required for heating conventional gas targets. The plasma channel length is controlled by the laser focus point (F), the laser intensity (I), the pump-probe delay time (t) and the laser height from a nozzle (z). The variation of the electron density for these parameters is also studied. We found that the highest density of 1.2 x 10(19) cm(-3) was obtained at I = 5.2 x 10(16) W/cm(2), z = 2 mm and t = 7.6 ns. It was demonstrated that by using a clustered jet, both the plasma waveguide length and the plasma density could be controlled. PMID:21934955

Mohamed, Walid Tawfik; Chen, Guanglong; Kim, Jaehoon; Tao, Geng Xiao; Ahn, Jungkwen; Kim, Dong Eon

2011-08-15

444

Laboratory modeling of pulsed regimes of electron cyclotron instabilities in a mirror confined plasma produced by ECR discharge  

Microsoft Academic Search

We demonstrate the use of a laboratory setup based on a magnetic mirror trap with plasma sustained by a gyrotron radiation under the electron cyclotron resonance (ECR) conditions for investigation of the cyclotron instabilities similar to the ones which take place in space plasmas. Three regimes of the cyclotron instability are studied. The first regime is related to quasi-periodic pulsed

Sergey Golubev; Dmitry Mansfeld; Alexander Vodopyanov; Andrei Demekhov; Alexander Shalashov

2010-01-01

445

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

446

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

E-print Network

-jet target. Computer simulations show that laser-heated electrons launch a collisionless shock that overtakes. Simulations predict the production of 200 MeV protons needed for radiotherapy by using current laser plasmas. The study of acceleration by shock waves is also important in astrophysical and space plasmas10

Loss, Daniel

447

IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 34, NO. 6, DECEMBER 2006 2637 Experimental Study of Laser-Initiated  

E-print Network

heating. Broadband plasma emission spectroscopy is used to illustrate the changes in the ionized species pressure, interferometry, plasma, radiofrequency (RF). I. INTRODUCTION HIGH-PRESSURE inductively coupledIEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 34, NO. 6, DECEMBER 2006 2637 Experimental Study of Laser

Scharer, John E.

448

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

NASA Astrophysics Data System (ADS)

Previous experimentsootnotetextJ. Oh, et al, GO5.4, APS DPP (2010) with Nike KrF laser (?=248nm, ??˜1THz) observed LPI signatures near quarter critical density (nc/4) in CH plasmas, however, detailed measurement of the temperature (Te) and density (ne) profiles was missing. The current Nike LPI campaign will perform experimental determination of the plasma profiles. A side-on grid imaging refractometer (GIR)ootnotetextR. S. Craxton, et al, Phys. Fluids B 5, 4419 (1993) is the main diagnostic to resolve Te and ne in space taking 2D snapshots of probe laser (?=266 nm, ?t=8psec) beamlets (50?m spacing) refracted by the plasma at laser peak time. Ray tracing of the beamlets through hydrodynamically simulated (FASTRAD3D) plasma profiles estimates the refrac