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1

HEIGHTS initial simulation of discharge produced plasma hydrodynamics and radiation transport for extreme ultraviolet lithography  

Microsoft Academic Search

Discharge-produced plasma (DPP) devices have been pro- posed as a light source for EUV lithography. A key challenge for DPP is achieving sufficient brightness to support the throughput requirements of exposure tools for high-volume manufacturing lithography. To simulate the environment of the EUV source and optimize the output of the source, an integrated model is being developed to describe the

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

2004-01-01

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

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

PubMed

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

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

2013-01-01

4

Tomographic Investigation of Plasma Jets Produced by Multielectrode Plasma Torches  

Microsoft Academic Search

Recent advances in the development of new plasma torches rely on the use of multiple electrodes to improve plasma jet stability.\\u000a Examples are the Triplex, employing three cathodes and a single anode, and the Delta, which uses three anodes with a single\\u000a common cathode. To characterize the plasma jet produced by these plasma torches, initial experiments have been performed using

J. Schein; M. Richter; K. D. Landes; G. Forster; J. Zierhut; M. Dzulko

2008-01-01

5

Tomographic Investigation of Plasma Jets Produced by Multielectrode Plasma Torches  

NASA Astrophysics Data System (ADS)

Recent advances in the development of new plasma torches rely on the use of multiple electrodes to improve plasma jet stability. Examples are the Triplex, employing three cathodes and a single anode, and the Delta, which uses three anodes with a single common cathode. To characterize the plasma jet produced by these plasma torches, initial experiments have been performed using tomography in the visible range. Due to the improved stability of the plasma jet in the multielectrode configuration it is possible to carry out tomography by means of a regular charge-coupled device (CCD) camera, which is rotated around the plasma jet axis. The two-dimensional information obtained by the CCD camera is subsequently processed to produce an image of the three-dimensional emission distribution. The tomographic analysis is mated with a simple but effective simulation tool, which can be used as a basis for parameter-dependent multielectrode plasma torch design.

Schein, J.; Richter, M.; Landes, K. D.; Forster, G.; Zierhut, J.; Dzulko, M.

2008-09-01

6

Plasma Properties of Microwave Produced Plasma in a Toroidal Device  

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

7

Laser initiated, RF sustained air plasmas  

NASA Astrophysics Data System (ADS)

Measurements and analysis of air breakdown processes and plasma production by focusing 193 nm, 260 mJ, 10 MW high power laser radiation inside a 6 cm diameter helical RF coil. We observe quantum resonant multi-photon (REMPI)2 and collisional cascade laser ionization processes that produce high density (ne7 x 1016/cm^3) cylindrical seed plasmas at 760 Torr. The focused laser and associated shock wave produces a seed plasma for sustaining by the RF (1-10 kW, 0.5-1.5 s) pulse. Measurements of the helical RF antenna load impedance obtained by measuring the reflection coefficient with and without the laser pulse and 105 mm wave interferometer density and temperature measurements are made. They demonstrate that the laser formed seed plasma allows RF sustainment at higher initial air pressures (15-30 Torr) than with RF only initiation. Spectroscopic measurements of the plasma and comparison with the SPECAIR code are made to determine rotational and vibrational temperatures. Comparison of the experimental measurements of helical antenna plasma loading with the ANTENAII code will be made and discussed.

Giar, Ryan; Scharer, John; Wiebold, Matt

2010-11-01

8

Impulsive Plasma Produced by a Coaxial Plasma Gun  

Microsoft Academic Search

This paper is concerned with an impulsive plasma mass produced by a coaxial plasma gun. According to spectroscopic observation the following results have been obtained. When the plasma is produced with an oscillatory current, the gun ejects more than two plasma masses successively. Except the first one they consist mainly of impurities. Spectral lines from helium are recognized only in

Katsumi Hirano; Juichi Irisawa; Yoshiei Nakano

1969-01-01

9

Gas lens laser produced plasma.  

PubMed

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

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

1989-07-01

10

Impurity Content of Plasma Produced by a Coaxial Plasma Gun  

Microsoft Academic Search

The impurity content of plasmas produced by a coaxial plasma gun, while ; low, has generally been estimated by measurements of qualitative nature. Since ; impurities constitute the primary source of radiation loss and cooling, a study ; was made to explore this plasma property. (R.E.U.);

Harold P. Eubank

1963-01-01

11

Laser Initiation and Radiofrequency Sustainment of Seeded Air Plasmas  

NASA Astrophysics Data System (ADS)

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 the density and temperature decay with TMAE mixed with nitrogen is presented. Simulations of antenna coupling, wave frequencies, wave propagation, and power absorption are compared with experimental observations for radiofrequency plasma sources. The source produces plasma densities of 2 10^13/cm^3in an 8500 cm^3 volume at electron temperatures of 5 eV in 10 mTorr Ar in a nonuniform magnetic field. Radiofrequency plasma production at pressures from 2-760 Torr using Ar and laser initiated TMAE plasmas as seeds will be discussed.

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

1999-11-01

12

APPARATUS FOR PRODUCING AND MANIPULATING PLASMAS  

DOEpatents

An electrical pinch discharge apparatus is described for producing and manipulating high-temperature plasmas. The apparatus may be of either the linear or toroidal pinch discharge type. Arrangements are provided whereby stabilizing fields may be trapped in the plasma external to the main pinch discharge path and the boundary condition of the stabilizing field programed so as to stabilize the discharge or to promote instabilities in the discharge as desired. The produced plasmas may be employed for various purposes, and fusion neutrons have been produced with the apparatus.

Colgate, S.A.; Ferguson, J.P.; Furth, H.P.; Wright, R.E.

1960-07-26

13

High beta plasma operation in a toroidal plasma producing device  

DOEpatents

A high beta plasma is produced in a plasma producing device of toroidal configuration by ohmic heating and auxiliary heating. The plasma pressure is continuously monitored and used in a control system to program the current in the poloidal field windings. Throughout the heating process, magnetic flux is conserved inside the plasma and the distortion of the flux surfaces drives a current in the plasma. As a consequence, the total current increases and the poloidal field windings are driven with an equal and opposing increasing current. The spatial distribution of the current in the poloidal field windings is determined by the plasma pressure. Plasma equilibrium is maintained thereby, and high temperature, high beta operation results.

Clarke, John F. (Oak Ridge, TN)

1978-01-01

14

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.

15

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

16

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

17

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

18

Laser Initiation and Radiofrequency Sustainment of Seeded Air Plasmas  

NASA Astrophysics Data System (ADS)

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 optical emission data illustrating the density and temperature decay with TMAE mixed with nitrogen is presented showing the existence of superexcited seed gas states which reduce the effective recombination rate. Simulations of antenna coupling, wave frequencies, wave propagation, and power absorption are compared with experimental observations for radiofrequency plasma sources. The source produces plasma densities of 2 x 1013/cm3 in an 8500 cm cm3 volume at electron temperatures of 5 eV in 10 mTorr Ar in a nonuniform magnetic field. Radiofrequency plasma sustainment at pressures from 2-760 Torr using Ar and laser initiated TMAE plasmas as seeds will be discussed.

Kelly, K.; Scharer, J.; Cao, R.; Ding, G.; Paller, E.

2000-10-01

19

Laser initiated, RF sustained air plasmas  

Microsoft Academic Search

Summary form only given. Measurements and analysis of air breakdown processes by focusing a 193 nm, 200 mJ, 10 MW high power UV laser radiation to 20-60 m spot sizes that produce maximum laser intensities of 1012-1013 W\\/cm2 are presented. Both classical quantum (multi-photon) and (collisional cascade) ionization processes affect the breakdown and plasma formation. Observations are made for a

Ryan Giar; Jason Hummelt; J. Scharer

2009-01-01

20

Coronal hydrodynamics of laser-produced plasmas.  

PubMed

We present the results of an experimental investigation of the temporal evolution of plasmas produced by high power laser irradiation of various types of target materials (at intensities I(L) < or = 10(14) W/cm2). We obtained interferometric data on the evolution of the plasma profile, which can directly be compared to analytical models and numerical simulations. For aluminum and plastic targets, the agreement with 1D simulations done with the hydrocode MULTI is excellent, at least for large times (t > or = 400 ps) . In this case, simulations also show that the effect of radiation transport is negligible. The situation is quite different for gold targets for which, in order to get a fair agreement, radiation transport must be taken into account. PMID:18999540

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

2008-10-27

21

Molybdenum disilicide composites produced by plasma spraying  

SciTech Connect

The intermetallic compound, molybdenum disilicide (MoSi{sub 2}) is being considered for high temperature structural applications because of its high melting point and superior oxidation resistance at elevated temperatures. The lack of high temperature strength, creep resistance and low temperature ductility has hindered its progress for structural applications. Plasma spraying of coatings and structural components of MoSi{sub 2}-based composites offers an exciting processing alternative to conventional powder processing methods due to superior flexibility and the ability to tailor properties. Laminate, discontinuous and in situ reinforced composites have been produced with secondary reinforcements of Ta, Al{sub 2}O{sub 3}, SiC, Si{sub 3}N{sub 4} and Mo{sub 5}Si{sub 3}. Laminate composites, in particular, have been shown to improve the damage tolerance of MoSi{sub 2} during high temperature melting operations. A review of research which as been performed at Los Alamos National Laboratory on plasma spraying of MoSi{sub 2}-based composites to improve low temperature fracture toughness, thermal shock resistance, high temperature strength and creep resistance will be discussed.

Castro, R.G.; Hollis, K.J.; Kung, H.H.; Bartlett, A.H.

1998-05-25

22

Laser produced plasma for efficient extreme ultraviolet light sources  

NASA Astrophysics Data System (ADS)

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 CO2 laser irradiation of a bulk Sn target. A maximum conversion efficiency of 1.7% has been measured and the influence of the CO2 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 Gd2O3 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

2012-05-01

23

Measurements of plasma bremsstrahlung and plasma energy density produced by electron cyclotron resonance ion source plasmas  

NASA Astrophysics Data System (ADS)

The goal of this dissertation was to gain an understanding on the relative importance of microwave power, neutral pressure, and magnetic field configuration on the behavior of the hot electrons within an Electron Cyclotron Resonance Ion Source (ECRIS) plasma. This was carried out through measurement of plasma bremsstrahlung with both NaI(Tl) (hv > 30 keV) and CdTe (2 keV < hv < 70 keV) x-ray detectors, and through measurement of the plasma energy density with a diamagnetic loop placed around the plasma chamber. We also examined the anisotropy in x-ray power by simultaneously measuring the x-ray spectra in two orthogonal directions: radially and axially, using NaI(Tl) detectors. We have seen that for a 6.4 GHz ECRIS, both the x-ray power produced by confined electrons and the plasma energy density behave logarithmically with microwave power. The x-ray flux created by electrons lost from the plasma, however, does not saturate. Thus, the small increase in plasma density that occurred at high microwave powers (> 150 W on a 6.4 GHz ECRIS) was accompanied by a large increase in total x-ray power. We suggest that the saturation of x-ray power and plasma energy density was due to rf-induced pitch-angle scattering of the electrons. X-ray power and plasma energy density were also shown to saturate with neutral pressure, and to increase nearly linearly as the gradient of the magnetic field in the resonance zone was decreased. All of these findings were in agreement with the theoretical models describing ECRIS plasmas. We have discussed the use of a diamagnetic loop as a means of exploring various plasma time scales on a relative basis. Specifically, we focused much of our attention on studying how changing ion source parameters, such as microwave power and neutral pressure, would effect the rise and decay of the integrated diamagnetic signal, which can be related to plasma energy density. We showed that increasing microwave power lowers the e-fold times at both the leading edge and the trailing edge of the microwave pulse. Microwave power, however, had almost no impact on the ignition times of the plasma. The plasma energy density e-fold times were insensitive to both neutral pressure and magnetic field setting. Neutral pressure, however, had a dramatic effect on the time of first appearance of the diamagnetic signal ("plasma ignition time"). In addition to neutral pressure, ignition times were also a function the relative abundance of electrons in the plasma chamber at the beginning of a microwave pulse. In all instances, the rise time of the integrated diamagnetic signal was seen to be faster than the decay time. By comparing the unintegrated diamagnetic signal to the ratio of reflected to forward microwave power we theorized that the initial, exponential rise in the diamagnetic signal at the leading edge of a microwave pulse was due to rapid changes in both the average electron energy and density. During the slowly decaying portion of the diamagnetic loop signal, only the hot tail of the electron population was increasing. This theory was supported by time resolved, low energy x-ray measurements that showed that the period of rapid change of the ratio of reflected to forward microwave power coincided with a rapid change in average photon energy. We have also showed that x-rays production in an ECRIS plasma was highly anisotropic, with radial x-ray counts being much greater than axial x-ray counts. This was shown to be true for both the "ECR" (operating at 6.4 GHz) and the higher performance "AECR-U" (operating at 14 GHz). Based on this, we can make the qualitative statement that the electron energy was also highly anisotropic, with a much larger perpendicular energy than parallel energy. The degree of anisotropy was shown to increase with the operating frequency of the ion source. This increase was most likely attributable to the higher power density and greater confinement associated with higher performance machines, and implies that superconducting ECRIS operating at very high freq

Noland, Jonathan David

24

Radiative preheat in laser produced aluminum plasma  

SciTech Connect

The preheat of the cold substrate by the x-rays generated in the coronal region of a laser produced aluminum plasma was calculated for a trapezoidal laser pulse in the intensity range I = 10/sup 13/--8 x 10/sup 14/ W/cm/sup 2/. The computer code incorporates nonlocal thermodynamic equilibrium (non-LTE) radiation emission rates in the hot region and photoionization as the main photoabsorbing process in the cold compressed region. The temperature and the density variations of the photoionization cross section were accounted for. Black-body radiation diffusion was also included. The results indicate the formation of a well-defined radiation heated zone in the back portion (close to the ablation surface) of the shock wave. Comparisons were made on the effects of the x-ray radiation and the black-body diffusion on the shock wave propagation. The similarities and differences between x-ray and fast electron preheat are also discussed. In a different set of computations an attempt was made to simulate the measurements of McLean et al. (Phys. Rev. Lett. 45, 1246 (1980)) of the backsurface temperature of laser irradiated aluminum foils. The computational results agree favorably with those of the experiments.

Salzmann, D.; Szichman, H.; Krumbein, A.D.; Capjack, C.E.

1987-02-01

25

METHOD OF INITIATING AND SUSTAINING AN ENERGETIC PLASMA FOR NEUTRON PRODUCTION  

DOEpatents

A method for producing an energetic plasma for neutron production and for faeling this plasma once it is formed is described. The plasma is initially fonmed as set forth in U. S. Patent No. 2,969,308. After the plasma is formed, cold neutral particles with an energy of at least 1 Kev are injected in a radial directinn and transverse to the axis of the device. These cold particles are substituted for the molecular ion injection and are used for fueling the plasma device on a continuous regulated basis in order to maintain a reaction temperature of about 60 Kev for producing neutrons. (AE C)

Bell, P.R.; Mackin, R.J. Jr.; Simon, A.

1961-08-22

26

Mesoscopic Plasma Modes Producing Magnetic Reconnection  

Microsoft Academic Search

Magnetic reconnection processes in collisionless regimes are shown to be difficult to excite in well confined plasmas and, when excited, they possess rather weak characteristics in that they depend on the physics of \\

B. Coppi; P. Detragiache

1993-01-01

27

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

28

Oxide cathodes produced by plasma deposition  

Microsoft Academic Search

Summary form only given. The best oxide cathodes have been capable of long life and high-current-density. The problem has been the ability to consistently reach maximum performance. The complex chemistry of the deposition and activation process have made consistent performance unrealizable. SLAC, UCD, and LBL are developing a plasma deposition process that eliminates the problems with binders, carbonate reduction, peeling,

G. Scheitrum; G. Caryotakis; T. Pi; R. Umstattd; I. Brown; O. Montiero

1997-01-01

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

Ion Emission and Expansion in Laser-Produced Tin Plasma  

NASA Astrophysics Data System (ADS)

Laser produced Sn plasma, in its role as an efficient extreme ultraviolet (EUV) x-ray source, is being studied extensively in support of next generation manufacturing of integrated circuits by nanolithography. The ability to diagnose and manipulate the properties of ions emitted from the laser produced plasma (LPP) must be achieved in order for the technology to meet stringent performance requirements. Here we study the emission and expansion of ions from Sn LPP, in parameter space relevant to the EUV x-ray source application. Several particle and radiation plasma diagnostics, in addition to analytical and numerical analysis, are all used to elucidate the complex relationships between the target properties, irradiation conditions, and resultant plasma and ion properties. Two specific laser systems of current interest to the application, at wavelengths of 1.064mum and 10.6mum, are both utilized, which allows for direct comparisons of the effects of laser wavelength on ion properties. Details of the available experimental apparatus, including the Nd:YAG and CO2 laser systems, are discussed first. Following, the design and realization of a custom charged particle plasma diagnostic, hereafter referred to as the ion probe, is described. The successful development of the ion probe enabled measurements of the energy distribution for each charge state of each ion species in expanding plasma, which is a new diagnostic capability. Measurements of mass ablation from Sn plasma produced by a 1.064mum laser are discussed next, specifically the scaling of mass ablation rate with laser intensity. These measurements are useful in the design of mass-limited targets, and also are used to infer mechanisms of laser energy absorption and heat conduction within the plasma. In addition to the ion probe, an EUV spectrometer and a calibrated EUV calorimeter were both utilized as diagnostics to measure the mass ablation rate by complementary methods. Laser intensity was scanned from 3x1011W/cm2 to 2x10 12W/cm2, encompassing parameter space of the EUV x-ray source application to the low end of parameter space of the laser fusion application. Accordingly, previous theoretical results relevant to the laser fusion application can be applied in the data analysis. Experiments at two different laser wavelengths to extensively study the dynamics of ion expansion into vacuum are discussed next. In one set of experiments, the ion probe was used to measure energy distributions for all charge states of Sn ions at laser intensities of 3x1011W/cm 2 and 2x1010W/cm2, from 1.064mum and 10.6mum lasers, respectively. At the longer laser wavelength, higher charge state ions are observed. At both laser wavelengths, the peak ion energies increase approximately linearly as a function of charge state, and all ion energies greatly exceed the initial thermal electron temperature. In a second set of experiments, the distance from the target surface over which the charge state distribution evolves in vacuum is investigated. A Faraday cup translated along the path of plasma expansion is utilized in these measurements. It was found that at the longer laser wavelength, the charge state distribution is decaying to lower charge states over distances up to hundreds of millimeters from the target surface, whereas at the shorter laser wavelength the charge state distribution reaches a frozen-in state within a few tens of millimeters from the target surface. These experimental results are used to infer mechanisms of ion acceleration and recombination in the expanding plasma. In the last section, analytical models of ion expansion into vacuum relevant to the experimental results are first discussed. More detailed analyses are then carried out through numerical simulations. First, a zero-dimensional code following the time evolution of plasma temperature and the population of each ion species is discussed and used to verify some qualitative features observed in the experiments. A more complex one-dimensional Lagrangian hydrodynamics code utilizing the zero-dimensional code as one step

Burdt, Russell Allen

31

Pulse erosion plasma injector for discharge initiating in electric arc generator of plasma  

Microsoft Academic Search

Pulse plasma injector (plasmatron) with power supply system, intended for arcs burning initiation in powerful plasma generators, and also for independent application in physical experiments, connected with obtaining dense plasma, and some branches of industrial technology, is described. Injector construction, physical processes taking place in the pulse discharge chamber, injected plasmoid velocity dependence on the pressure, current value and the

P. G. Rutberg; A. A. Safronov

1995-01-01

32

Centrifugal mass separation in rotating plasmas produced by a coaxial plasma gun  

Microsoft Academic Search

Rotating Cu\\/Zn plasmas produced by a coaxial plasma gun have been applied to plasma centrifuge. A separation factor of up to 10 is measured over a radius of 4 cm when a current of 13 kA and an axial magnetic field of 2.5 kG are applied. Plasma parameters are: rotation frequency ?=1.1106 rad\\/s, density n?1015 cm?3, and ion temperature Ti=10

T. Ikehata; M. Suzuki; T. Tanabe; H. Mase

1989-01-01

33

Producing titanium aluminide foil from plasma-sprayed preforms  

NASA Astrophysics Data System (ADS)

High-strength titanium alloy and titanium aluminide foils are required for fabricating composite structures and honeycombs for advanced aircraft engines and airframes. Titanium aluminide alloys possess limited workability, which results in significant yield loss when these materials are produced by the conventional ingot metallurgy route. This article describes the use of induction plasma spray technology to fabricate foil preforms of a titanium alloy and a titanium aluminide. These plasma-sprayed preforms were converted into 100% dense wrought titanium aluminide foil by a roll-consolidation process. The microstructure and mechanical properties of titanium aluminide foil produced from plasma-sprayed preforms were virtually identical to those of conventional ingot metallurgy foil. The plasma-spray plus roll-consolidation route may lead to the production of titanium aluminide foil as continuous coil, which would improve process efficiency and yield high-quality titanium aluminide foil at low cost.

Jha, Sunil C.; Forster, James A.

1993-07-01

34

Alternative analysis of CO2-laser-produced plasma waves  

NASA Astrophysics Data System (ADS)

McIntosh has carried out experiments in which electron plasma waves produced in a gas jet target by a CO2 laser pulse were studied by picosecond-resolution Thomson scattering of a ruby laser pulse. In addition, spectra of the scattered laser light and of the fast electron were obtained. Their analysis of the data was based on the assumption that the plasma waves are created by onset of the stimulated Raman scattering instability. This led to a number of difficulties in the interpretation of the data. We show here that an alternative model of the origin of these plasma waves used previously in analyzing Raman data in several other experiments, removes all these difficulties and is in agreement with the data. In this model, the plasma waves are produced by pulses of fast electrons arising at the quarter-critical surface.

Simon, A.; Short, R. W.

1988-02-01

35

Measurement of Heat Propagation in a Laser Produced Plasma  

SciTech Connect

We present the observation of a nonlocal heat wave by measuring spatially and temporally resolved electron temperature profiles in a laser produced nitrogen plasma. Absolutely calibrated measurements have been performed by resolving the ion-acoustic wave spectra across the plasma volume with Thomson scattering. We find that the experimental electron temperature profiles disagree with flux-limited models, but are consistent with transport models that account for the nonlocal effects in heat conduction by fast electrons.

Gregori, G; Glenzer, S H; Knight, J; Niemann, C; Price, D; Froula, D H; Edwards, J; Town, R P J; Brantov, A; Bychenkov, V Y; Rozmus, W

2003-08-22

36

A Experimental Study of Magnetized Laser-Produced Plasmas  

Microsoft Academic Search

The flow of a laser-produced barium plasma across a uniform, transverse magnetic field was studied, both in vacuum and in the presence of low-pressure photoionized xenon. The purpose was to investigate the mechanisms leading to cross-field flow in the case where magnetic pressure B('2)\\/8(pi) exceeds plasma kinetic pressure N(,i)m(,i)U('2), and to determine how this flow is modified by magnetically induced

Gerard Paul Jellison

1981-01-01

37

Velocity distribution of the yttrium atoms in laser produced plasma  

Microsoft Academic Search

We have investigated the velocity distribution functions of atoms in laser produced plasma. In our experiments plasma is cheated during the laser sputtering of YBa2Cu3O7-x ceramics target. We used KrF excimer laser for target sputtering. All sputtering conditions that were the same as usual for high Tc films deposition are used. We used time-of-flight method to investigate the velocity distribution

Alexander N. Zherikhin; Oleg V. Boyarkin; Vladimir N. Burimov; Vladimir S. Golubev; Valerie L. Popkov

1994-01-01

38

Time evolution of plasma afterglow produced by femtosecond laser pulses  

SciTech Connect

In this paper we investigate the time evolution of laser plasmas generated in atmospheric air by ultrashort (100 fs) laser pulses. The detected quantity is the time integrated photon yield emitted by the plasma, which monotonically depends on the amount of energy transferred by the laser pulses to the plasma. We study the effect of a preionizing pulse on the efficiency of plasma generation by a second 'probe' pulse and demonstrate that preionization results into a considerable increase of the overall photon yield emitted by the plasma. An explanation of this phenomenon relies on the fact that the larger the electron density experienced by the probe pulse, the more effective the energy transfer from the probe pulse to the residual plasma, the more intense is the light from the plasma. With this concept in mind and by relying on a pump-probe technique, we also measure the total photon yield emitted by the plasma produced by the combination of the two pulses, as a function of their relative delay time. We observe a considerable increase in the plasma brightness for delay times much longer than the laser pulse duration. This phenomenon is associated with an increase of the electron density even after the end of the pump pulse, due to secondary electron-impact ionization originating from highly-energetic primary photoelectrons, and to superelastic electron-molecule collisions. We also develop a simplified model describing the time evolution of the electron and ion densities and the electron temperature. From the calculated time evolution of these quantities produced by a single laser pulse, we can predict with a good approximation the main features of the plasma generated by an ultrashort laser pulse.

Martirosyan, A.E.; Altucci, C.; Bruno, A.; De Lisio, C.; Porzio, A.; Solimeno, S. [Institute for Physical Research, Armenian Academy of Sciences, Ashtarak, Armenia and Dipartimento di Scienze Fisiche, Universita di Napoli 'Federico II', Naples (Italy); Centro di Ricerca e Sviluppo 'Coherentia', Istituto Nazionale per la Fisica della Materia, Unita di Ricerca di Napoli, Naples (Italy); Dipartimento di Scienze Fisiche, Universita di Napoli 'Federico II', Complesso di Monte S. Angelo, Via Cintia, 80126 Naples (Italy)

2004-11-15

39

Measurements of Asymmetric Magnetic Reconnection in Laser-Produced Plasmas  

NASA Astrophysics Data System (ADS)

Magnetic topology changes due to reconnection of magnetic fields is of interest both in the context of basic plasma physics and in inertial confinement fusion (ICF), where laser-generated magnetic fields can affect energy transport in hohlraums and in ICF implosions. Face-on, monoenergetic proton radiography has been used to image and measure reconnection of MG magnetic fields in colliding laser-produced plasma bubbles. The timing of the interaction beams with respect to each other and to the backlighter was varied to provide snapshots of both symmetric and asymmetric reconnection at different stages in the plasma bubble evolution and between bubbles of different size and magnetic field strength. While symmetric reconnection produces near complete cancellation of the interacting magnetic fields, the asymmetric case produces only partial field cancellation. The results are presented and compared to 2-D PIC simulations. This work was performed at the LLE NLUF and was supported in part by SNL, DOE, LLE and LLNL.

Rosenberg, M.; Li, C.; Seguin, F.; Frenje, J.; Manuel, M.; Zylstra, A.; Petrasso, R.; Stoeckl, C.; Glebov, V.; Fox, W.; Nikroo, A.

2012-10-01

40

Initial stages of plasma electrolytic oxidation of titanium  

Microsoft Academic Search

The initial stages of oxide growth on titanium are examined in a recently developed commercial alkaline pyrophosphate\\/aluminate electrolyte of interest for plasma electrolytic oxidation of light metal alloys. Constant current anodizing was employed, with resultant films examined by scanning and transmission electron microscopies and Rutherford backscattering spectroscopy. The initial film is relatively uniform and composed of TiO2, with low concentrations

T. H Teh; A Berkani; S Mato; P Skeldon; G. E Thompson; H Habazaki; K Shimizu

2003-01-01

41

Studies on Fundamental Technologies for Producing Tokamak-Plasma.  

National Technical Information Service (NTIS)

The report describes studies on fundamental technologies to produce tokamak-plasma of the JFT-2 and JFT-2M tokamaks. (1) In order to measure the particle number of residual gases, calibration methods of vacuum gauges have been developed. (2) Devices for a...

Y. Matsuzaki

1987-01-01

42

Effect of transverse magnetic field on laser produced plasma expansion into vacuum  

SciTech Connect

A one-dimensional time-dependent magneto-hydrodynamic ideal model is used to investigate the dynamics of initially magnetized laser produced plasma expansion into vacuum, in the context of inertial fusion. The plasma is assumed to be fully ionized and in local thermodynamic equilibrium (LTE), allowing all charged particles to have the same temperatures. Self-similar solution shows that the density, velocity, and temperature increase with the strength of the magnetic field. The transverse magnetic field causes significant changes in the plasma expansion dynamics, including the plasma confinement. The plasma velocity increasing is also observed and the temperature is found to be larger compared to temperature in un-magnetized case.

Bennaceur-Doumaz, D.; Djebli, M. [Centre de Developpement des Technologies Avancees, B.P. 17 Baba Hassen, 16303 Algiers (Algeria)

2011-08-15

43

RESEARCH NOTE: RF power absorption of a plasma produced by a coaxial plasma gun  

Microsoft Academic Search

The RF heating of a plasma produced by a coaxial plasma gun is studied. The resonance absorptions at ?=?ce and ?=?ce\\/2 are observed, where ?ce is the electron cyclotron frequency. In the frequency range where ?

Masataka Masuda; Yuji Tanaka; Takayoshi Okuda

1972-01-01

44

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

Code of Federal Regulations, 2013 CFR

...Initial nomination and appointment of producer members and alternates. 1219.31...Initial nomination and appointment of producer members and alternates. (a) The Association will nominate producer members and alternates to serve...

2013-01-01

45

Microwave Produced Plasma Study in a Cylindrical System  

SciTech Connect

Hydrogen plasma using electron cyclotron resonance (ECR) technique is produced and is studied in a small linear system for breakdown parameters. Microwave power in the experimental system is delivered by a magnetron at 2.45 GHz for 30 ms during which the breakdown of neutral gas occurs. The axial magnetic field required for ECR in the system is such that the fundamental ECR surface (B = 875 G) resides at the geometrical centre of the plasma system. ECR breakdown parameters such as plasma delay and plasma decay time are observed from plasma density measurements, carried out at the centre of plasma system using a specially designed Langmuir probe. The operating parameters such as working gas pressure (10{sup -5}-10{sup -2} mbar) and input microwave power (160-800 W) are varied and the corresponding effect on the breakdown parameters is observed and the parameter space for operating the pulsed experimental system has been identified. All the relevant experimental results obtained are presented.

Yadav, V. K. [Centre for Space Physics, 43 Chalantika, Garia Station Road, Kolkata 700084, West Bengal (India); Sathyanarayana, K.; Bora, D. [Institute for Plasma Research, Bhat, NearIindira Bridge, Gandhinagar 382428, Gujarat (India)

2008-03-19

46

Producing Generalized Job Initiative in Severely Mentally Retarded Sheltered Workers.  

ERIC Educational Resources Information Center

|Development of generalized job initiative skills was examined with three severely retarded adult males through discrimination training, role play, and self-monitoring interventions. Although intensive training was required to establish an initial set of generalized job initiative responses, subsequent sets of responses were rapidly learned using

McCuller, Glen L.; And Others

1987-01-01

47

Burning Plasma Simulation Initiative and Its Recent Progress  

NASA Astrophysics Data System (ADS)

The purpose and recent progress of the Burning Plasma Simulation Initiative (BPSI) are discussed. Simulation of burning plasmas requires integrated modeling of various physics phenomena with wide-ranging spatial and time scales. The activities of the BPSI are of three types: development of the framework for integrated simulation codes, development of integrated modeling of multi-scale physics, and implementation of distributed parallel processing. Similar activities have been reported in the United States and the European Union. Features of the integrated transport code, TASK, being developed as a reference code for BPSI, are also described. Finally, asummary is given and future issues are discussed.

Fukuyama, Atsushi; Yagi, Masatoshi

48

Dynamics of colliding aluminium plasmas produced by laser ablation  

NASA Astrophysics Data System (ADS)

The collision of two aluminium plasmas was investigated by combining both time and space resolved spectroscopy and Langmuir probe measurements. Plasma plumes were produced by a Continuum Surelite Nd:YAG Laser System with pulse duration of FWHM of 6 ns and wavelength of 1064 nm, at a laser irradiance of 1011 W/cm2 on slab Al targets. By analyzing the emission spectra, the temporally and spatially resolved electron density and electron temperature at the stagnation layer were extracted, with a time resolution of 10 ns. Data analysis confirms that the electron density of the stagnation layer evolves over a longer timescale than in the single plume case. On the other hand, the temperature trends show that the electron temperature decreases much more rapidly at the stagnation layer than in the case for the single expanding plasma. In addition, a Langmuir probe was used to investigate the properties of the collisional front evolution. The overall experimental results show that colliding laser produced plasmas could be useful in the design of experiments devoted to fusion reaction rate measurements in a low energy domain by including the effect of the electron screening (ES).

Gambino, N.; Hayden, P.; Mascali, D.; Costello, J.; Fallon, C.; Hough, P.; Yeates, P.; Anzalone, A.; Musumeci, F.; Tudisco, S.

2013-05-01

49

[Soft X-ray reflectometer with laser produced plasma source].  

PubMed

A soft X-ray reflectometor with laser-produced plasma source developed in the authorial lab is presented for the measurements of efficiencies of gratings, transmission of filter and reflectance of multilayer coatings. The reflectometer is composed of a soft X-ray laser-produced plasma source, a grazing incidence monochromator with a constant deviation angle, a vacuum chamber, a sample table, a photo-electronic unit and a computer controlling unit. The working wavelength is from 8 to 30 nm and the maximum sample size is 130 mm long by 120 mm wide by 120 mm high. In order to test the performances of the reflectometer, the reflectivity of multilayer coatings was obtained by using this device. The measured results agree well with the theoretical calculation. The reproducibility of measured reflectance is +/-0.6%. PMID:16013331

Chen, Bo; Ni, Qi-liang; Cao, Ji-hong

2005-03-01

50

Non-equilibrium Ta plasmas produced by fast pulsed lasers  

Microsoft Academic Search

A Nd:YAG laser, 9ns pulse width, 30Hz repetition rate, a maximum pulse density of 1010W\\/cm2 and an iodine laser, 400ps pulse, operating in single pulse width with a maximum power density of 1016W\\/cm2, are employed to produce pulsed plasmas in vacuum. A comparison of the results obtained for the ablation of tantalum targets is presented, including the ablation yields, the

L. Torrisi; S. Gammino

2006-01-01

51

Initiation of plasma prorenin activation by Hageman factor-dependent conversion of plasma prekallikrein to kallikrein.  

PubMed Central

Plasma prorenin is an inactive form of renin (EC 3.4.99.19) that can be converted to active renin in acid-treated plasma by an endogenous serine protease that is active at alkaline pH (alkaline phase activation). To identify this enzyme we first tested the ability of Hageman factor fragments, plasma kallikrein (EC 3.4.21.8), and plasmin (EC 3.4.21.7) to activate prorenin in acid-treated plasma. All three enzymes initiated prorenin activation; 50% activation was achieved with Hageman factor fragments at 1 microgram/ml, plasma kallikrein at 2-4 microgram/ml, or plasmin at 5-10 microgram/ml. We then showed that the alkaline phase of acid activation occurred normally in plasminogen-free plasma but was almost completely absent in plasmas deficient in either Hageman factor or prekallikrein; alkaline phase activation was restored to these latter plasmas when equal parts were mixed together. Therefore, both Hageman factor and prekallikrein were required for alkaline phase activation to occur. We then found that, although plasma kallikrein could activate prorenin in plasma deficient in either Hageman factor or prekallikrein, Hageman factor fragments were unable to activate prorenin in prekallikrein-deficient plasma. These studies demonstrate that alkaline phase prorenin activation is initiated by Hageman factor-dependent conversion of prekallikrein to kallikrein which, in turn, leads to activation of prorenin. In this fashion, we have revealed a possible link between the coagulation-kinin pathway and the renin-angiotensin system.

Sealey, J E; Atlas, S A; Laragh, J H; Silverberg, M; Kaplan, A P

1979-01-01

52

Initiation and assembly of the plasma in a plasma flow switch  

SciTech Connect

A series of fast opening switch experiments was carried out on the Pegasus pulsed power facility. The first series of experiments characterized the assembly and run down of a 50 mg plasma flow switch operating in the 6 MA regime. The switch plasma arises from the vaporization of a wire array and a barrier foil. Arrays with different numbers of wires were examined. Two-dimensional (2-D) radiation magnetohydrodynamic simulations of the initial vaporization stage of the array plasma and its assembly on the barrier foil are presented, which include the effects of initial perturbations on the evolution of the switch plasma as it moves down a coaxial gun barrel. Sparse wire arrays were observed to perform poorly. A change in the experimental design, motivated by 2-D simulations, led to improved performance. Computational results which lead to these changes are discussed, and the results are compared with experimental data.

Bowers, R.L.; Greene, A.E.; Peterson, D.L.; Bartsch, R.R.; Cochrane, J.C.; Kruse, H. [Los Alamos National Lab., NM (United States); Roderick, N.F. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Chemical and Nuclear Engineering

1996-04-01

53

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

Microsoft Academic Search

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

Brian Sands; Biswa Ganguly

2008-01-01

54

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

Microsoft Academic Search

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

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

2010-01-01

55

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

56

Optical interferometric analysis of colliding laser produced air plasmas  

SciTech Connect

Colliding air plasmas produced using 1064 nm Nd:YAG laser were analyzed using optical interferometry. For generating multiple air plasmas, the spherical aberrations of the focusing lens were used. The three-dimensional (3D) distributions of the electron density and the gas density behind shock wave front were investigated. The two-dimensional fast Fourier transform technique was used to extract the phase shift of the interferograms and a numerical inverse Abel transformation was applied to reconstruct the 3D distribution of the refractive index. Based on the Gladston-Dale relation, high resolution images of the 3D distributions of the electron density and the gas density were achieved. From the results, a stagnation layer was formed due to the collision of shock waves and the succeeding plasmas. The enhancements of electron density and gas density were observed in the collision zone. It shows that the collision region depends on the pulse energy. With smaller pulse energy, the thickness of the stagnation layer increased, while the enhancement of the gas density behind the shock wave front in the collision zone reduced.

Zhang Hongchao; Lu Jian; Ni Xiaowu [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China)

2009-09-15

57

Laser produced plasma soft x-ray generation  

SciTech Connect

The efficiency of soft x-ray production from laser-irradiated plasmas is simulated for two different spectral regions. These two regions, 14{Angstrom} {plus minus} 15% and 130{Angstrom} {plus minus} 1%, were chosen for proximity mask or point-projection technological applications. Relatively large conversion efficiencies were obtained from irradiation of a stainless steel target using the conditions suggested by recent Hampshire Instruments' experiments for proximity masking. Pulse-width and laser frequency parameter studies were performed for point-projection applications which suggest that the conversion applications which suggest that the conversion efficiency is sensitive to pulse-width but not to laser frequency. One of the critical components of any x-ray lithographic scheme is of course the x-ray laser source. There are two primary contenders for a reliable, efficient source currently: synchrotron radiation and spectral emission from laser produced plasma. The dominant issue for laser-plasma emission is the conversion efficiency -- output in the intended operating spectral region relative the required incident laser energy. Simulations are described in the following for both high and low energy spectral regions which have been suggested by either the proximity masking or point-projection technology.

Cerjan, C.; Rosen, M.D.

1991-05-20

58

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

59

Producing the Initial State of X1 Cryogenic ICF Targets  

NASA Astrophysics Data System (ADS)

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

Alexander, N. B.

1998-11-01

60

Detection of electromagnetic pulses produced by hypervelocity micro particle impact plasmas  

NASA Astrophysics Data System (ADS)

Hypervelocity micro particles (mass < 1 ng), including meteoroids and space debris, routinely impact spacecraft and produce plasmas that are initially dense (~1028 m-3), but rapidly expand into the surrounding vacuum. We report the detection of radio frequency (RF) emission associated with electromagnetic pulses (EMPs) from hypervelocity impacts of micro particles in ground-based experiments using micro particles that are 15 orders of magnitude less massive than previously observed. The EMP production is a stochastic process that is influenced by plasma turbulence such that the EMP detection rate that is strongly dependent on impact speed and on the electrical charge conditions at the impact surface. In particular, impacts of the fastest micro particles occurring under spacecraft charging conditions representative of high geomagnetic activity are the most likely to produce RF emission. This new phenomenon may provide a source for unexplained RF measurements on spacecraft charged to high potentials.

Close, Sigrid; Linscott, Ivan; Lee, Nicolas; Johnson, Theresa; Strauss, David; Goel, Ashish; Fletcher, Alexander; Lauben, David; Srama, Ralf; Mocker, Anna; Bugiel, Sebastian

2013-09-01

61

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

SciTech Connect

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

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

2011-11-15

62

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

63

XUV spectra of laser-produced zirconium plasmas  

NASA Astrophysics Data System (ADS)

XUV spectra of laser-produced zirconium plasmas in the 20 to 65 wavelength range, where 3d-4p and 3d-4f transitions dominate the observed emission, were studied experimentally and theoretically. Atomic structure calculations were performed with the Cowan and flexible atomic codes. Spectator satellite transitions, especially 3dn-14s-3dn-24s4f, where the 4s electron acts as a real spectator, in Mn-, Fe-, Co-, Ni- and Cu-like ions have been found to play an important role. The resulting emission causes arrays resulting from 3dn-3dn4f transitions to broaden and must be included in spectral simulations in order to reproduce the overall spectral profile.

Li, Bowen; Higashiguchi, Takeshi; Otsuka, Takamitsu; Jiang, Weihua; Endo, Akira; Dunne, Padraig; O'Sullivan, Gerry

2012-12-01

64

Suprathermal electron transport in laser-produced plasmas  

SciTech Connect

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

Mason, R.J.

1981-01-01

65

Plasma Parameter of a Capillary Discharge-Produced Plasma Channel to Guide an Ultrashort Laser Pulse  

SciTech Connect

We have observed the optical guiding of a 100-fs laser pulse with the laser intensity in the range of 10{sup 16} W/cm{sup 2} using a 1.5-cm long capillary discharge-produced plasma channel for compact electron acceleration applications. The optical pulse propagation using the plasma channel is achieved with the electron densities of 10{sup 17}-10{sup 18} cm{sup -3} and the electron temperatures of 0.5-4 eV at a discharge time delay of around 150 ns and a discharge current of 500 A with a pulse duration of 100-150 ns. An energy spectrum of the accelerated electrons from a laser-plasma acceleration scheme showed a peak at 1.3 MeV with a maximum energy tail of 1.6 MeV.

Higashiguchi, Takeshi; Terauchi, Hiromitsu; Bai, Jin-xiang; Yugami, Noboru [Department of Energy and Environmental Science, Graduate School of Engineering, and Center for Optical Research and Education (CORE), Utsunomiya University, Yoto 7-1-2, Utsunomiya 321-8585 (Japan); Japan Science and Technology Agency, CREST, 4-1-8 Honcho, Kanagawa, Saitama 332-0012 (Japan)

2009-01-22

66

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

NASA Astrophysics Data System (ADS)

A set of kinetic equations is used to study equilibration of the anisotropic quark-gluon plasma produced by decays of color flux tubes possibly created at the very early stages of ultrarelativistic heavy-ion collisions. The decay rates of the initial color fields are given by the Schwinger formula, and the collision terms are treated in the relaxation-time approximation. By connecting the relaxation time with viscosity we are able to study production and thermalization processes in the plasma characterized by different values of the ratio of the shear viscosity to entropy density, ?. For the lowest (Kovtun-Son-Starinets) value of this ratio, 4??=1, and realistic initial conditions for the fields, the system approaches the viscous-hydrodynamics regime within 12fm/c. On the other hand, for larger values of the viscosity, 4???3, the collisions in the plasma become inefficient to destroy collective phenomena which manifest themselves as oscillations of different plasma parameters. The presence of such oscillations brings in differences between the kinetic and hydrodynamic descriptions, which suggest that the viscous-hydrodynamics approach after 12fm/c is not complete if 4???3 and should be extended to include dissipative phenomena connected with color conductivity.

Ryblewski, Radoslaw; Florkowski, Wojciech

2013-08-01

67

Initial experiments of RF gas plasma source for heavy ionfusion  

SciTech Connect

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

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

2002-05-22

68

Initial Studies of Core and Edge Transport of NSTX Plasmas  

SciTech Connect

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

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

2001-09-19

69

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

NASA Astrophysics Data System (ADS)

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

Kelvin, Loh; Abhijit, Kushari

2010-08-01

70

Magnetic Bubble Formation Produced by an Expanding Laser Plasma.  

National Technical Information Service (NTIS)

A magnetic depleted bubble resulting from the expansion of a laser-generated debris plasma into a low density magnetized background plasma is observed. A compressed magnetic field propagates slightly ahead of the debris plasma and has a thickness on the o...

S. T. Kacenjar B. H. Ripin J. A. Stamper J. Grun E. A. McLean

1984-01-01

71

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

72

Structure of an Exploding Laser-Produced Plasma  

SciTech Connect

We describe the first-ever volumetric, time-resolved measurements performed with a moving probe within an expanding dense plasma, embedded in a background magnetized plasma. High-resolution probe measurements of the magnetic field and floating potential in multiple 2D cut planes combined with a 1 Hz laser system reveal complex three-dimensional current systems within the expanding plasma. Static ({omega}{sub real}=0) flutelike density striations are observed at the leading edge of the plasma, which are correlated to variations in the current layer at the edge of the expanding plasma.

Collette, A.; Gekelman, W. [Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095 (United States)

2010-11-05

73

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

74

Recombination laser by laser-produced xenon plasmas  

SciTech Connect

A recombination laser of Xe plasma produced in a gaseous mixture of He and Xe with a CO/sub 2/ laser pulse of 10.6 micron wave is reported. The particle number is the result of electron-ion recombination. The wavelength of the Xe recombination laser obtained in the experiment is 2.03 microns with an output power of more than 80 watts and a pulse width of 2 microsec. The input CO/sub 2/ laser energy is supplied by a CO/sub 2/ laser with cold cathode electron beam controlled discharge. Each pulse has an energy of over 30 joules (pulse width 1 to 2 microsec). After being reflected by a cylindrical reflector of 6 cm focal length in the target chamber, the CO/sub 2/ laser beam is focussed on a metal target 8 cm long 3 mm wide. At the two ends of the chamber are Brewster angle windows at 2.03 microns made by quartz plates.

Lanying, L.; Zaitong, L.; Dounan, Z.; Zemin, W.

1982-09-01

75

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

SciTech Connect

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

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

1986-01-01

76

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 5107 suprathermal electrons with the outermost layer expanding at an average speed of 1.2107 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

77

PREUVE and the EXULITE project: modular laser-produced plasma EUV source  

NASA Astrophysics Data System (ADS)

Within the PREUVE project, the GAP of CEA Saclay has developed an EUV source that should meet (alpha) -tool specifications by the end of this year. In particular, a laser-produced plasma source has been developed that uses a dense and confined xenon jet target. Our technical solution is based on a specific target injector design and the use of well adapted nozzle materials to avoid debris formation by plasma erosion. After injection, the xenon is recycled and highly purified to reach a low cost round- the-clock operation. This source provides both high conversion efficiency and low debris flux. These are necessary conditions for its industrial application in the future EUV microlithography. The conception of the so-called ELSA (EUV Lithography Source Apparatus) prototype allows in principal 2 years full operation on the French lithography test bench BEL (Banc d'essai pour la lithographie) that has been developed during PREUVE. In parallel, the EXULITE consortium that is coordinated by Alcatel Vacuum Technology France (AVTF) has started its activities in the frame of the European MEDEA+ initiative on EUV source development. In collaboration with Thales and the CEA, AVTF develops a prototype power source for EUV lithography production tools by the end of 2004. A low cost and modular high power laser system architecture has been chosen and is developed by Thales and the CEA to pump the laser plasma- produced EUV source.

Ceccotti, Tiberio; Chichmanian, F.; Descamps, D.; Haltebourg, P.; Hergott, Jean-Francois; Hulin, S.; Normand, Didier; Segers, Marc; Sublemontier, Olivier; Schmidt, Martin; Cormont, Philippe; Neu, M.; Thro, Pierre-Yves; Weulersse, Jean-Marc; Barthod, B.; Bernard, R.; Veran, E.; Barbiche, Jean-Marie; D'Aux, Ph.; Marquis, E.

2002-09-01

78

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

79

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

80

The cooling of flare produced plasmas in the solar corona  

Microsoft Academic Search

Solar flare X-rays, at energies less than 10 keV, are emitted by hot plasmas located in the corona. Three plasma cooling models are examined in detail. The cooling of the electrons by Coulomb collisions with ions at a lower temperature would require the observed material to occupy very large volumes. Cooling could take place by conduction or by radiation and

J. L. Culhane; J. F. Vesecky; K. J. H. Phillips

1970-01-01

81

Plasma dynamics in laboratory-produced current sheets  

SciTech Connect

Evolution of currents and Ampere forces in current sheets are analyzed on the basis of magnetic measurements. Two new effects are observed in the current distributions at the later stage of the sheet evolution: first, a broadening of the current area at the side edges of the current sheet; second, a generation of reverse currents followed by their propagation from the edges to the center of the sheet. Super-thermal plasma flows moving across the width of the current sheet are observed by spectroscopic methods. The energies of plasma jets are consistent with the spatial structure and time dependences of the Ampere forces in the current sheets. The assumption is advanced that plasma acceleration may be more effective at the regions with lower plasma density, which are located at some distances from the sheet mid-plane. Generation of reverse currents provides an additional confirmation of transfer of energetic plasma jets toward the sheet edges.

Frank, Anna G.; Kyrie, Natalya P.; Satunin, Sergey N. [A.M. Prokhorov Institute of General Physics of the Russian Academy of Sciences, 38 Vavilov Street, Moscow 119991 (Russian Federation)

2011-11-15

82

Nonlinear regime of the filamentation of a microwave produced plasma  

SciTech Connect

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

Shokri, B.; Niknam, A. R. [Physics Department and Laser-Plasma Research Institute of Shahid Beheshti University, Evin, Tehran, Iran and Institute for Studies in Theoretical Physics and Mathematics, P.O. Box 19395-1795, Tehran (Iran, Islamic Republic of); Laser-Plasma Research Institute of Shahid Beheshti University, Evin, Tehran (Iran, Islamic Republic of)

2007-03-15

83

Precision Closed Bomb Calorimeter for Testing Flame and Gas Producing Initiators.  

National Technical Information Service (NTIS)

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' (clos...

A. C. Taylor D. R. Carpenter

1972-01-01

84

Diagnostics Techniques of Plasmas Produced by Laser Ablation  

NASA Astrophysics Data System (ADS)

Laser ablation in addition for thin film growing is also used for analytical techniques as Laser Induced Breakdown Spectroscopy and for applications as simulation of natural lightning. In this work we present several diagnostic techniques such as probe beam deflection, shadowgraphy, interferometry, pulsed laser photoacoustic and the electrical perturbation induced by laser ablation plasmas that's gives essential information of the plasma, hot core air and shock wave expansion.

Villagrn Muniz, M.; Sobral, H.; Snchez Ak, C.; Sangins de Castro, R.; Sterling, E.; Bredice, F.

2005-04-01

85

Experimental Investigation of Short Scalelength Density Fluctuations in Laser-Produced Plasmas  

Microsoft Academic Search

The technique of near forward laser. scattering is used to infer characteristics of intrinsic and controlled density fluctuations in laser-produced plasmas. Intrinsic fluctuations are studied in long scalelength plasmas where the fluctuations exhibit scale sizes related to the size of the intensity variations in the plasma forming and interaction beams. Stimulated Brillouin forward scattering and filamentation appear to be the

J. D. Moody; B. J. MacGowan; S. H. Glenzer; R. K. Kirkwood; W. L. Kruer; E. A. Williams; G. F. Stone; D. S. Montgomery; A. J. Schmitt

1999-01-01

86

Experimental investigation of short scalelength density fluctuations in laser-produced plasmas  

Microsoft Academic Search

The technique of near forward laser scattering is used to infer characteristics of intrinsic and controlled density fluctuations in laser-produced plasmas. Intrinsic fluctuations are studied in long-scalelength plasmas where it is found that the fluctuations exhibit scale sizes related to the intensity variation scales in the plasma forming and interaction beams. Stimulated Brillouin forward scattering and filamentation appear to be

J. D. Moody; B. J. MacGowan; S. H. Glenzer; R. K. Kirkwood; W. L. Kruer; D. S. Montgomery; A. J. Schmitt; E. A. Williams; G. F. Stone

2000-01-01

87

Use of multilayer targets to inject trace elements into laser-produced plasma  

SciTech Connect

The use of multilayer target with predrilled holes to inject trace elements into laser-produced plasma is presented. The tracer plasma obtained shows a smaller source size and reduced opacity compared to a plasma target. The preparation and alignment of the proposed target are extremely simple.

Zigler, A.; Kolbe, J.; Lee, R.W.

1987-04-27

88

Experimental evidence of charge separation (double layer) in laser-produced plasmas  

SciTech Connect

Simultaneous measurements of the plasma target potential and plasma charged particle currents have been made for Nd laser irradiances between 4 x 10/sup 12/ and 10/sup 15/ W/cm/sup 2/. The results appear to give the first direct indication of double layers in laser-produced plasmas.

Ludmirsky, A.; Arad, B.; Borowitz, A.; Eliezer, S.; Gazit, Y.; Jackel, S.; Krumbein, A.D.; Salzmann, D.; Szichman, H.

1985-06-01

89

Application of escape probability to line transfer in laser-produced plasmas  

Microsoft Academic Search

The application of an escape probability method to treat transfer of optically thick lines in laser-produced plasmas in plane-parallel geometry is described. The escape probability calculated is valid in a plasma with any locally linear velocity profile. It reduces to the standard result for a static plasma and to the result of Sobolev (Sov. Astron. Astrophys. J. {bold 1}, 678

Yim T. Lee; Richard A. London; George B. Zimmerman; Peter L. Hagelstein

1990-01-01

90

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

Microsoft Academic Search

Discharge produced plasma (DPP) devices have been proposed as a light source for EUV lithography. A key challenge for DPP is achieving sufficient brightness to support the throughput requirements of exposure tools for high-volume manufacturing lithography. To simulate the environment of the EUV source and optimize the output of the source, an integrated model is being developed to describe the

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

2003-01-01

91

Dynamic Simulation of Discharge and Laser Produced Plasma for EUV Lithography Devices  

Microsoft Academic Search

Summary form only given. Both laser and discharge produced plasma such as Z-pinch devices are being used as a light source for EUV lithography. A key challenge for discharge produced plasma (DPP) devices is achieving sufficient brightness to support the throughput requirements of high-volume manufacturing (HVM) lithography exposure tools. An integrated model for the description of hydrodynamics and optical processes

A. Hassanein; V. Sizyuk; V. Morozov; I. Konkashbaev; T. Sizyuk; B. Rice; V. Bakshi

2005-01-01

92

Initial H-mode experiments in DT plasmas on TFTR  

SciTech Connect

H-modes have been obtained for the first time in high temperature, high poloidal beta plasmas with significant tritium concentrations in TFTR. Tritium is provided mainly through high power neutral beam injection (NBI) with powers up to 28 MW and beam energies of 90--110 keV. Transition to a circular limiter H-mode has been obtained following a rapid ramp down of the plasma current. Some of the highest values of {tau}{sub E} have been achieved on TFTR during the ELM-free phase of these DT H-mode plasmas. {tau}{sub E} enhancements greater than four times L-mode have been achieved.

Bush, C.E. [Oak Ridge National Lab., TN (United States); Sabbagh, S.A. [Columbia Univ., New York, NY (United States); Bell, R.E. [Princeton Univ., NJ (United States). Plasma Physics Lab.] [and others

1995-01-01

93

Jupiter plasma wave observations: an initial voyager 1 overview.  

PubMed

The Voyager I 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 turbulence, and discrete whistlers, apparently associated with lightning. Some strong emissions in the tail region and some impulsive signals have not yet been positively identified. PMID:17800437

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

1979-06-01

94

Diamond-like carbon sputtering by laser produced Xe plasma  

NASA Astrophysics Data System (ADS)

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

Amano, Sho; Inoue, Tomoaki

2013-11-01

95

Plasma observations near saturn: initial results from voyager 2.  

PubMed

Results of measurements of plasma electrons and poitive ions made during the Voyager 2 encounter with Saturn have been combined with measurements from Voyager 1 and Pioneer 11 to define more clearly the configuration of plasma in the Saturnian magnetosphere. The general morphology is well represented by four regions: (i) the shocked solar wind plasma in the magnetosheath, observed between about 30 and 22 Saturn radii (RS) near the noon meridian; (ii) a variable density region between approximately 17 RS and the magnetopause; (iii) an extended thick plasma sheet between approximately 17 and approximately 7 RS symmetrical with respect to Saturn's equatorial plane and rotation axis; and (iv) an inner plasma torus that probably originates from local sources and extends inward from L approximately 7 to less than L approximately 2.7 (L is the magnetic shell parameter). In general, the heavy ions, probably O(+), are more closely confined to the equatorial plane than H(+), so that the ratio of heavy to light ions varies along the trajectory according to the distance of the spacecraft from the equatorial plane. The general configuration of the plasma sheet at Saturn found by Voyager 1 is confirmed, with some notable differences and additions. The "extended plasma sheet," observed between L approximately 7 and L approximately 15 by Voyager 1 is considerably thicker as observed by Voyager 2. Inward of L approximately 4, the plasma sheet collapses to a thin region about the equatorial plane. At the ring plane crossing, L approximately 2.7, the observations are consistent with a density of O(+) of approximately 100 per cubic centimeter, with a temperature of approximately 10 electron volts. The location of the bow shock and magnetopause crossings were consistent with those previously observed. The entire magnetosphere was larger during the outbound passage of Voyager 2 than had been previously observed; however, a magnetosphere of this size or larger is expected approximately 3 percent of the time. PMID:17771279

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

1982-01-29

96

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

SciTech Connect

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

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

2010-11-15

97

Plasma morphine levels produced by continuous infusion in children.  

PubMed

Blood samples were taken from six children aged between 10 months and 15 years, at intervals over a period of 40 hours while they were receiving continuous morphine infusions. The plasma morphine values obtained showed similar and consistent levels 15-30 minutes after starting the infusions. PMID:3752440

Bray, R J; Beeton, C; Hinton, W; Seviour, J A

1986-07-01

98

Hydrophobic corn starch thermoplastic films produced by plasma treatment.  

PubMed

Polymer coating technology is currently an important field in science as it can lead to final products with enhanced characteristics characterized by desired bulk and surface properties. Low power plasmas can induce the polymerization of a precursor gas on the substrate surface as well as introduce functional groups under specific plasma conditions. In the present work, we studied the possibility of reducing water sensitivity of corn starch films by sulfur hexafluoride (SF(6)) plasma treatment. Confocal laser microscopy as well as atomic force microscopy was used to observe the main surface modifications and results indicated starch cross-linking. Fluoride was incorporated to the surface and the relationship between fluoride and sulfur incorporation to the surface was very much dependent on plasma power. Results indicate that fluoride could be preferentially incorporated on polymeric surfaces at -100V self-bias and the overall surface morphology determined the measured contact angle. The dynamic behavior of surface contact angle was observed to be very much dependent on the treatment time and force-distance curves were used to further characterize the chemical surface modifications locally. Optimized treatment conditions led to water contact angles up to 130 degrees . Even after being in contact with water for 10min, surfaces remained hydrophobic, presenting contact angles over 100 degrees . PMID:19345017

Bastos, Daniele C; Santos, Anastcia E F; da Silva, Monica L V J; Simo, Renata A

2009-03-19

99

Spectral modeling of laser-produced underdense titanium plasmas  

NASA Astrophysics Data System (ADS)

Experiments were performed at the NIKE laser to create underdense low-Z plasmas with a small amount of high-Z dopant in order to study non-LTE population kinetics. An absolutely calibrated spectra in 470-3000 eV was measured in time-resolved and time-averaged fashion from SiO2 aerogel target with 3% Ti dopant. K-shell Ti emission was observed as well as L-shell Ti emission. Time-resolved emission show that lower energy photons peak later than higher energy photons due to plasma cooling. In this work, we compare the measured spectra with non-LTE spectral calculations of titanium emission at relatively low temperatures < 1 keV and electron densities from 1e19 to 1e21 cm-3. A temperature diagnostics using the charge state distributions dominated by L-shell ions will be discussed.

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

2004-11-01

100

Plasma observations near saturn: initial results from voyager 1.  

PubMed

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

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

1981-04-10

101

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

NASA Astrophysics Data System (ADS)

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.

2012-06-01

102

A laser-plasma accelerator producing monoenergetic electron beams  

Microsoft Academic Search

Particle accelerators are used in a wide variety of fields, ranging from medicine and biology to high-energy physics. The accelerating fields in conventional accelerators are limited to a few tens of MeVm-1, owing to material breakdown at the walls of the structure. Thus, the production of energetic particle beams currently requires large-scale accelerators and expensive infrastructures. Laser-plasma accelerators have been

J. Faure; Y. Glinec; A. Pukhov; S. Kiselev; S. Gordienko; E. Lefebvre; J.-P. Rousseau; F. Burgy; V. Malka

2004-01-01

103

Aminated graphene for DNA attachment produced via plasma functionalization  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

104

Modelling and experimental analysis of vacuum plasma spraying. Part I: prediction of initial plasma properties at plasma gun exit  

Microsoft Academic Search

The plasma energy input rate of a dc Ar + H2 plasma jet has been measured experimentally under a series of vacuum plasma spraying (VPS) processing conditions. The plasma energy input rate increased approximately linearly with increasing plasma current and Ar flow rate, increased approximately parabolically with increasing H2 flow rate, but did not vary measurably with changes in VPS

Y. Y. Zhao; P. S. Grant; B. Cantor

2000-01-01

105

Initiation of pentaerythritol tetranitrate using a fast and high power plasma arc source  

Microsoft Academic Search

Initiation of high explosives (HE) is the process of transitioning the HE from a quiescent state to one containing a propagating release of chemical energy. Plasma arc initiation is driven by a discharge across the surface on or through the HE. Experiments have found that at least one conventional high explosive (pentaerythritol tetranitrate, PETN) can be arc-initiated with low threshold

V. Tang; C. D. Grant; J. M. Zaug; J. F. McCarrick; H. Wang; E. A. Glascoe

2010-01-01

106

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

107

Laser-produced aluminum plasma expansion inside a plastic plasma envelope  

NASA Astrophysics Data System (ADS)

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 (?3 = 0.438 ?m). A plastic target with an Al cylindrical insert of 400 ?m in diameter as well as a bare Al target (for comparison) was used. The focal spot diameter (?L) 1200 ?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.; Renner, O.; Gus'kov, S. Yu.; Demchenko, N. N.; Ullschmied, J.; Krousky, E.; Pfeifer, M.; Rohlena, K.; Skala, J.

2012-09-01

108

Reconstruction of time-resolved continuum intensity profile of nonaxisymmetric laser-produced plasma  

NASA Astrophysics Data System (ADS)

A single laser pulse is used to produce weakly nonideal plasma from a metallic aluminum target immersed in a dense neutral gas. The attendant increase in plasma density due to neutral gas confinement precipitates interfacial instability when the gas density exceeds a threshold value. This is accompanied by large fluctuations in the total attenuation of the laser beam by the laser-produced plasma plume. We have developed a new diagnostic method utilizing two mutually orthogonal side-view streak photographs of plasma continuum luminosity at a fixed distance from the target surface. The lack of axial symmetry is overcome by using a front-view luminosity image of the plasma at time zero as a two-dimensional weighting factor. The resulting profile at one time is used as the weighting factor for the next time segment. The time-resolved reconstructed plasma profiles clearly exhibit the near-threshold behavior of Rayleigh-Taylor type instability.

Kim, Yong W.; Oh, Jaechul

2001-01-01

109

Influence of the laser pulse duration on laser-produced plasma properties  

NASA Astrophysics Data System (ADS)

In the framework of laser-induced plasma spectroscopy (LIPS) applications, time-resolved characteristics of laser-produced aluminium plasmas in air at atmospheric pressure are investigated for laser pulse durations ranging from 100 fs to 270 ps. Measurements show that for delays after the laser pulse longer than ~100 ns, the plasma temperature increases slightly with the laser pulse duration, while the electron density is independent of it. In addition, as the pulse duration increases, the plasma radiation emission lasts longer and the spectral lines arise later from the continuum emission. The time dependence of the continuum emission appears to be similar whatever the duration of the laser pulse is, while the temporal evolution of the line emission seems to be affected mainly by the plasma temperature. Finally, as far as spectrochemical applications (such as LIPS) of laser-produced plasmas are concerned, this study highlights the importance of the choice of appropriate temporal gating parameters for each laser pulse duration.

LeDrogoff, B.; Margot, J.; Vidal, F.; Laville, S.; Chaker, M.; Sabsabi, M.; Johnston, T. W.; Barthlemy, O.

2004-05-01

110

Developments of UV Collective Thomson Scattering for the ion acoustic decay instabilities in laser produced plasma  

SciTech Connect

We have developed a multi-channel UV Collective Thomson Scattering (CTS) system for plasmas produced by short wavelength lasers. The CTS diagnostic allows us to make significant improvement in the understanding of plasma wave instabilities. Previously, the IADI was studied by measuring the second harmonic (SH) emissions. The SH emissions are produced by the product of two unknown plasma waves, and integrated over the wave number, the propagation angle, and the plasma density. Using the CTS, we can directly measure an electron plasma wave, and an ion acoustic wave for a selected wave number, and a propagation angle. It is shown that the IADI is important in a large scale, hot plasma relevant to laser fusion. An important application is that the UV CTS from the IADI is a good diagnostic tool for a [ital local] electron temperature (T[sub e]) measurement. [copyright] 1994 [ital American] [ital Institute] [ital of] [ital Physics

Mizuno, K. (PPRI UCV Davis, Lawrence Livermore National Laboratory, PO Box 808, L-418, Livermore, California 94550 (United States))

1994-10-05

111

Beam heated linear theta-pinch device for producing hot plasmas  

DOEpatents

A device for producing hot plasmas comprising a single turn theta-pinch coil, a fast discharge capacitor bank connected to the coil, a fuel element disposed along the center axis of the coil, a predetermined gas disposed within the theta-pinch coil, and a high power photon, electron or ion beam generator concentrically aligned to the theta-pinch coil. Discharge of the capacitor bank generates a cylindrical plasma sheath within the theta-pinch coil which heats the outer layer of the fuel element to form a fuel element plasma layer. The beam deposits energy in either the cylindrical plasma sheath or the fuel element plasma layer to assist the implosion of the fuel element to produce a hot plasma.

Bohachevsky, Ihor O. (Los Alamos, NM)

1981-01-01

112

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

SciTech Connect

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

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

2010-10-13

113

Ignition Time Measurements in Repetitive Nanosecond Pulse HydrogenAir Plasmas at Elevated Initial Temperatures  

Microsoft Academic Search

Ignition time is measured in premixed preheated hydrogenair flows excited by a repetitive nanosecond pulse discharge in a plane-to-plane geometry. ICCD images of the plasma and the flame demonstrate that mild preheating of the fuelair flow greatly improves plasma stability and precludes filament formation. At the initial temperatures of $T_{0} = 100-200\\\\ ^{\\\\circ}\\\\hbox{C}$, hydrogenair plasmas remain stable and uniform up

Zhiyao Yin; Keisuke Takashima; Igor V. Adamovich

2011-01-01

114

315-nm optical sounding for laser-produced plasma  

Microsoft Academic Search

The heating and the sounding pulse are generated by the same laser. The laser output radiation is split into two independent channels, one of them is converted into an ultraviolet picosecond pulse by means of backward stimulated scattering. When a 3 - 10 ns pulse is produced by a Q- switched laser, the temporal compression of the sounding pulse is

Shaoxian Meng; Zhongmin Gu; Jingxin Yang; Qirong Lu

1993-01-01

115

Characteristics of Transported Ion Beam in Laser-Initiated Plasma Channels.  

National Technical Information Service (NTIS)

The propagation of intense ion beams through the laser-initiated plasma channel is reported. The ion beam was generated using a pinch-reflex ion diode on Reiden IV generator and transported over 40 cm in the plasma channel. Beam orbits, estimated from the...

T. Ozaki S. Miyamoto K. Imasaki H. Fujita S. Nakai

1981-01-01

116

Negative polarity plasma filled rod pinch: initial experiments on GAMBLE II  

Microsoft Academic Search

Summary form only given. Initial exploratory experiments on a Negative Polarity Plasma Filled Rod Pinch (NPPFRP) have been made on GAMBLE II. The Rod Pinch (RP) and the Plasma Filled Rod Pinch (PFRP) diodes, in the conventional positive polarity, have already been studied. Although proven useful as small spot size radiography sources, it is believed that the RP and the

D. M. Ponce; S. J. Stephanakis; F. C. Young; D. D. Hinshelwood; B. V. Weber

2004-01-01

117

Oxide ceramic coatings on aluminium alloys produced by a pulsed bipolar plasma electrolytic oxidation process  

Microsoft Academic Search

In the paper, a modified Plasma Electrolytic Oxidation process (PEO) to produce ceramic coatings on Al alloys, suitable for tribological applications, is discussed. The process utilises bipolar current pulses in the kHz frequency range, providing better control over plasma discharges occurring at the sample surface. The coatings, formed on a 2024 series Al alloy, are characterized by means of optical

A. L. Yerokhin; A. Shatrov; V. Samsonov; P. Shashkov; A. Pilkington; A. Leyland; A. Matthews

2005-01-01

118

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

Microsoft Academic Search

The electrogun is a type of electrothermal gun especially modified to produce metal and carbon plasma jets. These jets are capable of deep penetration into room temperature, atmospheric-pressure gases, so that the plasma composing the jet is vigorously mixed into an excess of cold gas. Reaction products are rapidly quenched and form a room-temperature gas suspension of nanoparticles which gradually

Dennis R. Peterson

1997-01-01

119

Polymorphous silicon thin films produced in dusty plasmas: application to solar cells  

Microsoft Academic Search

We summarize our current understanding of the optimization of PIN solar cells produced by plasma enhanced chemical vapour deposition from silane hydrogen mixtures. To increase the deposition rate, the discharge is operated under plasma conditions close to powder formation, where silicon nanocrystals contribute to the deposition of so-called polymorphous silicon thin films. We show that the increase in deposition rate

Pere Roca i. Cabarrocas; N. Chabane; A. V. Kharchenko; S. Tchakarov

2004-01-01

120

Method and apparatus for manufacturing plasma based plastics and bioplastics produced therefrom  

US Patent & Trademark Office Database

A method of making a bioplastic, and a bioplastic produced thereby, by using human plasma in which human plasma is clotted, either dried through its gel phase or dried and powdered, and processed into a bioplastic with the addition of at least one plasticizer followed by forming and heating to form a final bioplastic construct.

Burgess; James E. (Gibsonia, PA); Campbell; Phil G. (Pittsburgh, PA); Weiss; Lee E. (Pittsburgh, PA); Smith; Jason (Pittsburgh, PA)

2012-10-23

121

Interaction of a laser-produced copper plasma jet with ambient plastic plasma  

NASA Astrophysics Data System (ADS)

This work is aimed at the investigation of mutual interaction of plastic (CH) and copper axially symmetric plasmas, and the dependence on the ratio of their ablated masses. For that purpose we irradiated a plastic target with a Cu cylindrical insert of diameter 400 m with a laser beam of radius exceeding that of the insert. In such an arrangement we were able to control the volumes and masses of interacting CH and Cu plasmas by varying the laser beam diameter. The experiment was carried out at the Prague Asterix Laser System (PALS) iodine laser. The laser provided a 250 ps pulse with an energy of 130 J at the third harmonic frequency (i.e. a wavelength of ?3 = 0.438 m). The interaction of the laser-driven plasma jet with ambient plasma was studied by means of a three-frame interferometric system and a four-frame x-ray pinhole camera. For simulation of the experiment we used the two-dimensional hydrodynamic code ATLANT-HE. The reported results demonstrated that there is an optimal ratio of Cu and plastic plasma masses, at which stable extended Cu plasma jets can be created. Even a relatively thin plastic plasma envelope can compress the Cu plasma and control the jet formation. Thicker plastic plasma layers, however, lead to complex hydrodynamic motion accompanied by generation of transverse shock waves, which can completely suppress the jet formation. The pressure of the plastic plasma was found to be 1.35 times higher than that of the copper plasma. A theoretical analysis of the experimental results allows us to conclude that this difference in pressures follows from the essential differences in expansion dynamics of plasmas with low and high atomic numbers.

Kasperczuk, A.; Pisarczyk, T.; Badziak, J.; Borodziuk, S.; Chodukowski, T.; Gus'kov, S. Yu; Demchenko, N. N.; Klir, D.; Kravarik, J.; Kubes, P.; Rezac, K.; Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J.; Pisarczyk, P.

2011-09-01

122

Vacuum laser-initiated plasma shutters for retropulse isolation in Antares  

Microsoft Academic Search

We have demonstrated that sintered LiF spatial filters may be used in a 10⁻⁶-torr vacuum environment as laser-initiated plasma shutters for retropulse isolation in the Antares high-energy laser fusion system. In our experiments, a 1.1-ns pulsed CO laser, at a 10-..mu..m wavelength and an energy of up to 3.0 J, was used for plasma initiation; a chopped probe laser tuned

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

1983-01-01

123

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

National Technical Information Service (NTIS)

Here we consider the results of an experimental investigation of the temporal evolution of plasmas produced by high power laser irradiation of various types of target materials. The experiment was performed at the LULI Laboratory (Ecole Polytechnique, Par...

A. Aliverdiev D. Batani V. Malka T. Vinci M. Koenig

2005-01-01

124

Self-Phase Modulation of Laser Light in Laser Produced Plasma.  

National Technical Information Service (NTIS)

A spectrum broadening due to the self phase modulation of a laser light was observed in the laser produced deuterium and hydrogen plasmas. Qualitative treatments of the density modulation due to the self focusing process and the modulational instability w...

C. Yamanaka T. Yamanaka J. Mizui N. Yamaguchi

1975-01-01

125

Time of Flight Mass Spectrometer for the Analysis of Molecular Ions Produced by Plasma Desorption.  

National Technical Information Service (NTIS)

A time of flight spectrometer is described to be used in measurements of molecular mass in the range 1-2000 amu, produced by plasma desorption (induced by a Cf-252 source). (Atomindex citation 17:013505)

G. Bressanini C. Castellano G. Galeazzi G. Prete

1985-01-01

126

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

127

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

128

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 ne10^16cm-3, and lifetimes of 300 ?s.

Howard, Stephen

2010-11-01

129

Emittance of positron beams produced in intense laser plasma interaction  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

130

Resistive Collimation of Electron Beams in Laser-Produced Plasmas  

NASA Astrophysics Data System (ADS)

Intense relativistic electron beams, produced by high-intensity short-pulse laser irradiation of a solid target, have many potential applications including fusion by fast ignition. Using a unique Fokker-Planck code, supported by analytic calculations, we show that fast electrons can be collimated into a beam even when the fast electron source is not strongly anisotropic, and we derive a condition for collimation to occur.

Bell, A. R.; Kingham, R. J.

2003-07-01

131

Soft x-ray amplification in laser-produced recombination plasma  

NASA Astrophysics Data System (ADS)

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

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

1996-05-01

132

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

Microsoft Academic Search

Summary form only given. Results of parallel-plate plasma opening switch (POS) experiments on HAWK are presented. The Hawk generator produces a sinusoidal output current of amplitude ~750 kA and quarter period ~1.2 its. The POS used is a tri-plate with a single cathode and two anode plates, each 15 cm wide. The plasma is injected from plasma guns through slots

R. A. Riley; B. V. Weber; P. J. Goodrich; D. D. Hinshelwood; R. J. Commisso

1995-01-01

133

Time-resolved probing of electron thermal transport in plasma produced by femtosecond laser pulses  

SciTech Connect

We present the first direct evidence for a supersonically moving steep ionization front in a solid density hot plasma. The plasma was produced by irradiating a transparent solid target with 100 fsec laser pulses at a peak intensity of 5[times]10[sup 14] W/cm[sup 2]. Time-resolved measurements of reflectivity, transmissivity, and frequency shift of probe light, incident on the rear of the plasma, showed rapid formation of an overdense plasma layer with a steep gradient that penetrates supersonically into the bulk target. Calculations using a simple nonlinear heat wave model, driven by electron thermal transport, show good agreement with the experimental results.

Vu, B.V.; Szoke, A.; Landen, O.L. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))

1994-06-13

134

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

NASA Astrophysics Data System (ADS)

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.; Sakawa, Y.; Tomita, K.; Ide, T.; Kuramitsu, Y.; Nishio, K.; Nakayama, K.; Inoue, K.; Moritaka, T.; Ide, H.; Kuwada, M.; Tsubouchi, K.; Uchino, K.; Takabe, H.

2013-09-01

135

Properties of a capillary discharge-produced argon plasma waveguide for shorter wavelength source application.  

PubMed

We report the operation of a discharge-produced argon (Ar) plasma waveguide in an alumina (Al(2)O(3)) capillary to guide a 10(16)-W/cm(2) ultrashort laser pulse for shorter wavelength light sources at high repetition rate operation. The electron density in the plasma channel was measured to be 1 10(18) cm(-3). Modeling with a one-dimensional magnetrohydrodynamic code was used to evaluate the degree of ionization of Ar in the preformed plasma channel. The observed spectrum of the laser pulse after propagation in the argon plasma waveguide was not modified and was well reproduced by a particle in cell simulation. PMID:22047296

Sakai, Shohei; Higashiguchi, Takeshi; Bobrova, Nadezhda; Sasorov, Pavel; Miyazawa, Jun; Yugami, Noboru; Sentoku, Yasuhiko; Kodama, Ryosuke

2011-10-01

136

Experimental observations and modeling of nanoparticle formation in laser-produced expanding plasma  

SciTech Connect

Interaction of a laser beam with a target may generate a high velocity expanding plasma plume, solid debris, and liquid nano- and microparticles. They can be produced from plasma recombination, vapor condensation or by a direct expulsion of the heated liquid phase. Two distinct sizes of particles are observed depending on the temperature achieved in the plasma plume: Micrometer-size fragments for temperatures lower than the critical temperature, and nanometer-size particles for higher temperatures. The paper presents experimental observations of fragments and nanoparticles in plasma plumes created from gold targets. These results are compared with theoretical models of vapor condensation and microparticle formation.

Lescoute, E.; Hallo, L.; Chimier, B.; Tikhonchuk, V. T. [CELIA, Universite Bordeaux 1-CNRS-CEA, 351 Cours de la Liberation, 33405 Talence Cedex (France); Hebert, D.; Chevalier, J.-M. [CEA CESTA, BP 2, 33114 Le Barp Cedex (France); Etchessahar, B.; Combis, P. [CEA IDF, BP 12, 91680 Bruyeres Le Chatel (France)

2008-06-15

137

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

138

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

SciTech Connect

The impact of 1.064 mum laser absorption depth on the heating and in-band (2% bandwidth) 13.5 nm extreme ultraviolet emissions in Sn plasmas is investigated experimentally and numerically. In-band emission lasting longer than the laser pulse and separation between the laser absorption and in-band emission region are observed. Maximum efficiency is achieved by additional heating of the core of the plasma to allow the optimal temperature to expand to a lower and more optically thin density. This leads to higher temperature plasma that emits less in-band light as compared to CO{sub 2} produced plasma sources for the same application.

Yuspeh, S.; Sequoia, K. L.; Tao, Y.; Tillack, M. S.; Burdt, R. A.; Najmabadi, F. [Department of Electrical and Computer Engineering, Center for Energy Research, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0417 (United States)

2010-06-28

139

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

SciTech Connect

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

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

2010-01-04

140

Hydrogen ions produced by plasma-assisted catalytic ionization using nickel grid  

NASA Astrophysics Data System (ADS)

Positive and negative hydrogen ions are produced by plasma-assisted catalytic ionization using a nickel grid, where the irradiation current density of positive ions onto the grid can be controlled by the discharge power. The irradiation energy can be controlled by both the grid potential and the discharge plasma potential. Extraction properties and energy distributions of positive and negative ions produced in the cases of using the grid and a porous nickel plate are compared. Two production mechanisms of negative ions are found in the process of plasma-assisted catalytic ionization.

Oohara, W.; Kawata, K.; Hibino, T.

2013-06-01

141

Fueling and Plasma Initiation Tests with a Plasma Gun on the uc(Pegasus) Toroidal Experiment  

Microsoft Academic Search

Developing non-inductive startup and efficient fueling techniques is important for the ultralow-A uc(Pegasus) ST experiment, and the ST concept in general. A single low impurity, high current ( 1 KA) plasma gun( G. Fiksel et al.), Plasma Sources Sci. Technol. 5, 78 (1996). has been installed in the divertor region of uc(Pegasus) to test auxiliary plasma injection and toroidal

N. W. Eidietis; S. P. Burke; G. Fiksel; R. J. Fonck; G. D. Garstka; E. A. Unterberg; G. R. Winz

2004-01-01

142

Time-resolved OES measurement of microwave plasma produced inside controlled bubbles under water  

NASA Astrophysics Data System (ADS)

Plasma generation inside bubbles under liquid has been given much attention because of its potential industrial applications such as water purification, sterilization, materials processing and so on. In our previous study, we have demonstrated that liquid temperature and operating pressure have great influences on the plasma production and decomposition of organic solutes in de-ionized water. However, physical and chemical processes occurring inside the bubbles are still unclear because the plasma is not produced under well-defined experimental conditions. In this work, we have developed a microwave bubble plasma system where reproducible microwave plasma is produced inside size-controlled bubbles. With the aid of this system, temporal variations of He I emission from discharge gas and H or OH emission from water vapor are measured by time-resolved photon-counting technique. After the plasma ignition, He I intensity rapidly increases within less than 100 ns. However, OH and H intensities increase 1 ?s after the plasma ignition. This result suggests that the water vapor is produced by the plasma irradiation on the bubble surface.

Ishijima, Tatsuo; Suzuki, Haruka; Toyoda, Hirotaka

2011-11-01

143

Characterization of ion emission of an extreme ultraviolet generating discharge produced Sn plasma  

SciTech Connect

The ion emission of a Sn-based discharge produced extreme ultraviolet producing plasma is characterized with the combined use of different time-of-flight techniques. An electrostatic ion spectrometer is employed to measure the average charge distribution of the emitted Sn ions. A dedicated Faraday cup configuration is used to measure the total ion flux from the source for different discharge energies. High-energy Sn ions emitted by the plasma with energies up to 100 keV have been identified. The number of high-energy ions increases for higher electrical input energy into the plasma while the signal associated with the expanding plasma ions does not show such dependence. The ion energy distribution for a bulk of detected ions is calculated based on the Faraday cup measurements and compared with theoretical plasma expansion dynamics.

Gielissen, K.; Mullen, J. J. A. M. v. d. [Eindhoven University of Technology, Den Dolech 2, 5600 MB Eindhoven (Netherlands); Sidelnikov, Y. [ISAN Institute of Spectroscopy, Fizicheskaya Str. 5, Troitsk, Moscow Region 142190 (Russian Federation); Glushkov, D.; Banine, V. [ASML, De Run 6501, 5504 DR Veldhoven (Netherlands); Soer, W. A. [Philips Research, High Tech Campus 4, 5656 AE Eindhoven (Netherlands)

2010-01-15

144

Laser wavelength dependence on angular emission dynamics of Nd?:?YAG laser-produced Sn plasmas  

NASA Astrophysics Data System (ADS)

We investigated the laser wavelength effect on angular atomic and ionic emission from laser-produced Sn plasma, since it is regarded as a viable candidate for an EUV lithography source. For producing plasmas, the fundamental, second and fourth harmonics radiation from a Nd?:?YAG laser were used. The angular variation of atomic and ionic particle analysis was carried out using quartz crystal microbalance and Faraday cups by moving them in a circular path at a constant distance from the target normal. Along with atomic and ionic emission, we also compared the plasma emission features in the visible and EUV spectral regions. Results indicate strong forward bias in atomic and ionic plasma debris at all wavelengths. Shorter wavelength plasmas are found to generate more atomic particles while ion flux showed a similar trend irrespective of the excitation wavelength.

Freeman, J. R.; Harilal, S. S.; Verhoff, B.; Hassanein, A.; Rice, B.

2012-10-01

145

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

146

Thomson-scattering measurements in the collective and noncollective regimes in laser produced plasmas (invited)  

SciTech Connect

We present simultaneous Thomson-scattering measurements of light scattered from ion-acoustic and electron-plasma fluctuations in a N{sub 2} gas jet plasma. By varying the plasma density from 1.5x10{sup 18} to 4.0x10{sup 19} cm{sup -3} and the temperature from 100 to 600 eV, we observe the transition from the collective regime to the noncollective regime in the high-frequency Thomson-scattering spectrum. These measurements allow an accurate local measurement of fundamental plasma parameters: electron temperature, density, and ion temperature. Furthermore, experiments performed in the high densities typically found in laser produced plasmas result in scattering from electrons moving near the phase velocity of the relativistic plasma waves. Therefore, it is shown that even at low temperatures relativistic corrections to the scattered power must be included.

Ross, J. S.; Pollock, B. B. [Lawrence Livermore National Laboratory, University of California, P.O. Box 808, Livermore, California 94551 (United States); Department of Mechanical and Aerospace Engineering, University of California at San Diego, 9500 Gilman Drive, La Jolla, California 92093-0411 (United States); Glenzer, S. H.; Price, D.; Froula, D. H. [Lawrence Livermore National Laboratory, University of California, P.O. Box 808, Livermore, California 94551 (United States); Palastro, J. P. [Institute for Research in Electronics and Applied Physics, College Park, Maryland 20740 (United States); Tynan, G. R. [Department of Mechanical and Aerospace Engineering, University of California at San Diego, 9500 Gilman Drive, La Jolla, California 92093-0411 (United States)

2010-10-15

147

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

148

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

149

Single-shot microscopic electron imaging of intense femtosecond laser-produced plasmas  

SciTech Connect

A simple technique for single-shot microscopic electron imaging was demonstrated for the study of intense femtosecond laser-produced plasmas. Passed through a permanent magnet lens designed for 110-keV electrons, hot electrons emitted from the plasma produced by a single laser pulse of 0.8 mJ with intensity of 3 x 10{sup 16} W/cm{sup 2} were successfully imaged. Analyzing this image, we found that electrons were emitted from an area of 3 {mu}m in diameter. At higher laser intensity of 10{sup 18} W/cm{sup 2}, distinct structures were observed in and near the focal spot of the laser; that is, the electrons were emitted from several separate spots. These results show that laser-plasma electron imaging is promising for studying the interactions of femtosecond lasers with high-density plasmas.

Inoue, Shunsuke; Tokita, Shigeki; Nishoji, Toshihiko; Masuno, Shinichiro; Otani, Kazuto; Hashida, Masaki; Sakabe, Shuji [Department of Physics, Graduate School of Science, Kyoto University Kitashirakawa, Sakyo, Kyoto 606-8502 (Japan) and Advanced Research Center for Beam Science, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

2010-12-15

150

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

151

Experimental and theoretical investigations of a laser-produced aluminum plasma.  

PubMed

The formation and dynamics of a laser-produced aluminum plasma have been experimentally and theoretically investigated. The visible-emitting regions of the plasma form two structures with different lifetimes and expansion velocities. The first part of the transient ionic signal simultaneously recorded by a Langmuir probe presents an oscillatory structure. A hydrodynamic model in a nondifferentiable space-time has been established. The numerical simulation of the plasma expansion showed the plasma plume separation into two patterns. Moreover, the self-structuring of the interface appears through a negative differential conductance and the current oscillations are explained as being induced by thermal fluctuations that appear in the plasma cooling processes. PMID:18850944

Gurlui, S; Agop, M; Nica, P; Ziskind, M; Focsa, C

2008-08-13

152

Characterization of single and colliding laser-produced plasma bubbles using Thomson scattering and proton radiography  

NASA Astrophysics Data System (ADS)

Time-resolved measurements of electron and ion temperatures using Thomson scattering have been combined with proton radiography data for comprehensive characterization of individual laser-produced plasma bubbles or the interaction of bubble pairs, where reconnection of azimuthal magnetic fields occurs. Measurements of ion and electron temperatures agree with lasnex simulations of single plasma bubbles, which include the physics of magnetic fields. There is negligible difference in temperatures between a single plasma bubble and the interaction region of bubble pairs, although the ion temperature may be slightly higher due to the collision of expanding plasmas. These results are consistent with reconnection in a ?8 plasma, where the release of magnetic energy (<5% of the electron thermal energy) does not appreciably affect the hydrodynamics.

Rosenberg, M. J.; Ross, J. S.; Li, C. K.; Town, R. P. J.; Sguin, F. H.; Frenje, J. A.; Froula, D. H.; Petrasso, R. D.

2012-11-01

153

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

NASA Astrophysics Data System (ADS)

The purpose of the Fluxus-1 and -2 active experiments is to study plasma jets injected parallel to the magnetic field and to study the interaction of these jets with the magnetic field. The experiments were conducted using a shaped-charge device, known as an explosive type generator (ETG), that produced an artificial aluminum plasma jet. In Fluxus-1 and -2 the jet was injected nearly parallel to the geomagnetic field at an altitude of 140 km toward an instrumented diagnostic payload located about 100 m away from the ETG. A ?50% reduction in the magnetic field was observed as the plasma jet passed by the diagnostic payload. Comparisons of 3-dimensional simulation results with the observed magnetic field perturbations suggest that the Fluxus-1 plasma jet was ?30 from the magnetic field direction while the Fluxus-2 plasma jet was directed nearly parallel to the magnetic field.

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

154

Experimental evidence of Langmuir-wave-caused features in spectral lines of laser-produced plasmas  

Microsoft Academic Search

The structures observed in profiles of the L? line of Al XIII emitted from the laser-produced plasma are identified as the Langmuir-wave-caused dips (L-dips). Hitherto, the L-dips were found in hydrogen and deuterium spectral lines only; we report the first experiment dedicated to their identification in higher-Z plasmas. The L-dip phenomenon has a fundamental importance as a nonlinear dynamic-resonance effect

O. Renner; E. Dalimier; E. Oks; F. Krasniqi; E. Dufour; R. Schott; E. Frster

2006-01-01

155

Observation of motional Doppler decoupling effect in a 10 ps KrF laser produced plasma  

SciTech Connect

Observation of reduction of opacity in a 10 ps KrF laser produced plasma is reported. The opacity of Ly{beta} line is estimated from the line intensity ratio to H{alpha} line. The opacity nearer to the target surface was lower. The reduction of the opacity is considered to have been caused by velocity gradient of the plasma blow-off.

Miura, E.; Tomie, T.; Okuda, I.; Owadano, Y. [Electrotechnical Laboratory, 1-1-4 Umezono, Tsukuba, Ibaraki, 305 (Japan)

1995-05-01

156

Generation of electron-beam produced plasmas and applications to surface modification  

Microsoft Academic Search

NRL has developed a number of hollow cathodes to generate sheets of electrons culminating in a Large Area Plasma Processing System (LAPPS) based on the electron-beam ionization process. Beam ionization is fairly independent of gas composition and produces low temperature plasma electrons (<0.5 eV in molecular gases) in high densities (1091012 cm?3). The present system consists of a pulsed planar

D. Leonhardt; C. Muratore; S. G. Walton; D. D. Blackwell; R. F. Fernsler; R. A. Meger

2004-01-01

157

Self-sustained plasma waveguide structures produced by ionizing laser radiation in a dense gas  

Microsoft Academic Search

The propagation of high-power laser radiation producing rapid ionization in a dense gas is analyzed by using a nonlinear electrodynamical model. It is shown that the interplay between the Kerr-type and the defocusing ionization nonlinearities may lead to the formation of self-sustained plasma waveguide filaments. Quasi-steady-state laser-plasma structures supported by various electromagnetic field configurations are considered.

D. Anderson; A. V. Kim; M. Lisak; V. A. Mironov; A. M. Sergeev; L. Stenflo

1995-01-01

158

Oxygen radicals produced by plant plasma membranes: an EPR spin-trap study  

Microsoft Academic Search

Plant plasma membranes are known to produce super- oxide radicals, while the production of the hydroxyl radical, previously detected in complex plant tissues, is thought to occur in the cell wall. The mechanism of production of superoxide radicals by plant plasma mem- branes is, however, under dispute. It is shown, using electron paramagnetic resonance spectroscopy with a 5- diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide

Mirjana Vuletic ; Goran G. Bacic; Zeljko Vucinic

159

The electron temperature and density diagnostic of Laser-produced Plasma  

NASA Astrophysics Data System (ADS)

X-ray spectroscopic methods for the determination of electron temperature and density of Laser-produced Plasma are reviewed. The experiment results are as follows: (i) The electron temperature and density distribution of the foam Al target surface was determined by trace element Al;(ii) The electron temperature of the radiation region of CH target was determined by trace element C; (iii) The electron temperature of Au Plasma was determined by trace element Mg/Al.

Wang, Hongbin; Li, Sanwei; Cheng, Bo

2000-10-01

160

On the fitting of displaced Maxwellians to laser-produced plasma ion velocity distributions  

Microsoft Academic Search

The empirical fitting of displaced Maxwellians to ion velocity distributions measured at some distance from the target in laser-produced plasma studies is shown to lack a theoretical basis. A similar ion velocity spectrum to a displaced Maxwellian is obtained if a simple self-similar plasma expansion is assumed. The discussion is illustrated by experimental ion velocity distributions measured at 0.8 m

G. J. Tallents

1981-01-01

161

Development of Detectors for Measurement of Neutron and Gammaradiation from Laser-Produced Plasma  

Microsoft Academic Search

The paper describes the development of the detectors widely used in the nuclear physics for measurement of neutron and gamma-radiation in laser-produced plasma. Under investigation is plasmas generated by action on solid-state target by radiation from picosecond terawatt Nd-glass laser having intensity of 10 to the power 16 10 to the power 18 Watt per centimeter squared. Peculiarities of such

Anatoly Matafonov

2000-01-01

162

Modeling Study of Asymmetric Plasma Properties Produced by Pumping and Gas Injection in Inductively Coupled Plasmas  

NASA Astrophysics Data System (ADS)

The trend towards operating with lower gas pressures for plasma processing is partly motivated by the desire to operate in a "diffusive" environment with the goal of obtaining more uniform reactant fluxes to the substrate. Based on the premise that reactant transport is dominantly diffusive, low pressure, high plasma density reactors often use azimuthally asymmetric gas injection and pumping. In this paper, the consequences of asymmetric gas injection and pumping on the uniformity of reactant fluxes in inductively coupled plasma reactors are computationally investigated using a 3-dimensional plasma equipment model. Cl2 and Ar/SiH4 gas mixtures are studied as examples of etching and deposition systems while injecting gas from discrete nozzles with side or symmetrical pumping. We found that under nominal operating conditions (10 mTorr, 400 W, 150 sccm) fluxes of ions to the wafer are little affected by asymmetric gas injection and pumping due to the dominance of ambipolar transport. Reactant fluxes to the substrate, such as Cl, can display significant asymmetries, which worsen with increasing pressure and increasing reactive sticking coefficient.

Keiter, Eric; Kushner, Mark J.

1997-10-01

163

Initial growth process of carbon nanowalls synthesized by radical injection plasma-enhanced chemical vapor deposition  

Microsoft Academic Search

We synthesized carbon nanowalls (CNWs) using radical injection plasma-enhanced chemical vapor deposition. The initial growth process of CNWs was investigated with and without O2 gas addition to a C2F6 capacitively coupled plasma with H radical injection. In the case of the CNW synthesis without the addition of O2 gas, scanning electron microscopy (SEM), transmission electron microscopy, x-ray photoelectron spectroscopy (XPS),

Shingo Kondo; Shinji Kawai; Wakana Takeuchi; Koji Yamakawa; Shoji den; Hiroyuki Kano; Mineo Hiramatsu; Masaru Hori

2009-01-01

164

Relativistic stimulated Brillouin and Raman scattering in a laser-produced plasma  

NASA Astrophysics Data System (ADS)

An investigation is made of the relativistic effect on the nonlinear stimulated scattering of large-amplitude laser radiation in the presence of the self-generated magnetic field in a laser-produced plasma. The relativistic Vlasov equation expressed in terms of the guiding-center coordinates has been solved to obtain the response of the magnetized plasma electrons. It is noted that the extreme relativistic effect increases the growth rates of the stimulated scattering by a factor of c/ve, where c and ve are the free-space speed of light and thermal velocity of the plasma electrons.

Salimullah, M.; Hassan, M. H. A.

1990-06-01

165

Refraction effects on x-ray and ultraviolet interferometric probing of laser-produced plasmas  

NASA Astrophysics Data System (ADS)

We present a study detailing the effects of refraction on the analysis and interpretation of line-of-site optical probe characterization techniques within laser-produced plasmas. Results using x-ray laser backlit grid deflectometry and ray-tracing simulations illustrate the extent to which refraction can be a limiting factor in diagnosing high-density, short-scale-length plasmas. Analysis is applied to a recent experiment in which soft-x-ray interferometry was used to measure the electron density within a fast-evolving Al plasma. Comparisons are drawn between extreme ultraviolet and ultraviolet probe wavelengths.

Smith, Raymond F.; Dunn, James; Nilsen, Joseph; Hunter, James R.; Shlyaptsev, Vyacheslev N.; Rocca, Jorge J.; Filevich, Jorge; Marconi, Mario C.

2003-01-01

166

Scalable THz generation in two-color laser-produced plasma  

NASA Astrophysics Data System (ADS)

We report ultrafast, high-power terahertz (THz) generation in two-color laser-produced plasmas. For scalable THz generation, we have studied two schemes---long (one-dimensional) and fat (two-dimensional) plasma filamentation. In the case of long filament formation, we observe phase-matched THz generation, which occurs naturally due to off-axis constructive interference between locally produced THz waves. This emits conical THz radiation in the off-axis direction, peaked at 47 degrees depending on the radiation frequencies. In this case, the total THz yield increases almost linearly with the filament length. Because of this, one can effectively increase THz output energy by simply extending the filament length. This overcomes the saturation effect previously reported, mainly caused by overdense plasma creation and laser intensity clamping in filamentation. In addition, we observe THz polarization rotation and control along long plasma filaments. In the second scheme, a cylindrical lens is used to produce two-dimensional plasma sheets. This also provides a simple method for scalable THz generation with enhanced plasma volume and coherent THz field addition.

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

2012-10-01

167

Impact of cranberry juice on initial adhesion of the EPS producing bacterium Burkholderia cepacia.  

PubMed

The impact of cranberry juice was investigated with respect to the initial adhesion of three isogenic strains of the bacterium Burkholderia cepacia with different extracellular polymeric substance (EPS) producing capacities, viz. a wild-type cepacian EPS producer PC184 and its mutant strains PC184rml with reduced EPS production and PC184bceK with a deficiency in EPS production. Adhesion experiments conducted in a parallel-plate flow chamber demonstrated that, in the absence of cranberry juice, strain PC184 had a significantly higher adhesive capacity compared to the mutant strains. In the presence of cranberry juice, the adhesive capacity of the EPS-producing strain PC184 was largely reduced, while cranberry juice had little impact on the adhesion behavior of either mutant strain. Thermodynamic modeling supported the results from adhesion experiments. Surface force apparatus (SFA) and scanning electron microscope (SEM) studies demonstrated a strong association between cranberry juice components and bacterial EPS. It was concluded that cranberry juice components could impact bacterial initial adhesion by adhering to the EPS and impairing the adhesive capacity of the cells, which provides an insight into the development of novel treatment strategies to block the biofilm formation associated with bacterial infection. PMID:22554250

Yang, Xuejiao; Teng, Fucheng; Zeng, Hongbo; Liu, Yang

2012-01-01

168

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

169

Initiation of an early-stage plasma during picosecond laser ablation of solids  

SciTech Connect

Picosecond time-resolved images of plasma initiation were recorded during pulsed-laser ablation of metal targets in an air atmosphere. An early-stage plasma was observed to form before the release of a material vapor plume. Close to the target surface, interferometry measurements indicate that the early-stage plasma has an electron number density on the order of 10{sup 20}cm{sup -3}. The longitudinal expansion of the ionization front for this plasma has a velocity 10{sup 9}cm/s, during the laser pulse. In contrast, a material--vapor plume forms approximately 200 ps after the laser pulse, and it moves away from the target at 10{sup 6}cm/s. The experimental observations of the early-stage plasma were simulated by using a theoretical model based on a two-fluids description of laser plasmas. The results indicate that the initiation of the plasma is due to air breakdown assisted by electron emission from the target.

Mao, Samuel S.; Mao, Xianglei; Greif, Ralph; Russo, Richard E.

2000-10-16

170

A phosphopantetheinylating polyketide synthase producing a linear polyene to initiate enediyne antitumor antibiotic biosynthesis  

PubMed Central

The enediynes, unified by their unique molecular architecture and mode of action, represent some of the most potent anticancer drugs ever discovered. The biosynthesis of the enediyne core has been predicted to be initiated by a polyketide synthase (PKS) that is distinct from all known PKSs. Characterization of the enediyne PKS involved in C-1027 (SgcE) and neocarzinostatin (NcsE) biosynthesis has now revealed that (i) the PKSs contain a central acyl carrier protein domain and C-terminal phosphopantetheinyl transferase domain; (ii) the PKSs are functional in heterologous hosts, and coexpression with an enediyne thioesterase gene produces the first isolable compound, 1,3,5,7,9,11,13-pentadecaheptaene, in enediyne core biosynthesis; and (iii) the findings for SgcE and NcsE are likely shared among all nine-membered enediynes, thereby supporting a common mechanism to initiate enediyne biosynthesis.

Zhang, Jian; Van Lanen, Steven G.; Ju, Jianhua; Liu, Wen; Dorrestein, Pieter C.; Li, Wenli; Kelleher, Neil L.; Shen, Ben

2008-01-01

171

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

DOEpatents

Method and apparatus for generating x-rays for use in, for instance, x-ray photolithography is disclosed. The method of generating x-rays includes the steps of providing a target and irradiating the target with a laser system which produces a train of sub-pulses to generate an x-ray producing plasma. The sub-pulses are of both high intensity and short duration. The apparatus for generating x-rays from a plasma includes a vacuum chamber, a target supported within the chamber and a laser system, including a short storage time laser. 8 figs.

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

1992-12-29

172

Initial plasma of a magnetically insulated ion diode in bipolar-pulse mode  

SciTech Connect

Initial anode plasma formation in a magnetically insulated ion diode (MID) of bipolar-pulse mode with self-magnetic field is studied for high-intensity pulsed ion beam generation in TEMP-6-type apparatus [X. P. Zhu, M. K. Lei, and T. C. Ma, Rev. Sci. Instrum. 73, 1728 (2002)]. The field emission characteristics on graphite anode, the self-magnetic field, the perveance, and the impedance of the MID are obtained by analysis of the time-dependent diode voltage-current characteristics during the initial negative pulse stage of 100 ns, with peak values of 250 kV and 30 kA, respectively. The anode plasma is initiated by explosive emission on the anode due to a significant field enhancement effect up to four orders of magnitude, and the subsequent merging and movement of the anode plasma are affected by the superimposing space-charge effect and magnetic insulation of the self-magnetic field. The formation process of the initial anode plasma in the MID corresponds to the diode response under the initial negative pulse of the bipolar pulse.

Xin, J. P.; Zhu, X. P.; Lei, M. K. [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)

2008-12-15

173

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

Microsoft Academic Search

We have investigated the growth kinetics of plasma-enhanced Ti atomic layer deposition (ALD) using a quartz crystal microbalance. Ti ALD films were grown at temperatures from 20 to 200 C using TiCl4 as a source gas and rf plasma-produced atomic H as the reducing agent. Postdeposition ex situ chemical analyses of thin films showed that the main impurity is oxygen,

H. Kim; S. M. Rossnagel

2002-01-01

174

Interferometric investigation of shock waves induced by a TEA-CO/sub 2/ laser-produced plasma in air in front of a solid target  

SciTech Connect

The shock waves induced in the surrounding atmosphere by an air plasma were investigated by laser interferometry. The air-breakdown plasma was produced by a TEA-CO/sub 2/ laser in front of a solid target. The results were compared to the predictions of the theory of intense explosions in gases and a good agreement was inferred. It was also determined that the symmetry of the expansion of the initial shock wave is determined by the plasma-source shape and, accordingly, depends on the laser power density incident on the target surface. However, for further stages all the shock waves expand spherically.

Apostol, D.; Apostol, I.; Cojocaru, E.; Draganescu, V.; Mihailescu, I.N.; Morjan, I.; Konov, V.I.

1980-02-01

175

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

NASA Astrophysics Data System (ADS)

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

Popil, Roman Ewhen

176

Characteristics of THz emission from a femtosecond-laser produced dense plasma  

NASA Astrophysics Data System (ADS)

Recently, the THz radiation from a femtosecond-laser-produced dense plasma have been studied. The short electromagnetic pulse in THz spectral region emits by the interaction between a laser wakefield in a static magnetic field. The magnetized wakefield has both electrostatic and electromagnetic components, and has nonzero group velocity. This enables the wake to propagate through the plasma and couples radiation into the vacuum. This phenomenon is called the Cherenkov wake radiation, and the emitted frequency is expected to be close to the plasma frequency. The theory predicts the production of GHz to THz radiation at a power approaching GW level by using the wakefield excited by current laser systems and the appropriate magnetic field. We demonstrated a proof-of-principle experiment of a Cherenkov wake radiation from the femtosecond-laser-produced magnetized wakefield. A maximum frequency up to 0.3 THz with a pulse width of 200 ps (FWHM) was observed. In addition, we also observed an angular distribution of the radiation, which has an annular cone profile at far-field attributed TM01 mode in a plasma. In addition, we also show the development of an electro-optic (EO) sampling system for detecting coherent THz emission from a laser-produced dense plasma.

Yugami, Noboru; Ninomiya, Kenichi; Saito, Tomonobu; Li, Kun; Higahiguchi, Takeshi

2006-10-01

177

Development of Detectors for Measurement of Neutron and Gamma-radiation from Laser-Produced Plasma  

NASA Astrophysics Data System (ADS)

The paper describes the development of the detectors widely used in the nuclear physics for measurement of neutron and gamma-radiation in laser-produced plasma. Under investigation is plasmas generated by action on solid-state target by radiation from picosecond terawatt Nd-glass laser having intensity of 10 to the power 16 10 to the power 18 Watt per centimeter squared. Peculiarities of such plasmas have called for modernization of conventional methods and detectors for measurement of neutron and gamma-radiation. Diagnostic methods imply use of scintillation counters based on stilbene crystal, scintillation gamma-spectrometer based on NaI(Tl) crystal and proportional counters based on He III. The paper as well presents results of the experimental investigation on generation of gamma-quanta and neutrons in laser-produced plasma. The experimental methods and detectors described in the paper provide a basis for studies on a wide spectrum of atomic and nuclear processes going in the laser-produced dense plasmas. The present work was supported by International Science and Technology Center under Project number 856.

Matafonov, Anatoly

2000-03-01

178

Residual stresses in plasma electrolytic oxidation coatings on Al alloy produced by pulsed unipolar current  

Microsoft Academic Search

Plasma electrolytic oxidation (PEO) coatings have been produced on aluminium substrates using a pulsed unipolar current mode at different duty cycle and frequency, along with reference samples produced using direct current. Residual stresses attributed to the ?-Al2O3 constituent of the coating have been evaluated by X-ray diffraction using the Sin2? method. It is found that compressive normal and shear stresses

R. H. U. Khan; A. L. Yerokhin; T. Pilkington; A. Leyland; A. Matthews

2005-01-01

179

X-ray Laser Satellites from Subpicosecond Laser-Produced Plasma  

Microsoft Academic Search

We measure experimentally previously unobserved x-ray lines that are produced during the interaction high-intensity subpicosecond laser pulses (400 fs, 2J, 10^18 W\\/cm^2) with solid targets. These satellites are the result of the nonlinear interaction of the intense laser field with the plasma, which produces new spectral line in keV region around parity-forbidden transitions B^* arrow B of the multiply charged

A. Maksimchuk; M. Nantel; G. Ma; D. Umstadter; S. A. Pikuz; I. Yu. Skobelev; A. Ya. Faenov

1998-01-01

180

Single-walled carbon nanotubes produced by plasma-enhanced chemical vapor deposition  

Microsoft Academic Search

Single-walled carbon nanotubes (SWNTs) are produced for the first time using plasma-enhanced chemical vapor deposition method. In this method, not only SWNTs in the form of thin bundles but also individually grown SWNTs are produced at a quite low-synthesis temperature (550 C). According to analyses by field emission gun transmission electron microscopy and Raman scattering spectroscopy, it is conjectured that

Toshiaki Kato; Goo-Hwan Jeong; Takamichi Hirata; Rikizo Hatakeyama; Kazuyuki Tohji; Kenichi Motomiya

2003-01-01

181

Properties of a capillary discharge-produced argon plasma waveguide for shorter wavelength source application  

SciTech Connect

We report the operation of a discharge-produced argon (Ar) plasma waveguide in an alumina (Al{sub 2}O{sub 3}) capillary to guide a 10{sup 16}-W/cm{sup 2} ultrashort laser pulse for shorter wavelength light sources at high repetition rate operation. The electron density in the plasma channel was measured to be 1 x 10{sup 18} cm{sup -3}. Modeling with a one-dimensional magnetrohydrodynamic code was used to evaluate the degree of ionization of Ar in the preformed plasma channel. The observed spectrum of the laser pulse after propagation in the argon plasma waveguide was not modified and was well reproduced by a particle in cell simulation.

Sakai, Shohei; Miyazawa, Jun [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); 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); 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)

2011-10-15

182

Dynamics of C{sub 2} formation in laser-produced carbon plasma in helium environment  

SciTech Connect

We investigated the role of helium ambient gas on the dynamics of C{sub 2} species formation in laser-produced carbon plasma. The plasma was produced by focusing 1064 nm pulses from an Nd:YAG laser onto a carbon target. The emission from the C{sub 2} species was studied using optical emission spectroscopy, and spectrally resolved and integrated fast imaging. Our results indicate that the formation of C{sub 2} in the plasma plume is strongly affected by the pressure of the He gas. In vacuum, the C{sub 2} emission zone was located near the target and C{sub 2} intensity oscillations were observed both in axial and radial directions with increasing the He pressure. The oscillations in C{sub 2} intensity at higher pressures in the expanding plume could be caused by various formation zones of carbon dimers.

Al-Shboul, K. F.; Harilal, S. S.; Hassanein, A.; Polek, M. [School of Nuclear Engineering and Center for Materials Under Extreme Environment, Purdue University, 400 Central Dr., West Lafayette, Indiana 47907 (United States)

2011-03-01

183

Spectroscopic system for emission and absorption studies of laser produced plasmas in the extreme ultraviolet  

SciTech Connect

The experimental characterization of a stigmatic spectroscopic system for the diagnostics of laser-produced plasmas in the 50-450 A spectral region is presented. The instrument provides stigmatic spectra for on-axis sources and fully preserves spectral resolution also for off-axis sources. Expected theoretical performances have been compared with experimental results. Spectral and spatial resolution capabilities have been proved to match the nominal ones theoretically predicted. A laser-produced plasma experiment has been also carried out to demonstrate the instrument capabilities. The use of a stigmatic spectrometer and an image detector gives spectrally and spatially resolved images of the plasma source. The good instrumental sensitivity and high dynamic range allow to acquire complete spectra in almost single-shot experiments.

Nicolosi, P.; Pelizzo, M.-G.; Poletto, L.; Epulandi, L. [INFM Laboratory for Ultraviolet and X-Ray Optical Research, Department of Information Engineering, University of Padova, Padova (Italy)

2005-08-15

184

Similarity of Skeletal Structures Observed in Laser-Produced Plasmas and High-Current Electric Discharges  

NASA Astrophysics Data System (ADS)

The paper reports on the presence of skeletal structures in the filtered x-ray pinhole images of plasma corona produced in former experiments [1] on irradiating the foils by a pulsed laser beam. These structures are shown to be similar to tubular and cartwheel-like structures previously found [2] in the visible light images of the plasma in various fusion plasmas (Z-pinch, plasma focus, tokamak). Such topological identity allows to draw a parallel between laser-produced plasmas and electric breakdown stage of various high-current electric discharges. This allows, in turn, to extend to the case of laser-produced plasmas some points of the hypothesis [3] which suggested the probable necessity to go beyond the frame of classical electrodynamics in describing the long-range (macroscopic) correlations/bonds in a broad range of plasmas. REFERENCES [1] Bolshov L.A., et. al., Sov. Phys. JETP 65 (1987) 1160; Burdonskii I.N., et. al., Laser and Part. Beams, 6(2) (1988) 327. [2] Kukushkin A.B., Rantsev-Kartinov V.A., Proc. 27-th EPS PPCF (2000) p2-029 p2-028 p2-051. [3] Kukushkin A.B., Rantsev-Kartinov V.A., Fusion Energy 1998 (IAEA, Vienna, 1999, IAEA-CSP-1/P, Vol. 3) p.1131; Proc. 26-th EPS PPCF (1999) p2-087.

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

2001-10-01

185

Patterning of Thick Parylene Films by Oxygen Plasma for Application as Exploding Foil Initiator Flyer Material.  

National Technical Information Service (NTIS)

Parylene is an attractive flyer material for the exploding foil initiator due to its superior conformal step coverage and inert properties. A process for patterning thick films of Parylene using a thin metal masking layer and oxygen plasma has been develo...

E. Zakar M. D. Grapes

2009-01-01

186

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

Microsoft Academic Search

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

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

2010-01-01

187

Influence of laser satellite transitions on spectroscopy of high-intensity laser-produced plasmas  

Microsoft Academic Search

The oscillating electromagnetic field of an intense laser pulse can significantly affect the emission properties of ions in a plasma. For sufficiently intense laser fields, induced second order processes produce discrete radiative transitions. In addition, these induced radiative processes alter the level population kinetics, and the spectrum of spontaneous transitions. We discuss the effects of these processes on the n

A. L. Osterheld; B. K. F. Young; J. Dunn; R. E. Stewart; I. Yu. Skobelev; A. Ya. Faenov; A. I. Magunov

1997-01-01

188

Towards laboratory-produced relativistic electron-positron pair-plasmas  

SciTech Connect

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 last 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{sup 16} cm{sup -3} and 10{sup 13} cm{sup -3}, respectively. With the advent of high-energy ultra-short laser pulses, we expect that a charge-neutral, relativistic pair-plasma is achievable, a novel regime of laboratory-produced hot dense matter. This talk will present some details of the laser-produced pair-plasma experiments.

Chen, H; Wilks, S C; Meyerhofer, D D; Beiersdorfer, P; Cauble, R; Dollar, F; Falk, K; Hazi, A; Murphy, C D; Park, J; Seely, J; Szabo, C I; Shepherd, R; Tommasini, R; Zulick, K

2010-08-31

189

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

Microsoft Academic Search

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

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

2006-01-01

190

Laser produced plasmas in Hg: a source of pulsed XUV radiation  

SciTech Connect

The authors used a laser produced plasma in Hg to generate pulsed XUV radiation which is widely tunable from 900A to shorter than 300A. Preliminary estimates of the power exiting the slits of a 1 meter normal incidence XUV monochromator is approximately 5 x 10/sup 3/ photons/shot/A at 10 pps. at 500A.

Jopson, R.M.; Freeman, R.R.; Bokor, J.

1982-01-01

191

Experimental investigations of multicharged ion fluxes from laser-produced plasmas  

Microsoft Academic Search

A summary of experimental investigations of multicharged ions in the far expansion zone at about 23 m, generated from laser-produced plasmas, is presented. The results have been obtained on different laser systems with different wavelengths ?, laser pulse lengths ? and laser energies E. As the targets, the following materials have been used: Al, Cu, Fe, Mo, Ta, Pt, and

W. Mrz; P. Parys; J. Wo?owski; E. Woryna; L. Lska; K. Maek; K. Rohlena; J. Collier; H. Haseroth; H. Kugler; K. L. Langbein; O. B. Shamaev; B. Yu. Sharkov; A. V. Shumshurov

1996-01-01

192

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

SciTech Connect

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

Aliverdiev, A. [Institute of Physics of Daghestan Scientific Center of Russian Academy of the Science, 367003, Russia, Daghestan, Makhachkala, 94 Yaragskogo Street (Russian Federation); Dipartimento di Fisica 'G. Occhialini', Universita degli Studi di Milano, Bicocca (Italy); International Humanitarian and Technical Academy, Russia, Daghestan, Makhachkala, 4 Komarova Street (Russian Federation); Batani, D.; Dezulian, R. [Dipartimento di Fisica 'G. Occhialini', Universita degli Studi di Milano, Bicocca (Italy); Malka, V. [Laboratoire d'Optique Appliquee, UMR CNRS - ENSTA - Ecole Polytechnique, Palaiseau (France); Vinci, T. [Dipartimento di Fisica 'G. Occhialini', Universita degli Studi di Milano, Bicocca (Italy); Laboratore pour l'Utilisation des Lasers Intenses (LULI), UMR, 7605, CNRS CEA -- Universite Paris VI - Ecole Polytechnique, 91128 Palaiseau Cedex (France); Koenig, M.; Benuzzi-Mounaix, A. [Laboratore pour l'Utilisation des Lasers Intenses (LULI), UMR, 7605, CNRS CEA - Universite Paris VI - Ecole Polytechnique, 91128 Palaiseau Cedex (France)

2005-05-16

193

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

194

Effect of Different Initial Conditions on the Evolution of the E X B Gradient Drift Instability in Ionospheric Plasma Clouds.  

National Technical Information Service (NTIS)

Both small and large amplitude monochromatic (one wave) and random (many waves) initial perturbations have been used to seed initially slablike plasma clouds with different magnetic field line integrated Pedersen conductivity gradient scale lengths L = 4,...

M. J. Keskinen S. L. Ossakow

1981-01-01

195

Work function dependence of surface produced H/sup -/ in the presence of a plasma  

SciTech Connect

The maximum H/sup -/ flux from a netatively biased converter cathode occurs at the work function minimum. A cesiated hydrogen plasma produces a partially-cesiated surface at the converter. The cesium coverage can be be controlled by the cesium partial pressure, the bias on the converter and the plasma density, while the work function of the converter surface is measured by the photo-electric effect, using a bright light source and a series of filters. The angular dependence is measured by rotating the converter.

Wada, M.; Pyle, R.V.; Stearns, J.W.

1983-11-01

196

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

SciTech Connect

We studied the spatial and temporal distributions of ionic, neutral, and molecular species generated by femtosecond laser produced plasma under varying ambient nitrogen gas pressures. Plasmas were generated by irradiating planar graphite targets using 40 fs pulses of 800 nm radiation from a Ti:Sapphire laser. The results show that in the presence of an ambient gas, the molecular species spatial extension and lifetime are directly correlated to the evolution of excited ions. The present studies also provide valuable insights into the evolution history of various species and their excitation during ultrafast laser ablation.

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

2012-05-28

197

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

NASA Astrophysics Data System (ADS)

Emission of multiply charged ions and soft x-rays from the plasmas produced by laser pulses focused on (111) surface of Fe and Fe-2 mass % Si single crystals is investigated for wavelengths of 1064 and 248 nm and intensities up to ~11010 W/cm2. It is demonstrated that the Si admixture in the Fe plasma results in a higher emission of Feq+ ions (1<=q<=4) but in a markedly lower x-ray emission. The relation of wavelengths and pulse durations of laser beams used is figured in the fluence dependence of the ion emission.

Krsa, Josef; Lska, Leo; Rohlena, Karel; Velyhan, Andriy; Lorusso, Antonella; Nassisi, Vincenzo; Czarnecka, Agata; Parys, Piotr; Ry?, Leszek; Wolowski, Jerzy

2008-11-01

198

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

SciTech Connect

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

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

2011-10-17

199

Stigmatic observations of laser-produced plasmas with a grazing-incidence spectrograph  

SciTech Connect

A stigmatic spectrograph composed of a toroidal mirror and a concave grating both working at grazing incidence has been built and applied to the observation of laser-produced plasmas. Spatial resolution of 20--30 ..mu..m over a region of 1-mm extension and spectral resoltuion of approx. =1500 have been obtained with a considerable increase in speed of the spectrograph. By varying the relative positions of the optical elements, it is possible to change the wavelength of sigmatic condition in the range 10--300 A. Examples of observations of a beryllium plasma are shown.

Jannitti, E.; Nicolosi, P.; Tondello, G.

1979-06-01

200

Density profile of the ablating plasma produced by soft x-ray irradiation  

NASA Astrophysics Data System (ADS)

Indirect/direct-hybrid irradiation has been proposed for suppressing the initial imprint of laser-irradiation nonuniformities. Indirect soft x-ray preirradiation of the target generates a plasma expansion layer on the target surface. When the drive laser beam comes later, the target has a substantial stand-off distance between the ablation front and the beam absorption region, in which the thermal smoothing effect is expected to take place, and then, the initial imprint of the laser irradiation nonuniformities can be significantly reduced. Stand-off distance is of great importance in the imprint mitigation. We measured the preformed plasma profile by using the x-ray side-on backlighting method. The preformed plasma was backlit by x rays and imaged onto an x-ray streak camera. The scale length of the preformed plasma was found to increase with duration of the soft x-ray irradiation. The expansion velocity was found to be 6105 cm/s at an x-ray irradiation of 11011 W/cm2.

Nishikino, M.; Shiraga, H.; Matsuoka, M.; Fujioka, S.; Shigemori, K.; Nakai, M.; Azechi, H.; Miyanaga, N.; Yamanaka, T.; Nakai, S.

2001-01-01

201

Density profile of the ablating plasma produced by soft x-ray irradiation  

Microsoft Academic Search

Indirect\\/direct-hybrid irradiation has been proposed for suppressing the initial imprint of laser-irradiation nonuniformities. Indirect soft x-ray preirradiation of the target generates a plasma expansion layer on the target surface. When the drive laser beam comes later, the target has a substantial stand-off distance between the ablation front and the beam absorption region, in which the thermal smoothing effect is expected

M. Nishikino; H. Shiraga; M. Matsuoka; S. Fujioka; K. Shigemori; M. Nakai; H. Azechi; N. Miyanaga; T. Yamanaka; S. Nakai

2001-01-01

202

Parabolic lithium mirror for a laser-driven hot plasma producing device  

DOEpatents

A hot plasma producing device is provided, wherein pellets, singly injected, of frozen fuel are each ignited with a plurality of pulsed laser beams. Ignition takes place within a void area in liquid lithium contained within a pressure vessel. The void in the liquid lithium is created by rotating the pressure vessel such that the free liquid surface of molten lithium therein forms a paraboloid of revolution. The paraboloid functions as a laser mirror with a reflectivity greater than 90%. A hot plasma is produced when each of the frozen deuterium-tritium pellets sequentially arrive at the paraboloid focus, at which time each pellet is illuminated by the plurality of pulsed lasers whose rays pass through circular annuli across the top of the paraboloid. The beams from the lasers are respectively directed by associated mirrors, or by means of a single conical mirror in another embodiment, and by the mirror-like paraboloid formed by the rotating liquid lithium onto the fuel pellet such that the optical flux reaching the pellet can be made to be uniform over 96% of the pellet surface area. The very hot plasma produced by the action of the lasers on the respective singly injected fuel pellets in turn produces a copious quantity of neutrons and X-rays such that the device has utility as a neutron source or as an x-ray source. In addition, the neutrons produced in the device may be utilized to produce tritium in a lithium blanket and is thus a mechanism for producing tritium.

Baird, James K. (Clinton, TN)

1979-06-19

203

13.5 nm extreme ultraviolet emission from tin based laser produced plasma sources  

SciTech Connect

An examination of the influence of target composition and viewing angle on the extreme ultraviolet spectra of laser produced plasmas formed from tin and tin doped planar targets is reported. Spectra have been recorded in the 9-17 nm region from plasmas created by a 700 mJ, 15 ns full width at half maximum intensity, 1064 nm Nd:YAG laser pulse using an absolutely calibrated 0.25 m grazing incidence vacuum spectrograph. The influence of absorption by tin ions (Sn I-Sn X) in the plasma is clearly seen in the shape of the peak feature at 13.5 nm, while the density of tin ions in the target is also seen to influence the level of radiation in the 9-17 nm region.

Hayden, Paddy; Cummings, Anthony; Murphy, Nicola; O'Sullivan, Gerry; Sheridan, Paul; White, John; Dunne, Padraig [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)

2006-05-01

204

Application of electrostatic Langmuir probe to atmospheric arc plasmas producing nanostructures  

SciTech Connect

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

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

2011-07-15

205

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

SciTech Connect

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

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

2010-01-15

206

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

207

Thomson scattering in the corona of laser-produced gold plasmas  

SciTech Connect

Thomson scattering measurements of the electron temperature in laser- produced gold plasmas are presented. We irradiated a flat gold disk target with one laser beam of the Nova laser facility. A second laser beam probed the plasma at a distance of 500{mu}m with temporally resolved Thomson scattering. The electron temperature measurements are compared with hydrodynamic simulations using the code LASNEX for experiments applying smoothed and unsmoothed heater beams. In case of an unsmoothed heater beam the simulations predict temperatures which are about 40% higher than our measured data. Although the agreement is improved for a smoothed heater beam, discrepancies exist in the decay phase of the plasma. We discuss possible explanations for these observations.

Glenzer, S.H.; Back, C.A.; Estabrook, K.G.; MacGowan, B.J.

1996-05-08

208

Application of electrostatic Langmuir probe to atmospheric arc plasmas producing nanostructures  

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

209

Generation and characterization of spatially distributed laser produced plasma extreme ultraviolet source  

NASA Astrophysics Data System (ADS)

Two and three dot laser produced plasma extreme ultraviolet sources have been generated using a Fourier diffractive optical element (DOE). The DOE featured a >90% diffraction efficiency and a power handling capability of >100 MW. The plasmas were formed on a planar bulk tin target by pulses from a Nd:YAG laser delivering up to 360 mJ per pulse in a time of 15 ns (full-width half-maximum intensity) at the fundamental wavelength of 1064 nm. After passing through the DOE, the laser beam was focused onto the target by a pair of lens. The resulting spot radius was estimated to be 8.2+/-0.2 ?m 1/e2 on the target. The extreme ultraviolet radiation emitted by the plasma was imaged using a 122 ?m imaging slit in conjunction with the 38 ?m slit of the spectrometer. The one dimensional image of the laser produced plasma extreme ultraviolet source, together with its spectrum, was recorded by an absolutely calibrated Jenoptic 0.25 m EUV spectrograph. The spectrograph was located at an observation angle of 45 degrees with respect to the target. The vacuum chamber and spectrograph were both maintained at a base pressure of 10-6 Torr. The recorded 1D spatial distribution and EUV spectra demonstrate the feasibility of EUV patterning by the novel optical method. The characteristics and potential applications of this method are investigated in this paper.

Chang, Kuang-Po; Morris, Oran; O'Reilly, Fergal; Dunne, Padraig; O'Sullivan, Gerard

2009-12-01

210

Plasma density irregularities in the equatorial D-region produced by neutral turbulence  

NASA Astrophysics Data System (ADS)

Plasma density irregularities in the D-region are studied in a large-scale size range (1-300 m) during the daytime. The amplitude of these irregularities ranges from a few percent for small-scale sizes (under 15 m) to 10-15 percent for larger-scale sizes (15-300 m). Spectra of all the daytime irregularities clearly exhibit a change in the spectral index at a scale corresponding to a few tens of meters. Turbulence parameters, namely the vertical turbulent velocity, the energy dissipation rate, the eddy diffusion coefficient, the bouyancy scale, and the Kolmogorov microscale are derived. The spectral index of the irregularities in the inertial subrange is found to be very close to -5/3, indicating that these irregularities are produced by the neutral turbulence mechanism. These irregularities are distinctly different, in their appearance and extent, from the irregularities produced by plasma instabilities such as cross-field and two-stream instabilities.

Sinha, H. S. S.

1992-01-01

211

Effective extreme ultraviolet radiation source based on laser-produced plasma in supersonic xenon jet  

NASA Astrophysics Data System (ADS)

Development of highly effective debris free EUV (extreme ultraviolet) radiation source is an actual problem today. Experimental results on EUV output from the source based on laser-produced plasma in supersonic Xe jet have been obtained. The conversion efficiency is 0.08% at a wavelength of 13.5 nm (?? = 0.35 nm, 2? sterrad). The methods of optimization of gas-jet converter have been determined. Measurements of EUV radiation energy dependence on the laser energy and the target material (solid-state Cu, Mo, W, Ta and supersonic Xe jet) have been made. The conversion efficiency of laser-produced plasma (CELPP) has been determined and the experimental values have been obtained for different materials of the target.

Bobashev, S. V.; Domracheva, I. V.; Petrenko, M. V.; Tumakaev, G. K.; Stepanova, Z. A.

2007-04-01

212

Collisionless shocks in laser-produced plasma generate monoenergetic high-energy proton beams  

NASA Astrophysics Data System (ADS)

Compact and affordable ion accelerators based on laser-produced plasmas have potential applications in many fields of science and medicine. However, the requirement of producing focusable, narrow-energy-spread, energetic beams has proved to be challenging. Here we demonstrate that laser-driven collisionless shocks can accelerate proton beams to ~20MeV with extremely narrow energy spreads of about 1% and low emittances. This is achieved using a linearly polarized train of multiterawatt CO2 laser pulses interacting with a gas-jet target. Computer simulations show that laser-heated electrons launch a collisionless shock that overtakes and reflects the protons in the slowly expanding hydrogen plasma, resulting in a narrow energy spectrum. Simulations predict the production of ~200MeV protons needed for radiotherapy by using current laser technology. These results open a way for developing a compact and versatile, high-repetition-rate ion source for medical and other applications.

Haberberger, Dan; Tochitsky, Sergei; Fiuza, Frederico; Gong, Chao; Fonseca, Ricardo A.; Silva, Luis O.; Mori, Warren B.; Joshi, Chan

2012-01-01

213

Temporal behavior of the tungsten plasma produced by 1064 nm pulsed Nd-YAG laser  

NASA Astrophysics Data System (ADS)

A time-resolving Langmuir probe was used to investigate the expansion of tungsten plasma produced by the pulsed Nd-YAG laser (wavelength = 1064 nm, pulse duration = 10 ns). Currentvoltage (IV) plots at various times after the laser shot hit the target were obtained from probe electron and ion currents. Langmuir probe theory was used to determine the temporal variation of the plasma potential, electron temperature and electron density. These plasma parameters sharply rise to a maximum value and then slowly decrease during the plume expansion. For the laser irradiance of 10.88 108 W/cm2, maximum values of plasma potential, electron temperature and electron density were about 24 V, 15.8 eV and 2.24 1016 cm?3 respectively. The measurements performed with time-of-flight electrostatic energy analyzer confirmed the presence of highly charged tungsten ions in the plasma and charge state of ions found to increase with the laser irradiance.

Ilyas, B.; Hussain, M. S.; Dogar, A. H.; Ullah, S.; Nadeem, A.; Qayyum, A.

2013-01-01

214

Time-resolved spectroscopy of nonequilibrium ionization in laser-produced plasmas  

NASA Astrophysics Data System (ADS)

The highly transient ionization characteristic of laser-produced plasmas at high energy densities has been investigated experimentally, using x ray spectroscopy with time resolution of less than 20 ps. Spectroscopic diagnostics of plasma density and temperature were used, including line ratios, line profile broadening and continuum emission, to characterize the plasma conditions without relying immediately on ionization modeling. The experimentally measured plasma parameters were used as independent variables, driving an ionization code, as a test of ionization modelling, divorced from hydrodynamic calculations. Several state-of-the-art streak spectrographs, each recording a fiducial of the laser peak along with the time-resolved spectrum, characterized the laser heating of thin signature layers of different atomic numbers imbedded in plastic targets. Spherical targets were illuminated uniformly with the OMEGA 351 nm laser system, to approximate a one-dimensional homogeneous plasma. A novel design of crystal spectrograph, with a conically curved crystal, was developed. Coupled with a streak camera, it provided high resolution and a collection efficiency roughly 20 to 50 times that of planar crystal spectrographs, affording improved spectra for quantitative reduction and greater sensitivity for the diagnosis of weak emitters.

Marjoribanks, Robin Stewart

1990-03-01

215

Studies of H-Mode Plasmas Produced Directly by Pellet Injection in the DIII-D Tokamak  

Microsoft Academic Search

A key issue for the physics of H-mode plasmas is to determine which plasma quantities are critical for the formation of the edge transport barrier. One approach is to directly perturb the edge plasma and observe the subsequent changes. In DIII-D, pellet injection has been used to directly change the edge plasma conditions and produce H-mode transitions. One hypothesis for

P. Gohil; L. R. Baylor; T. C. Jernigan; K. H. Burrell; T. N. Carlstrom; G. R. McKee; T. L. Rhodes

2000-01-01

216

X-UV Absorption Spectroscopy with Laser-Produced Plasmas: A Review  

Microsoft Academic Search

Exteme-ultraviolet (X-UV) absorption spectroscopy has gained impetus in recent years, spurred on by a growing interest in the physics of core excited atomic, molecular and solid species. Progress in this field has been helped in no small measure by developments in X-UV light sources. One such source is the laser-produced plasma which, by suitable choice of target material, can be

John T Costello; Jean-Paul Mosnier; Eugene T Kennedy; P K Carroll; Gerry OSullivan

1991-01-01

217

CO2-laserproduced plasma columns in a solenoidal magnetic field  

Microsoft Academic Search

A 1-GW CO2 laser pulse has been used to produce extended column breakdown of hydrogen at low pressure in a 20-cm-long solenoid. Magnetic fields of up to 110 kG were used to inhibit radial losses of the plasma column. A differential pumping scheme was devised to prevent formation of an opaque absorption wave travelling out of the solenoid back toward

A. A. Offenberger; M. R. Cervenan; P. R. Smy

1976-01-01

218

CO2-laser-produced plasma columns in a solenoidal magnetic field  

Microsoft Academic Search

A 1-GW CO2 laser pulse has been used to produce extended column breakdown of hydrogen at low pressure in a 20-cm long solenoid. Magnetic fields of up to 110 kG were used to inhibit radial losses of the plasma column. A differential pumping scheme was devised to prevent formation of an opaque absorption wave traveling out of the solenoid back

A. A. Offenberger; M. R. Cervenan; P. R. Smy

1976-01-01

219

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

Microsoft Academic Search

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

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

2012-01-01

220

Methane steam reforming for producing hydrogen in an atmospheric-pressure microwave plasma reactor  

Microsoft Academic Search

A methane steam reforming process for producing mainly hydrogen in an atmospheric-pressure microwave plasma reactor is demonstrated. Nano carbon powders, COx, C2H2, C2H4, and HCN were also formed. Intermediates such as OH, NH, CH, and active N2 were identified using optical emission spectroscopy. The selectivity of H2 was greater than 92.7% at inlet H2O\\/CH4 molar ratio (R) ? 0.5, and

Ya-Fen Wang; Cheng-Hsien Tsai; Wan-Yu Chang; Yi-Ming Kuo

2010-01-01

221

Light chain types in plasma cells that produce IgD  

PubMed Central

The IgD-immunoglobulin producing plasma cells of six human spleens have been localized with specific antisera and the type of the light chains present in each of them has been determined by sequential staining with anti-K and anti-L antisera. About 87 per cent of IgD cells have L-type light chains. This is in accord with the prevalence of L-type light chains in IgD myeloma proteins.

Pernis, B.; Governa, M.; Rowe, D. S.

1969-01-01

222

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

Microsoft Academic Search

Laser satellites are detected in the emission spectra of magnesium and aluminum plasmas produced by femtosecond laser pulses.\\u000a This is made possible by the realization of picosecond time resolution in a high-luminosity x-ray spectrograph with a spherically\\u000a curved mica crystal. The temporal characteristics of these newly recorded spectral lines show unequivocally that they are\\u000a formed as a result of nonlinear

S. A. Pikuz; A. Maksimchuk; D. Umstadter; M. Nantel; I. Yu. Skobelev; A. Ya. Faenov; A. Osterheld

1997-01-01

223

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

SciTech Connect

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

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

2007-05-15

224

Soft x-ray reflectometry with a laser-produced plasma source  

Microsoft Academic Search

A compact soft x-ray reflectometer usable in a small laboratory is developed for measurement of the soft x-ray reflectance of a multilayer mirror in a wide wavelength range, i.e., including the water window (23 to 44 angstroms). In this reflectometer, the reflectance can be measured as a function of wavelength or incidence angle. A laser-produced plasma soft x-ray source, which

Yoshiaki Horikawa; Koumei Nagai; Yoshinori Iketaki

1994-01-01

225

Behavior of easily ionizable additives in the combustion wave of a solid, plasma-producing fuel  

Microsoft Academic Search

The combustion products of solid, plasma-producing fuels (SPF) are used as the working medium in pulsed geophysical MHD generators [i]. To ensure the required specific electrical conductivity of the gas at the entry into the MHD channel (50-70 mho\\/m), easily ionizable additives (IA) are introduced into the composition of such fuels. These additives usually consist of nitates of cesium, or

V. A. Novikov; V. M. Polonskii; S. I. Yakovlev

1990-01-01

226

Effective extreme ultraviolet radiation source based on laser-produced plasma in supersonic xenon jet  

Microsoft Academic Search

Development of highly effective debris free EUV (extreme ultraviolet) radiation source is an actual problem today. Experimental results on EUV output from the source based on laser-produced plasma in supersonic Xe jet have been obtained. The conversion efficiency is 0.08% at a wavelength of 13.5 nm (Deltalambda = 0.35 nm, 2pi sterrad). The methods of optimization of gas-jet converter have

S. V. Bobashev; I. V. Domracheva; M. V. Petrenko; G. K. Tumakaev; Z. A. Stepanova

2007-01-01

227

Comprehensive 3-D modeling and simulation of laser produced plasma for euv lithography and other applications  

Microsoft Academic Search

Summary form only given. This study presents the first detail 3-D full modeling of all physical processes in laser-produced plasma (LPP) for various applications. The evolution of the target in 3-D full hydrodynamic response coupled with 3-D photon transport in the LPP with detail atomic physics are simulated for multiple-laser on target systems. For example, several concepts are considered in

A. Hassanein; V. Sizyuk; V. Morozov; I. Konkashbaev; T. Sizyuk; B. Rice

2006-01-01

228

Average velocity distribution measurements of target debris from a laser-produced plasma  

Microsoft Academic Search

Measurements of the velocity and particulate size distributions as well as calculations of ejected mass have been made on solid Sn and Au laser-produced plasma (LPP) targets. The experiments were conducted under conditions associated with soft x-ray projection lithography (SXPL). Results indicate that small particulates, less than 1 - 2 micrometers in diameter, with speeds in excess of 9000 cm\\/s,

Howard Bender; Ann Marie P. Eligon; D. O'Connell; William T. Silfvast

1994-01-01

229

Grid spectral purity filters for suppression of infrared radiation in laser-produced plasma EUV sources  

Microsoft Academic Search

We have developed a grid-type spectral purity filter (SPF) for suppression of infrared radiation in laser-produced plasma (LPP) EUV sources for high-volume EUV lithography. The SPF is a silicon grid with sub-wavelength periodicity that is metalized to make it reflective for infrared radiation. EUV radiation is transmitted geometrically through the open area of the grid. The first prototype samples show

Wouter A. Soer; Martin J. J. Jak; Andrei M. Yakunin; Maarten M. J. W. van Herpen; Vadim Y. Banine

2009-01-01

230

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

NASA Astrophysics Data System (ADS)

An optimized way of producing washers of titanium hydride for the application to a plasma gun using the occluded gas is presented. The amount of H2 gas (equivalently, gas pressure p) is entirely preadjusted in a gas reservoir of a simple instrument. The temperature T of a furnace is completely feedback controlled. Data show that when p is the order of 1 atm, T needs to be higher than about 450 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~0.85:1.

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

2006-07-01

231

Plasma Channel Transport for Heavy Ion Fusion: Investigation of Beam Transport, Channel Initiation and Stability  

NASA Astrophysics Data System (ADS)

For final beam transport in an IFE reactor three alternatives are mainly discussed. These are neutralized ballistic transport, self-pinched transport, and plasma channel transport. Discharge plasma channels were investigated in the recent years at GSI Darmstadt and at LBNL Berkeley in a number of experiments. Different initiation mechanisms for gas discharges of up to 60 kA were studied and compared. In the Berkeley experiments laser ionization of organic vapors in a buffer gas was used to initiate and direct the discharge while at GSI laser gas heating and ion beam induced gas ionization were tested as initiation mechanisms. Measurements of temperature, electron density, gas density, and magnetic field distribution in the channels are compared with results of beam transport experiments at the GSI UNILAC accelerator and with MHD simulations of the 1D-fluidcode CYCLOPS, which was developed in Berkeley. Good agreement between plasma diagnostics results, measured ion optical properties and MHD simulations was found. Parameters that are required for a reactor application are a discharge current of 50 kA, a channel diameter below 1 cm, a pointing stability better than 500 ?m, and MHD stability for more than 10 ?s. These parameters have been demonstrated in the recent experiments. The results imply that transport channels work with sufficient stability, reproducibility and ion optical properties in a wide pressure range and for various discharge gases.

Tauschwitz, Andreas; Niemann, Christoph; Penache, Dan; Birkner, Richard; Hoffmann, Dieter H. H.; Kobloch, Renate; Neff, Stefan; Presura, Radu; Ponce, Dave; Rosmej, Frank; Yu, Simon

2002-12-01

232

Time and space resolved visible spectroscopic imaging CO2 laser produced extreme ultraviolet emitting tin plasmas  

NASA Astrophysics Data System (ADS)

Experiments involving laser produced tin plasma have been carried out using a CO2 laser with an energy of 800 mJ/pulse and a full width at half maximum (FWHM) of 80 ns in vacuum. Time-integrated extreme ultraviolet spectral measurement showed that the peak of the extreme ultraviolet lithography spectrum was located at 13.5 nm and the spectrum profile's FWHM of the unresolved transition arrays was 1.1 nm. Plasma parameters of the electron temperature and density measurements in both axial and radial directions at later times had been obtained from a two-dimensional time and space resolved image spectra analysis. The axial spatial distribution of the electron density showed a 1/d2.6 decrease profile, and the radial spatial distribution of the electron density showed a 1/r1.1 profile, in which d is the axial distance from the target surface and r is the radial distance. The electron density was found to maintain symmetry across the radial distance at all delay times. Near the plasma plume center, the electron temperature Te varied slightly with increasing axial or radial distance, which was related to collisional decoupling and reheating of the ionized species in the plasma at distances longer than 3 to 4 mm. The space averaged electron temperature was measured in the range of 3.4-1.0 eV, and the space averaged electron density was measured in the range of 2.0 1017 to 2.2 1016 cm-3, as the time delay varied from 1.6 ?s to 3.6 ?s with respect to the pulse discharge. Time evolutions of the plasma temperature and density were found to have an apparent rise at a delay time of 2.4 ?s in the corresponding time of the laser pulse tail peak. This suggests that plasma parameters and extreme ultraviolet emission intensity can be controlled by a double pulse combined laser.

Wu, Tao; Wang, Xinbing; Wang, Shaoyi; Tang, Jian; Lu, Peixiang; Lu, Hong

2012-03-01

233

Effects of equation of state on nuclear suppression and the initial entropy density of quark gluon plasma  

NASA Astrophysics Data System (ADS)

We study the effects of the equation of state on the nuclear suppression of heavy flavors in quark gluon plasma and estimate the initial entropy density of the system produced in Au + Au collision at the highest Relativistic Heavy Ion Collider (RHIC) energy. For this purpose the experimental data on the charged-particle multiplicity and the nuclear suppression of single-electron spectra originating from the semileptonic decays of open charm and beauty mesons have been employed. We have used inputs from lattice QCD to minimize the model dependence of the results. We obtain the value of the initial entropy density, which varies from 20 to 59/fm3 depending on the value of the velocity of sound that one uses for the analysis. Our investigation leads to a conservative value of the initial entropy density of 20/fm3 with a corresponding initial temperature of 210 MeV, which is well above the value of the transition temperature predicted by lattice QCD.

Mazumder, Surasree; Alam, Jan-e.

2012-04-01

234

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

SciTech Connect

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

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

2009-05-15

235

Specific In Situ Visualization of Plasma Cells Producing Antibodies against Porphyromonas gingivalis in Gingival Radicular Cyst  

PubMed Central

The enzyme-labeled antigen method was applied to visualize plasma cells producing antibodies to Porphyromonas gingivalis, flora of the human oral cavity. Antibodies to P. gingivalis have reportedly been detected in sera of patients with periodontitis. Biotinylated bacterial antigens, Ag53, and four gingipain domains (Arg-pro, Arg-hgp, Lys-pro, and Lys-hgp) were prepared by the cell-free protein synthesis system using the wheat germ extract. In paraformaldehyde-fixed frozen sections of rat lymph nodes experimentally immunized with Ag53-positive and Ag53-negative P. gingivalis, plasma cells were labeled with biotinylated Arg-hgp and Lys-hgp. Antibodies to Ag53 were detected only in the nodes immunized with Ag53-positive bacteria. In two of eight lesions of gingival radicular cyst with inflammatory infiltration, CD138-positive plasma cells in frozen sections were signalized for Arg-hgp and Lys-hgp. An absorption study using unlabeled antigens confirmed the specificity of staining. The AlphaScreen method identified the same-type antibodies in tissue extracts but not in sera. Antibodies to Ag53, Arg-pro, and Lys-pro were undetectable. In two cases, serum antibodies to Arg-hgp and Lys-hgp were AlphaScreen positive, whereas plasma cells were scarcely observed within the lesions. These findings indicate the validity of the enzyme-labeled antigen method. This is the very first application of this novel histochemical technique to human clinical samples.

Tsuge, Shinya; Mizutani, Yasuyoshi; Matsuoka, Kazuhiro; Sawasaki, Tatsuya; Endo, Yaeta; Naruishi, Koji; Maeda, Hiroshi; Takashiba, Shogo; Shiogama, Kazuya; Inada, Ken-ichi; Tsutsumi, Yutaka

2011-01-01

236

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

SciTech Connect

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

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

2005-12-26

237

Resonant third harmonic generation in a laser produced thin foil plasma  

SciTech Connect

An analytical model is developed for third harmonic generation (THG) efficiency from a high-density inhomogeneous plasma produced by laser irradiation of a thin metallic film. The laser suffers strong reflection from the critical layer. The superposition of forward and backward waves creates a quasistatic density ripple of wave number 2k and a second harmonic density ripple at 2{omega}, 4k, where {omega} and k are the frequency and wave number of the laser. The density ripple couples with the oscillatory electron velocity at {omega}, k to produce a nonlinear current at 3{omega}, 5k driving a resonant third harmonic radiation in the region where 5k=k{sub 3} and k{sub 3} is the wave number at 3{omega} frequency. As the density scale length of the plasma is increased, the efficiency of THG increases. The same behavior is reproduced in two particle in cell simulation by launching a laser in a rippled density underdense plasma of phase-matched density and a ripple period of half-laser wavelength.

Kaur, Sukhdeep; Sharma, A. K. [Center for Energy Studies, Indian Institute of Technology Delhi, New Delhi-110016 (India)

2008-10-15

238

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

239

Supersonic propagation of ionization waves in an underdense, laser-produced plasma  

SciTech Connect

A laser-driven supersonic ionization wave propagating through a millimeter-scale plasma of subcritical density up to 2-3 keV electron temperatures was observed. Propagation velocities initially ten times the sound speed were measured by means of time-resolved x-ray imaging diagnostics. The measured ionization wave trajectory is modeled analytically and by a two-dimensional radiation-hydrodynamics code. The comparison to the modeling suggests that nonlocal heat transport effects may contribute to the attenuation of the heat-wave propagation.

Constantin, C.; Back, C.A.; Fournier, K.B.; Gregori, G.; Landen, O.L.; Glenzer, S.H.; Dewald, E.L.; Miller, M.C. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2005-06-15

240

Supersonic propagation of ionization waves in an under-dense, laser-produced plasma  

SciTech Connect

We observe a laser-driven supersonic ionization wave heating a mm-scale plasma of sub-critical density up to 2-3 keV electron temperatures. Propagation velocities initially 10 times the sound speed were measured by means of time-resolved x-ray imaging diagnostics. The measured ionization wave trajectory is modeled analytically and by a 2D radiation-hydrodynamics code. The comparison to the modeling suggests that nonlocal heat transport effects may contribute to the attenuation of the heat wave propagation.

Constantin, C; Back, C A; Fournier, K B; Gregori, G; Landen, O L; Glenzer, S H; Dewald, E L; Miller, M C

2004-10-22

241

Time-resolved probing of electron thermal conduction in femtosecond-laser-pulse-produced plasmas  

SciTech Connect

We present time-resolved measurements of reflectivity, transmissivity and frequency shifts of probe light interacting with the rear of a disk-like plasma produced by irradiation of a transparent solid target with 0.1ps FWHM laser pulses at peak intensity 5 {times} 10{sup l4}W/CM{sup 2}. Experimental results show a large increase in reflection, revealing rapid formation of a steep gradient and overdense surface plasma layer during the first picosecond after irradiation. Frequency shifts due to a moving ionization created by thermal conduction into the solid target are recorded. Calculations using a nonlinear thermal heat wave model show good agreement with the measured frequency shifts, further confining the strong thermal transport effect.

Vue, B.T.V. [Lawrence Livermore National Lab., CA (United States)]|[California Univ., Livermore, CA (United States). Dept. of Applied Science; Szoke, A.; Landen, O.L. [Lawrence Livermore National Lab., CA (United States)

1993-06-01

242

Time-resolved probing of electron thermal conduction in femtosecond-laser-pulse-produced plasma  

SciTech Connect

We present time-resolved measurements of reflectivity, transmissivity and frequency shifts of probe light interacting with the rear of a disk-like plasma produced by irradiation of a transparent solid target with 0.1ps FWHM laser pulses at peak intensity 5[times]10[sup 14] W/cm[sup 2]. Experimental results show a large increase in reflection, revealing rapid formation of a steep gradient and overdense surface plasma layer during the first picosecond after irradiation. Frequency shifts due to a moving ionization created by thermal conduction in to the solid target are recorded. Calculations using a nonlinear thermal heat wave model show good agreement with the measured frequency shifts, further confirming the strong thermal transport effect.

Vu, B.V. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States) Dept. of Applied Science, U.C.D., Livermore, California 94550 (United States)); Szoke, A.; Landen, O.L. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))

1993-10-10

243

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

244

Optical pyrometer system for collisionless shock experiments in high-power laser-produced plasmas  

SciTech Connect

A temporally and spatially resolved optical pyrometer system has been fielded on Gekko XII experiments. The system is based on the self-emission measurements with a gated optical imager (GOI) and a streaked optical pyrometer (SOP). Both detectors measure the intensity of the self-emission from laser-produced plasmas at the wavelength of 450 nm with a bandpass filter with a width of {approx}10 nm in FWHM. The measurements were calibrated with different methods, and both results agreed with each other within 30% as previously reported [T. Morita et al., Astrophys. Space Sci. 336, 283 (2011)]. As a tool for measuring the properties of low-density plasmas, the system is applicable for the measurements of the electron temperature and density in collisionless shock experiments [Y. Kuramitsu et al., Phys. Rev. Lett. 106, 175002 (2011)].

Morita, T.; Sakawa, Y.; Kuramitsu, Y.; Sano, T.; Takabe, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Dono, S.; Ide, T.; Tanji, H.; Shiroshita, A. [Graduate School of Engineering, Osaka University, 1-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Shibata, S.; Aoki, H. [Graduate School of Science, Osaka University, 1-1 Machikane-yama, Toyonaka, Osaka 560-0043 (Japan); Waugh, J. N.; Woolsey, N. C. [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Gregory, C. D. [LULI, Ecole Polytechnique, CNRS, CEA, UPMC, Route de Saclay, 91128 Palaiseau (France)

2012-10-15

245

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

NASA Astrophysics Data System (ADS)

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

2013-09-01

246

Thermodynamic Characterization in CO2 Plasma Jet Produced by VKI Plasmatron Facility  

NASA Astrophysics Data System (ADS)

The radiation of the CO2 plasma jet produced by the VKI-Plasmatron high enthalpy wind tunnel is investigated by means of Optical Emission Spectroscopy (OES) diagnostic in the visible spectral range. Radial thermodynamic state characterization was conducted at 200 mbar operating pressures using absolute measurements of O and C atomic lines and emission of vibrational bands of C2 Swan system. Approaches based on LTE assumption as well on thermal equilibrium and chemical non equilibrium have been adopted. The good agreement on temperature profiles derived from different methods allows to assert the thermal equilibrium of the plasma. Measured temperature at the center of the jet was found to be about 6500 K. The line of sight intensity, due to C2 Swan emission, have been rebuilt using resulting measured temperature profiles, and are critically compared with experimental data.

Le Quang, D.; Babou, Y.; Bultel, A.; Marraffa, L.

2011-08-01

247

Fine structure and spectral broadening of Balmer lines in laser-produced plasmas  

SciTech Connect

The profiles of the Balmer lines emitted in a laser-produced plasma by the ions B/sup +4/ to F/sup +8/ have been observed. For the Balmer-..cap alpha.. line the fine-structure components are broadened and partially merged by the Stark effect, the thermal Doppler broadening, and the motional Doppler shift. To these lines a simplified model for a expanding plasma, used previously for the analysis of the Lyman lines of the same ions, has been applied. The results are in very good agreement with the observations, showing the overall validity of the interpretation. The various broadening mechanisms have been unfolded and, in particular, for the range of electron densities considered here, a transition between the weak- and strong-field approximations for the Stark broadening is evident.

Nicolosi, P.; Tondello, G.; Jannitti, E.

1979-12-01

248

Analysis of laser-produced heavy ions for direct plasma injection scheme  

SciTech Connect

To accelerate highly charged intense ion beam, we have developed the direct plasma injection scheme (DPIS) with laser ion source. In this scheme an ion beam from a laser ion source is injected directly to a radio frequency quadrupole (RFQ) linac without a low energy beam transport (LEBT) line and then beam losses in the LEBT can be avoided. We achieved high current acceleration of carbon ions (60 mA) by DPIS with the RFQ specially designed for high current heavy ions. As the next step we will use heavier elements such as Al, Fe, and Ta as targets in laser ion source (using high power laser, for example, glass laser) for DPIS and will examine properties of laser-produced plasma for highly charged ion production.

Sakakibara, K.; Okamura, M.; Kondrashev, S.; Hattori, T.; Kashiwagi, H.; Kanesue, T. [Tokyo Institute of Technology (TITech), 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Institute of Theoretical and Experimental Physics (ITEP), Bolshaya Cheremushkinskaya 25, 117259 Moscow (Russian Federation); Tokyo Institute of Technology (TITech), 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Japan Atomic Energy Research Institute (JAERI), 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan)

2006-03-15

249

Production of metastable 23S1 helium in a laser produced plasma at low pressures  

NASA Astrophysics Data System (ADS)

We used cavity ringdown spectroscopy to study how the laser ablation of various materials (graphite, aluminum and iron) influences production of 23S1 metastable helium in the regime of low pressure helium gas. Plasma was produced by nanosecond Nd:YAG laser at 1064 nm with irradiance from 0.8 to 10.9 109 W/cm2. Helium pressure ranged from 0.03 to 0.2 mbar. It was found that at higher irradiances, metastable production for all materials reaches saturation due to plasma shielding and is more pronounced for graphite. The highest yield of metastables was found in the case of aluminum target (0.05%). For metals, production rate is discussed in terms of work function and ionization potential.

Bi?an, M.; Miloevi?, S.

2013-03-01

250

Analysis of laser-produced heavy ions for direct plasma injection scheme  

NASA Astrophysics Data System (ADS)

To accelerate highly charged intense ion beam, we have developed the direct plasma injection scheme (DPIS) with laser ion source. In this scheme an ion beam from a laser ion source is injected directly to a radio frequency quadrupole (RFQ) linac without a low energy beam transport (LEBT) line and then beam losses in the LEBT can be avoided. We achieved high current acceleration of carbon ions (60 mA) by DPIS with the RFQ specially designed for high current heavy ions. As the next step we will use heavier elements such as Al, Fe, and Ta as targets in laser ion source (using high power laser, for example, glass laser) for DPIS and will examine properties of laser-produced plasma for highly charged ion production.

Sakakibara, K.; Okamura, M.; Kondrashev, S.; Hattori, T.; Kashiwagi, H.; Kanesue, T.

2006-03-01

251

Time-Resolved Spectroscopy of Nonequilibrium Ionization in Laser-Produced Plasmas.  

NASA Astrophysics Data System (ADS)

The highly transient ionization characteristic of laser-produced plasmas at high energy densities has been investigated experimentally, using x-ray spectroscopy with time resolution of less than 20 ps. Spectroscopic diagnostics of plasma density and temperature were used, including line ratios, line profile broadening and continuum emission, to characterize the plasma conditions without relying immediately on ionization modelling. The experimentally measured plasma parameters were used as independent variables, driving an ionization code, as a test of ionization modelling, divorced from hydrodynamic calculations. Several state-of-the-art streak spectrographs, each recording a fiducial of the laser peak along with the time-resolved spectrum, characterized the laser heating of thin signature layers of different atomic numbers imbedded in plastic targets. Spherical targets were illuminated uniformly with the OMEGA 351 nm laser system ( tau ~ 1 ns, I ~ 5 times 10 ^{14} Wcm^{ -2}), to approximate a one-dimensional homogeneous plasma. A novel design of crystal spectrograph, with a conically curved crystal, was developed. Coupled with a streak camera, it provided high resolution ( lambda/Deltalambda > 1000) and a collection efficiency roughly 20-50 times that of planar crystal spectrographs, affording improved spectra for quantitative reduction and greater sensitivity for the diagnosis of weak emitters. A novel temperature diagnostic was developed, using special targets with a known proportion of elements: analogous emission lines from isoelectronic charge-states were used to provide a temperature-sensitive diagnostic ratio. Experimental results were compared to hydrocode and ionization code simulations, with poor agreement. The conclusions question the appropriateness of describing electron velocity distributions by a temperature parameter during the time of laser illumination and emphasize the importance of characterizing the distribution more generally.

Marjoribanks, Robin Stewart

252

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

PubMed

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

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

2009-11-20

253

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

SciTech Connect

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

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

1984-06-01

254

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

255

Enhancement of extreme ultraviolet radiations from a laser-produced plasma using copper-tungsten alloy  

NASA Astrophysics Data System (ADS)

Continuous extreme ultraviolet (EUV) emission intensity from a laser-produced plasma in the wavelength between 40 and 200 nm for a copper-tungsten alloy target was observed to be 1.3 times higher than that for a tungsten target. Using the alloy target, low-opacity regions of one material were filled with high-opacity regions of another material. This opacity effect resulted in the increase of a calculated Rosseland mean opacity compared with either of the constituents, which may explain the increase of the EUV emission intensity.

Matsuura, Yuta; Kaku, Masanori; Kubodera, Shoichi

2013-03-01

256

Study of K? absorption structures in a subcritical-density laser-produced plasma  

NASA Astrophysics Data System (ADS)

The study of K? line absorption by point-projection backlighting is presented for a laser-produced aluminum plasma at electronic densities below 51021 cm-3. The appearance of ionic species as a function of distance from the target is measured absolutely by the use of a knife edge as a spatial fiducial. These data are used to determine the gradient of the average charge as a function of space. A non-local-thermodynamic-equilibrium ionization model has been developed to determine temperature and densities consistent with this measure. Comparisons with hydrodynamic codes are presented, along with a discussion of the inferred temperature.

Back, C. A.; Chenais-Popovics, C.; Renaudin, P.; Geindre, J. P.; Audebert, P.; Gauthier, J. C.

1992-09-01

257

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

NASA Astrophysics Data System (ADS)

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

Nayak, B. B.

2012-01-01

258

Debris characteristics of a laser-produced tin plasma for extreme ultraviolet source  

SciTech Connect

We measured debris characteristics of a tin (Sn) plasma produced by a 10-ns infrared Nd:YAG laser. A maximum kinetic energy of 7 keV of tin ions was observed. Such suprathermal tin ions emitted from a solid planar target consisted of singly and doubly ionized tin ions. Both suprathermal ions and neutral fragments emitted from a target showed the angular distributions of cos{sup 4} {theta} which were narrower than the 13.5-nm extreme ultraviolet (EUV) emission distribution of cos{sup 0.5} {theta}. These measurements would give important information on debris mitigation for efficient EUV sources in the next generation lithography.

Higashiguchi, Takeshi; Rajyaguru, Chirag; Dojyo, Naoto; Taniguchi, Yosuke; Sakita, Koji; Kubodera, Shoichi; Sasaki, Wataru [Department of Electrical and Electronic Engineering and Photon Science Center, University of Miyazaki, Gakuen Kibanadai Nishi 1-1, Miyazaki 889-2192 (Japan); NTP Inc., Gakuen Kibanadai Nishi 1-1, Miyazaki, Miyazaki 889-2192 (Japan)

2005-12-15

259

Observation of megagauss-field topology changes due to magnetic reconnection in laser-produced plasmas.  

PubMed

The spatial structure and temporal evolution of megagauss magnetic fields generated by interactions of up to 4 laser beams with matter were studied with an innovative, time-gated proton radiography method that produces images of unprecedented clarity because it uses an isotropic, truly monoenergetic back-lighter (14.7-MeV protons from D3He nuclear fusion reactions). Quantitative field maps reveal precisely and directly, for the first time, changes in the magnetic topology due to reconnection in a high-energy-density plasma (n(e) approximately 10(20)-10(22) cm(-3), T(e) approximately 1 keV). PMID:17930762

Li, C K; Sguin, F H; Frenje, J A; Rygg, J R; Petrasso, R D; Town, R P J; Landen, O L; Knauer, J P; Smalyuk, V A

2007-08-02

260

Radial characterisation of the helium plasma produced by the axial injection torch (TIA) at atmospheric pressure  

NASA Astrophysics Data System (ADS)

This work presents the radial characterisation of a helium plasma produced by the Torch Injection Axiale by means of the determination of the electron density and electron temperature. Through the Abel inversion technique on the experimental data, the radial distribution of absolute intensity along the flame is obtained, from which we can study the spatial distribution of the excited states as a function of the helium flow rate and the absorbed HF power. Finally, using a collisional-radiative model for helium at atmospheric pressure, the electronic density and electronic temperature at each point in the flame are obtained.

lvarez, R.; Rodero, A.; Quintero, M. C.

2000-03-01

261

Emission from ionic cesium fluoride excimers excited by a laser-produced plasma.  

PubMed

CsF vapor generated in a heat pipe was excited by a laser-produced plasma. Temporally integrated spectra and time-resolved fluorescence on the ionic excimer transition Cs(2+)F(-) ? Cs(+)F were observed at 185 nm. The pressure dependence of the fluorescence is influenced by self-absorption in the CsF vapor. The fluorescence is assigned to the Cs(2+)F(-) ((2)Sigma(1/2), B)? Cs(+)F ((2)Sigma(1/2),X) transition. PMID:19745927

Kubodera, S; Frey, L; Wisoff, P J; Sauerbrey, R

1988-06-01

262

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

SciTech Connect

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

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

1991-01-01

263

Thomson scattering measurements of heat flux from ion-acoustic waves in laser-produced aluminum plasmas  

SciTech Connect

Thomson scattering (TS) measurements are performed at different locations in a laser-produced aluminum plasma. Variations of the separation, wavelength shift, and asymmetric distribution of the two ion-acoustic waves are investigated from their spectral-time-resolved TS images. Detailed information on the space-time evolution of the plasma parameters is obtained. Electron distribution and variation of the heat flux in the plasma are also obtained for a steep temperature gradient.

Yu, Q.Z.; Zhang, J.; Li, Y.T.; Lu, X.; Hawreliak, J.; Wark, J.; Chambers, D.M.; Wang, Z.B.; Yu, C.X.; Jiang, X.H.; Li, W.H.; Liu, S.Y.; Zheng, Z.J. [Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences, P. O. Box 603, Beijing 100080 (China); Department of Physics, Clarendon Laboratory, Oxford University, Oxford OX1 3PU (United Kingdom); Steward Observatory, University of Arizona, Tucson, Arizona 85721 (United States); Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China); Research Center for Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China)

2005-04-01

264

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Implantation of high-energy ions produced by femtosecond laser pulses  

NASA Astrophysics Data System (ADS)

Germanium ions of an expanding plasma were implanted in a silicon collector. The plasma was produced by a femtosecond laser pulse with an intensity of ~1015 W cm-2 at the surface of the solid-state target. A technique was proposed for determining the energy characteristics of the ion component of the laser plasma from the density profile of the ions implanted in the substrate.

Volkov, Roman V.; Golishnikov, D. M.; Gordienko, Vyacheslav M.; Savel'ev, Andrei B.; Chernysh, V. S.

2005-01-01

265

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

266

Mitigation of ion and particulate emission from laser-produced plasmas used for extreme ultraviolet lithography  

NASA Astrophysics Data System (ADS)

While developing a laboratory-scale micro-exposure tool for extreme ultraviolet (EUV) projection lithography which uses a laser-produced plasma emitting EUV pulsed radiation, we faced the problem of suppressing the various debris (ions, neutrals, particulate, clusters, droplets) emitted by the plasma target. The suppression of debris is a crucial task in the frame of EUV projection lithography, mainly because debris seriously limit both lifetime and performance of the expensive optics and filters put close to the plasma source. In this paper we present the experimental measurements of main debris characteristics (velocity, size, charge, momentum, spectral energy, spatial distribution). Then, we present the operating results of a patented debris mitigation systems (DMS) specifically designed to suppress debris with the measured characteristics. We achieved reduction factors 800 for atoms and nm-size clusters, and 1600 for particles larger than 500 nm. These results are at the forefront in this field. The excellent performance of our DMS was a breakthrough to achieve a 90-nm patterning on commercial resists by our micro-exposure tool EUV projection lithography.

Di Lazzaro, Paolo; Bollanti, Sarah; Flora, Francesco; Mezi, Luca; Murra, Daniele; Torre, Amalia

2013-05-01

267

Fast Magnetic Reconnection in High-Energy-Density Laser-Produced Plasmas  

NASA Astrophysics Data System (ADS)

Recent experiments have observed magnetic reconnection in high-energy-density, laser-produced plasma bubbles [1,2], with reconnection rates observed to be much higher than can be explained by classical theory. This is a novel regime for magnetic reconnection study, characterized by extremely high magnetic fields, high plasma beta and strong, supersonic plasma inflow. Reconnection in this regime is investigated with particle-in-cell simulations. Collisionless simulations have identified two key ingredients, simultaneously present for the first time: two-fluid reconnection mediated by collisionless effects (that is, the Hall current and electron pressure tensor), and strong flux pile-up of the inflowing magnetic field [3]. These effects combine to yield reconnection rates independent of the nominal Alfvn speed (based on the magnetic field before interaction), and simply given by the dynamic time L/V, in qualitative agreement with the experiments. We present detailed simulations spanning the parameter ranges of the experiments, and further compare the results of simulations with and without binary collisions, in 2D and 3D. Finally we discuss plans for future laser-driven reconnection experiments.[4pt] [1] P. M. Nilson, et al, Phys. Rev. Lett. 97, 255001 (2006).[0pt] [2] C. K. Li, et al, Phys. Rev. Lett. 99, 055001 (2007).[0pt] [3] W. Fox, A. Bhattacharjee, K. Germaschewski, Phys. Rev. Lett. 106, 215003 (2011).

Fox, William

2011-11-01

268

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

NASA Astrophysics Data System (ADS)

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

2013-09-01

269

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

NASA Astrophysics Data System (ADS)

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

Renner, O.; Admek, P.; Angelo, P.; Dalimier, E.; Frster, E.; Krousky, E.; Rosmej, F. B.; Schott, R.

2006-05-01

270

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

SciTech Connect

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 with basis functions using a Krook collision operator. An electrostatic test case with artificial parameters for the toroidal drift mode destabilized by the combined effects of trapped particles and an ion temperature gradient has been carefully analyzed both in the collisionless limit and with varying collisionality. Good agreement is found. Results from applied studies using parameters from the Tokamak Fusion Test Reactor (TFTR) experiment are also compared.

Kotschenreuther, M. [Univ. of Texas, Austin, TX (United States). Institute for Fusion Studies; Rewoldt, G.; Tang, W.M. [Princeton Univ., NJ (United States). Plasma Physics Lab.

1994-04-01

271

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

Microsoft Academic Search

This study proposes using thermal plasma technology to treat municipal solid waste incinerator ashes. A feasible fiberization method was developed and applied to produce man-made vitreous fiber (MMVF) from plasma vitrified slag. MMVF were obtained through directly blending the oxide melt stream with high velocity compressed air. The basic technological characteristics of MMVF, including morphology, diameter, shot content, length and

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

2010-01-01

272

A scaling model for plasma columns produced by CO2 laser-induced breakdown in a solenoidal field  

Microsoft Academic Search

An analytical model is derived for the plasma cylinder produced by a long pulse (approximately ?sec) CO2 laser of power pl (watts) which is incident upon neutral hydrogen imbedded in a strong axial magnetic field. Under certain conditions the leading edge of the plasma propagates away from the laser as an optical detonation where the leading shock front fully ionizes

Boye Ahlborn; G. C. Vlases; Z. A. Pietrzyk

1982-01-01

273

A scaling model for plasma columns produced by CO2 laser-induced breakdown in a solenoidal field  

Microsoft Academic Search

An analytical model is derived for the plasma cylinder produced by a long pulse (approximately microsec) CO2 laser of power p(l) (watts) which is incident upon neutral hydrogen imbedded in a strong axial magnetic field. Under certain conditions the leading edge of the plasma propagates away from the laser as an optical detonation, where the leading shock front fully ionizes

B. Ahlborn; G. C. Vlases; Z. A. Pietrzyk

1982-01-01

274

Geomagnetic signatures of current wedge produced by fast flows in a plasma sheet  

NASA Astrophysics Data System (ADS)

This paper uses the plasma data from Cluster and TC-1 and geomagnetic data to study the geomagnetic signatures of the current wedge produced by fast-flow braking in the plasma sheet. The three fast flows studied here occurred in a very quiet background and were accompanied by no (or weak) particle injections, thus avoiding the influences from other disturbances. All the geomagnetic signatures of a substorm current wedge can be found in the geomagnetic signatures of a current system produced by the braking of fast flows, indicating that the fast flows can produce a complete current wedge which contains postmidnight downward and premidnight upward field-aligned currents, as well as a westward electrojet. The Pi2 precursors exist not only at high latitudes but also at midlatitudes. The starting times of midlatitude Pi2 precursors can be identified more precisely than those of high-latitude Pi2 precursors, providing a possible method to determine the starting time of fast flows in their source regions. The AL drop that a bursty bulk flow produces is proportional to its velocity and duration. In three cases, the AL drops are <100 nT. Because the AE increase of a typical substorm is >200 nT, whether a substorm can be triggered depends mainly on the conditions of the braking regions before fast flows. The observations of solar wind before the three fast flows suggest that it is difficult for the fast flows to trigger a substorm when the interplanetary magnetic field Bz of solar wind is weakly southward.

Cao, Jin-Bin; Yan, Chunxiao; Dunlop, Malcolm; Reme, Henri; Dandouras, Iannis; Zhang, Tielong; Yang, Dongmei; Moiseyev, Alexey; Solovyev, Stepan I.; Wang, Z. Q.; Leonoviche, A.; Zolotukhina, N.; Mishin, V.

2010-08-01

275

Time-resolved probing of electron thermal transport in plasma produced by femtosecond laser pulses. Revision 1  

SciTech Connect

We present the first direct observation of a supersonic ionization front supported by electron thermal transport in a hot solid density plasma produced by 100fsec-laser-pulse irradiation of a transparent fused quartz target.

Vu, B.T.V.; Szoke, A.; Landen, O.L.; Lee, R.W.

1994-04-20

276

Initiation of BMP2 signaling in domains on the plasma membrane.  

PubMed

Bone morphogenetic protein 2 (BMP2) is a potent growth factor crucial for cell fate determination. It directs the differentiation of mesenchymal stem cells into osteoblasts, chondrocytes, adipocytes, and myocytes. Initiation of BMP2 signaling pathways occurs at the cell surface through type I and type II serine/threonine kinases housed in specific membrane domains such as caveolae enriched in the caveolin-1 beta isoform (CAV1?, caveolae) and clathrin-coated pits (CCPs). In order for BMP2 to initiate Smad signaling it must bind to its receptors on the plasma membrane resulting in the phosphorylation of the BMP type Ia receptor (BMPRIa) followed by activation of Smad signaling. The current model suggests that the canonical BMP signaling pathway, Smad, occurs in CCPs. However, several recent studies suggested Smad signaling may occur outside of CCPs. Here, we determined; (i) The location of BMP2 binding to receptors localized in caveolae, CCPs, or outside of these domains using AFM and confocal microscopy. (ii) The location of phosphorylation of BMPRIa on the plasma membrane using membrane fractionation, and (iii) the effect of down regulation of caveolae on Smad signaling. Our data indicate that BMP2 binds with highest force to BMP receptors (BMPRs) localized in caveolae. BMPRIa is phosphorylated in caveolae and the disruption of caveolae-inhibited Smad signaling in the presence of BMP2. This suggests caveolae are necessary for the initiation of Smad signaling. We propose an extension of the current model of BMP2 signaling, in which the initiation of Smad signaling is mediated by BMPRs in caveolae. PMID:21938723

Bonor, Jeremy; Adams, Elizabeth L; Bragdon, Beth; Moseychuk, Oleksandra; Czymmek, Kirk J; Nohe, Anja

2012-07-01

277

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

278

Focal Smooth Muscle Proliferation in the Aortic Intima Produced by an Initiation--Promotion Sequence  

Microsoft Academic Search

Human atherosclerotic fibrous plaques display a clonal character similar to many benign neoplasms. We report here that chickens treated with an initiation--promotion sequence developed focal intimal smooth muscle lesions in the thoracic aorta that resemble early forms of atherosclerosis. Scanning electron microscopy revealed small mound-like lesions protruding from an intact endothelium in birds treated with an initiating dose of 7,12-dimethylbenz[a]anthracene

Mark W. Majesky; Michael A. Reidy; Earl P. Benditt; Mont R. Juchau

1985-01-01

279

Debris mitigation power of various buffer gases for CO2 laser produced tin plasmas  

NASA Astrophysics Data System (ADS)

Debris mitigation using an ambient gas is the easiest way for laser-produced plasma extreme ultraviolet light source. The debris mitigation power of hydrogen, helium and argon buffer gases against CO2 laser produced tin plasma plumes was quantitatively estimated by means of the visualization imaging system as well as the optical emission spectroscopy technique. The debris mitigation power of hydrogen buffer gas was assessed under ambient pressure ranging from 30 to 104 Pa. The debris mitigation power of the hydrogen buffer gas was determined as 150 eV mm-1 for energetic particles of 400 eV under a pressure of 104 Pa, which remained as high as 40 eV mm-1 at a pressure of 100 Pa. The maximum stopping power and collision scattering cross section of argon were measured to be almost three times larger in comparison with hydrogen and one and a half times larger than helium atmosphere at a pressure of 2000 Pa. Time-resolved optical emission spectroscopy showed that thermalizing collisions were responsible for slowing down the fast energetic ions and atoms towards a thermal equilibrium.

Wu, Tao; Wang, Xinbing; Lu, Hong; Lu, Peixiang

2012-11-01

280

Type III bursts produced by power law injected electrons in Maxwellian background coronal plasmas  

NASA Astrophysics Data System (ADS)

Simulations are presented for coronal type III bursts produced by injection of energetic electrons with power law speed spectra onto open magnetic field lines embedded in an otherwise unmagnetized Maxwellian background coronal plasma, including quasi-linear wave-particle interactions and nonlinear wave-wave processes. The simulations show that although fast electrons with speeds >0.3c are injected, they are important only to the onset and not to the peak of fp emission, where fp is the local electron plasma frequency. Instead, slower beam electrons are the major drivers of the peak fp emission. Therefore, the type III beam speeds derived from the drift rates of peak fp emission are less than the typical speeds of c/3 observed for coronal type III bursts. This occurs mainly because the number of fast beam electrons with speeds >0.3c is much less than the slower ones, causing weaker fp emission from these fast beam electrons. Comparisons are made with injected electrons having Maxwellian spectra. We find that type III beams are faster when the injection has power law spectra, since there are more fast electrons injected than for Maxwellian spectra. These results suggest that type III beams produced in the corona with Maxwellian background particle distributions and either power law or Maxwellian spectra can account only for the lower half of the observed range 0.1-0.6c of type III beam speeds but not for the upper half.

Li, Bo; Cairns, Iver H.

2013-08-01

281

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

SciTech Connect

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

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

1998-03-01

282

Density mapping of species in low-temperature laser- produced plasmas  

NASA Astrophysics Data System (ADS)

Spectroscopy and interferometry have been used to quantitatively map the number densities in low temperature laser-produced plasmas. Optical absorption and laser induced fluorescence spectroscopy were used to determine neutral and ion ground state number densities following the 248 nm irradiation of a magnesium target in vacuum. The Doppler broadening of the absorption lineshapes allowed the three dimensional mapping of the plume and the nature of the expansion to be investigated. Single wavelength optical interferometry was used to quantify spatially and temporally resolved electron number densities in the early stages of expansion, i.e. <100 ns, for laser-produced magnesium, copper and titanium plasma plumes. The electron densities were measured as a function of fluence, distance from target and time delay. The three-dimensional mapping of the plume yielded densities ranging from 0.5 1012 cm-3 to greater than 8 1012 cm-3 for an incident fluence of 2 Jcm-2 and at a time delay of 1 ?s after the ablating laser pulse. Higher number densities could not be probed due to resulting optical densities greater than the detection limit of the system. Two distinct components within the plume were detected, i.e. a fast component of ions and neutrals travelling in a highly forward directed plume with velocities of ~10 6 cms-1 and a high density region, ~1015 cm- 3, composed of slow neutral material peaked at the target surface. Electron densities in the range ~0.5 10 17 cm-3 to 1 1019 cm -3, were measured at distances <700 ?m from the magnesium target surface and for delays <100 ns after the onset of the ablating pulse using laser fluences in the range 3-9 Jcm-2. Copper and titanium plasma plumes were also investigated with copper showing lower electron densities than magnesium but higher values than titanium for all fluences.

Doyle, Liam Alistair

283

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

SciTech Connect

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

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

2010-12-09

284

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

National Technical Information Service (NTIS)

The understanding of laser beam propagation through underdense plasmas is of vital importance to laser-plasma interaction experiments, as well as being a fundamental physics issue. Formation of plasma channels has numerous applications including table-top...

P. E. Young S. C. Wilks L. L. Kruer J. H. Hammer G. Guethlein

1996-01-01

285

Development of critical surface diagnostic based on the ion acoustic decay instability in laser produced high density plasma  

SciTech Connect

We have developed a large angle, UV collective Thomson scattering (CTS) diagnostic for high density, hot plasma relevant to laser fusion. The CTS measured the basic parameters of the plasma waves (frequency, wave number), or the spectral density function for selected wave vectors of plasma waves, which were excited by the IADI (ion acoustic parametric decay instability). It is a good diagnostic tool for a local electron temperature measurement. The electron temperature was estimated by measuring either ion acoustic wave or electron plasma wave in the laser intensity window of 1plasma waves in laser produced high density plasma.

Mizuno, K.; DeGroot, J.S.; Drake, R.P.; Seka, W.; Craxton, R.S.; Estabrook, K.G.

1994-12-31

286

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

SciTech Connect

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

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

2011-08-15

287

Current measurements in plasma produced by the train of 10.6-um subnanosecond laser pulses  

NASA Astrophysics Data System (ADS)

Results of current probe measurements for a plasma produced by the train of approximately 200 ps 10.6 micrometers laser pulses are reported. The train of pulses was obtained as a result of regenerative amplification of approximately 100 ps laser pulse in a 5 cm aperture 6 atm TE-CO2 laser. Experiments were carried out for Wo and Al targets dispersed in vacuum, two values of the interpulses separation in the train (Delta) T equals 9.3 and 29 ns and wide range of energy density on the target, corresponding to peak intensities of single pulses Ip equals 1 divided by 300 GW/cm2. Experiments had shown large difference of temporal structure of current signal with Wo and Al targets due to the considerable different in melting temperatures of these materials as well as radiation loses of laser plasma. We detected large ratio of current signal amplitudes for targets irradiation by the pulse train or gain switched pulse generated in TE-CO2 laser without injection of a short pulse. Results of these measurements are compared with those earlier obtained for nanosecond pulse train.

Apollonov, Victor V.; Kazakov, K. K.; Pletnyev, N. V.; Sorochenko, Vladimir R.

2000-01-01

288

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

NASA Astrophysics Data System (ADS)

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

Farid, N.; Harilal, S. S.; Ding, H.; Hassanein, A.

2013-07-01

289

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

290

Transgenically produced human antithrombin: structural and functional comparison to human plasma-derived antithrombin.  

PubMed

Recombinant human antithrombin (rhAT) produced in transgenic goat milk was purified to greater than 99%. The specific activity of the rhAT was identical to human plasma-derived AT (phAT) in an in vitro thrombin inhibition assay. However, rhAT had a fourfold higher affinity for heparin than phAT. The rhAT was analyzed and compared with phAT by reverse phase high-performance liquid chromatography, circular dichroism, fluorophore-assisted carbohydrate electrophoresis (FACE), amino acid sequence, and liquid chromatography/mass spectrography peptide mapping. Based on these analyses, rhAT was determined to be structurally identical to phAT except for differences in glycosylation. Oligomannose structures were found on the Asn 155 site of the transgenic protein, whereas only complex structures were observed on the plasma protein. RhAT contained a GalNAc for galactose substitution on some N-linked oligosaccharides, as well as a high degree of fucosylation. RhAT was less sialylated than phAT and contained both N-acetylneuraminic and N-glycolylneuraminic acid. We postulate that the increase in affinity for heparin found with rhAT resulted from the presence of oligomannose-type structures on the Asn 155 glycosylation site and differences in sialylation. PMID:9616152

Edmunds, T; Van Patten, S M; Pollock, J; Hanson, E; Bernasconi, R; Higgins, E; Manavalan, P; Ziomek, C; Meade, H; McPherson, J M; Cole, E S

1998-06-15

291

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

292

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

NASA Astrophysics Data System (ADS)

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

Masnavi, Majid; Nakajima, Mitsuo; Horioka, Kazuhiko; Araghy, Homaira Parchamy; Endo, Akira

2011-06-01

293

Spectroscopic characterization of plane multilayer diffraction gratings using a laser-produced plasma XUV radiation source  

NASA Astrophysics Data System (ADS)

Spectral characteristics of plane multilayer amplitude molybdenum-silicon diffraction gratings (1000 and 2000 lines/mm, d-spacing of 115 angstrom), fabricated by electron- beam lithography, were determined using a laser-produced plasma XUV radiation source. The gratings were studied at near-normal incidence and at an angle of incidence of 36 degrees in stigmatic and quasi-stigmatic spectrograph systems with moderate dispersion. The task of focusing radiation was imposed on either a grazing-incidence toroidal mirror or a normal-incidence Mo-Si multilayer mirror with a d-spacing of 115 angstrom. The spectral profile of resonance reflection by the gratings was determined in the first and second Bragg orders of the multilayer structure for different angles of incidence. Line spectra of multiply charged F, Na, Mg, and Cl ions were recorded in the 160 - 230 angstrom range by means of these multilayer gratings, and the resolving power of the gratings was determined.

Kolachevsky, Nikolai N.; Mitropolsky, Mikhail M.; Ragozin, Eugene N.; Bac, S.; Troussel, Philippe

1998-06-01

294

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

295

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

SciTech Connect

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

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

2010-10-15

296

Measurements of radial heat wave propagation in laser-produced exploding-foil plasmas  

SciTech Connect

Time-resolved, 2D images of x-ray emission from thin, laser-irradiated titanium foils are presented. The foils are irradiated with 0.35 [mu]m light at intensities of 1[times]10[sup 15] W/cm[sup 2] which produces a plasma with electron densities [le]10[sup 22] cm[sup [minus]3] and electron temperature of 3--4 keV. X-ray emission that is characteristic of the thermal heat front is observed to propagate radially outward from the heated region. Comparison of these measurements with 2D hydrodynamic simulations of the experiment suggests the radial heat flux to be about 3% of the free-streaming heat flux.

Montgomery, D.S.; Landen, O.L.; Drake, R.P.; Estabrook, K.G.; Baldis, H.A.; Batha, S.H.; Bradley, K.S.; Procassini, R.J. (Lawrence Livermore National Laboratory, Livermore, California 94551 (United States) Plasma Physics Research Institute, University of California Davis, Lawrence Livermore National Laboratory, Livermore, California 94551 (United States) Department of Applied Science, University of California Davis, Davis, California 95616 (United States))

1994-10-10

297

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

PubMed

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

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

2012-10-01

298

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

299

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 m 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

300

Influence of spot size on propagation dynamics of laser-produced tin plasma  

SciTech Connect

The plume dynamics in the presence of an ambient gas is very intriguing physics. The expansion of a laser-produced plasma in the presence of an ambient gas leads to internal plume structures, plume splitting, sharpening, confinement, etc. We investigated propagation dynamics of an expanding tin plume for various spot sizes using a fast visible plume imaging and Faraday cup diagnostic tools. Our results indicate that the sharpening of the plume depends strongly on the spot size. With a smaller spot size, the lateral expansion is found to be higher and the plume expansion is spherical while with a larger spot size the plume expansion is more cylindrical. Analysis of time resolved imaging also showed internal structures inside the plume.

Harilal, S. S. [Center for Energy Research, University of California San Diego, La Jolla, California 92093 (United States)

2007-12-15

301

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

302

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

303

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

304

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

305

Modeling of initial imprinting caused by laser-intensity nonuniformities in ablative plasmas  

SciTech Connect

A theoretical model that studies smoothing of non-uniform ablation pressure is presented. The {open_quote}{open_quote}cloudy day{close_quote}{close_quote} model that is widely used to estimate the smoothing considers only thermal wave in homogeneous plasmas. However, sound wave caused by temperature perturbation and steep ablation structure are considered in presented model. Previous work of Manheimer {ital et} {ital al}. tries to include these. However, we newly (1) consider ablation structure with finite density ratio between sonic point and ablation surface; (2) solve eigen value problem to initialize the variables consistently with fluid equations in the shock compression region; (3) impose different boundary condition at the sonic point; and (4) consider higher mode. A nonlinear relation between the perturbed ablation pressure ratio at sonic point to ablation surface, and transverse wave number of perturbation is shown. As the wavenumber becomes larger, the smoothing becomes more efficient. {copyright} {ital 1996 American Institute of Physics.}

Shimuta, Y.; Nishihara, K. [Osaka University, 2-6 Yamada-oka Suita, Osaka 565 (Japan)

1996-05-01

306

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Multiply charged ion spectra of a laser plasma produced on both sides of the target  

NASA Astrophysics Data System (ADS)

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-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.

Bedilov, M. R.; Davletov, I. Yu; Sabitov, M. S.; Berdierov, G. R.; Tsoi, T. G.

2001-05-01

307

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

Microsoft Academic Search

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

Elliot Slamovich; James Fleetwood; James F. McCloskey; Aaron Christopher Hall; Rodney Wayne Trice

2010-01-01

308

Properties of plasmas produced by short double pulse laser ablation of metals  

NASA Astrophysics Data System (ADS)

We investigate the composition of plasmas produced by laser ablation of metals with two time-delayed short laser pulses using fast imaging and time- and space-resolved optical emission spectroscopy. The ablated material is deposited on mica substrates and analyzed by atomic force microscopy. The laser-produced craters are inspected by optical microscopy to evaluate the ablated material quantity. It is shown that the fraction of nanoparticles in the ablation plume is strongly altered when a second laser pulse of sufficiently large delay is applied. Comparing the results obtained for different metals, we observe a significant nanoparticle reduction for interpulse delays of the order of the characteristic time of electron-lattice thermalization. More detailed analyses show that the plume changes occur on two different characteristic times, indicating two different mechanisms at its origin. Here, we discuss the involved processes and we propose a simple and efficient technique for the measurement of electron-lattice thermalization times based on plume observations during double pulse laser ablation.

Hermann, J.; Mercadier, L.; Axente, E.; Nol, S.

2012-11-01

309

A Soft X-Ray/EUV Reflectometer Based on a Laser Produced Plasma Source.  

PubMed

A soft x-ray reflectometer is described which is based on a laser-produced plasma source and is continuously tunable over the range 40 < ? < 400 . The source is produced by focusing 0.532-?m light from a Q-switched Nd:YAG laser on a solid target. The x-ray wavelength is defined using a high throughput spherical grating monochromator with moderate resolving power (?/?? ? 100 to 500). A time-averaged monochromatized flux of more than 109 photons/s in a 1% bandwidth at 100 eV is obtained. Photon "shot noise" limited measurements are obtained by the use of an I0 detector to normalize out the shot-to-shot variations in source intensity. Measurements with submillimeter spot sizes are readily obtainable. Various detectors have been used and the advantages and disadvantages of each are discussed. The higher order contamination of the monochromator output has been analyzed using a second grating for the purpose of making measurement corrections. The reflectometer thus provides the capability for precision absolute measurements of the reflectance of gratings and multilayer mirrors, the transmittance of thin film filters, or other properties of x-ray optical elements. PMID:21307445

Gullikson, E M; Underwood, J H; Batson, P C; Nikitin, V

1992-01-01

310

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

PubMed Central

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

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

2012-01-01

311

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

SciTech Connect

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

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

1989-05-01

312

Measurement of the electron temperature and density of a helium plasma produced by a hollow cathode arc discharge  

Microsoft Academic Search

The electron temperature and electron density of a steady state helium plasma produced by a hollow cathode arc discharge have been measured with the aid of Thomson scattering as functions of the radial distance to the plasma axis. Electron densities in the range of 1*1019 to 4*1019 m-3 and electron temperatures 0.5*105 to 2.5*105K were determined with an accuracy of

W. Kohsiek

1975-01-01

313

Evidence of filamentation \\/self-focusing\\/ of a laser beam propagating in a laser-produced aluminium plasma  

Microsoft Academic Search

The thresholds for self-focusing of a laser beam in a laser-produced plasma computed for propagation of a nanosecond duration pulses in short, high density multiply ionized absorbing plasmas are reported. Theoretical treatment of self-focusing used a computational model TRSF (Siegrist, 1976) to calculate the self-focusing behavior of a laser beam which is Gaussian in time and space and propagating through

V. del Pizzo; B. Luther-Davies

1979-01-01

314

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

315

[New technics for producing inhalation aerosols--initial experiences and results with the piezoelectric inhalation device].  

PubMed

In the treatment of chronic obstructive airway diseases, the inhalative application of medicaments with a bronchodilatory effect is given preference throughout the world. In addition to inhalation solutions and powder capsules, so-called metered-dose aerosols have formed an established part of the treatment plan for approximately 30 years now. With the piezoelectric inhalation device, a fully portable ultrasonic atomiser that is small enough to fit within the pocket, has been developed for the first time. In this device, the piezoelectric effect is utilised to produced, pressure-free, microfine aerosols. Within it, an accurately metered volume containing the therapeutic dose is applied to an atomising element oscillating in the ultrasonic range. The particle spectrum generated with the piezo-system corresponds, in terms of size, to that of metered aerosol devices, and the mean particle diameter is approximately 2.1 microns. The atomisation process takes approximately one second. PMID:2195514

Fischer, J; Khler, D; Morr, H; Wettengel, R; Mtterlein, R; Fleischer, W; Rauber, G; Stechert, R

1990-02-01

316

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Moderation of recombination in an ultracold laser-produced plasma  

NASA Astrophysics Data System (ADS)

It is shown that the recent production [T C Killian et al. Phys. Rev. Lett. 83 4776 (1999)] of an ultracold laser plasma (Ne ~ 2 109 cm-3, Te ~ 0.1 K, Ti ~ 10 ?K) can be considered as the first experimental demonstration of the metastable state of a supercooled plasma which we predicted theoretically. Our theory provides an explanation for the moderation of three-body recombination observed in the above-cited paper. We present the calculations that simulate the conditions of the ultracold-plasma experiments.

Tkachev, Aleksei N.; Yakovlenko, Sergei I.

2000-12-01

317

Large-Scale Filamentary Structures in Laser-Produced Plasmas as a Sign of Strong Magnetic Field Generation  

NASA Astrophysics Data System (ADS)

The method [1] of multilevel dynamical contrasting is applied to available database from experiments on interaction of a powerful short-pulsed laser beam with a flat target. It was found from processing the soft X-ray images that the expanding plasma produces a dynamical filamentary structures, a long-living ones as compared to inertial lifetimes of plasma inhomogeneities in laser-produced plasmas. Such a structuring appears to be similar to the networking of filamented electric currents in high-current gaseous discharges (dense Z-pinch [1] and plasma focus [2]). The structuring disclosed suggests a view into the role of electric current filamentation in the following phenomena in laser-produced plasmas: (i) generation of a strong magnetic field by the strong filamentary electric currents; (ii) formation of closed electric currents and large-scale closed magnetic configurations; (iii) axial stratification of the emerging dense Z-pinch; (iv) formation of long-range bonds between the core and the periphery of expanding plasma. [1] Kukushkin A.B., Rantsev-Kartinov V.A., Laser and Particle Beams, 16(3) 1998 (to be published). [2] Kukushkin A.B., Rantsev-Kartinov V.A., Terentiev A.R., Fusion Technology, 32 (1997) 83.

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

1998-11-01

318

Self-consistent modelling of atmospheric micro-plasmas produced by a microwave source  

NASA Astrophysics Data System (ADS)

This paper presents the self-consistent modelling of argon micro-plasmas, produced by a microwave source (2.45 GHz) at atmospheric pressure. The source is a microstrip-like transmission line, with a 50-200 m final gap where the micro-plasmas are created. Simulations use a one-dimensional, stationary code that solves the fluid-type transport equations for electrons, positive ions Ar+ and Ar^+_2 , and the electron mean energy; the rate balance equations for the main neutral species; Poisson's equation for the space-charge electrostatic field; Maxwell's equations for the electromagnetic excitation field; the gas energy balance equation for its temperature distribution; and the kinetic electron Boltzmann equation considering several direct and stepwize electron collision processes. The model uses a kinetic scheme that considers the atomic excited states Ar(4s) and Ar(4p), two excimer states Ar_2^\\star and Ar_2^{\\star\\star} , and two ionization states associated with the atomic and the molecular ions. The model predicts average gas temperatures of 600 K (similar to the measured rotational temperatures), power densities of 1-10 kW cm-3 (which overestimate measurements at low gap sizes), and excitation temperatures of 0.5-0.8 eV (which, at short gap sizes, are slightly above the experimental value of 0.5 eV, obtained by optical emission spectroscopy measurements), for on-axis electron densities of 5 1013, 1014, 5 1014 cm-3 and wall gas temperatures of 500, 550, 600 K, at gap sizes of 150, 100, 50 m.

Gregrio, J.; Leprince, P.; Boisse-Laporte, C.; Alves, L. L.

2012-02-01

319

Process for producing plasma sprayed carbide-based coatings with minimal decarburization and near theoretical density.  

National Technical Information Service (NTIS)

Plasma spray deposition of carbide/metal hardcoatings is difficult because complex chemical transformations can occur while spraying, especially in the presence of oxygen. A commercial plasma spray torch has been modified to simultaneously inject carbide ...

W. J. Lenling M. F. Smith J. A. Henfling

1990-01-01

320

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

321

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

NASA Astrophysics Data System (ADS)

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? 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; Bai, Ya; Song, Liwei; Liu, Peng; Li, Ruxin; Xu, Zhizhan

2013-08-01

322

Plasma channels produced by a laser-triggered high-voltage discharge  

NASA Astrophysics Data System (ADS)

A plasma waveguide scheme for high-intensity laser guiding with densities and lengths suitable for laser-plasma particle accelerators is presented. This scheme uses a laser-triggered high-voltage discharge, presents negligible jitter, allows full access to the plasma, and can be scaled to large distances. Experimental results showing the feasibility of this scheme are presented.

Lopes, N. C.; Figueira, G.; Silva, L. O.; Dias, J. M.; Fonseca, R.; Cardoso, L.; Russo, C.; Carias, C.; Mendes, G.; Vieira, J.; Mendona, J. T.

2003-09-01

323

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

324

Laser-produced lithium plasma as a narrow-band extended ultraviolet radiation source for photoelectron spectroscopy.  

PubMed

Extended ultraviolet (EUV) emission characteristics of a laser-produced lithium plasma are determined with regard to the requirements of x-ray photoelectron spectroscopy. The main features of interest are spectral distribution, photon flux, bandwidth, source size, and emission duration. Laser-produced lithium plasmas are characterized as emitters of intense narrow-band EUV radiation. It can be estimated that the lithium Lyman-alpha line emission in combination with an ellipsoidal silicon/molybdenum multilayer mirror is a suitable EUV source for an x-ray photoelectron spectroscopy microscope with a 50-meV energy resolution and a 10-mum lateral resolution. PMID:18268711

Schriever, G; Mager, S; Naweed, A; Engel, A; Bergmann, K; Lebert, R

1998-03-01

325

The application of photoconductive detectors to the measurement of x-ray production in laser produced plasmas  

SciTech Connect

Photoconductive detectors (PCDs) offer an attractive alternative for the measurement of pulsed x-rays from laser produced plasmas. These devices are fast (FWHM approx.100 ps), sensitive and simple to use. We have used InP, GaAs, and Type IIa diamond as PCDs to measure x-rays emission from 100 eV to 100 keV. Specifically, we have used these detectors to measure total radiation yields, corona temperatures, and hot electron generated x-rays from laser produced plasmas. 5 refs., 4 figs.

Kania, D.R.; Bell, P.; Trebes, J.

1987-08-01

326

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  

Microsoft Academic Search

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

Xiaoyu Luo

2006-01-01

327

Multi-keV X-Ray Conversion Efficiency in Laser-Produced Plasmas  

SciTech Connect

X-ray sources are created at the Nova and Omega laser by irradiating a confined volume of Ar, Xe, or Kr gas. The gas is heated by forty 0.35 {micro}m wavelength, 1-ns square laser beams to produce He-like ions that radiate K-shell emission over mm-sized dimensions. The targets are designed to be ''underdense'', meaning that the initial gas density is lower than the critical density of the laser, n{sub c} {approx} 10{sup 21} cm{sup -3}. The laser energy is primarily absorbed by inverse bremsstrahlung and a supersonic heat wave efficiently ionizes the gas. Results from time-resolved and time-integrated diagnostics over a range of experimental parameters are compared. This work represents an important, new method for development of efficient, large-area, tailored multi-keV x-ray sources.

Back, C A; Landen, O L; Hammer, J H; Suter, L J; Miller, M C; Davis, J; Grun, J

2002-10-31

328

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

SciTech Connect

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

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

2008-10-15

329

Characterization of gas targets for laser produced extreme ultraviolet plasmas with a Hartmann-Shack sensor  

SciTech Connect

A table top extreme ultraviolet (EUV)-source was developed at Laser-Laboratorium Goettingen for the characterization of optical components and sensoric devices in the wavelength region from 11 to 13 nm. EUV radiation is generated by focusing the beam of a Q-switched Nd:YAG laser into a pulsed xenon gas jet. Since a directed gas jet with a high number density is needed for an optimal performance of the source, conical nozzles with different cone angles were drilled with an excimer laser to produce a supersonic gas jet. The influence of the nozzle geometry on the gas jet was characterized with a Hartmann-Shack wave front sensor. The deformation of a planar wave front after passing the gas jet was analyzed with this sensor, allowing a reconstruction of the gas density distribution. Thus, the gas jet was optimized resulting in an increase of EUV emission by a factor of two and a decrease of the plasma size at the same time.

Peth, Christian; Kranzusch, Sebastian; Mann, Klaus; Vioel, Wolfgang [Laser-Laboratorium Goettingen e. V., Hans-Adolf-Krebs-Weg 1, D-37077 Goettingen (Germany); Fachhochschule Hildesheim/Holzminden/Goettingen, Fakultaet Naturwissenschaften und Technik, Von-Ossietzky-Str. 99, D-37085 Goettingen (Germany)

2004-10-01

330

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

PubMed

The Electron Beam Ion Trap (EBIT) facility at the Lawrence Livermore National Laboratory is being used to absolutely calibrate the transmission efficiency of x-ray filters employed by diodes and spectrometers used to diagnose laser-produced plasmas. EBIT emits strong, discrete monoenergetic lines at appropriately chosen x-ray energies. X rays are detected using the high resolution EBIT Calorimeter Spectrometer (ECS), developed for LLNL at the NASA/Goddard Space Flight Center. X-ray filter transmission efficiency is determined by dividing the x-ray counts detected when the filter is in the line of sight by those detected when out of the line of sight. Verification of filter thickness can be completed in only a few hours, and absolute efficiencies can be calibrated in a single day over a broad range from about 0.1 to 15 keV. The EBIT calibration lab has been used to field diagnostics (e.g., the OZSPEC instrument) with fully calibrated x-ray filters at the OMEGA laser. Extensions to use the capability for calibrating filter transmission for the DANTE instrument on the National Ignition Facility are discussed. PMID:19044471

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

2008-10-01

331

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

332

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

SciTech Connect

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

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

2008-05-11

333

Diagnostic value of odd-integer half-harmonic emission from laser-produced plasmas  

SciTech Connect

The diagostic value of odd-integer half-harmonic emission from laser-produced plasmas is evaluated in the light of recent spectral measurements on UV irradiation experiments. It has been found that under certain conditions a sharp, slightly red-shifted feature is observed in the ..omega../2 spectra. This feature has been identified with a particular mode of the 2..omega../sub p/ decay instability for which one of the plasmon wave vectors vanishes. This feature is eminently well suited for coronal electron temperature measurements. Another half-harmonic (blue-shifted) feature is more easily observed and may serve as a secondary: though less accurate: temperature diagnostic. In contrast, the spectral splitting of the (3)/(2) harmonic emission proved to be ill suited for temperature diagnostics because of its sensitivity to irradiation and observation geometry. Either ..omega../2 or 3..omega../2 emission is, however, a good qualitative indicator for the presence of the 2..omega../sub p/ decay instability although quantitative inferences on the level of the 2..omega../sub p/ decay instability are not possible at this point.

Seka, W.; Afeyan, B.B.; Boni, R.; Goldman, L.M.; Short, R.W.; Tanaka, K.; Johnston, T.W.

1985-08-01

334

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

335

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

NASA Astrophysics Data System (ADS)

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

Ugai, M.

2011-10-01

336

Statistics and characteristics of xuv transition arrays from laser-produced plasmas of the elements tin through iodine  

Microsoft Academic Search

Spectra of laser-produced plasmas of the elements from tin to iodine contain weak bands of quasicontinuum overlaid by weak emission lines in the 70-120- region. Multiconfiguration-Dirac-Fock calculations show that these features are consistent with theoretical spectra for 4dN-4dN-1(5f+6p) transitions in a number of adjacent ion stages which are predicted to produce unresolved transition arrays (UTA) in this spectral region. Moreover,

Winnie Svendsen; Gerard O'sullivan

1994-01-01

337

The visibility of UV and visible lines of highly ionized carbon in spectra of laser-produced plasmas  

Microsoft Academic Search

A complete UVVIS spectrum of laser-produced carbon plasmas, produced by a 5J, 15ns ruby laser was recorded and searched for spectral lines of highly ionized carbon (C V and C VI lines). Several C V and C VI lines are observed, but are weak, compared to other carbon lines. Still, some C V lines are distinctive enough to be used

. Andrei?; D. Gracin; L. Aschke; H.-J. Kunze

2001-01-01

338

Initial Results from the CRRES/MICS Empirical Model of Ion Plasma in the Inner Magnetosphere  

NASA Astrophysics Data System (ADS)

We present initial results from a recently developed empirical model of low energy ion plasma (~1-300 keV/e) in the inner magnetosphere. This model is constructed from data taken by the Magnetospheric Ion Composition Spectrometer (MICS) on-board the Combined Release and Radiation Effects Satellite (CRRES). The model has been constructed in a similar fashion to the Roeder et al., [2005] CAMMICE/MICS model, which used NASA Polar satellite data. The orbital differences between CRRES (GTO) and Polar (highly-inclined polar orbit) result in each spacecraft sampling different portions of the ion pitch-angle distributions. Such models can be used to estimate the average flux for major ion species (e.g. H+, He+, He++, O+) along any orbit in the inner magnetosphere. To construct this new model, CRRES/MICS ion fluxes were computed and sorted into bins of magnetic coordinates L, MLT, MLAT, equatorial pitch-angle and activity indices. Preliminary comparisons are made between the CAMMICE/MICS and CRRES/MICS models, highlighting the strengths and limitations of both. We also consider the average O+ ion flux deduced from the model in various spatial and activity ranges and qualitatively compare with what is to be expected from O+ ion transport and loss processes.

Claudepierre, Seth; Roeder, James; Chen, Margaret; Lemon, Colby; Guild, Timothy

2013-04-01

339

Photoionization of an He-like aluminum plasma by a laser-produced X-ray source  

NASA Astrophysics Data System (ADS)

We present preliminary experiments and calculations performed to optimize the photoionization of an He-like aluminum plasma. The high emissivity of the 3d-4f M-band of tantalum or tungsten is used as the pump. The plasmas are produced by two 500 ps duration beams of a frequency doubled Nd-glass laser. The pump beam is delayed by 1 ns with respect to the main beam. The Al plasma ionization state has been measured with K-alpha absorption measurements. X-ray diodes and space-resolving crystal spectrographs have been used to measure the intensity of the pump source in the desired spectral range. Optimization of the pumping scheme is analyzed with a numerical description of the photopumping process by a collisional-radiative modeling of the Al plasma including the X-ray pump.

Chenais-Popovics, C.; Back, C. A.; Renaudin, P.; Geindre, J. P.; Gauthier, J. C.

1992-02-01

340

Risk factors for initial respiratory disease in United States' feedlots based on producer-collected daily morbidity counts  

PubMed Central

The incidence of initial respiratory disease was followed for 12 weeks in 122 pens of feedlot cattle, based on producer-collected daily morbidity counts. Weekly incidence density was calculated based on the number of new cases and the population at risk. Incidence density was greatest in the 1st week after arrival and decreased in following weeks. Weekly incidence rate varied between pens and over time from 0 to 27.7 cases per 100 animal weeks at risk. A negative binomial model controlling for multiple events within pens and over time was used to model effects on the number of new cases. Mixed gender groups, cattle from multiple sources and increasing distance shipped were associated with increased risk for initial respiratory morbidity. Heavier entry weight was associated with decreased morbidity risk. These factors may be useful in categorizing groups of calves into risk groups for targeted purchase and management decision making.

Sanderson, Michael W.; Dargatz, David A.; Wagner, Bruce A.

2008-01-01

341

Time-resolved probing of femtosecond-laser-produced plasmas in transparent solids by electron thermal transport  

SciTech Connect

This paper is a comprehensive report on both the experimental and theoretical aspects of the recently observed supersonic ionization front in solid density plasmas, produced on the surface of a transparent fused quartz target by 100 fs-laser-pulse irradiation. The ionization front is driven by electron thermal conduction into the bulk region of the target on a time scale of [similar to]1 ps, before any significant hydrodynamic expansion. The observed large and persistent increase in the reflectivity of the plasma--quartz region indicates that the plasma--quartz interface is steep and long lived ([similar to]15 ps). The experiments include pump-probe schemes with the probe incident on either side of the target, to provide different but complementary information on the plasma evolution and energy transport mechanisms. A simple analytical model, modified from earlier nonlinear heat wave models, is proposed to account for the ionization front velocity and plasma evolution in both time and space. Calculations of the probe light reflectance after interacting with the plasma at the plasma--quartz region lead to a time history of the electron--ion collision frequency. The result shows the electron scattering length comparable with the average interionic spacing ([similar to]3 A), implying localization of thermal electrons.

Vu, B.V.; Landen, O.L.; Szoke, A. (L-059, P.O. Box 808, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))

1995-02-01

342

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

PubMed

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

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

2010-06-09

343

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

SciTech Connect

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

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

2010-10-15

344

Characterization of a laser-produced plasma source for a laboratory EUV reflectometer  

NASA Astrophysics Data System (ADS)

With the development of EUV lithography there is an increasing need for high-accuracy at-wavelength metrology. In particular, there is an urgent need for metrology at optical components like mirrors or masks close to the production line. Sources for metrology have to fit different demands on EUV power and spectral shape than sources for steppers systems. We present the results of the radiometric characterization of a laser produced plasma (LPP)-source, newly developed at Max-Born-Institute Berlin for use in an EUV reflectometer. It is operated with a high-power pointing-stabilized laser beam (energy per pulse up to 700 mJ, 10 ns pulse duration, < 25 rad pointing stability) at 532 nm which is focussed on a rotating Au target cylinder. The incident angle of the laser beam is set to 63, the detecting angle 55 to the target normal. The source has been characterized regarding spectral photon flux, source size and source point stability. Two independently calibrated instruments, an imaging spectrometer and a double multilayer tool for in-band power measurements were used to obtain highly reliable quantitative values for the EUV emission of the Au-LPP source. Both instruments were calibrated by Physikalisch-Technische Bundesanstalt in its radiometry laboratory at the electron storage ring BESSY II. We obtained a source size of 30 m by 50 m (2s horizontal by vertical) and a stability of better than 2s=5 m horizontally and 2s=9 m vertically. A spectral photon flux of 1*10e14 /(s sr 0.1 nm) at 13.4 nm at a laser pulse energy of 630 mJ is obtained. The shot-to-shot stability of the source is about 5% (1s) for laser pulse energies above 200 mJ. For pulse energies between 200 mJ and 700 mJ, there is a linear relation between laser pulse energy and EUV output. The spectrum shows a flat continuos emission in the EUV spectral range, which is important for wavelength scanning reflectometry. High stability in total flux and spectral shape of the plasma emission as well as low debris was only obtained using a new target position for each shot. There is also a trade off between source size and EUV power. For a slightly defocused laser, an increase in EUV power up to a factor of two is obtained, while the source size also increases by about a factor of two. It is shown that an Au-LPP source provides spectrally flat reproducible emission with sufficient power at low debris conditions for the operation of a laboratory based EUV reflectometer.

Scholze, Frank; Scholz, Frank; Tuemmler, Johannes; Ulm, Gerhard; Legall, Herbert; Nickles, Peter-Viktor; Sandner, Wolfgang; Stiel, Holger; van Loyen, Ludwig

2003-06-01

345

Process for producing plasma sprayed carbide-based coatings with minimal decarburization and near theoretical density  

Microsoft Academic Search

Plasma spray deposition of carbide\\/metal hardcoatings is difficult because complex chemical transformations can occur while spraying, especially in the presence of oxygen. A commercial plasma spray torch has been modified to simultaneously inject carbide powder and a metal alloy powder at two different locations in the plasma stream. Composite hardcoatings of tungsten carbide\\/cobalt with a nickel-base alloy matrix have been

W. J. Lenling; M. F. Smith; J. A. Henfling

1990-01-01

346

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

347

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

348

Measurement of the local electron density by means of stimulated Raman scattering in a laser-produced gas jet plasma  

Microsoft Academic Search

By measuring the spectrum of the backscattered light from a short-pulse laser-produced plasma in a gas jet, a direct and highly accurate measurement of the local electron density can be obtained. The measurement is based on the density-dependent spectral shift of the backscattered Raman wave.

M. D. Perry; C. Darrow; C. Coverdale; J. K. Crane

1992-01-01

349

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

NASA Astrophysics Data System (ADS)

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

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

2003-06-01

350

Chirped pulse interferometry for time resolved density and velocity measurements of laser produced plasmas  

SciTech Connect

An optical diagnostic method to record the evolution of plasma density on picosecond time scale with {approx}8 ps resolution in a single shot is presented. A chirped laser pulse of 200 ps is used for obtaining the time resolved interferograms to provide the temporal evolution of plasma density (10{sup 17}/cm{sup 3}) during the probe beam duration. It is shown that the plasma expansion velocity can also be measured from the diffraction pattern superimposed on the interferograms. Plasma velocity of {approx}1.2 x 10{sup 7} cm/s was estimated along with its temporal profile. The details of the method and the results are presented.

Prasad, Y. B. S. R.; Barnwal, S.; Naik, P. A.; Chakera, J. A.; Gupta, P. D. [Laser Plasma Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

2011-07-15

351

Chirped pulse interferometry for time resolved density and velocity measurements of laser produced plasmas  

NASA Astrophysics Data System (ADS)

An optical diagnostic method to record the evolution of plasma density on picosecond time scale with ~8 ps resolution in a single shot is presented. A chirped laser pulse of 200 ps is used for obtaining the time resolved interferograms to provide the temporal evolution of plasma density (1017/cm3) during the probe beam duration. It is shown that the plasma expansion velocity can also be measured from the diffraction pattern superimposed on the interferograms. Plasma velocity of ~1.2 107 cm/s was estimated along with its temporal profile. The details of the method and the results are presented.

Prasad, Y. B. S. R.; Barnwal, S.; Naik, P. A.; Chakera, J. A.; Gupta, P. D.

2011-07-01

352

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

NASA Astrophysics Data System (ADS)

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

Short, R. W.; Simon, A.

1997-11-01

353

Bipolar plasma vaporization in secondary bladder neck sclerosis - initial experience with a new technique  

PubMed Central

Introduction: Secondary bladder neck sclerosis (BNS) represents one of the most common long-term complications after prostate surgical treatment. In this retrospective study, we aimed to evaluate our initial experience concerning the bipolar plasma vaporization (BPV) performed in patients with secondary BNS and to assess the efficiency, safety and short-term postoperative results of this approach. Materials & Methods: Between May 2009 and May 2010, a total of 30 male patients with BNS underwent BPV and were followed for a period of 6 months. BNS was secondary to monopolar transurethral resection of prostate (TURP) in 19 cases, to open surgery for BPH (open prostatectomy) in 8 cases and to radical prostatectomy for prostate cancer in 3 cases. The follow-up protocol included the International Prostate Symptom Score (IPSS), quality of life score (QoL), maximum flow rate (Qmax) and post-voiding residual urinary volume (RV) evaluated at 1, 3 and 6 months after surgery. Results: BPV was successfully performed in all cases. All patients were able to void spontaneously and were continent after catheter removal. The mean operating time was 9 minutes, the mean catheterization period was 18 hours and the mean hospital stay was 24 hours. Preoperatively and at 1, 3 and 6 months after surgery, the mean values for Qmax and RV were 7.2 ml/s and 110 ml, 23.9 ml/s and 20 ml, 23.8 ml/s and 28 ml, and 23.4 ml/s and 26 ml, respectively. Before surgery and at 1, 3 and 6 months, the IPSS and QoL scores were 22.6 and 4.1, 3.4 and 1.2, 3.6 and 1.4, and 3.7 and 1.4, respectively. Conclusions: BPV represents a valuable endoscopic treatment alternative for secondary BNS with good efficacy, reduced morbidity, fast postoperative recovery and satisfactory follow-up parameters. Abbreviations BNS bladder neck sclerosis, BPV bipolar plasma vaporization, TURP transurethral resection of the prostate, IPSS International Prostate Symptom Score, QoL quality of life score, Qmax maximum flow rate, RV post-voiding residual urinary volume

Geavlete, B; Stanescu, F; Nita, Gh; Jecu, M; Moldoveanu, C; Geavlete, P

2012-01-01

354

Super Hard X-Rays from Two-Plasmon Decay in Laser Produced Plasmas.  

NASA Astrophysics Data System (ADS)

X-ray Bremsstrahlung photons with energies in the vicinity of 100 KEV are routinely observed in short pulse high intensity infra-red laser fusion experiments. The purpose of this work is to identify the source mechanism for these x-rays. The x-rays are generated by illuminating glass microballoons with light intensities of 10('15) to 10('16) W/cm('2) using a Nd laser. A pair of NaI(Tl) scintillator detectors with lead absorber filters are used to measure the average photon energy and spectral intensity of the super hard spectrum. This spectrum was assumed to decay exponentially with photon energy. Laser prepulse were used to control the density gradient scale length presented to the main beam. Unexpectedly the prepulses had no effect on the super hard x-ray spectrum. Happenstance changes in laser intensity resulted in variations in the x-ray energy output and also variations in spectrum's exponential decay constant. A strong correlation between the fraction of incident laser energy which was radiated and the decay constant was observed. The relation was found to be consistent with the temperature of the super fast electron distribution scaling with laser intensity as T (TURN) I('1/3). This is characteristic of absorption mechanisms which produce high phase velocity electron plasma waves such as Raman scattering or Two-Plasmon Decay. But of the hard x-ray generating mechanisms considered to date only Two-Plasmon Decay can exhibit independence from prepulses. It does so by forming its own local density scale length. In this experiment the fraction of energy absorbed into the mechanism is small, however in longer pulse experiments needed for breakeven the effect is expected to be more important.

McAdoo, John Hart

355

LLNL large-area inductively coupled plasma (ICP) source: Experiments.  

National Technical Information Service (NTIS)

We describe initial experiments with a large (76-cm diameter) plasma source chamber to explore the problems associated with large-area inductively coupled plasma (ICP) sources to produce high density plasmas useful for processing 400-mm semiconductor wafe...

R. A. Richardson P. O. Egan R. D. Benjamin

1995-01-01

356

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 USDAs 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 ...

357

Composition and dynamics of an erosion plasma produced by microsecond laser pulses  

Microsoft Academic Search

The ion and energy compositions were determined and the dynamics was studied of an erosion plume formed by microsecond CO2 laser pulses incident on a graphite target. The ionic emission lines were used to find the electron density and temperature of the plasma on the target surface. The temperature of the plasma source did not change throughout the line emission

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

1995-01-01

358

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

359

Characterization of laser-produced aluminum plasma in ambient atmosphere of nitrogen using fast photography  

NASA Astrophysics Data System (ADS)

We report on the pulsed-laser ablation of aluminum in ambient pressure of nitrogen varying from 0.01 to 70 Torr using images of the expanding plasma plume. At pressures >=1 Torr plasma-gas interface showed severe distortion in the front of the expanding plume. The plasma expansion velocity showed oscillatory behavior with delay time beyond 260 ns and is attributed to Rayleigh-Taylor instability. The effect of background gas on inducing polarization in the ablated plasma is also reported. At low pressure of 0.1 Torr the degree of polarization of Al III transition 4s 2S1/2-4p 2P3/20 at 569.6 nm increased with delay time. At pressures >=1 Torr it showed an oscillatory behavior. The observed steep pressure gradient at the plasma-gas interface may result in strong self-generated magnetic field due to Rayleigh-Taylor instability.

Sharma, A. K.; Thareja, R. K.

2004-05-01

360

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

PubMed Central

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

Crank, M.; Harilal, S. S.; Hassan, S. M.; Hassanein, A.

2012-01-01

361

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

362

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

NASA Astrophysics Data System (ADS)

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.; Chang, P.-Y.; Drake, R. P.; Fiksel, G.; Froula, D. H.; Glenzer, S. H.; Gregori, G.; Grosskopf, M.; Huntington, C.; Koenig, M.; Kuramitsu, Y.; Kuranz, C.; Levy, M. C.; Liang, E.; Martinez, D.; Meinecke, J.; Miniati, F.; Morita, T.; Pelka, A.; Plechaty, C.; Presura, R.; Ravasio, A.; Remington, B. A.; Reville, B.; Ryutov, D. D.; Sakawa, Y.; Spitkovsky, A.; Takabe, H.; Park, H.-S.

2013-05-01

363

X-ray spectrum in the range (6-12) A emitted by laser-produced plasma of samarium  

SciTech Connect

A detailed analysis of the x-ray spectrum emitted by laser-produced plasma of samarium (6-12 A) is presented, using ab initio calculations with the HULLAC relativistic code and isoelectronic considerations. Resonance 3d-nf (n=4 to 7), 3p-4d, 3d-4p, and 3p-4s transitions in Ni samarium ions and in neighboring ionization states (from Mn to Zn ions) were identified. The experiment results show changes in the fine details of the plasma spectrum for different laser intensities.

Louzon, Einat; Henis, Zohar; Levi, Izhak; Hurvitz, Gilad; Ehrlich, Yosi; Fraenkel, Moshe; Maman, Shlomo [Soreq Research Center, Yavne 81800 (Israel); Mandelbaum, Pinchas [Jerusalem College of Engineering, Ramat Beth Hakerem, Jerusalem 91035 (Israel)

2009-05-15

364

Experimental studies of the high and low frequency electromagnetic radiation produced from nonlinear laser-plasma interactions  

NASA Astrophysics Data System (ADS)

We present the results of experiments on the generation of both high and low frequency electromagnetic radiation from the nonlinear interaction of intense laser beams with underdense plasmas. High frequency radiation is generated as a result of the reflection of a near-infrared laser beam by breaking plasma waves. In the proof-of-principle experiment, a 2 TW, 76 fs Ti:sapphire laser pulse was focused to generate wake waves, and a ~0.1 TW laser pulse was focused to collide with the electron density modulations. Frequencies of the reflected light were 56-110 times higher than that of the initial laser. The estimated number of photons per solid angle was 3107 photons/sr. Low frequency radiation is emitted by the plasma as well. We found that the polarization of the radiation was similar to that of the driver laser. These properties are in accordance with the generation mechanism by relativistic solitons.

Kando, M.; Pirozhkov, A. S.; Fukuda, Y.; Esirkepov, T. Zh.; Daito, I.; Kawase, K.; Ma, J. L.; Chen, L. M.; Hayashi, Y.; Mori, M.; Ogura, K.; Kotaki, H.; Sagisaka, A.; Ragozin, E. N.; Faenov, A.; Pikuz, T.; Kiriyama, H.; Okada, H.; Kameshima, T.; Koga, J. K.; Belyaev, K.; Kamenets, F. F.; Sugiyama, A.; Kawachi, T.; Daido, H.; Kimura, T.; Kato, Y.; Tajima, T.; Bulanov, S. V.

2009-11-01

365

Transient ionization in plasmas produced by point-like irradiation of solid Al targets  

NASA Astrophysics Data System (ADS)

Time-resolved x-ray spectroscopy has been used to investigate ionization dynamics of a micrometer-sized nanosecond laser-plasma during the plasma start-up phase. Experimental results are modeled using two-dimensional hydrodynamic simulations and time-dependent collisional-radiative calculations. The study clearly shows that, due to the rapid expansion cooling, x-ray emission originates predominantly from a well-localized plasma region characterized by rapidly evolving hydrodynamic conditions. In this region, ionization dynamics is found to depart substantially from the steady-state regime. The measurements provide clear evidence of this transient ionization regime showing good agreement with the time-dependent calculations.

Gizzi, L. A.; Cecchetti, C. A.; Galimberti, M.; Giulietti, A.; Giulietti, D.; Labate, L.; Laville, S.; Tomassini, P.

2003-12-01

366

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

367

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

SciTech Connect

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

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

2005-11-01

368

Experimental investigation of stimulated Brillouin scattering in laser-produced plasmas relevant to inertial confinement fusion.  

National Technical Information Service (NTIS)

Despite the apparent simplicity of controlled fusion, there are many phenomena which have prevented its achievement. One phenomenon is laser-plasma instabilities. An investigation of one such instability, stimulated Brillouin scattering (SBS), is reported...

K. S. Bradley

1993-01-01

369

Complete chemical analysis of produced water by modern inductively coupled plasma spectroscopy (ICP).  

National Technical Information Service (NTIS)

ICP (Inductively Coupled Plasma) spectroscopy is recognised as a very effective tool for monitoring ion compositions in many different waters. It has also been used by a number of laboratories to determine residual levels of phosphonate (PH) scale inhibit...

G. M. Graham K. S. Sorbie A. Johnston L. S. Boak

1996-01-01

370

Small-scale plasma irregularities produced during electron attachment chemical releases  

SciTech Connect

In situ measurements of small-scale plasma density irregularities made during sounding rocket experiments that released electron attachment materials into the ionosphere are presented. A 2D electrostatic simulation model that includes attachment chemistry is used to study the source and evolution of these irregularities. The simulation shows (1) that large electron flow velocity shears develop on the boundary of the electron depletion and (2) these shears drive a plasma instability that is the likely source of the irregularities.

Scales, W.A.; Bernhardt, P.A.; Ganguli, G.; Siefring, C.L.; Rodriguez, P.

1994-04-01

371

Characterisation of ceramic coatings produced by plasma electrolytic oxidation of aluminum alloy  

Microsoft Academic Search

Ceramic coatings were prepared on aluminum alloy by plasma electrolytic oxidation method in an environmental-friendly solution. Evolvement of surface morphology, composition and thickness of ceramic coatings on aluminum alloy were studied during plasma electrolytic processes by scanning electron microscopy and X-ray diffractometer. Analysis show that the two-layer structure ceramic coatings consist of different states of Al2O3 such as ?-Al2O3, ?-Al2O3

Wei-Chao Gu; Guo-Hua Lv; Huan Chen; Guang-Liang Chen; Wen-Ran Feng; Si-Ze Yang

2007-01-01

372

Ultra-shallow junctions produced by plasma doping and flash lamp annealing  

Microsoft Academic Search

The capabilities of plasma doping (PLAD) and flash lamp annealing (FLA) for use in ultra-shallow junction (USJ) fabrication have been evaluated. Silicon wafers have been doped in a BF3 plasma using wafer biases ranging from 0.6 to 1kV and a dose of 4 1015cm?2. The wafers so implanted have been heat-treated by FLA using pre-heating temperatures in the range

Wolfgang Skorupa; Rossen A. Yankov; Wolfgang Anwand; Matthias Voelskow; Thoralf Gebel; Daniel F. Downey; Edwin A. Arevalo

2004-01-01

373

Observations of ionic species produced in an atmospheric pressure pulse-modulated RF plasma needle  

NASA Astrophysics Data System (ADS)

Pulse-modulated generation of atmospheric pressure plasma promises lower operating temperatures and enhanced energy efficiencies compared with those generated using continuous excitation. In this study, the effect of pulse modulation on the ionic content of a radio-frequency helium plasma needle was explored using molecular beam mass spectrometry (MBMS). In all cases reported the pulse repetition frequency was held constant at 6 kHz while the duty cycle and distance between the plasma needle and MBMS were varied from 30% to 90% and 4 mm to 10 mm, respectively. Decreasing the duty cycle was seen to enhance the negative ion flux to the MBMS and yields a clear shift to higher masses for positive ion species. Time-resolved ion intensity measurements (5 s resolution) demonstrated that negative ions were created almost exclusively in the pulse off-time while positive ions were generated mainly in the on-time. The ions detected were also seen to change as the distance between the sampling orifice and tip of the plasma needle increased, highlighting the effect of different ion mobilities in the flowing gas stream and the presence of an extended cooler afterglow region. The results suggest that there is a possibility of tailoring the ionic plasma chemistry through pulsed modulation, increasing the versatility of the already widely studied plasma needle device.

McKay, K.; Walsh, J. L.; Bradley, J. W.

2013-06-01

374

Spectra of multiply charged hollow ions in the plasma produced by a short-wavelength nanosecond laser  

SciTech Connect

Complex spectral structures located between the resonance lines of H- and He-like MgXII and MgXI ions were recorded in experiments on plasma heating by the radiation of a low-power short-wavelength excimer XeCl laser (12-ns pulses with an energy of 2 J). The above spectral structures were shown to arise from transitions in the so-called hollow multicharged ions, i.e., in ions with an empty 1s-shell, which were previously observed in laser produced plasmas only with ultrahigh-power femto- and picosecond laser facilities having extremely high-contrast laser pulses. (interaction of laser radiation with matter. laser plasma)

Abdallah, J [Los Alamos National Laboratory, Los Alamos (United States); Skobelev, I Yu; Faenov, A Ya [Multicharged Ion Spectra Data Center, All-Russia Research Institute of Psysicotechnical and Radio Enginering Measurments, Mendeleevo, Moscow Region (Russian Federation); Magunov, A I [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Pikuz, T A [N.E. Bauman Moscow State Technical University, Moscow (Russian Federation); Flora, F; Bollanti, S; DiLazzaro, P; Letardi, T [ENEA, Frascati (Italy); Burattini, E; Grilli, A [Instituto Nazionale di Fisica Nucleare (Italy); Reale, A; Palladino, L; Tomassetti, G; Scafati, A; Reale, L [L'Aquila University (Italy)

2000-08-31

375

Measurement of Laser Plasma Instability (LPI) Driven Light Scattering from Plasmas Produced by Nike KrF Laser  

NASA Astrophysics Data System (ADS)

With short wavelength (248 nm), large bandwidth (13 THz), and ISI beam smoothing, Nike KrF laser provides unique research opportunities and potential for direct-drive inertial confinement fusion. Previous Nike experiments observed two plasmon decay (TPD) driven signals from CH plasmas at the laser intensities above 2x10^15 W/cm^2 with total laser energies up to 1 kJ of 350 ps FWHM pulses. We have performed a further experiment with longer laser pulses (0.54.0 ns FWHM) and will present combined results of the experiments focusing on light emission data in spectral ranges relevant to the Raman (SRS) and TPD instabilities. Time- or space-resolved spectral features of TPD were detected at different viewing angles and the absolute intensity calibrated spectra of thermal background were used to obtain blackbody temperatures in the plasma corona. The wave vector distribution in k-space of the participating TPD plasmons will be also discussed. These results show promise for the proposed direct-drive designs.

Oh, Jaechul; Weaver, J. L.; Phillips, L.; Obenschain, S. P.; Schmitt, A. J.; Kehne, D. M.; Serlin, V.; Lehmberg, R. H.; McLean, E. A.; Manka, C. K.

2010-11-01

376

The Effects of Resonantly Enhanced Fields in Picosecond Laser Produced Plasmas  

NASA Astrophysics Data System (ADS)

Picosecond laser-plasma interactions have been studied experimentally using a 1-ps, 1-mu m laser interacting with solid targets. The experiments have been conducted with a detailed knowledge of the laser pulse shape. High intensity contrast laser pulses ensure that no preformed plasma exists before the arrival of the main picosecond pulse in an intensity range where nonlinear processes start to dominate the laser absorption namely from 10^{14} to 10 ^{16} W/cm^2.. When no preformed plasma exists, the resonantly oscillating field at the critical surface can be significantly enhanced and can accelerate plasma particles to superthermal energies. This field enhancement was studied in terms of the amplitude of p-polarized (laser electric field vector component parallel to the plane of incidence) component through an extensive characterization of the ion blowoff including the ion current, angular distribution, ion charge state as a function of velocity and velocity distribution. Two primary findings from this characterization are: (1) the ion blowoff characteristics depend entirely on the p-polarized component of laser and not on the laser energy, and (2) the nonthermal electrons driving the plasma expansion are highly monoenergetic. These findings are supported by several other plasma diagnostics which include laser energy absorption, continuum and K_alpha x-ray measurements. It is suggested from the experimental observation that the electrons are accelerated by the ponderomotive force in the resonantly oscillating field. The intensity enhancement at the critical surface was calculated based on the ponderomotive picture using experimentally measured electron kinetic energy. The experimental values are compared with theoretical values that include plasma-wave dispersion effects on the resonantly oscillating field strength. The ponderomotive acceleration mechanism is compared to wavebreaking as an explanation for the nonthermal electron acceleration.

Uchida, Shigeaki

377

Optimizing 13.5 nm laser-produced tin plasma emission as a function of laser wavelength  

SciTech Connect

Extreme ultraviolet lithography requires a light source at 13.5 nm to match the proposed multilayer optics reflectivity. The impact of wavelength and power density on the ion distribution and electron temperature in a laser-produced plasma is calculated for Nd:YAG and CO{sub 2} lasers. A steady-state figure of merit, calculated to optimize emission as a function of laser wavelength, shows an increase with a CO{sub 2} laser. The influence of reduced electron density in the CO{sub 2} laser-produced plasma is considered in a one-dimensional radiation transport model, where a more than twofold increase in conversion efficiency over that attainable with the Nd:YAG is predicted.

White, J.; Dunne, P.; Hayden, P.; O'Reilly, F.; O'Sullivan, G. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)

2007-04-30

378

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

SciTech Connect

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

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

2010-11-15

379

Measurements of the energies of negative ions produced in processing plasmas  

NASA Astrophysics Data System (ADS)

The quality of the thin oxide films deposited on a variety of materials during exposure to plasmas containing oxygen depends strongly on the identity and energies of the negative oxygen ions arriving at the growing films. There have, however, been few experimental studies in which these ion energies have been measured and the available data is markedly less abundant than for the corresponding positive ions. We discuss reasons for the lack of data and suggest suitable techniques for obtaining energy distributions for mass identified ions for a variety of plasmas, including both steady-state and pulsed DC and RF plasmas. For asymmetric RF plasmas the distributions depend on the relative dimensions of the sheath regions in front of the discharge electrodes, whereas for DC magnetron systems a dominant parameter is the voltage applied to the magnetron cathode, particularly when this is pulsed. Sample data for O-, O2-,and O3- ions are shown for mixtures of oxygen and argon for a number of systems including a DC plasma system in which the ions were sampled through an orifice in the anode electrode, and a small magnetron device for which the ions arriving at a grounded substrate were observed.

Seymour, David; Greenwood, Claire; Davies, Sean; Rees, Alan

2012-10-01

380

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

NASA Astrophysics Data System (ADS)

X-ray diagnostics of the interaction of femtosecond laser pulses with intensities of 1016-1018 W/cm2 with CO2 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 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 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.; Magunov, A. I.; Boldarev, A. S.; Gasilov, V. A.

2010-12-01

381

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

382

Soft X-ray Radiation from Nitrogen Z-pinch Plasma Produced by Capillary Discharge  

NASA Astrophysics Data System (ADS)

Characteristics of soft X-ray radiation from nitrogen filled Z-pinch plasma columns energized by capillary discharge are reported in order to evaluate optimum plasma parameters for an H-like N recombination pumped soft X-ray laser, wavelength of which is 13.4 nm emitted by quantum transition from n=3 to n=2. The discharge system used in this experiment consists of a 3-stage Marx generator, a step-up transformer and a 3-nF water capacitor. Soft X-ray radiation from Z-pinch nitrogen plasma was measured by using a transmission grating spectrometer with a CCD array detector. Multiply-ionized ions up to N VII were confirmed to exist, and existence of N VIII was anticipated. This suggests that a plasma temperature at the pinch time is the order of 100 eV and might reaches over 150 eV. From these experimental results, plasma parameters and the discharge current required for realizing an H-like N recombination soft X-ray laser were estimated.

Sakai, Yusuke; Komatsu, Takanori; Xiao, Yifan; Song, Inho; Niimi, Gota; Watanabe, Masato; Okino, Akitoshi; Hotta, Eiki

383

Effect of $q\\\\bar q$ Initial-state Interaction on Dilepton Emission Rate from Quark-Gluon Plasma  

Microsoft Academic Search

We calculate the dilepton production rate from a thermalized quark-gluon plasma in heavy-ion collisions at RHIC energies. Higher-order QCD corrections are included by using an analytical correction factor $K^{(i)}$, which takes into account the $q\\\\bar q$ initial-state interactions. We show that the analytic correction factor gives very good agreement with experimental Drell-Yan data and leads to large enhancement of the

M. G.-H. Mostafa; Cheuk-Yin Wong; Lali Chatterjee; Zhong-Qi Wang

1995-01-01

384

Structural characteristics and residual stresses in oxide films produced on Ti by pulsed unipolar plasma electrolytic oxidation  

Microsoft Academic Search

Oxide films, 710 m thick, were produced on commercially pure titanium by plasma electrolytic oxidation in a sodium orthophosphate electrolyte using a pulsed unipolar current with frequency (f) and duty cycle (?) varying within f = 0.110 kHz and ? = 0.80.2, respectively. The coatings comprised a mixture of an amorphous phase with nanocrystalline anatase and rutile phases, where the

R. H. U. Khan; A. L. Yerokhin; A. Matthews

2008-01-01

385

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

386

X-ray microradiography of inertial fusion targets using a laser-produced plasma as an x-ray source  

Microsoft Academic Search

Optically opaque and multilayered inertial fusion targets can be characterized by x-ray microradiography. A major factor controlling the resolution of this process is the x-ray source size. We have developed an x-ray radiographic method which uses a laser-produced plasma as an x-ray source. Such a source has several advantages over conventional x-ray sources: very small size (< or approx. =100

Hyo-Gun Kim; Mark D. Wittman

1985-01-01

387

Enhanced Water-Window X-Ray Pulse Generation from Femtosecond-Laser-Produced Plasma with a Carbon Nanotube Target  

Microsoft Academic Search

We adopt a carbon nanotube target to increase the efficiency of water-window X-ray pulse conversion from femtosecond-laser-produced plasma. The target is an array of vertically aligned multiwalled carbon nanotubes, each 30 nm in diameter and about 12-mum long. Center-to-center nanotube distance is around 150 nm. The X-ray fluence enhancement in the water-window region is seven-fold compared with a conventional carbon

Tadashi Nishikawa; Katsuya Oguri; Satoru Suzuki; Yoshio Watanabe; Otto Zhou; Hidetoshi Nakano

2003-01-01

388

X-ray production 130 from laser-produced plasmas for projection x-ray lithography applications  

Microsoft Academic Search

X-ray production in the region around 130 from laser-produced plasmas have been investigated as a source for projection x-ray lithography. The dependence of x-ray conversion efficiency on target material, intensity, and pulse length has been studied using a 0.53 μm laser with a maximum of 0.3 J. Conversion efficiency of 1% into a 3 bandwidth has been demonstrated

R. L. Kauffman; D. W. Phillion; R. C. Spitzer

1992-01-01

389

X ray production (approximately)130 (Angstrom) from laser-produced plasmas for projection x ray lithography applications  

Microsoft Academic Search

X-ray production in the region around 130 A from laser-produced plasmas have been investigated as a source for projection x-ray lithography. The dependence of x-ray conversion efficiency on target material, intensity, and pulse length has been studied using a 0.53 micron laser with a maximum of 0.3 J. Conversion efficiency of 1% into a 3 A bandwidth has been demonstrated

R. L. Kauffman; D. W. Phillion; R. C. Spitzer

1992-01-01

390

LETTER TO THE EDITOR: Charge-exchange-induced formation of hollow atoms in high-intensity laser-produced plasmas  

Microsoft Academic Search

For the first time registration of high-resolution soft x-ray emission and atomic data calculations of hollow-atom dielectronic satellite spectra of highly charged nitrogen have been performed. Double-electron charge-exchange processes from excited states are proposed for the formation of autoionizing levels 0953-4075\\/32\\/5\\/031\\/img12 in high-intensity laser-produced plasmas, when field-ionized ions penetrate into the residual gas. Good agreement is found between theory and

F. B. Rosmej; A. Ya Faenov; T. A. Pikuz; A. I. Magunov; I. Yu Skobelev; T. Auguste; P. D'Oliveira; S. Hulin; P. Monot; N. E. Andreev; M. V. Chegotov; M. E. Veisman

1999-01-01

391

X-ray production [similar to]13 nm from laser-produced plasmas for projection x-ray lithography applications  

Microsoft Academic Search

X-ray production in the region [similar to]13 nm from laser-produced plasmas has been investigated as a source for projection x-ray lithography. The dependence of x-ray conversion efficiency on target material, intensity, and pulse length has been studied by using a 0.53-[mu]m laser with a maximum of 0.3 J. A conversion efficiency of 1% into a 0.3-nm bandwidth has been demonstrated

R. L. Kauffman; D. W. Phillion; R. C. Spitzer

1993-01-01

392

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

National Technical Information Service (NTIS)

During the in-ecliptic flight of Ulysses from the Earth toward its encounter with Jupiter, the Los Alamos solar wind plasma experiment has performed well. Briefly described, the instrumentation contains two independent electrostatic analyzers, one for ion...

S. J. Bame J. L. Phillips D. J. McComas J. T. Gosling B. E. Goldstein

1991-01-01

393

Initial Report on the Lunar Plasma Measurement by MAP-PACE Onboard Kaguya  

NASA Astrophysics Data System (ADS)

MAP-PACE onboard Kaguya started continuous observation of the lunar plasma in mid-December 2007. During the commissioning period, MAP-PACE-IMA (Ion Mass Analyzer) discovered alkali ions originated from the lunar surface or lunar atmosphere.

Saito, Y.; Yokota, S.; Asamura, K.; Tanaka, T.; Kaguya Map-Pace Team

2008-03-01

394

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

NASA Astrophysics Data System (ADS)

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

Boschetto, D.; Mourou, G.; Rousse, A.; Mordovanakis, A.; Hou, Bixue; Nees, J.; Kumah, D.; Clarke, R.

2007-01-01

395

Initial measurement of the kinetic dust temperature of a weakly coupled dusty plasma  

SciTech Connect

Measurements of the velocity space distribution function of 2.9 {mu}m diameter silica particles in an argon dc glow discharge dusty plasma are made through the use of stereoscopic particle image velocimetry (stereo-PIV). These distribution functions are then used to determine the kinetic temperature of the dust component. These measurements show that the kinetic temperature of the dust component is significantly larger than the other plasma components (electrons, ions, and background neutrals)

Williams, Jeremiah D.; Thomas, Edward Jr. [Department of Physics, Auburn University, Auburn, Alabama 36849 (United States)

2006-06-15

396

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

397

Time-resolved x-ray line diagnostics of laser-produced plasmas  

SciTech Connect

We have examined the underdense plasma conditions of laser irradiated disks using K x-rays from highly ionized ions. A 900 ps laser pulse of 0.532 ..mu..m light is used to irradiate various Z disks which have been doped with low concentrations of tracer materials. The tracers whose Z's range from 13 to 22 are chosen so that their K x-ray spectrum is sensitive to typical underdense plasma temperatures and densities. Spectra are measured using a time-resolved crystal spectrograph recording the time history of the x-ray spectrum. A spatially-resolved, time-integrated crystal spectrograph also monitors the x-ray lines. Large differences in Al spectra are observed when the host plasma is changed from SiO/sub 2/ to PbO or In. Spectra will be presented along with preliminary analysis of the data.

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

1982-01-01

398

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

399

Comparative study of an argon plasma and an argon copper plasma produced by an ICP torch at atmospheric pressure based on spectroscopic methods  

NASA Astrophysics Data System (ADS)

The aim of the paper is to test the accuracy of classical spectroscopic methods in the visible domain dedicated to measurements of temperature and electron density in order to conclude about the validity of thermal disequilibrium. The influence of various factors is studied: accuracy of the intensity calibration, Abel inversion of the experimental spectra, excitation temperature deduced from the relative method, absolute excitation temperature, influence of the transition probability accuracy, influence of the Biberman factor value, electron temperature from the line-to-continuum intensity ratio, electron density deduced from Stark broadening, and electron density deduced from the continuum intensity. This spectroscopic investigation is carried out for argon plasma and argon copper plasma both produced by means of an ICP torch operating at atmospheric pressure. Results are given with uncertainties for each evaluated parameter. We show that, first, the electron temperature deduced from the line-to-continuum intensity ratio has to be considered with great care; second, for argon plasma no evidence of thermal disequilibrium can be discerned, whereas for argon copper plasma a small disequilibrium of 1.2 to 1.4 at most is experimentally observed.

Bussire, W.; Vacher, D.; Menecier, S.; Andr, P.

2011-08-01

400

Improved protocol for measurement of plasma ?-amyloid in longitudinal evaluation of Alzheimer's Disease Neuroimaging Initiative study patients  

PubMed Central

Background The interassay variability and inconsistency of plasma ?-amyloid (A?) measurements among centers are major factors precluding the interpretation of results and a substantial obstacle in the meta-analysis across studies of this biomarker. The goal of this investigation was to address these problems by improving the performance of the bioanalytical method. Methods We used the Luminex immunoassay platform with a multiplex microsphere-based reagent kit from Innogenetics. A robotic pipetting system was used to perform crucial steps of the procedure. The performance of this method was evaluated using two kit control samples and two quality control plasma samples from volunteer donors, and by retesting previously assayed patient samples in each run. This setup was applied to process 2454 patient plasma samples from the Alzheimer's Disease Neuroimaging Initiative study biofluid repository. We have additionally evaluated the correlations between our results and cerebrospinal fluid (CSF) biomarker data using mixed-effects modeling. Results The average precision values of the kit controls were 8.3% for A?1-40 and 4.0% for A?1-42, whereas the values for the plasma quality controls were 6.4% for A?1-40 and 4.8% for A?1-42. From the testretest evaluation, the average precision was 7.2% for A?1-40 and 4.5% for A?1-42. The range of final plasma results for Alzheimer's Disease Neuroimaging Initiative patients was 13 to 372 pg/mL (median: 164 pg/mL) for A?1-40 and 3.5 to 103 pg/mL (median: 39.3 pg/mL) for A?1-42. We found that sample collection parameters (blood volume and time to freeze) have a small, but significant, influence on the result. No significant difference was found between plasma A? levels for patients with Alzheimer's disease and healthy control subjects. We have determined multiple significant correlations of plasma A?1-42 levels with CSF biomarkers. The relatively strongest, although modest, correlation was found between plasma A?1-42 levels and CSF p-tau181/A?1-42 ratio in patients with mild cognitive impairment. Plasma A?1-40 correlations with CSF biomarkers were weaker and diminished completely when we used longitudinal data. No significant correlations were found for the plasma A?1-42/A?1-40 ratio. Conclusions The precision of our robotized method represents a substantial improvement over results reported in the literature. Multiple significant correlations between plasma and CSF biomarkers were found. Although these correlations are not strong enough to support the use of plasma A? measurement as a diagnostic screening test, plasma A?1-42 levels are well suited for use as a pharmacodynamic marker.

Figurski, Michal J.; Waligorska, Teresa; Toledo, Jon; Vanderstichele, Hugo; Korecka, Magdalena; Lee, Virginia M. Y.; Trojanowski, John Q.; Shaw, Leslie M.

2013-01-01

401

Dose and energy-dependent behaviour of silicon nitride films produced by plasma immersion ion implantation  

Microsoft Academic Search

Schottky devices having guard ring structures were fabricated with conventional silicon processing technology. Nitrogen ions were implanted in contact area silicon at three doses corresponding to low, moderate and high regime. The implantation was carried out employing Plasma Immersion Ion Implantation (PIII) technique at two pulse voltages, i.e. ?10 and ?20 kV. The dose of nitrogen ions was controlled by

R Rajkumar; Mukesh Kumar; P. J George; S Mukherjee; K. S Chari

2002-01-01

402

Infrared reflection by alumina films produced on aluminum alloy by plasma electrolytic oxidation  

Microsoft Academic Search

Reflection of active or passive infrared waves is of practical interest and in this paper, we report the use of plasma electrolytic oxidation (PEO) to fabricate a porous and rough ceramic coating that is capable of reflecting active or passive infrared waves. The pore dimensions of the coatings are on the order of infrared wavelength. In addition to heat isolation,

Fan-Ya Jin; Ke Wang; Ming Zhu; Li-Ru Shen; Jiong Li; Hong-Hui Hong; Paul K. Chu

2009-01-01

403

Characterization of a plasma produced by pulsed arc using an electrostatic double probe  

SciTech Connect

In this work the determination of plasma parameters of a pulsed-arc discharge by using an electrostatic double probe is presented. The system to generate the plasma is composed mainly of a reaction chamber, where the electrodes of different materials (Ti, Zr, Al) were placed in order to identify the variation of the plasma parameters when the cathode material is changed. An automatic system has been implemented for acquiring data starting from the bias of a double electrostatic probe. This system allowed registering complete curves of current-voltage in relatively short times ({approx_equal}30 ms). The electron density n{sub e} and electron temperature T{sub e} can be extracted from the I-V characteristic curves obtained. The advantage of this technique is its facility to provide the whole quantity of 'in situ' information, which can be compared with the theoretical results using numeric methods for the I-V curves simulation. By means of a suitable fit this allowed the determination of the plasma parameters. The values obtained for T{sub e} were in the order of 1 eV and for n{sub e} of about 10{sup 13} cm{sup -3}. A significant variation for n{sub e} was not found.

Garcia, L.A.; Pulzara, A.O.; Devia, A.; Restrepo, E. [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Campus La Nubia, Manizales (Colombia)

2005-05-01

404

Are VLF rapid onset, rapid decay perturbations produced by scattering off sprite plasma?  

Microsoft Academic Search

Rapid onset, rapid decay perturbations (RORDs) of subionospheric VLF propagation require highly localized or laterally structured plasma at low altitudes to explain the wide angle scattering observed and the rapid decay. Simultaneous occurrence of RORDs and red sprites, illu- strated by a single event here, together with VLF phase and group delay measurements from a pair of spaced receivers suggest

R. L. Dowden; J. B. Brundell; W. A. Lyons

1996-01-01

405

Field emission from patterned carbon nanotube emitters produced by microwave plasma chemical vapor deposition  

Microsoft Academic Search

Large area carbon nanotube patterns were fabricated by microwave plasma chemical vapor deposition. The carbon nanotubes were grown on pre-patterned catalyst films. Scanning electron microscopy and Raman spectroscopy were used to characterize the structure of the carbon nanotubes. The carbon nanotubes were very uniform and approximately 100 nm in diameter. The Raman spectrum shows a good graphitization for the carbon

J Yu; Q Zhang; J Ahn; S. F Yoon; Rusli; Y. J Li; B Gan; K Chew; K. H Tan

2001-01-01

406

Extended high-order harmonics from laser-produced Cd and Cr plasmas  

SciTech Connect

We observed the extended harmonic spectra generated in the Cd and Cr plasmas. The mechanism of harmonic extension was attributed to the harmonic generation in doubly charged particles and the influence of broadband ionic resonances in the range of 20-25 nm. The extension of harmonic cutoff up to the 73rd (Cd) and 83rd (Cr) orders was achieved.

Ganeev, R. A. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Scientific Association Akadempribor, Academy of Sciences of Uzbekistan, Akademgorodok, Tashkent 100125 (Uzbekistan); Suzuki, M.; Baba, M.; Kuroda, H. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

2009-02-02

407

Spectral Investigation of Light Reflected from a Laser-Produced Deuterium Plasma  

Microsoft Academic Search

Plasma is created from solid deuterium targets by neodymium laser irradiation. The reflected laser light is shifted by 2.5 towards longer wavelengths. This is interpreted as a Doppler shift of the laser light reflected at a layer moving in the direction of the incident radiation with a velocity of 3.5106 cm sec?1.

K. Bchl K. Eidmann; H. Salzmann; R. Sigel

1972-01-01

408

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

Microsoft Academic Search

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

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

1996-01-01

409

Demonstration of the 101st harmonic generated from a laser-produced manganese plasma  

SciTech Connect

We demonstrate the generation of the 101st harmonic (wavelength {lambda}=7.9 nm) from manganese plasma, which is generated using the plasma high-order harmonic technique. We also investigate the variation of the high-order harmonic distribution from the manganese plasma plume as a function of the prepulse and main pulse intensities. The harmonic cutoff was at the 31st order, for pump intensities below the barrier suppression intensity for singly charged Mn ions. However, by using higher prepulse and main pulse intensities, the harmonic cutoff was extended to the 101st order, with an appearance of second plateau for harmonics higher than the 31st order. In this case, the low-order harmonics decreased in intensity, or completely disappeared, and the spectrum for wavelengths longer than 27.6 nm was dominated by plasma line emission. The origin of the harmonics appearing at this short wavelength plateau is attributed to the interaction of the intense main pump laser field with doubly charged manganese ions.

Ganeev, R. A. [Institut National de la Recherche Scientifique, Centre Energie, Materiaux et Telecommunications, 1650 Lionel-Boulet, Varennes, Quebec, J3X 1S2 (Canada); Scientific Association Akadempribor, Academy of Sciences of Uzbekistan, Akademgorodok, Tashkent 100125 (Uzbekistan); Bom, L. B. Elouga; Kieffer, J.-C.; Ozaki, T. [Institut National de la Recherche Scientifique, Centre Energie, Materiaux et Telecommunications, 1650 Lionel-Boulet, Varennes, Quebec, J3X 1S2 (Canada); Suzuki, M.; Kuroda, H. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

2007-08-15

410

Characterizing Species Composition in Radio-Frequency Plasma Produced from Water Vapor  

Microsoft Academic Search

Using hydrogen as an energy carrier has the potential to address the need to reduce oil consumption and pollution. However, hydrogen is only as clean as the method employed for its production. This work experimentally investigates an unconventional method of hydrogen production by breaking up water molecules in a radio-frequency plasma. This paper demonstrates that this proposed method can successfully

Sonca Nguyen; Kristina Lemmer; John Foster; Alec Gallimore

2007-01-01

411

Plasma Metanephrines Are Markers of Pheochromocytoma Produced by Catechol-O- Methyltransferase Within Tumors  

Microsoft Academic Search

This study examined whether the high sensitivity of plasma free metanephrines for diagnosis of pheochromocytoma may result from production of free metanephrines within tumors. Presence in pheo- chromocytomas of catechol-O-methyltransferase (COMT), the en- zyme responsible for conversion of catecholamines to metanephrines, was confirmed by Western blot analysis, enzyme assay, and immu- nohistochemistry. Western blot analysis and enzyme assay indicated that

GRAEME EISENHOFER; HARRY KEISER; PETER FRIBERG; EVA MEZEY; THANH-TRUC HUYNH; BHARGAVA HIREMAGALUR; TODD ELLINGSON; SUSHIL DUDDEMPUDI; AGNES EIJSBOUTS; JACQUES W. M. LENDERS

412

Production of spectrally narrow soft-x-ray radiation through the use of broadband laser-produced plasma sources and multilayer-coated reflecting optics.  

PubMed

We describe a special filter design that produces spectrally narrow soft-x-ray radiation by using a broadband laser-produced plasma source and multilayer-coated reflecting optics. Calculations for the design were carried out at several laser-produced plasma-source temperatures and various multilayermirror combinations with and without a soft-x-ray filter. We determined that the best arrangement for a laser-produced plasma source consists of two multilayer mirrors and one soft-x-ray filter for each temperature investigated. PMID:21052324

Eligon, A M; Gruber, N; Silfvast, W T

1995-08-01

413

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: High-temperature plasma produced on a free liquid surface by femtosecond laser pulses  

NASA Astrophysics Data System (ADS)

The plasma formed by femtosecond laser radiation with an intensity higher than 1016 W cm-2 at the free surface of a liquid (VM-1 vacuum oil) in vacuum has parameters which are similar to the parameters of the high-temperature plasma produced at the surface of a solid target. The hot-electron temperature (derived from X-ray and ion time-of-flight measurements) is 6 3 keV for the VM-1 oil target and 4 1 keV for a crystal silicon target. The optical diagnostics of the relaxation of the liquid target surface revealed that the limiting laser pulse-repetition rate whereby the interaction takes place with the unperturbed liquid surface may be as high as 10 Hz.

Volkov, Roman V.; Gordienko, Vyacheslav M.; Mikheev, Pavel M.; Savel'ev, Andrei B.; Uryupina, D. S.

2004-02-01

414

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

415

A comparison of kinetic and multifluid simulations of laser-produced colliding plasmas  

SciTech Connect

The collision and subsequent interaction of counter-streaming plasmas occurs in several areas of laser-plasma research including double foil targets for x-ray lasers and the plasma blow-off inside ICF hohlraums. Because a single fluid model allows for only one value of the flow velocity at any one spatial location, interpenetration of the plamas is not allowed resulting in immediate stagnation with complete conversion of the ion-streaming kinetic energy to thermal energy. Multifluid models have been developed which employ multiple ion fluid species that interact through the self-consistent electrostatic field and collisional coupling. Because they are approximations to a kinetic situation, the form of these coupling coefficients is not unique, with various workers using differing approximations. More recently, Larroche has implemented a finite difference approach to the ion Fokker-Planck equation while Jones and co-workers have performed two-dimensional simulations of colliding plasmas using a particle-in-cell code with a new collisional model. Our kinetic modeling also makes use of particle in cell (PIC) techniques with Monte Carlo (MC) particle-particle collisions algorithm that is equivalent to the Fokker-Planck collision operator. We have made direct comparison of this MC-PIC model to multifluid simulations on both simple slowing-down and equilibration problems as well as problems characteristic of laser generated colliding plasmas. These comparisons have established the validity of the multifluid model as well as aided in the development of the kinetic capability for more challenging geometries.

Rambo, P.W.; Procassini, R.J.

1994-09-01

416

Stable confinement of electron plasma and initial results on positron injection in RT-1  

NASA Astrophysics Data System (ADS)

The Ring Trap 1 (RT-1) device is a dipole field configuration generated by a levitated superconducting magnet. It offers very interesting opportunities for research on the fundamental properties on non-neutral plasmas, such as self-organization of charged particles in the strongly positive and negative charged particles on magnetic surfaces. When strong positron sources will be available in the future, the dipole field configuration will be potentially applicable to the formation of an electron-positron plasma. We have realized stable, long trap of toroidal pure electron plasma in RT-1; Magnetic levitation of the superconducting magnet resulted in more than 300s of confinement for electron plasma of ~ 1011 m-3. Aiming for the confinement of positrons as a next step, we started a positron injection experiment. For the formation of positron plasma in the closed magnetic surfaces, one of the key issues to be solved is the efficient injection method of positron across closed magnetic surfaces. In contrast to linear configurations, toroidal configurations have the advantage that they are capable of trapping high energy positrons in the dipole field configuration and consider the possibility of direct trapping of positrons emitted from a 22Na source.

Saitoh, H.; Yoshida, Z.; Morikawa, J.; Yano, Y.; Kasaoka, N.; Sakamoto, W.; Nogami, T.

2013-03-01

417

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

418

Inhomogeneity of plasma formed in high-current discharge channels under different methods of initiation  

Microsoft Academic Search

Different methods for the initiation of meter-length discharges in air at atmospheric pressure were experimentally studied and compared. Studies were conducted for a discharge capacitance of 27 microfarads, a voltage of 30 kV, a discharge gap of 20-50 cm, and an initial current of 67 kA. It is shown that methods of initiation that involve exploding foils, exploding wires, exploding

S. I. Andreev; E. A. Zobov; A. N. Sidorov; T. I. Smirnova; V. G. Sokolov

1980-01-01

419

Gas-discharge plasma initiated in air by a radiation pulse  

SciTech Connect

The authors consider the formation of a non-equilibrium gas-discharge plasma in air under the action of a radiation at a wavelength of 10.6 micrometers with a duration of 10/sup -6/ seconds. They show that the air discharge occurs under nonequilibrium conditions by formation of an autoionization complex with subsequent oscillatory excitation of molecules. They use the diffusion approximation to find the molecular distribution function over oscillatory degrees of freedom. They calculate the electron temperature and concentration in the breakdown plasma with consideration of multistep ionization of molecules and dissociative recombination of charged particles. In conclusion, they find that experimental results agree with their calculations.

Butakyi, V.I.; Tel'nikin, A.A.

1985-08-01

420

Plasma nonuniformities of the channel of a high-power discharge initiated by various methods  

NASA Astrophysics Data System (ADS)

Different methods for the initiation of meter-length discharges in air at atmospheric pressure were experimentally studied and compared. Studies were conducted for a discharge capacitance of 27 microfarads, a voltage of 30 kV, a discharge gap of 20-50 cm, and an initial current of 67 kA. It is shown that methods of initiation that involve exploding foils, exploding wires, exploding graphite threads, and multiple sparks lead to the formation of small initial inhomogeneities in the discharge channel that continue to exist in the high-current stage. The excitation of the discharge by a sliding spark occurs without the formation of inhomogeneities.

Andreev, S. I.; Zobov, E. A.; Sidorov, A. N.; Smirnova, T. I.; Sokolov, V. G.

1980-10-01

421

A laser produced plasma as a pulsed source of continuum infrared radiation for time resolved absorption spectroscopy  

NASA Astrophysics Data System (ADS)

The focussed beam from the 20 ns pulse of an amplified Nd glass laser produces a high temperature plasma in air or other media. Such plasmas, while well known as phenomena, seem not to have been investigated as a source of infrared radiation. We find the emission in the chemical infrared region, 2100-1700/CM, to be a continuum or white, and at least twenty five times more intense than that from a typical glow bar used in conventional infrared absorption spectroscopy. Emission from the plasma formed in air decays with a wavelength dependent lifetime, about 150 ns for the visible portion, and 2 microsecond for the infrared portion. When formed in argon, the plasma emission is more intense, and the decay time of the infrared emission rises to 4 microsec. Use of this source is demonstrated in a measurement of the carbonyl stretching absorption for W(C0)6 and plans are to apply the method to the determination of infrared absorption spectra of thermally equilibrated excited states of organic molecules and of coordination compounds.

Adamson, A. W.; Cimolino, M. C.

1983-06-01

422

Study of Nanodispersed Iron Oxides Produced in Steel Drilling by Contracted Electric-Arc Air Plasma Torch  

NASA Astrophysics Data System (ADS)

The optimal conditions on the plasma-forming gas flowrate, discharge current and voltage, distance between the plasma-torch nozzle and the metal plate surface for the process of penetration in and vaporization of steel plates by the contracted electric-arc air plasma torch accompanied by water quenching, were determined. The X-ray structural and phase studies as well as Mssbauer and electron microscope studies on the samples treated were performed. It was demonstrated that the vaporized elemental iron was oxidized by the oxygen present in the air plasma jet to form iron oxides (wstite, magnetite, hematite), which, depending on their mass ratios, determined the color of the iron oxide pigments, namely, beginning from light yellow, through deep yellow, light brown, deep brown, violet, red-violet, to black. A high degree of dispersity of the iron oxides is thus produced, with an averaged diameter of the particles below 500 nm, and their defective crystal structure form the basis of their potential application as components of iron-containing catalysts and pigments.

Stefanov, P.; Galanov, D.; Vissokov, G.; Paneva, D.; Kunev, B.; Mitov, I.

2008-06-01

423

Helicon mode formation and radio frequency power deposition in a helicon-produced plasma  

SciTech Connect

Time- and space-resolved magnetic (B-dot) probe measurements in combination with measurements of the plasma parameters were carried out to investigate the relationship between the formation and propagation of helicon modes and the radio frequency (rf) power deposition in the core of a helicon plasma. The Poynting flux and the absorbed power density are deduced from the measured rf magnetic field distribution in amplitude and phase. Special attention is devoted to the helicon absorption under linear and nonlinear conditions. The present investigations are attached to recent observations in which the nonlinear nature of the helicon wave absorption has been demonstrated by showing that the strong absorption of helicon waves is correlated with parametric excitation of electrostatic fluctuations.

Niemi, K.; Kraemer, M. [Institut fuer Experimentalphysik II, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

2008-07-15

424

EUV emission from gas discharges produced plasmas with solid tin as target  

NASA Astrophysics Data System (ADS)

Extreme ultraviolet (EUV) radiation with wavelengths of 11-14 nm is seen as the most promising candidate for a new lithographic technology. In the development of our Z-pinch plasma EUV source, xenon (Xe) is used for the background gas discharges and a solid tin (Sn) rod is used as target material due to its potential for high conversion efficiency (CE) from input electric energy to EUV radiation. The Z-pinch plasma was driven by pulsed current with amplitude of 30 kA and pulse duration of 110 ns. Pinhole imaging, an EUV spectrograph and an in-band EUV energy monitor were used to characterize the EUV emission from the Z-pinch discharge. Previously reported experimental analyses by Horita et al have demonstrated that the CE was as high as 3%.

Zhang, C. H.; Katsuki, S.; Imamura, H.; Horita, H.; Namihira, T.; Akiyama, H.

2005-12-01

425

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

426

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

Microsoft Academic Search

The nitrogen-contained amorphous carbon (a-C:N) films were deposited in a dc plasma chemical vapor deposition system with different substrate bias voltages. The structural, mechanical, and tribological properties of the a-C:N films were investigated. The influence of the bias voltage on the tribological behaviors of the a-C:N films was evaluated under various environments (dry air, O2, N2, and vacuum) using a

Wei Zhang; Koichiro Wazumi; Akihiro Tanaka; Yoshinori Koga

2003-01-01

427

Platelet-rich plasma: intra-articular knee injections produced favorable results on degenerative cartilage lesions  

Microsoft Academic Search

Platelet-rich plasma (PRP) is a natural concentrate of autologous blood growth factors experimented in different fields of\\u000a medicine in order to test its potential to enhance tissue regeneration. The aim of our study is to explore this novel approach\\u000a to treat degenerative lesions of articular cartilage of the knee. One hundred consecutive patients, affected by chronic degenerative\\u000a condition of the

Elizaveta KonRoberto; Roberto Buda; Giuseppe Filardo; Alessandro Di Martino; Antonio Timoncini; Annarita Cenacchi; Pier Maria Fornasari; Sandro Giannini; Maurilio Marcacci

2010-01-01

428

Synthesis and characterization of nanoscaled and nanostructured carbon containing materials produced by thermal plasma technology  

Microsoft Academic Search

Single-walled carbon nanotubes (SWNT) and carbon nitride films are synthesized by a direct current (dc) arc discharge at slightly reduced pressure and by an inductively coupled r.f. plasma (ICP) at atmospheric pressure, respectively. By treatment with nitric acid SWNT are purified from by-products and characterized by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. ICP

H.-D Klotz; R. Mach; F. Oleszak; H.-E Maneck; H. Goering; K.-W Brzezinka

2001-01-01

429

Deposition and qualification of tungsten coatings produced by plasma deposition in WF6 precursor gas  

NASA Astrophysics Data System (ADS)

A strong R&D programme is at present ongoing to qualify tungsten as the plasma-facing material in ITER and possible future devices. Since the use of solid W tiles poses a number of problems, mainly with respect to increased forces, weight and costs, W coatings on graphite wall tiles are often used instead. These coatings are deposited in a special deposition apparatus, while in situ plasma-assisted techniques are widely used for low-Z wall coatings such as, for example, in carbonization, boronization or siliconization. To develop a similar procedure for the in situ coating of plasma-facing materials with tungsten, a deposition technique based on a mixture of 95% H2 and 5% WF6 was analysed. Tungsten coatings up to 0.5 ?m have been deposited in laboratory experiments and the coatings were characterized by a number of methods. The W coatings deposited on fine-grain graphite have a dense structure with a rough surface and are free of fluorine. The coatings show excellent high-heat-flux resistance with no failures in transient heat flux tests up to 600-700 MW m-2 for 1 ms.

Philipps, V.; Kogut, D.; Esser, H. G.; Sergienko, G.; Zlobinski, M.; Coenen, J. W.; Brezinsek, S.; Nachtrodt, F.; Sanyasi, A. K.

2011-12-01

430

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

SciTech Connect

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

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

2004-10-20

431

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

432

Reduction in plasma cell proliferation after initial therapy in newly diagnosed multiple myeloma measures treatment response and predicts improved survival  

PubMed Central

Standard myeloma treatment response criteria are determined principally by changes in the monoclonal protein. Reduction in the size of the proliferative component of malignant plasma cells may be an additional metric of assessing response to therapy. We retrospectively analyzed 176 patients with newly diagnosed myeloma with a measurable plasma cell labeling index (PCLI) at diagnosis and repeat measurement 4 months after initiation of therapy. PCLI response was defined as a ? 60% reduction. Baseline PCLI is an independent prognostic factor; therefore, we categorized patients into 3 groups: PCLI ? 3% (high), ? 1% (intermediate), and < 1% (low). Patients achieving a greater PCLI response had improved median overall survival of 54 months compared with 29 months in nonresponders (P = .02). Improved median overall survival with PCLI response occurred in the high initial PCLI group (28 vs 7 months; P = .003) and intermediate group (64 vs 24 months; P = .002). The application of PCLI response and serum M-spike response together provided further prognostic information. On multivariate analysis, the prognostic value of PCLI response was independent of ?2-microglobulin, elevated creatinine, serum M-spike response, and baseline PCLI. We conclude that a significant reduction in plasma cell proliferation in patients with newly diagnosed myeloma is an important predictor of survival.

Larsen, Jeremy T.; Chee, Cheng E.; Lust, John A.; Greipp, Philip R.

2011-01-01

433

Faster-than-light EMP source initiated by short X-ray pulse of laser plasma  

Microsoft Academic Search

The effect which manifests itself in the form of directed electromagnetic pulses initiated by an X-ray incident obliquely on the conducting surface has been confirmed and investigated experimentally in detail. The existence of the above-mentioned phenomenon was predicted more than 25 years ago. So, experimentally, a planar accelerating diode comprising a metallic cathode and grid anode was initiated by an

Alexander V. Bessarab; Alexander A. Gorbunov; Sergey P. Martynenko; Nikolay A. Prudkoy

2004-01-01

434

Electromagnetic and plasma environment in the near-moon space: Initial result of SELENE/MAP observations  

NASA Astrophysics Data System (ADS)

Investigation of electromagnetic and plasma environment around the lunar surface and the near-moon space is of great importance from the viewpoints of science, technology, and manned explorations in the near future. One of the remarkable features of the lunar environment is charging up of the surface of the moon; above all, the lunar surface on the night side occasionally charges strongly negative, and upward-accelerated electrons by a large potential difference between the surface and the spacecraft can be measured in the near-moon space. However, accurate estimation of the lunar surface potential has been difficult, because the spacecraft itself should have an unknown electrostatic potential relative to the ambient plasma. Here we study electromagnetic and plasma environment of the near-moon space, making use of ion, electron, and magnetic field data from a Japanese lunar orbiter KAGUYA (SELENE), which was launched on 14 September 2007 and is traveling at 100 km altitude in a polar orbit. The simultaneous measurement of ions and electrons by the KAGUYA-MAP instrument helps us understand more quantitatively the near-moon space environment. Initial observation shows that electrons accelerated upward from the moon surface toward the spacecraft are at times accompanied by a variation in flux or energy of ions. Such correlation between electrons and ions suggests complex electrostatic potential distribution not only on the lunar surface but also around the spacecraft. We will discuss possible potential distribution and plasma environment in the near-moon space.

Nishino, Masaki N.; Saito, Yoshifumi; Yokota, Shoichiro; Asamura, Kazushi; Tanaka, Takaaki; Terasawa, Toshio; Tsunakawa, Hideo; Yamamoto, Tadateru I.; Fujimoto, Masaki

435

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

SciTech Connect

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

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

2011-12-15

436

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

437

X-ray emission spectra of the plasma produced by an ultrashort laser pulse in cluster targets  

SciTech Connect

The first observation of x-ray emission spectra of multiply charged ions in the plasma produced by a 35-fs laser pulse with an intensity up to 10{sup 17} W cm{sup -2} in CO{sub 2} and Kr gas jet targets is reported. The emission in the wavelength ranges of the 1snp-1s{sup 2}(n=3-6) transitions of O VII ions and the Ly{sub {alpha}} line of O VIII ions, as well as of the (2s{sub 1/2}2p{sup 6}3p{sub 3/2}){sub 1}-2s{sup 2}2p{sup 6} {sup 1}S{sub 0} and (2s{sub 1/2}2p{sup 6}3p{sub 1/2}){sub 1}-2s{sup 2}2p{sup 6} {sup 1}S{sub 0} lines of Ne-like KrXXVII ions testifies that the highly ionised plasma is formed by collision processes in clusters. Modelling the shape of the spectral lines of oxygen ions by including the principal mechanisms of broadening and absorption in optically dense plasmas reveals that the main contribution to the time-integrated intensity is made by the plasma with the parameters N{sub e}=(2-20)x10{sup 20} cm{sup -3} and T{sub e}=100 - 115 eV. (interaction of laser radiation with matter. laser plasma)

Stenz, C; Bagnoud, V; Blasco, F; Roche, J R; Salin, F [Centre Laser Intenses et Applications, Universite Bordeaux, Talence (France); Faenov, A Ya; Skobelev, I Yu [Multicharged Ion Spectra Data Center, All-Russia Research Institute of Psysicotechnical and Radio Enginering Measurments, Mendeleevo, Moscow Region (Russian Federation); Magunov, A I [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Pikuz, T A [N.E. Bauman Moscow State Technical University, Moscow (Russian Federation)

2000-08-31

438

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

SciTech Connect

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

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

2008-05-06

439

Photoconductive Detectors with Fast Temporal Response for Laser Produced Plasma Experiments  

SciTech Connect

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

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

2008-06-01

440

Splash plasma channels produced by picosecond laser pulses in argon gas for laser wakefield acceleration  

NASA Astrophysics Data System (ADS)

Short-lived, 10ps, deep plasma channels, with their lengths of 1mm and diameters of 20?m, are observed and characterized in Ar gas jets irradiated by moderate intensity, 1015-16W/cm2, laser pulses with a duration from subpicosecond to several picoseconds. The channels, upon 2D particle-in-cell simulations including ionization, fit well in the guiding of high intensity femtosecond laser pulses and, therefore, in laser wakefield acceleration with a controllable electron self-injection.

Mizuta, Y.; Hosokai, T.; Masuda, S.; Zhidkov, A.; Makito, K.; Nakanii, N.; Kajino, S.; Nishida, A.; Kando, M.; Mori, M.; Kotaki, H.; Hayashi, Y.; Bulanov, S. V.; Kodama, R.

2012-12-01

441

Analysis of neon soft x-ray spectra from short-pulse laser-produced plasmas  

SciTech Connect

We report preliminary results from the analysis of streaked soft x-ray neon spectra obtained from the interaction of a picosecond Nd:glass laser with a gas jet target. In these experiments streaked spectra show prompt harmonic emission followed by longer time duration soft x-ray line emission. The majority of the line emission observed was found to originate from Li- and Be-like Ne and the major transitions in the observed spectra have been identified. Li-like emission lines were observed to decay faster in time than Be-like transitions, suggesting that recombination is taking place. Line ratios of n=4-2 and n=3-2 transitions supported the view that these lines were optically thin and thick, respectively. The time history of Li-like Ne 2p-4d and 2p-3d lines is in good agreement with a simple adiabatic expansion model coupled to a time dependent collisional-radiative code. Further x-ray spectroscopic analysis is underway which is aimed at diagnosing plasma conditions and assessing the potential of this recombining neon plasma as a quasi-steady-state recombination x-ray laser medium.

Abare, A.C. [Florida Univ., Gainesville, FL (United States); Keane, C.J.; Crane, J.K.; DaSilva, L.B.; Lee, R.W.; Perry, M.D. [Lawrence Livermore National Lab., CA (United States); Falcone, R.W. [California Univ., Berkeley, CA (United States). Dept. of Physics

1993-04-01

442

Soft x-ray emission from postpulse expanding laser-produced plasmas  

NASA Astrophysics Data System (ADS)

A diagnostic spectrometer has been developed at the Naval Research Laboratory to measure the time resolved absolute intensity of radiation emitted from targets irradiated by the Nike laser. The spectrometer consists of a dispersive transmission grating of 2500 lines/mm or 5000 lines/mm and a detection system consisting of an absolutely calibrated Si photodiode array and a charge coupled device camera. In this article, this spectrometer was used to study the spatial distribution of soft x-ray radiation from low Z elements (primarily carbon) that lasted tens of nanoseconds after the main laser illumination was over. We recorded soft x-ray emission as a function of the target material and target orientation with respect to the incoming laser beam and the spectrometer line of sight. While a number of spectral features have been identified in the data, the instrument's combined temporal and spatial resolution allowed observation of the plasma expansion from CH targets for up to ~25 ns after the cessation of the main laser pulse. The inferred plasma expansion velocities are slightly higher than those previously reported.

Weaver, J. L.; Feldman, U.; Mostovych, A. N.; Seely, J. F.; Colombant, D.; Holland, G.

2003-12-01

443

Thomson scattering from laser-produced gold plasmas in radiation conversion layer  

SciTech Connect

With a 263.3 nm probe laser beam, the Thomson scattering (TS) spectra are measured at the distance from the surface of gold disc targets as close as 50 {mu}m. All of the TS spectra become narrower with time, which indicates the overall drop of plasma temperature as the high-Z plasmas blow off. The experimental data show that there are distinct characteristics between the inner region (i.e., 50 and 100 {mu}m away from target surface) and the outer region. The gradient of the electron temperature in outer region is toward the target and becomes opposite to that in the inner region. The asymmetries of the TS spectra in the inner region are in good agreement with calculation based on the Spitzer-Haerm theory. In the outer region, however, the discrepancies between the experiments and calculations are significant, which may be a hint that the electron energy transport becomes flux limited or nonlocal in this region.

Wang Zhebin; Zheng Jian; Zhao Bin; Yu, C.X.; Jiang Xiaohua; Li Wenhong; Liu Shenye; Ding Yongkun; Zheng Zhijian [CAS Key Laboratory of Basic Plasma Physics, Universit