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1

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

SciTech Connect

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

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

2006-06-19

2

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

3

Laser-produced annular plasmas  

SciTech Connect

A new technique is presented for the formation of annular plasmas on a metal surface with a high-power laser using a combination of axicon and converging lenses. The annular plasma formed on a titanium target in a chamber of hydrogen gas was investigated using schlieren imaging and Mach Zehnder interferometry. Expansion of the plasma was shown to be anisotropic with velocities of {approx}10{sup 3}-10{sup 4} m/s. Electron densities of 10{sup 18} cm{sup -3} were measured with radial profiles that confirm the presence of a hollow structure. The interferometric observations also show the presence of an inward shock wave traveling to the center of the annular plasma, which compresses the background neutrals, reaching a density around 18 times initial gas density, at 95 ns after the initial annular plasma is produced.

Veloso, F.; Chuaqui, H.; Aliaga-Rossel, R.; Favre, M.; Mitchell, I. H.; Wyndham, E. [Departamento de Fisica, Pontificia Universidad Catolica de Chile, Vicuna Mackenna 4860 Macul, Santiago 782-0436 (Chile)

2006-06-15

4

Numerical Analysis of Plasma Initiated Polymerization  

Microsoft Academic Search

Plasma initiated polymerization is a kind of well-known radical polymerization mechanism, but it has the `living' polymerization feature and produces ultra-high molecular weight polymer. In order to explain such phenomena, we calculate the basic data of plasma initiated polymerization of methylmethacrylate (MMA) according to the principle of polymer physics and chemistry. It results in that the radical concentration ranges from

Qingliang You; Jianhua Wang; Yuedong Meng; Xingsheng Shu; Qiongrong Ou; Xu Xu; Keming Shen

2006-01-01

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

Initial measurements in the Fisk Plasma Source  

NASA Astrophysics Data System (ADS)

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

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

1997-11-01

7

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

8

Numerical Analysis of Plasma Initiated Polymerization  

NASA Astrophysics Data System (ADS)

Plasma initiated polymerization is a kind of well-known radical polymerization mechanism, but it has the `living' polymerization feature and produces ultra-high molecular weight polymer. In order to explain such phenomena, we calculate the basic data of plasma initiated polymerization of methylmethacrylate (MMA) according to the principle of polymer physics and chemistry. It results in that the radical concentration ranges from 10-12mol/L to 10-16mol/L corresponding to the radical life in 104s to 108s, which means the radicals have a long lifetime. Moreover because of the long lifetime radicals it causes a unique feature rather than the common radical polymerization, and also shows no ``living polymerization''. It is noticed in experiments that there are two key factors playing important roles. One is the effective radical amount produced during the plasma discharging while the another is the diffusion factor.

You, Qingliang; Wang, Jianhua; Meng, Yuedong; Shu, Xingsheng; Ou, Qiongrong; Xu, Xu; Shen, Keming

2006-07-01

9

Radiofrequency Produced Air Constituent Plasmas*  

NASA Astrophysics Data System (ADS)

A high power(1-25 kW) pulsed radiofrequency source is used to create and sustain a high-density(10^11-14 /cm^3, large volume plasmas of air constituents(N_2, O_2, Ar and air mixtures) at high gas pressures. Initial experiments at 1-30 Torr reveal that a noble gas mix improves the antenna loading and is beneficial for the breakdown of air constituents. It also leads to a lower recombination rate and reduced power requirements. Radiofrequency power is coupled through various antenna configurations including a multi-turn helical antenna and a double half-turn helix, using a capacitive matching network. Research results with the new, high power pulsed units will be presented at pressures from 30 to 760 Torr with different gas mixes. Plasma density measurements which use and 105 GHz interferometer as well as network analyzer measurements of the antenna coupling impedance and spectroscopic data will be presented. These will be used to describe the chemical and physical processes and ionic constituents as well as plasma decay processes for the different gas mixtures.

Akhtar, Kamran; Scharer, John; Paller, Eric; White, Ben; Tysk, Shane

2001-10-01

10

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

11

Double layers in laser-produced plasmas  

Microsoft Academic Search

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

S. Eliezer; H. Hora

1989-01-01

12

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

13

Energy Transport in Laser Produced Plasmas.  

National Technical Information Service (NTIS)

Energy transport is a major factor in applications of laser produced plasma. In laser fusion research compressed density is limited by the maximum ablation pressure, by preheating and by imperfect spherical symmetry each which is influenced by aspects of ...

M. H. Key

1989-01-01

14

Field reversal produced by a plasma gun  

SciTech Connect

Experimental results are presented of the production of Field-Reversed Plasma with a high energy coaxial plasma gun. The gun is magnetized with solenoids inside the center electrode and outside the outer electrode so that plasma emerging from the gun entrains the radial fringer field at the muzzle. The plasma flow extends field lines propagating a high electrical conductivity, the flux inside the center electrode should be preserved. However, for low flux, the trapped flux exceeds by 2 or more the initial flux, possibly because of helical deformation of the current channel extending from the center electrode.

Hartman, C.W.; Condit, W.; Granneman, E.H.A.; Prono, D.; Smith, A.C. Jr.; Taska, J.; Turner, W.C.

1980-04-02

15

Laser-produced plasmas in medicine  

NASA Astrophysics Data System (ADS)

The laser has found numerous applications in medicine, beginning with uses in ophthalmology in the 1960's. Today, lasers are used in tissue cutting, blood coagulation, photo-dynamic cancer therapy, arterial plaque removal, dental drilling, etc. Those areas of laser medicine are examined in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential for the application at hand to succeed. Examples are examined for the plasmas produced in ophthalmology (e.g., lens membrane destruction following cataract surgery), in urology and gastroenterology (e.g., kidney and gall stone ablation and fragmentation) and in cardiology and vascular surgery (e.g., laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included.

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

16

Laser-produced plasmas in medicine  

NASA Astrophysics Data System (ADS)

The laser has found numerous applications in medicine, beginning with uses in ophthalmology in the 1960's. Today, lasers are used in tissue cutting, blood coagulation, photo-dynamic cancer therapy, arterial plaque removal, dental drilling, etc. In this paper, we examine those areas of laser medicine in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential for the application at hand to succeed. We consider examples of the plasmas produced in ophthalmology (e.g. lens membrane destruction following cataract surgery), in urology and gastroenterology (e.g. kidney and gall stone ablation and fragmentation) and in cardiology and vascular surgery (e.g. laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included.

Gitomer, Steven J.; Jones, Roger D.

1990-06-01

17

Laser-produced plasmas in medicine  

SciTech Connect

The laser has found numerous applications in medicine, beginning with uses in ophthalmology in the 1960's. Today, lasers are used in tissue cutting, blood coagulation, photo-dynamic cancer therapy, arterial plaque removal, dental drilling, etc. In this paper, we examine those areas of laser medicine in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential for the application at hand to succeed. We consider examples of the plasmas produced in ophthalmology (e.g., lens membrane destruction following cataract surgery), in urology and gastroenterology (e.g., kidney and gall stone ablation and fragmentation) and in cardiology and vascular surgery (e.g., laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included. 63 refs.

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

1990-01-01

18

Characterization of a laser plasma produced from a graphite target  

NASA Astrophysics Data System (ADS)

In order to improve the understanding of pulsed laser deposition (PLD) of diamondlike carbon (DLC) films, we have initiated a detailed study of the plasma dynamics of laser produced carbon plasmas. The carbon plasma is produced by focusing a Nd:YAG laser pulse, 380 mJ, 4 ns at 1.06 ?m, onto a graphite target, at a background pressure of 0.3 mTorr. Time resolved optical emission spectroscopic (OES) observations of the carbon plasma plume are obtained, with time and space resolution, using a SpectraPro 275 spectrograph, with a 15 ns MCP gated OMA. Line emission from CII to CIV carbon ions is identified at different stages of the plasma evolution. Line intensity ratios of successive ionization stages, CIII/CIV, was used to estimate the electron temperature throughout the Saha-Boltzmann equation, under the assumption of local thermodynamic equilibrium (LTE), and Stark broadening of CII lines was used to obtain measurements of the electron density. Characteristic plasma parameters, short after plasma formation, are 3.0 eV and 2-1017 cm?3which after 60 ns of plasma expansion decay to 2.7 eV and 5·10 cm?3, respectively.

Ruiz, M.; Guzmán, F.; Favre, M.; Hevia, S.; Correa, N.; Bhuyan, H.; Wynham, E. S.; Chuaqui, H.

2014-05-01

19

Initial operation of NSTX with plasma control  

SciTech Connect

First plasma, with a maximum current of 300kA, was achieved on NSTX in February 1999. These results were obtained using preprogrammed coil currents. The first controlled plasmas on NSTX were made starting in August 1999 with the full 1MA plasma current achieved in December 1999. The controlled quantities were plasma position (R, Z) and current (Ip). Variations in the plasma shape are achieved by adding preprogrammed currents to those determined by the control parameters. The control system is fully digital, with plasma position and current control, data acquisition, and power supply control all occurring in the same four-processor real time computer. The system uses the PCS (Plasma Control Software) system designed at General Atomics. Modular control algorithms, specific to NSTX, were written and incorporated into the PCS. The application algorithms do the actual control calculations, with the PCS handling data passing. The control system, including planned upgrades, will be described, along with results of the initial controlled plasma operations. Analysis of the performance of the control system will also be presented.

D. Gates; M. Bell; J. Ferron; S. Kaye; J. Menard; D. Mueller; C. Neumeyer; S. Sabbagh

2000-06-13

20

Plasma cell leukemia producing monoclonal immunoglobulin E  

Microsoft Academic Search

A 78-year-old male with lumbar pain and dim consciousness presented the clinical pictures of plasma cell leukemia (PCL) producing\\u000a a large amount of monoclonal immunoglobulin E (IgE)\\/kappa protein. Laboratory investigation demonstrated an elevated serum\\u000a calcium level and renal dysfunction. Systemic bone X-ray survey disclosed only a solitary osteolytic lesion. Circulating plasma\\u000a cells demonstrated CD19?\\/CD56? and MPC-1?\\/CD49e?\\/CD45+\\/?, the latter indicating the

Yuzuru Takemura; Masanobu Ikeda; Kahori Kobayashi; Yuji Nakazawa; Yuichi Mori; Toshimi Mitsuishi; Hiroki Ishigame; Fumiko Kameko; Kiyotaka Fujita; Ryo Ichinohasama

2009-01-01

21

Arc initiation in cathodic arc plasma sources  

DOEpatents

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

Anders, Andre (Albany, CA)

2002-01-01

22

Plasma treatment for producing electron emitters  

DOEpatents

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

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

2001-01-01

23

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

2008-10-01

24

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

25

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

26

Initial results on high enthalpy plasma generation in a magnetized coaxial source  

SciTech Connect

Initial investigation on high enthalpy plasma stream generation in the North Carolina State University Coaxial Plasma Source (CPS) facility is presented. Tenuous, yet high enthalpy, flows are produced from this Magnetized Coaxial plasma Gun (MCG) which allow laboratory study of plasma streams with a wide variety of applications. The applicability includes, but is not limited to, advanced thrusters for electric space propulsion, astrophysical jets and critical ionization phenomena, magnetic fusion compact toroid devices and tokamak fueling, large scale plasma etching and deposition, etc.

Mayo, R.M.; Bourham, M.A.; Caress, R.W.; Black, D.C.; Glover, M.E. [North Carolina State Univ., Raleigh, NC (United States)

1994-11-01

27

Laser-produced plasma source system development  

NASA Astrophysics Data System (ADS)

This paper describes the development of laser produced plasma (LPP) technology as an EUV source for advanced scanner lithography applications in high volume manufacturing. EUV lithography is expected to succeed 193 nm immersion technology for critical layer patterning below 32 nm beginning with beta generation scanners in 2009. This paper describes the development status of subsystems most critical to the performance to meet joint scanner manufacturer requirements and semiconductor industry standards for reliability and economic targets for cost of ownership. The intensity and power of the drive laser are critical parameters in the development of extreme ultraviolet LPP lithography sources. The conversion efficiency (CE) of laser light into EUV light is strongly dependent on the intensity of the laser energy on the target material at the point of interaction. The total EUV light generated then scales directly with the total incident laser power. The progress on the development of a short pulse, high power CO2 laser for EUV applications is reported. The lifetime of the collector mirror is a critical parameter in the development of extreme ultra-violet LPP lithography sources. The deposition of target materials and contaminants, as well as sputtering of the collector multilayer coating and implantation of incident particles can reduce the reflectivity of the mirror substantially over the exposure time even though debris mitigation schemes are being employed. The results of measurements of high energy ions generated by a short-pulse CO2 laser on a laser-produced plasma EUV light source with Sn target are presented. Droplet generation is a key element of the LPP source being developed at Cymer for EUV lithography applications. The main purpose of this device is to deliver small quantities of liquid target material as droplets to the laser focus. The EUV light in such configuration is obtained as a result of creating a highly ionized plasma from the material of the droplets. Liquid tin is the material of choice to be used as a target due to the relatively high CE of the laser energy into in-band EUV radiation. Results obtained with the droplet generator and technical challenges related to successful implementation of the device are discussed.

Fomenkov, Igor V.; Brandt, David C.; Bykanov, Alexander N.; Ershov, Alexander I.; Partlo, William N.; Myers, David W.; Böwering, Norbert R.; Vaschenko, Georgiy O.; Khodykin, Oleh V.; Hoffman, Jerzy R.; Vargas L., Ernesto; Simmons, Rodney D.; Chavez, Juan A.; Chrobak, Christopher P.

2007-03-01

28

Measurement of Debye length in laser-produced plasma.  

NASA Technical Reports Server (NTRS)

The Debye length of an expanded plasma created by placing an evacuated chamber with an entrance slit in the path of a freely expanding laser produced plasma was measured, using the slab geometry. An independent measurement of electron density together with the observed value for the Debye length also provided a means for evaluating the plasma electron temperature. This temperature has applications in ascertaining plasma conductivity and magnetic field necessary for confinement of the laser produced plasma. Also, the temperature obtained would be useful in analyzing electron-ion recombination rates in the expanded plasma and the dynamics of the cooling process of the plasma expansion.

Ehler, W.

1973-01-01

29

Storage of ions from laser-produced plasmas  

NASA Technical Reports Server (NTRS)

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

Knight, R. D.

1981-01-01

30

Effects of Initial Plasma Properties on Plasma Recovery in Plasma Source Ion Implantation  

Microsoft Academic Search

Summary form only given. An expanded plasma sheath in front of a negatively biased target immersed in low-pressure plasmas recovers to its initial state after turning off the negative bias. This recovery process has been assumed to be governed by the ambipolar diffusion model (Wood, 1993) or Bohm sheath collapse model (En et al., 1995). However, the detailed explanations for

K. J. Chung; S. W. Jung; J. M. Choe; G. H. Kim; Y. S. Hwang

2007-01-01

31

Evolution of Spontaneous Magnetic Fields in an Expanding Laser-Produced Plasma.  

National Technical Information Service (NTIS)

The generation process of spontaneous magnetic fields in an expanding laser-produced plasma is studied. It is shown that the initial stage of magnetic fields evolution in plasma heated with laser radiation is correctly reflected in the magnetic-thermal st...

L. A. Bol'shov A. M. Dykhne V. P. Kiselev A. P. Favorskij A. I. Yudin

1982-01-01

32

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

33

Plasma kallikrein: the bradykinin-producing enzyme.  

PubMed

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

Björkqvist, J; Jämsä, A; Renné, T

2013-09-01

34

Nanosized lithium titanates produced by plasma technique  

Microsoft Academic Search

The synthesis of nanosized lithium titanates is studied by evaporation of coarse grained commercially available titanium and lithium carbonate particles in radio-frequency plasma flow with subsequent controlling formation and growth conditions of product particles. In accordance with the XRD analysis the phase composition of the obtained powders is determined by feeding rate of precursors and strongly by ratio of lithium

J. Grabis; A. Orlovs; Dz Rasmane

2007-01-01

35

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

Microsoft Academic Search

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

Heinrich Hora; Paraskevas Lalousis; Shalom Eliezer

1984-01-01

36

Attenuated APC alleles produce functional protein from internal translation initiation  

PubMed Central

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

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

2002-01-01

37

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

38

Laser produced plasma for efficient extreme ultraviolet light sources  

SciTech Connect

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

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

2012-05-25

39

Ablation and plasma emission produced by dual femtosecond laser pulses  

SciTech Connect

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

Singha, Sima; Gordon, Robert J. [Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607-7061 (United States); Hu Zhan [Institute of Atomic and Molecular Physics, Jilin University, Changchun 130021 (China)

2008-12-01

40

ALE Method for Simulations of Laser-Produced Plasmas  

Microsoft Academic Search

\\u000a Simulations of laser-produced plasmas are essential for laser-plasma interaction studies and for inertial confinement fusion\\u000a (ICF) technology. Dynamics of such plasmas typically involves regions of large scale expansion or compression, which requires\\u000a to use the moving Lagrangian coordinates. For some kind of flows such as shear or vortex the moving Lagrangian mesh however\\u000a tangles and such flows require the use

R. Liska; M. Kucha???k; J. Limpouch; O. Renner; P. Váchal; L. Bednárik; J. Velechovský

41

Structure of an Exploding Laser-Produced Plasma  

NASA Astrophysics Data System (ADS)

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

Collette, Andrew

2010-11-01

42

Strongly Polarized Plasma Emission Produced by Laser Ablation of Aluminum  

Microsoft Academic Search

We have found that continuum emission produced in the laser ablation of a material may be strongly polarized, whereas as discrete atomic or ionic emission lines appear as minima in the plasma polarization spectrum [1]. This effect is indicative of strong directionality of electrons recombining in the plasma. By placing a polarizer before the detector, it is possible to suppress

Robert Gordon; Yaoming Liu; John Penczak; Youbo Zhao

2009-01-01

43

Enhanced line emission from laser-produced plasmas  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

44

Origin of 'energetic' ions from laser-produced plasmas.  

NASA Technical Reports Server (NTRS)

A fast-ion current peak, measured with an ion collector placed in the path of an expanding laser-produced plasma, was identified as carbon, nitrogen, and oxygen contaminants which originated from a tungsten target surface.

Ehler, W.; Linlor, W. I.

1973-01-01

45

Laser-produced plasma light source for extreme ultraviolet lithography  

Microsoft Academic Search

Pulsed Nd:YAG lasers have been developed to achieve high peak power and high pulse repetition rate. These systems are being used as drivers for laser-produced plasmas which efficiently convert the 1064-nm laser output to extreme ultraviolet (EUV) light at 13.5 nm for future microlithography systems. The requirements for laser-produced plasma EUV light sources and their integration in lithography tools for

HARRY SHIELDS; STEVEN W. FORNACA; MICHAEL B. PETACH; ROCCO A. ORSINI; RICHARD H. MOYER; R. J. St Pierre

2002-01-01

46

Research of pulse CO2 laser produced tin plasma  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

47

Interruption of the explosion of plasma initiator wires  

Microsoft Academic Search

Many designs of plasma generators, used for the electrothermal-chemical (ETC) gun concept, utilise a length of fuse wire to initiate an electrothermal plasma discharge. The detailed study of the generation of the plasma from such devices has been carried out at QinetiQ for a number of years. Such studies have allowed the development and validation of the computer hydrocode EDEN-IB,

Michael J Taylor; Fort Halstead; Sevenoaks Kent TN

2004-01-01

48

X-ray diagnostics for an MTF initial target plasma  

Microsoft Academic Search

Summary form only given. Theoretical and experimental investigations are in progress at the Los Alamos National Laboratory (LANL) in developing a suitable initial plasma for magnetized target fusion (MTF). Current investigation involves the production of a plasma using a z-directed current of 1-2 MA through either a gas fill or a 200 mm diameter frozen gas fiber along the axis.

Y. C. F. Thio; R. C. Kirkpatrick; G. C. Idzorek; F. Wysocki; P. Sheehey; J. R. Lindemuth; J. H. Degnan

1998-01-01

49

Plasma waves near Saturn: initial results from Voyager 1  

Microsoft Academic Search

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

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

1981-01-01

50

Operation of an auto-initiated pulsed plasma thruster  

Microsoft Academic Search

Purpose – The purpose of this paper is to develop and characterize a pulsed plasma thruster (PPT) that does not need a spark plug to initiate the plasma discharge. Design\\/methodology\\/approach – Two parallel rail thrusters were built and their performances were characterized inside a vacuum chamber to elucidate the effect of vacuum level and thruster geometry on the performance. The

Abhijit Kushari; Kelvin Loh

2010-01-01

51

Laser-produced plasma in high-speed flows  

NASA Astrophysics Data System (ADS)

For the purpose of constructing the design rules of air- breathing laser launcher, the expansion of plasma, which was produced from air by focusing pulse laser, was investigated. A 10-J-pulse TEA CO2 laser was used for these experiments. First, plasma was formed in a quiescent atmospheric air. Photographs and shadowgraphs were taken using an ICCD camera with high-speed gating. From the photographs, the propagation velocity along the laser axis was measured. The velocity was found around 104 m/s much higher than that of a detonation wave calculated using LSD model. Since laser intensity at the plasma front was below the threshold for LSD regime, absorption/expansion mechanism other than LSD might predominate under the experimental condition. Shadowgraphs were taken to measure the expansion velocity of plasma and that of shock wave around plasma. The flow facility, in which plasma is formed in Mach 2 stream, was presented.

Mori, Koichi; Komurasaki, Kimiya; Arakawa, Yasuhiko

2001-04-01

52

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

NASA Astrophysics Data System (ADS)

We have reported the argon (Ar) plasma waveguide produced in an alumina (Al2O3) capillary discharge and used to guide ultrashort laser pulses at intensities of the order of 1016 W/cm2. The electron density in the plasma waveguide was measured to be 1×1018 cm-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 Ar3+ 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 Ar3+ 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; Bobrova, Nadezhda; Sasorov, Pavel; Sakai, Shohei; Sentoku, Yasuhiko; Kodama, Ryosuke; Yugami, Noboru

2012-05-01

53

New method to produce an annular cylindrical plasma for imploding plasma experiments  

SciTech Connect

We present a new method to produce a hollow cylindrical metallic plasma. A metallic foil is exploded by discharging a capacitor bank; the vapor which is produced expands through an annular diaphragm and forms a cylindrical shell of weakly ionized gas, which can be imploded to produce a hot, dense plasma, resulting in a high-power soft x-ray pulse. The density of the hollow cylindrical plasma is measured by resonant interferometry, a new and powerful diagnostic for probing the plasma mass density before the compression (neutral density approx. =10/sup 16/ cm/sup -3/). Our device is complementary to supersonic gas-puff or exploding wires experiments.

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

1984-12-01

54

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 ?=1.1×106 rad\\/s, density n?1015 cm?3, and ion temperature Ti=10

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

1989-01-01

55

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

Microsoft Academic Search

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

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

1998-01-01

56

Characteristics of Ion Beams Produced in a Plasma Focus Device  

Microsoft Academic Search

The characteristics of the ion beams produced in a plasma focus device were studied. In the experiment, a Mather-type plasma focus device was used which was prefilled with H2 at 2.3 Torr. Ion species and their energy spectra were evaluated with a Thomson parabola spectrometer. The particle pinhole image was obtained with an aluminum filtered particle pinhole camera. The ion

Kazuto Takao; Yasuhiko Doi; Satoshi Hirata; Masaki Shiotani; Iwao Kitamura; Takakazu Takahashi; Katsumi Masugata

2001-01-01

57

Collisional coupling in counterstreaming laser-produced plasmas  

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

58

Using Laser-produced Plasmas to Study Magnetized Collisionless Shocks  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

59

Plasma puff initiation of high Coulomb transfer switches  

NASA Technical Reports Server (NTRS)

The plasma-puff triggering mechanism based on a hypocycloidal pinch geometry was investigated to determine the optimal operating conditions for the azimuthally uniform surface flashover which initiates plasma-puff under wide range of fill gas pressure of Ar, He and N2. The optimal fill gas pressure for the azimuthally uniform plasma-puff was about 120 mTorr and 450 Torr for He and N2, and between 120 mTorr and 5 Torr for Ar. The inverse pinch switch was triggered with the plasma-puff and the switching capability under various electrical parameters and working gas pressures of Ar, He and N2 was determined. It was also shown that the azimuthally uniform switching discharges were dependent on the type of fill gas and its fill pressure. A new concept of plasma-focus driven plasma-puff was also discussed in comparison with the hypocycloidal pinch plasma-puff triggering. The main discharge of inverse pinch switch with plasma-focus driven plasma-puff trigger is found to be more azimuthally uniform than that with hypocycloidal pinch plasma-puff trigger in a gas pressure region between 80 mTorr and 1 Torr.

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

1990-01-01

60

Characterization of laser-produced plasmas by ultraviolet Thomson scattering  

SciTech Connect

Space--time-resolved Thomson scattering was used to characterize the electron and ion temperatures in laser produced plasmas of various atomic numbers ([ital Z]=6, 13, 32, 73, 92). A Nd:glass laser with intensity between 10[sup 13] and 5[times]10[sup 14] W/cm[sup 2] was used to produce plasmas of relevance to laser fusion and x-ray laser studies. A comparison of the electron temperature and density deduced from Thomson scattering, x-ray spectroscopy, and LASNEX hydrocode simulations is presented.

La Fontaine, B.; Baldis, H.A.; Villeneuve, D.M.; Dunn, J.; Enright, G.D. (National Research Council of Canada, Ottawa, Ontario K1A 0R6 (Canada)); Kieffer, J.C.; Pepin, H. (Institut National de la Recherche Scientifique (INRS-Energie), 1650 Montee Ste-Julie, Varennes, Quebec J3X 1S2 (Canada)); Rosen, M.D.; Matthews, D.L.; Maxon, S. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))

1994-07-01

61

Microscale Plasma-Initiated Patterning of Electrospun Polymer Scaffolds  

PubMed Central

Microscale plasma-initiated patterning (?PIP) is a novel micropatterning technique used to create biomolecular micropatterns on polymer surfaces. The patterning method uses a polydimethylsiloxane (PDMS) stamp to selectively protect regions of an underlying substrate from oxygen plasma treatment resulting in hydrophobic and hydrophilic regions. Preferential adsorption of the biomolecules onto either the plasma-exposed (hydrophilic) or plasma-protected (hydrophobic) regions leads to the biomolecular micropatterns. In the current work, laminin-1 was applied to an electrospun polyamide nanofibrillar matrix following plasma treatment. Radial glial clones (neural precursors) selectively adhered to these patterned matrices following the contours of proteins on the surface. This work demonstrates that textured surfaces, such as nanofibrillar scaffolds, can be micropatterned to provide external chemical cues for cellular organization.

Delgado-Rivera, Roberto; Griffin, Jeremy; Ricupero, Christopher L.; Grumet, Martin; Meiners, Sally; Uhrich, Kathryn E.

2011-01-01

62

Plasma double-layers produced by ponderomotive force  

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

63

Photorecombination to excited states of Xe in laser produced plasmas  

Microsoft Academic Search

In the present work, we report the frequency spectra of the continuum generated in a laser produced plasma of Xe, in the region 3000–5800 Å. From these studies it can be concluded that we have identified the photorecombination thresholds (radiative recombination, RR) to the excited levels of Xe I and Xe II and some autoionizing resonances nl?El? transitions where with

G. Bertuccelli; H. O. Di Rocco; D. Iriarte; H. F. Ranea Sandoval; M. Romeo Y Bidegain

1997-01-01

64

Recent Developments in Understanding the Physics of Laser Produced Plasmas.  

National Technical Information Service (NTIS)

The absorption of intense laser light by a plasma is known to produce a high energy component of electrons. Even though the hot electron pressure may be larger than the cold background pressure, the background temperature can control the self-consistent p...

B. Bezzerides D. F. DuBois D. W. Forslund J. M. Kindel K. Lee

1976-01-01

65

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

SciTech Connect

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 primary mechanism through which these fluctuations originate. The beam spray which results from these fluctuations is important to understand since it can affect symmetry in an inertial confinement fusion (ICF) experiment. Controlled fluctuations are studied in foam and exploding foil targets. Forward scattered light from foam targets shows evidence that the initial target inhomogeneities remain after the target is laser heated. Forward scattered light from an exploding foil plasma shows that a regular intensity pattern can be used to produce a spatially correlated density fluctuation pattern. These results provide data which can be used to benchmark numerical models of beam spray.

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

1999-11-01

66

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

67

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

68

Lateral energy transport in laser-produced plasmas  

NASA Astrophysics Data System (ADS)

Lateral energy transport in laser-produced plasmas has been studied by irradiating planar polystyrene foils with 0.53-?m-wavelength, spatially nonuniform laser beams. Spatially resolved x-ray emission patterns and spectra were recorded to infer the temperatures, ionization states, and time-integrated hydrodynamic histories of plasma originating from tracer layers embedded in the targets. The conditions of the experiment have been simulated using a two-dimensional single fluid hydrodynamic code. The experimental results and code predictions are in good agreement, indicating that a moderate amount of ablation occurs in the nonirradiated region of the target. (c) 1995 The American Physical Society

Vick, D.; Kado, M.; Yamamoto, H.; Tanaka, K. A.; Offenberger, A. A.; Capjack, C. E.; Nishiguchi, A.; Mima, K.; Nakai, S.

1995-12-01

69

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

70

Plasma-puff initiation of high Coulomb transfer switches  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

71

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

72

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

PubMed

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

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

2014-01-01

73

Current Systems Generated by Colliding Laser-Produced Plasmas  

NASA Astrophysics Data System (ADS)

There are many situations, either in space (e.g. CMEs, supernovae), or man-made, in which a dense plasma expands into a magnetized background plasma capable of supporting Alfvén waves. The generation of shear Alfvén waves by an expanding laser-produced plasma (lpp) has been observed previously at the LArge Plasma Device at UCLA [1]. In a recent experiment at LAPD, the collision of two dense (?n/n0>> 1, where n0˜ 1-4 x 10^12/cm^3) lpps within an ambient, highly magnetized (Rci˜ 4mm << ?˜ 1m, where ? is the machine diameter) is studied. A 150MW laser is pulsed with the background plasma at 1Hz, in a reproducible experiment to obtain a large volumetric dataset. We have directly observed a system of complex, fully 3-dimensional time-dependent current systems associated with the shear Alfvén waves generated by the two lpps. The magnetic helicity associated with these current systems will be presented and compared to their topology, along with a process which strongly resembles magnetic reconnection at a point where the two current channels pull apart. Data will be presented as a 3-D movie. [1] M. Van Zeeland et al, Phys. Rev. Lett., 87(10):100501-1-100501-4, 2001.

Collette, Andrew; Gekelman, Walter

2006-10-01

74

Extreme Ultraviolet Source Using Laser-Produced Li Plasma  

NASA Astrophysics Data System (ADS)

An extreme ultraviolet source using laser-produced lithium plasma has been studied. The authors obtained an enhancement of extreme ultraviolet conversion efficiency by a factor of about 2 with recombination wall. In a planar lithium target experiment, the maximum conversion efficiency of 2.3% was achieved by using pulsed 2? YAG laser irradiation. These results suggest that a Li target is a reasonable candidate for the EUV lithography source.

Nagano, Akihisa; Amano, Sho; Miyamoto, Shuji; Mochizuki, Takayasu

75

Extreme Ultraviolet Source Using Laser-Produced Li Plasma  

Microsoft Academic Search

An extreme ultraviolet source using laser-produced lithium plasma has been studied. The authors obtained an enhancement of extreme ultraviolet conversion efficiency by a factor of about 2 with recombination wall. In a planar lithium target experiment, the maximum conversion efficiency of 2.3% was achieved by using pulsed 2omega YAG laser irradiation. These results suggest that a Li target is a

Akihisa Nagano; Sho Amano; Shuji Miyamoto; Takayasu Mochizuki

2009-01-01

76

Characterization of short pulse laser-produced plasmas  

NASA Astrophysics Data System (ADS)

The K-shell emission from porous aluminum targets is used to infer the density and temperature of plasmas created with 800 and 400 nm, 140 fsec laser light. The laser beam is focused to a minimum spot size of 5 micrometers with 800 nm light and 3 micrometers with 400 nm light, producing a normal incidence peak intensity of 10(exp 18) W/sq cm. The effects of design, laser characteristics, and diagnostic needs is discussed.

Shepherd, R.; Price, D.; White, W.; Gordan, S.; Osterheld, Al.; Walling, R.; Goldstein, W.; Stewart, R.

1994-02-01

77

Hydrolysis of hemicellulose to produce fermentable monosaccharides by plasma acid.  

PubMed

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

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

2013-09-12

78

Interplanetary field and plasma during initial phase of geomagnetic storms  

NASA Technical Reports Server (NTRS)

Twenty-three geomagnetic storm events during 1966 to 1970 were studied by using simultaneous interplanetary magnetic field and plasma parameters. Explorer 33 and 35 field and plasma data were analyzed on large-scale (hourly) and small-scale (3 min.) during the time interval coincident with the initial phase of the geomagnetic storms. The solar-ecliptic Bz component turns southward at the end of the initial phase, thus triggering the main phase decrease in Dst geomagnetic field. The By component also shows large fluctuations along with Bz. When there are no clear changes in the Bz component, the By shows abrupt changes at the main phase onset. On the small-scale, behavior of the magnetic field and electric field were studied in detail for the three events; it is found that the field fluctuations in By, Bz and Ey and Ez are present in the initial phase. In the large-scale, the behavior field remains quiet because the small-scale variations are averaged out. It appears that large as well as small time scale fluctuations in the interplanetary field and plasma help to alter the internal electromagnetic state of the magnetosphere so that a ring current could causing a geomagnetic storm decrease.

Patel, V. L.; Wiskerchen, M. J.

1975-01-01

79

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

SciTech Connect

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 {omega}=1.1{times}10{sup 6} rad/s, density {ital n}{similar to}10{sup 15} cm{sup {minus}3}, and ion temperature {ital T}{sub {ital i}}=10 eV. The separation factor of 2 is attained even in the plasma core where the density is higher than one-half of the peak value. This is attributed to the fact that a strong centrifugal force forms a hollow density profile which gives the density peak at a radius of 2 cm.

Ikehata, T.; Suzuki, M.; Tanabe, T.; Mase, H. (Department of Electronic Engineering, Ibaraki University, Nakanarusawa-cho, Hitachi 316, Japan (JP))

1989-09-25

80

Optical emission spectra of a copper plasma produced by a metal vapour vacuum arc plasma source  

NASA Astrophysics Data System (ADS)

Optical emission spectroscopy in the range 200-800 nm was applied for investigation of the copper plasma produced by a metal vapour vacuum arc plasma source. The experiments were conducted for the cases when the plasma was guided by straight and ?-shaped curved solenoids as well as without solenoids, and also for different vacuum conditions. It was found that, besides singly- and doubly-charged ions, a relatively high concentration of excited neutral copper atoms was present in the plasma. The relative fraction of excited atoms was much higher in the region close to the cathode surface than in the plasma column inside the solenoid. The concentration of excited neutral, singly- and doubly-ionized atoms increased proportionally when the arc current was increased to 400 A. Some weak lines were attributed to more highly ionized copper species and impurities in the cathode material.

Yotsombat, B.; Davydov, S.; Poolcharuansin, P.; Vilaithong, T.; Brown, I. G.

2001-06-01

81

Relative ion expansion velocity in laser-produced plasmas  

NASA Technical Reports Server (NTRS)

The spectra of highly ionized titanium, Ti XIII through Ti XXI, and C VI Lyman lines were excited in laser-produced plasmas. The plasma was produced by uniformly irradiating spherical glass microballoons coated with thin layers of titanium and parylene. The 24-beam Omega laser system produced short, 0.6 ns, and high-intensity, 4 x 10 to the 14th W/sq cm, laser pulses at a wavelength of 351 nm. The measured wavelength for the 2p-3s Ti XIII resonance lines had an average shift of + 0.023 A relative to the C VI and Ti XX spectral lines. No shift was found between the C VI, Ti XIX, and Ti XX lines. The shift is attributed to a Doppler effect, resulting from a difference of (2.6 + or - 0.2) x 10 to the 7th cm/s in the expansion velocities of Ti XIX and Ti XX ions compared to Ti XIII ions.

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

1988-01-01

82

Monitoring of hydrocarbon concentrations in dust-producing RF plasmas  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

83

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)] [Los Alamos National Lab., NM (United States); Roderick, N.F. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Chemical and Nuclear Engineering] [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Chemical and Nuclear Engineering

1996-04-01

84

Fast Magnetic Reconnection in Laser-Produced Plasma Bubbles  

SciTech Connect

Recent experiments have observed magnetic reconnection in high-energy-density, laser-produced plasma bubbles, with reconnection rates observed to be much higher than can be explained by classical theory. Based on fully kinetic particle simulations we find that fast reconnection in these strongly driven systems can be explained by magnetic flux pileup at the shoulder of the current sheet and subsequent fast reconnection via two-fluid, collisionless mechanisms. In the strong drive regime with two-fluid effects, we find that the ultimate reconnection time is insensitive to the nominal system Alfven time.

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)

2011-05-27

85

Diagnostics of cadmium plasma produced by laser ablation  

SciTech Connect

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

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

2006-10-01

86

Thermal Smoothing by Laser-Produced Plasma of Porous Matter  

SciTech Connect

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

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

2003-05-15

87

Porous materials produced from incineration ash using thermal plasma technology.  

PubMed

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

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

2014-06-01

88

Plasma waves near Saturn: initial results from Voyager 1  

SciTech Connect

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

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

1981-01-01

89

Initiation of Rayleigh-Taylor Instability in Wire Array Plasmas  

NASA Astrophysics Data System (ADS)

The heating and expansion of the wire plasmas play a key role in determining the perturbations that are amplified by the R-T instability. The wire instabilities (see poster by Hammer in this session) can be prevented if the plasma crosses the gaps between the wires while the magnetic pressure is small. An analytical theory has been developed of the wire heating and expansion. It is shown that the wire dynamics are determined by the temperature dependence of the resistivity. Initially, the resistivity increases as T which results in a uniformly expanding wire. Later, in the Spitzer regime, the resistivity decreases as T-3/2 resulting in a high density core and a low density, rapidly expanding corona as seen in MHD simulations (see poster by Reisman in this session) and experiments (see next poster by Bauer).

de Groot, J. S.; Spielman, R. B.; Reisman, D. B.; Hammer, J. H.; Sanford, T. W. L.; Cuneo, M. E.; Deeney, C.; Ryutov, D.; Toor, A.

1998-11-01

90

Initiation of nuclear reactions in femtosecond laser plasma  

SciTech Connect

Mechanisms of electron interaction with a nucleus via a direct electron-nucleus collision and via bremsstrahlung generated in electron scattering on a nucleus in a femtosecond laser plasma are considered. The description of this interaction is simplified substantially by using the instantaneous-impact and equivalent-photon approximations. The yields of photons, electron-positron pairs, and products of nuclear reactions initiated by a laser pulse for some nuclei are calculated. In particular, this is done for {sup 235}U, {sup 236}U, {sup 238}U, and {sup 232}Th fission in a laser field of intensity 10{sup 20} to 10{sup 22} W/cm{sup 2}.

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

2013-01-15

91

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

92

Transport in dense plasmas produced by femtosecond laser pulses  

NASA Astrophysics Data System (ADS)

Within the last 10 years high power, sub-picosecond pulse lasers have become available. Optical and x-ray investigations of dense plasmas and shock waves created and driven by ultra-short laser pulses are presented in this thesis. Ultra-short pulse interaction with solids is reviewed. Ideal and non-ideal plasmas are quantified and the plasma formation process considered. The transport of laser energy into the bulk of the target by thermal and electrical conduction and shock waves is described. Ultra-short pulse lasers and details of those used in the experimental work (Ti:Sapphire CPA and CPM dye) are outlined. Optical diagnostics of laser produced plasmas are discussed. The novel technique of frequency domain interferometry is described in detail as a diagnostic technique for plasmas created by ultra-short laser pulses. Three experiments which used frequency domain interferometry are presented. Both time- and space- resolved measurements on the rear surface of thin aluminium layers (8nm-400nm) evaporated onto transparent fused silica substrates have been made. The experimental results are compared with simulations made using two 1D Lagrangian hydrodynamic codes, scMULTI and scMEDUSA, together with a multilayer dielectric reflection code and a simple postprocessor based on the Fresnel relations respectively. Experimental results for the thinnest aluminium layers are not reproduced well by simulations, which do not include effects such as the Optical Kerr effect in the fused silica. For intermediate thicknesses, simulations indicate that the aluminium at the interface is both heated and compressed. Experimental results differ from simulations, showing evidence of non-equilibrium effects which are not simulated in the hydrodynamic codes used. Results from the thickest aluminium layers where heating effects at the interface were negligible, enabled the Equation of State of shocked aluminium at the interface to be measured. Pressures of 1-3Mbar were inferred from the simultaneous measurement of the shock and particle velocities. Experimental results are reproduced well by simulations and agree with the scSESAME (3717) Hugoniot curve for aluminium. Finally, qualitative results of both thermal and hot electron energy transport in solid bi-layered targets, inferred from recorded x-ray emission spectra are presented. The spectra were recorded using a von Hamos crystal spectrometer and x-ray CCD camera.

Badger, Antony Daniel

93

A Controlled Prepulse for Wire Array Plasmas to Reduce the Initial Perturbation of the Rayleigh-Taylor Instability  

NASA Astrophysics Data System (ADS)

The initial heating and expansion of a wire plasma plays a key role in setting the initial perturbations driving the R-T instability. A controlled prepulse consisting of a fast (10 ns) heating current followed by a sustaining current may reduce these perturbations. The fast pulse rapidly heats the wires before a significant coronal plasma (see De Groot this session) seen in simulations (see Reisman this session) and experiments is formed. The plasma would fill the initial gap between the wires while the magnetic pressure is small and avoid MHD instabilities of the individual wires (see Hammer this session). The sustaining current would continue to heat the plasma while smoothing out perturbations as the plasma expands to produce a more uniform shell.

Spielman, R. B.; Degroot, J. S.; Deeney, C.; Hammer, J. H.; Reisman, D. B.; Toor, A.

1998-11-01

94

Detection of electromagnetic pulses produced by hypervelocity micro particle impact plasmas  

SciTech Connect

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

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

2013-09-15

95

Tool produced by a plasma-activated CVD process  

US Patent & Trademark Office Database

A tool having an extended service lift and including a hard metal body, and at least one surface layer composed of at least one hard substance selected from the group consisting of carbides, nitrides, and carbonitrides of titanium and zirconium, and having a chlorine content ranging from a finite amount up to 4 mass percent, the tool being produced by plasma-activated CVD process including: a. positioning the hard metal body in a CVD chamber having means for supplying direct voltage thereto, the hard metal body being connected to the direct voltage supplying means as a cathode thereof, b. introducing into the CVD chamber a reactive gas mixture including a nitrogen-containing substance, a carbon-containing substance, and at least one compound containing at least one of titanium and zirconium, and c. exciting plasma formation at the hard metal body and coating same by chemical vapor deposition by applying a pulsed direct voltage and a residual direct voltage thereto, the residual direct voltage having a magnitude which is at least equal to the lowest ionization potential of any gas in the reactive gas mixture but does not exceed 50% of the maximum value of the pulsed direct voltage.

1993-06-29

96

Plasma Characteristics of the Discharge Produced during Mechanoluminescence  

SciTech Connect

The conditions during light emission from the fracture of solids have been difficult to determine because such mechanoluminescence (ML) is usually weak. When ML is produced by acoustic cavitation of a liquid slurry of resorcinol crystals, however, we observe bright light emission, which makes it possible to measure plasma conditions by emission spectra: a bimodal heavy atom emission temperature profile is observed with 405{+-}22 K (for 80% of emitting CH) and 4015{+-}730 K (for 20%), with an electron density and energy of 1.3{+-}0.13x10{sup 14} cm{sup -3} and {approx}3.5 eV (i.e., an effective T{sub e}{approx}41 000 K)

Eddingsaas, Nathan C.; Suslick, Kenneth S. [School of Chemical Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

2007-12-07

97

Laser produced plasma light source development for HVM  

NASA Astrophysics Data System (ADS)

This paper describes the development of a laser-produced-plasma (LPP) extreme-ultraviolet (EUV) source for advanced lithography applications in high volume manufacturing. EUV lithography is expected to succeed 193nm immersion double patterning technology for sub- 20nm critical layer patterning. In this paper we discuss the most recent results from high power testing on our development systems targeted at the 250W configuration, and describe the requirements and technical challenges related to successful implementation of these technologies. Subsystem performance will be shown including Conversion Efficiency (CE), dose control, collector protection and out-of-band (OOB) radiation measurements. This presentation reviews the experimental results obtained on systems with a focus on the topics most critical for a 250W HVM LPP source.

Fomenkov, Igor V.; Brandt, David C.; Farrar, Nigel R.; La Fontaine, Bruno; Myers, David W.; Brown, Daniel J.; Ershov, Alex I.; Böwering, Norbert R.; Riggs, Daniel J.; Rafac, Robert J.; De Dea, Silvia; Purvis, Michael; Peeters, Rudy; Meiling, Hans; Harned, Noreen; Smith, Daniel; Kazinczi, Robert; Pirati, Alberto

2014-04-01

98

Effect of a transverse magnetic field on the plume emission in laser-produced plasma: An atomic analysis  

Microsoft Academic Search

We have investigated the effect of varying transverse magnetic field on the plasma plume emission of laser-produced lithium plasma. Two atomic transitions for lithium neutral Li (I) and two for Li ion LI (II) are taken for the study. It has been found that for Li (I), the emission from 670.8nm transition (2s2S1\\/2?2p2P3\\/2?1\\/2) shows initial enhancement and then subsequent decrease

H. C. Joshi; Ajai Kumar; R. K. Singh; V. Prahlad

2010-01-01

99

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

SciTech Connect

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-scale length plasmas where we find 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 the primary mechanism through which these fluctuations originate. The beam spray resulting from these fluctuations is important to understand since it can affect symmetry in an inertial confinement fusion (ICF) experiment. Controlled fluctuations are studied in foam and exploding foil targets. Forward scattered light from foam targets shows evidence that the initial target inhomogeneities remain after the target is laser heated. Forward scattered light from an exploding foil plasma shows that a regular intensity pattern can be used to produce a spatially correlated density fluctuation pattern. These results provide data which are being used to benchmark numerical models of beam spray.

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

2000-01-05

100

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

SciTech Connect

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

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

2013-12-15

101

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

102

Visible spectral power emitted from a laser produced uranium plasma  

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

103

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

104

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

105

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

106

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

Microsoft Academic Search

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

Loh Kelvin; Kushari Abhijit

2010-01-01

107

Preparation and properties of plasma-initiated graft copolymerized membranes for blood plasma separation  

NASA Astrophysics Data System (ADS)

A hydrophilic composite membrane for blood plasma separation has been prepared by surface graft copolymerization initiated by low-temperature plasma (LTP). After short LTP pre-irradiation onto a microporous polypropylene (PP) membrane, N-N-dimethylacrylamide (DMAA) vapor was introduced for grafting. The PP membrane had a 0.45 ?m effective pore size and a 130 ?m thickness. The rate of DMAA grafting onto PP was very high, even in vapor-solid phase reaction under reduced pressure; DMAA 1 mm Hg (133Pa). The percentage of grafted poly-DMAA (PDMAA) reached 15% within 5 min post graft polymerization, and the membrane surface, including the interior surface of pores, became completely hydrophilic. There was no apparent change observed in the membrane morphology in the dry state after the PDMAA-grafted layer was formed. However, water flux significantly decreased, probably due to swelling of the PDMAA-grafted layer. With a grafting yield below 17%, the PDMAA-grafted PP (PP-g-PDMAA) membrane showed a good separation capability of plasma from whole blood. The PP-g-PDMAA membrane exhibited low complement activating potential, high sieving coefficient for plasma proteins and high blood compatibility. Decreases in adsorption of blood cells, plasma proteins, and other biomolecules may be the reason for the membrane performance.

Onishi, M.; Shimura, K.; Seita, Y.; Yamashita, S.; Takahashi, A.; Masuoka, T.

108

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

109

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

110

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

111

A plasma jet produced in a segmented plasmatron: modelling and experiment  

NASA Astrophysics Data System (ADS)

Nitrogen and argon plasmas with a small admixture of air produced in a segmented plasmatron are studied both experimentally and theoretically. A two-temperature hydrodynamic model is used to simulate the plasma flow inside the plasmatron. The calculated plasma temperature and electron density are in reasonable agreement with the experimental values obtained from emission spectroscopy. The electron temperatures are several thousand kelvins higher than the atom temperatures, showing that the plasmas produced in the segmented plasmatron are in non-equilibrium.

Kaminska, Aniela; Dudeck, Michel; Hoffman, Jacek; Szymanski, Zygmunt; Gouy, Pierre-Alban; Vacher, Damien

2014-05-01

112

Electricity producing renewable energy technologies. Common costing methodology. Initial development study. V. 1. Final report.  

National Technical Information Service (NTIS)

This is the report of the initial development of a common costing methodology for electricity producing renewable energy schemes. The aim of the overall development programme is to provide a self contained method for forecasting the costs associated with ...

1989-01-01

113

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

Microsoft Academic Search

The understanding of laser beam propagation through underdense plasmas is of vital importance to laser-plasma interaction experiments, as well as being a fundamental physics issue. Formation of plasma channels has numerous applications including table-top x-ray lasers and laser-plasma-produced particle accelerators. The fast ignitor concept, for example, requires the formation of an evacuated channel through a large, underdense plasma. Scaled experiments

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

1996-01-01

114

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

115

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

116

A study of long aerosol initiated laser induced air breakdown plasmas  

NASA Astrophysics Data System (ADS)

Results from three separate experiments on aerosol initiated, laser induced, air breakdown are described. The purpose of these experiments was to determine the maximum length of air breakdown plasma that can be created with a given laser pulse. Two separate neodymium glass lasers were used; the first produced an output pulse of 30 J in 60 ns and the second produced 200 J in 4 ns. Both pulses were at the wavelength of 1.06 micron. Two of the experiments used the aerosol produced by burning black gunpowder in the atmosphere which gave a mean particle size of about 0.5 micron. The third experiment attempted to use ragweed pollen with a mean particle size of about 10 micron, but these particles could not be adequately dispersed and no useful results were obtained.

Pechacek, R. E.; Raleigh, M.; Greig, J. R.; Murphy, D. P.; Camelio, F.

1984-06-01

117

Isotope fractionation in lithium plasma produced by argon contact ionization  

Microsoft Academic Search

The plasma isotope separation by the use of the secondary contact ionization ion source was studied. The electromagnetic wave tuned with the cyclotron frequency of lithium-7 ion was applied to the lithium-argon mixture plasma. The lithium deposited on the collector was measured by a mass spectrometer. It was confirmed that the isotope ratio of the sample taken after ICR heating

T Suzuki; M Nomura; M Okamoto; Y Fujii

1996-01-01

118

RADIATIVE MECHANISMS IN LASER-PRODUCED PLASMAS IN Xe  

Microsoft Academic Search

In the present paper the LPP in Xenon at nearly atmospheric pressure is studied by frequency as well as temporal resolved spectroscopy. Experimental evidence confirms that the radiative recombination in the aftermath of the laser pulse, is the main mechanism by which the plasma dissipates its energy. It is also evident that the plasma observed is heated after the laser

G. Bertuccelli; H. O. DI ROCCO; D. I. IRIARTE; M. ROMEO Y BIDEGAIN; H. F. RANEA-SANDOVAL

1999-01-01

119

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

120

Waves and Fine Structure in Expanding Laser-Produced Plasmas  

NASA Astrophysics Data System (ADS)

The behavior of expanding dense plasmas has long been a topic of interest in space plasma research, particularly in the case of expansion within a magnetized background. Previous laser-plasma experiments at the UCLA Large Plasma Device have observed the creation of strong (?BB > 50%) diamagnetic cavities, along with large-scale wave activity and hints of fine-scale structure. A new series of experiments conducted recently at the LaPD performs direct measurement of the fields inside the expanding plasma via a novel 2D probe drive system. This system combines small-scale (0.5mm-1mm) magnetic and electric field probes with high-accuracy vacuum ceramic motors, to allow measurement of the plasma volume over a 2000-point grid at 1mm resolution. The data reveal both coherent high-amplitude waves associated with the formation of these magnetic features, and complicated small-scale structure in both the magnetic field and floating potential. In addition, we will present correlation techniques using multiple independent B and E field probes. This reveals behavior of turbulent, non-phase-locked phenomena. Both the case of a single expanding plasma and two colliding plasmas were studied.

Collette, Andrew; Gekelman, Walter

2009-11-01

121

Jupiter plasma wave observations: an initial Voyager 1 overview  

Microsoft Academic Search

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

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

1979-01-01

122

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

SciTech Connect

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

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

2012-02-15

123

Plasma wave observations near jupiter: initial results from voyager 2.  

PubMed

This report provides an initial survey of results from the plasma wave instrument on the Voyager 2 spacecraft, which flew by Jupiter on 9 July 1979. Measurements made during the approach to the planet show that low-frequency radio emissions from Jupiter have a strong latitudinal dependence, with a sharply defined shadow zone near the equatorial plane. At the magnetopause a new type of broadband electric field turbulence was detected, and strong electrostatic emissions near the upper hybrid resonance frequency were discovered near the low-frequency cutoff of the continuum radiation. Strong whistler-mode turbulence was again detected in the inner magnetosphere, although in this case extending out to substantially larger radial distances than for Voyager 1. In the predawn tail region, continuum radiation was observed extending down to extremely low frequencies, approximately 30 hertz, an indication that the spacecraft was entering a region of very low density, approximately 1.0 x 10(-5) per cubic centimeter, possibly similar to the lobes of Earth's magnetotail. PMID:17733920

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

1979-11-23

124

Laser-produced plasma source development for EUV lithography  

NASA Astrophysics Data System (ADS)

We are developing a CO2 laser driven Tin plasma EUV source for HVM EUVL. This approach enables cost-effective EUV power scaling by high-conversion efficiency and full recovery of Tin fuel. The RF-excited, multi 10 kW average power pulsed CO2 laser system is a MOPA (master oscillator power amplifier) configuration and operates at 100 kHz with 20 ns pulse width. The EUV light source is scalable to in-band 200 W IF power with a single 20-kW CO2 laser beam. EUV chamber is kept uncontaminated by using a small size droplet target and effective Tin exhaust by magnetic plasma guiding. Characterization of the plasma flow in uniform magnetic field was studied by monitoring the motion of Tin plasma stream in a large vacuum chamber, depending on the magnetic flux up to 2 T. Topics relevant for HVM source is reported on continuous operation and Tin vapor evacuation.

Endo, Akira; Komori, Hiroshi; Ueno, Yoshifumi; Nowak, Krzysztof M.; Takayuki, Yabu; Tatsuya, Yanagida; Suganuma, Takashi; Asayama, Takeshi; Someya, Hiroshi; Hoshino, Hideo; Nakano, Masaki; Moriya, Masato; Nishisaka, Toshihiro; Abe, Tamotsu; Sumitani, Akira; Nagano, Hitoshi; Sasaki, Youichi; Nagai, Shinji; Watanabe, Yukio; Soumagne, Georg; Ishihara, Takanobu; Wakabayashi, Osamu; Kakizaki, Kouji; Mizoguchi, Hakaru

2009-03-01

125

Persistence of uranium emission in laser-produced plasmas  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

126

Diagnostics Techniques of Plasmas Produced by Laser Ablation  

SciTech Connect

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.

Villagran Muniz, M.; Sobral, H.; Sanchez Ake, C.; Sangines de Castro, R.; Sterling, E. [Laboratorio de Fotofisica, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, Mexico D.F. 04510 (Mexico); Bredice, F. [Centro de Investigaciones Opticas, P.O.Box 124, C.P.1900, La Plata (Argentina)

2005-04-21

127

Research on plasma-puff initiation of high Coulomb transfer switches  

NASA Technical Reports Server (NTRS)

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

Venable, Demetrius D.; Han, Kwang S.

1993-01-01

128

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

129

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

130

Stationaere, Eindimensionale Modelle fuer Lasererzeugte Plasmen (Stationary, One-Dimensional Models for Laser-Produced Plasmas).  

National Technical Information Service (NTIS)

One-dimensional, stationary models for laser-produced plasmas were compared. The most interesting models seem to be those with the assumption of a self regulation of the plasma, i.e., based on the defined geometrical dimensions of the plasma. Such a model...

K. Daree

1985-01-01

131

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

NASA Technical Reports Server (NTRS)

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

Auer, Siegfried

1994-01-01

132

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

NASA Astrophysics Data System (ADS)

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 from flow-driven APPJs by its ability to generate excited species in situ over its length. The presence of the cathode downstream provides ionization gain that is not characteristic of flow-driven APPJs in similar configurations but rather is characteristic of a single dielectric barrier microdischarge filament that is confined to the capillary axis. With a conducting cathode, this discharge filament can carry several Amps of current in a ˜30 ns pulse. In this experiment, we study this atmospheric pressure plasma source with cathode materials of varying resistivity including conducting metals, semiconducting silicon, and insulating dielectrics at distances up to 3 cm from the capillary tip. We monitored spatiotemporally resolved emission intensities from the Ar/He/air discharge to track the relative gain of electron impact excitation across the gap. This will be correlated with current and voltage measurements to estimate energy deposition in the gap.

Sands, Brian; Ganguly, Biswa

2008-10-01

133

Emission properties of tin droplets laser-produced-plasma light sources  

NASA Astrophysics Data System (ADS)

Laser produced plasma (LPP) light sources for extreme ultraviolet (EUV) lithography currently has been extensively studied. Most of the studies are based on CO2 laser induced plasma from mass limited tin targets. In this work, a droplet dispenser that produces uniform droplets size of about 150?m was established. A pulsed TEA-CO2 laser and a Nd: YAG laser irradiated the droplets producing plasma respectively to get EUV emission. An X-ray Spectrometer and EUV photodiodes were used to collect the spectra and EUV radiation. The different EUV spectral composition and angular distribution of EUV emission from plasmas induced by the CO2 and Nd: YAG laser were studied.

Chen, Hong; Wang, Xinbing; Zuo, Duluo; Lu, Peixiang; Zhu, Haihong; Wu, Tao

2014-04-01

134

Transient fields produced by a cylindrical electron beam flowing through a plasma  

NASA Astrophysics Data System (ADS)

Fast ignition schemes (FIS) for inertial confinement fusion should involve in their final stage the interaction of an ignition beam composed of MeV electrons laser generated at the critical density surface with a dense plasma target. In this study, the out-of-equilibrium situation in which an initially sharp-edged cylindrical electron beam, that could e.g. model electrons flowing within a wire [1], is injected into a plasma is considered. A detailed computation of the subsequently produced magnetic field is presented [2]. The control parameter of the problem is shown to be the ratio of the beam radius to the electron skin depth. Two alternative ways to address analytically the problem are considered: one uses the usual Laplace transform approach, the other one involves Riemann's method in which causality conditions manifest through some integrals of triple products of Bessel functions.[4pt] [1] J.S. Green et al., Surface heating of wire plasmas using laser-irradiated cone geometries, Nature Physics 3, 853--856 (2007).[0pt] [2] M.-C. Firpo, http://hal.archives-ouvertes.fr/hal-00695629, to be published (2012).

Firpo, Marie-Christine

2012-10-01

135

Temperature and electron density gradient in Xe laser produced plasmas, by spectral analysis  

Microsoft Academic Search

We have performed a spectroscopic analysis on laser produced plasmas in Xe at intermediates pressures (less than 1 atm), resolved both spectrally and temporally, also discriminating different regions of the plasma. This is produced by tightly focusing the radiation of a Q-switched Nd:YAG laser on a cell equipped with an observation window at right angles with respect to the laser.

G. Bertuccelli; H. O. Di Rocco; H. F. Ranea-Sandoval

2000-01-01

136

Characterization of laser-produced fusion plasmas with thomson scattering  

SciTech Connect

Thomson scattering has been developed at the Nova laser facility as a direct and accurate diagnostic to characterize inertial confinement fusion plasmas. Measurements from methane-filled, ignition relevant hohlraums apply the theory for two ion species plasmas, which has been tested in separate open geometry experiments, to obtain electron and ion temperatures. The experimental data provide a benchmark for two-dimensional hydrodynamic simulations using LASNEX, which is presently in use to predict he performance of future megajoule laser- driven hohlraums of the National Ignition Facility (NIF). The data are consistent with modeling using significantly inhibited heat transport at the peak of the drive. Furthermore, we find that stagnating plasma regions on the hohlraum axis are well described by the calculations. The result implies that stagnation in gas-filled hohlraums occurs too late to directly affect the capsule implosion in ignition experiments.

Glenzer, S.H.; Back, C.A.; Suter, L.J.; MacGowan, B.J.; Landen, O.L.; Lindl, J.D.; Blain, M.A.

1997-07-09

137

Laser produced plasma clouds as a source and obstacle for multi-ion Alfven wave propagation  

Microsoft Academic Search

We present results on the interaction of Alfven waves and energetic, laser-produced plasmas (LPP's). The experiment consists of a large, ambient, magnetized plasma, within which the carbon LPP is created. The LPP is generated using a turn-key Nd:YAG (1064nm, 1J, 10ns) laser. The background plasma is generated by the Large Plasma Device (LAPD) at UCLA. The background species is helium,

S. Vincena; W. Gekelman; F. Tsung

2010-01-01

138

Interaction of high Mach-number shocks in laser-produced plasmas  

NASA Astrophysics Data System (ADS)

We report the laboratory experiment for high Mach-number collisionless shock formation and for studying the interaction of them. These shocks are formed in high-velocity counterstreaming plasmas produced by ablating a double-foil plastic target with a high-power laser. The laser-produced plasmas are diagnosed with space and time-resolved optical pyrometry and shadowgraphy. Multiple shocks are formed and interact with each other, resulting in the increase of plasma temperature and density.

Morita, T.; Sakawa, Y.; Kuramitsu, Y.; Dono, S.; Tanji, H.; Aoki, H.; Ide, T.; Nishio, K.; Gregory, C. D.; Waugh, J. N.; Woolsey, N.; Diziére, A.; Koenig, M.; Ide, H.; Tsubouchi, K.; Takabe, H.

2013-03-01

139

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

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

140

Plasma observations near Saturn - Initial results from Voyager 1  

Microsoft Academic Search

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

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

1981-01-01

141

Parameters of the plasma produced at the surface of a ferroelectric cathode by different driving pulses  

NASA Astrophysics Data System (ADS)

Spectroscopic investigations of the properties of a plasma produced by a ferroelectric-plasma source are presented. The electron plasma density, the electron and ion temperature, and the density of desorbed neutrals near the ferroelectric surface are determined from spectral line intensities and profiles. Three different methods of surface plasma formation are analyzed using a simplified model for the plasma production. The model predicts the total amount of charge in the plasma to be proportional to the dielectric constant of the ferroelectric material. Also, the model shows a strong dependence of the plasma parameters on the resistivity of the plasma transition layer. A maximal plasma density of ~1015 cm-3 is achieved when the electrons that were attached by the driving field to the ferroelectric surface are released from the surface owing to driving pulse sharp decay and ionized heavy atoms desorbed from the ferroelectric.

Peleg, O.; Chirko, K.; Gurovich, V.; Felsteiner, J.; Krasik, Ya. E.; Bernshtam, V.

2005-06-01

142

Investigation of plasma produced by laser and electron pulse ablation  

Microsoft Academic Search

Short laser pulses with high energy are a very promising tool for controlled ablation of materials, both for structurization and for deposition. They are especially suited for the ablation of non-conducting and of complex materials. The plasmas induced by the laser irradiation are distinguished by their high degree of ionization and excitation. A new source with comparable pulse properties is

Th. Witke; A. Lenk; B. Schultrich; C. Schultheiss

1995-01-01

143

Multilayer refractory nozzles produced by plasma-spray process  

NASA Technical Reports Server (NTRS)

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

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

1966-01-01

144

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

145

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

146

Features of plasma produced by excimer laser at low intensities  

Microsoft Academic Search

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

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

1997-01-01

147

Astrophysical Weibel instability in counterstreaming laser-produced plasmas  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

148

Topical applications of resonance internal conversion in laser produced plasma  

NASA Astrophysics Data System (ADS)

Physical aspects of resonance effects arising in plasma due to interactions of nuclei with the electrons are considered. Among them are resonance conversion (TEEN) and the reverse process of NEET. These processes are of great importance for pumping the excited nuclear states (isomers) and for accelerating their decay. Experiment is discussed on studying the unique 3.5-eV229m Th nuclide.

Karpeshin, F. F.

2007-04-01

149

Plasma observations near uranus: initial results from voyager 2.  

PubMed

Extensive measurements of low-energy positive ions and electrons in the vicinity of Uranus have revealed a fully developed magnetosphere. The magnetospheric plasma has a warm component with a temperature of 4 to 50 electron volts and a peak density of roughly 2 protons per cubic centimeter, and a hot component, with a temperature of a few kiloelectron volts and a peak density of roughly 0.1 proton per cubic centimeter. The warm component is observed both inside and outside of L = 5, whereas the hot component is excluded from the region inside of that L shell. Possible sources of the plasma in the magnetosphere are the extended hydrogen corona, the solar wind, and the ionosphere. The Uranian moons do not appear to be a significant plasma source. The boundary of the hot plasma component at L = 5 may be associated either with Miranda or with the inner limit of a deeply penetrating, solar wind-driven magnetospheric convection system. The Voyager 2 spacecraft repeatedly encountered the plasma sheet in the magnetotail at locations that are consistent with a geometric model for the plasma sheet similar to that at Earth. PMID:17812895

Bridge, H S; Belcher, J W; Coppi, B; Lazarus, A J; McNutt, R L; Olbert, S; Richardson, J D; Sands, M R; Selesnick, R S; Sullivan, J D; Hartle, R E; Ogilvie, K W; Sittler, E C; Bagenal, F; Wolff, R S; Vasyliunas, V M; Siscoe, G L; Goertz, C K; Eviatar, A

1986-07-01

150

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

151

Laser-produced plasmas and radiation sources. Final report 1 Jul 75-30 Sep 79  

SciTech Connect

The research performed under this program has covered a broad range of subjects involving laser interaction with both gaseous and solid target laser plasmas, and with development of plasma diagnostic techniques suitable for laser-produced plasmas. Included are detailed descriptions of research activities during fiscal years 1978 and 1979. These include a study of stimulated Brillouin scattering in transverse magnetic fields; development of x-ray diagnostics including x-ray continuum measurements, spectroscopy, and imaging techniques and their use in studying solid target plasmas; development of a fast schlieren photography system; and a theoretical study of nonlinear scattering techniques for plasma diagnostics.

Scudder, D.W.; Praddaude, H.C.

1980-01-31

152

Producing titanium aluminide foil from plasma-sprayed preforms  

SciTech Connect

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

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

1993-07-01

153

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

154

Ion beam and plasma methods of producing diamondlike carbon films  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

155

Experiments on hot and dense laser-produced plasmas  

SciTech Connect

Plasmas generated by irradiating targets with {approx}20 kJ of laser energy are routinely created in inertial confinement fusion research. X-ray spectroscopy provides one of the few methods for diagnosing the electron temperature and electron density. For example, electron densities approaching 10{sup 24} cm{sup -3} have been diagnosed by spectral linewidths. However, the accuracy of the spectroscopic diagnostics depends on the population kinetics, the radiative transfer, and the line shape calculations. Analysis for the complex line transitions has recently been improved and accelerated by the use of a database where detailed calculations can be accessed rapidly and interactively. Examples of data from Xe and Ar doped targets demonstrate the current analytic methods. First we will illustrate complications that arise from the presence of a multitude of underlying spectral lines. Then, we will consider the Ar He-like 1s{sup 2}({sup 1}S{sub 0}) - 1s3p({sup 1}P{sub 0}) transition where ion dynamic effects may affect the profile. Here, the plasma conditions are such that the static ion microfield approximation is no longer valid; therefore in addition to the width, the details of the line shape can be used to provide additional information. We will compare the data to simulations and discuss the possible pitfalls involved in demonstrating the effect of ion dynamics on lineshapes.

Back, C.A.; Woolsey, N.C.; Asfaw, A.; Glenzer, S.H.; Hammel, B.A.; Keane, C.J.; Lee, R.W.; Liedahl, D.; Moreno, J.C.; Nash, J.K.; Osterheld, A.L. [Lawrence Livermore National Lab., CA (United States); Calisti, A.; Stamm, R.; Talin, B.; Godbert, L.; Mosse, C.; Ferri, S.; Klein, L. [Universite de Provence, 13 - Marseille (France)

1996-08-05

156

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) [Los Alamos, NM

1981-01-01

157

Initial phase in plasma focus device — model and computer simulation  

Microsoft Academic Search

This paper reports on a two-dimensional computer simulation of the breakdown phase performed for a plasma focus (PF) device. The spatial and temporal development of the electron density and the potential of the electric field are calculated by numerically solving the continuity equations for electrons and ions together with the Poisson equation. This model has been used to study the

M. Scholz; I. M. Ivanova-Stanik

2000-01-01

158

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

159

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

SciTech Connect

Using an ultrafast electron probe capable of four-dimensional diagnosis, the initial stage of fast evolving plasmas produced by a 10{sup 14} W/cm{sup 2} 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 5x10{sup 7} suprathermal electrons with the outermost layer expanding at an average speed of 1.2x10{sup 7} m/s.

Zhu Pengfei; Wang Weimin [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Zhang Zhongchao; Chen Long; Zheng Jun; Li Runze; Qian Dong [Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Li Junjie; Wang Xuan; Cao Jianming [Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 (United States); Sheng Zhengming; Zhang Jie [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China)

2010-11-22

160

Characteristics of shock wave from nanosecond laser-produced aluminum plasma in air  

NASA Astrophysics Data System (ADS)

Characteristics of shock wave as well as its evolution of aluminum plasma produced by nanosecond YAG laser is investigated by time-resolved optical shadowgraph images. Experimental results show that shock wave is strongly influenced by the laser parameters and target arrangement. Shock waves from aluminum plasma and air plasma are observed simultaneously by shadowgraphs when the distance from lens to target surface (DLTS) is longer than the lens focal length, and a narrow bright "line" is observed in the region where shock waves from Al plasma and air plasma meet. The longitudinal expansion velocity of shock wave from Al plasma is largely influenced by DLTS and laser intensity as well, and it increases with laser intensity at the early stage of plasma expansion and reach to a maximum of 8.1×104 m/s.

Liu, Tianhang; Gao, Xun; Liu, Zehao; Sun, Changkai; Hao, Zuoqiang; Jin, Guangyong; Lin, Jingquan

2013-05-01

161

Design of a laser-produced lithium anode plasma experiment on the Helia extraction diode  

Microsoft Academic Search

Summary form only. Recent experimental evidence on PBFA II (Particle Beam Fusion Accelerator II) has suggested that poor source turn-on and nonuniformity may contribute to the late focusability achieved with passive lithium ion sources to date, further emphasizing the need for a preformed anode plasma. The authors are planning to field a direct laser-produced lithium anode plasma source on the

K. W. Bieg; G. C. Tisone; J. E. Bailey; R. A. Hamil

1989-01-01

162

Electron energy transport in ion waves and its relevance to laser-produced plasmas  

Microsoft Academic Search

Electron energy transport in plasmas is examined in the context of ion waves which are intermediate between collisionless isothermal ion acoustic waves and collisional adiabatic sound waves. The conductivity is found to be much less than the Spitzer-Haerm result for wavelengths less than 1000 electron mean free paths. This is expected to be relevant to laser-produced ablating plasmas in which

A. R. Bell

1983-01-01

163

Millimeter-Wave Measurements of the Transmission and Reflection of Detonation Plasmas Produced by Solid Explosives.  

National Technical Information Service (NTIS)

Transmission and reflection coefficients of detonation plasmas produced by solid explosives are measured by means of millimeter waves and used to calculate their conductivity and relative permittivity. Because of the limited spatial resolution correspondi...

H. D. vom Stein B. Koch

1977-01-01

164

Ballistic Pendula for Measuring the Momentum of a Laser-Produced Plasma.  

National Technical Information Service (NTIS)

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.

J. Grun B. H. Ripin

1982-01-01

165

Medium- and Long-Wavelength Infrared Emission from a Laser-Produced Oxygen Plasma.  

National Technical Information Service (NTIS)

Experiments on a laser-produced oxygen plasma were observed by medium wavelength (MWIR) and long wavelength (LWIR) infrared emission. This research is part of a continuing series of LINUS (Laser Induced Nuclear Simulation) experiments starting in the shor...

J. B. Lurie J. C. Baird

1985-01-01

166

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

NASA Astrophysics Data System (ADS)

The properties of microheterogeneous plasma produced by irradiation of a polymer aerogel target with an intense (1014 W/cm3) short (0.5 ps) 1.064-?m laser pulse were studied. It is found that, even at plasma densities exceeding the critical density, a small fraction of the incident laser radiation penetrates through the plasma in which the processes of density and temperature equalization still take place. The intensification (as compared to plasmas produced from denser foams and solid films) of transport processes in such plasma along and across the laser beam can be caused by the initial microheterogeneity of the solid target. The replacement of a small (10% by mass) part of the polymer with copper nanoparticles leads to a nearly twofold increase in the intensity of the plasma X-ray emission.

Borisenko, N. G.; Merkul'ev, Yu. A.; Orekhov, A. S.; Chaurasia, S.; Tripathi, S.; Munda, D. S.; Dhareshwar, L. J.; Pimenov, V. G.; Sheveleva, E. E.

2013-08-01

167

Spectroscopic study of laser-produced plasmas in hydrogen  

SciTech Connect

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

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

1995-08-01

168

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

Microsoft Academic Search

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

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

2010-01-01

169

Precision closed bomb calorimeter for testing flame and gas producing initiators  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

170

A study of subsurface crack initiation produced by rolling contact fatigue  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

171

Current initiation in low-density foam z-pinch plasmas  

Microsoft Academic Search

Low density agar and aerogel foams were tested as z-pinch loads on the Saturn accelerator to study current flow initiation. In these first experiments, we studied the initial plasma conditions by measuring the visible emission at early times with a framing camera and a streaked one-dimensional imaging system. Later, near the stagnation when the plasma is hotter, x-ray imaging and

M. S. Derzon; T. J. Nash; G. O. Allshouse; A. J. Antolak; C. Deeney; M. Hurst; J. S. McGurn; D. J. Muron; J. F. Seaman; J. Macfarlane; T. Demiris; L. Hrubesh; H. Lewis; D. Ryutov; T. Barber; D. Jobe; S. Lazier

1997-01-01

172

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

173

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

SciTech Connect

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

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

2013-09-15

174

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

175

Characteristics of laser produced plasmas and lasers for pulsed ion sources  

SciTech Connect

Preliminary experiments were performed to investigate the fundamental characteristics of the laser produced plasmas and the KrF lasers for the pulsed ion beam production. (1) Lithium target was irradiated by a small e-beam pumped KrF laser and the exhausted plasmas were measured. (2) A larger KrF laser of the same kind was operated and the output characteristics were observed. (3) The mode patterns of a discharge-pumped KrF laser was also measured most recently to prepare the future target irradiation to produce ion-source plasmas. {copyright} {ital 1996 American Institute of Physics.}

Kasuya, K.; Suzuki, T.; Itoh, Y.; Kamiya, T.; Watanabe, M.; Kawakita, Y.; Shioda, K.; Kanazawa, H. [Department of Energy Sciences, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Nagatsuta 4259, Midori-ku, Yokohama 226 (Japan)

1996-05-01

176

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

177

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

178

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

SciTech Connect

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. [Department of Electronic Device Engineering, Yamaguchi University, Ube 755-8611 (Japan)] [Department of Electronic Device Engineering, Yamaguchi University, Ube 755-8611 (Japan)

2013-06-15

179

Experimental Results from Initial Operation of Plasma Injector 1  

NASA Astrophysics Data System (ADS)

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

Howard, Stephen

2010-11-01

180

Studies of electron energy distribution in plasma produced by a resonant laser pulse  

NASA Astrophysics Data System (ADS)

Using the Langmuir probe method we evaluated the electron energy distribution (EED) in plasma produced in a Na+He mixture by a laser pulse tuned to the 3S-3P transition. We proposed a new method of retrieving the EED from the probe characteristics at high gas pressures, when the free path of the electrons is less than the probe radius, i.e. in the range of 2-100 Torr. The method consists of using a combination of the first and second derivatives of the electron current. The systematic error that usually occurs when the EED is treated by means of traditional Langmuir and diffusion probes was reduced by two to three times when treated this way. Two phase temporal evolution of the electron distribution was observed. Initially the shape of the EED was close to the Maxwellian function. Its temperature corresponded to the effective excitation temperature, which can characterize the total population of excited sodium atoms. When the concentration of excited atoms decreased, one observed a transformation of the EED function. At the second phase it became well Maxwellized only in the low energy region. The high energy part of the EED had a non-equilibrium shape. This was caused by relaxation of fast electrons produced by super-elastic collisions with residual excited atoms.

Gorbunov, N. A.; Grochola, A.; Kruk, P.; Pietruczuk, A.; Stacewicz, T.

2002-11-01

181

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

182

Sterilization of Medical Equipment Using Radicals Produced by Oxygen/Water Vapor RF Plasma  

NASA Astrophysics Data System (ADS)

The sterilization of medical equipment was performed using low-pressure RF discharge plasma. Oxygen radicals as oxidizing materials for sterilization were produced from oxygen or water vapor. The generation of atomic oxygen and OH radicals was confirmed using the light emission spectra of the plasma. The pressure in the discharge region was varied periodically during inactivation in order to produce radicals effectively and to penetrate the produced radicals into tiny gaps. Medium sheets for microbial detection indicated that the decimal reduction value of active bacillus was 5 and 8 min using oxygen plasma and water vapor plasma with ne=109 cm-3, respectively. Biological indicators clarified that the sterilization of bacilli spores was successful for a treatment time of 90 min.

Hayashi, Nobuya; Guan, Weimin; Tsutsui, Shinsuke; Tomari, Tetsushi; Hanada, Yasushi

2006-10-01

183

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

184

Initial simulation of MHD instabilites in a high speed plasma accelerator  

NASA Astrophysics Data System (ADS)

High density, high Mach number plasma jets are under development for a variety of critical fusion applications. These applications include fueling, rotation driving, and disruption mitigation in magnetic fusion devices. They also include a range of innovative approaches to high energy density plasmas. FAR-TECH, Inc. has begun 3D MHD simulations using the LSP code [1] to examine such high speed plasma jets. An initial study to benchmark the code is currently underway. The blow-by instability will be simulated in a coaxial plasma accelerator using the 3D LSP code and compared with the 2D MACH2 code results. [1] LSP-Manual-MRC-ABQ-R-1942.pdf

Kim, Jin-Soo; Hughes, Tom; Thio, Francis

2005-10-01

185

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

186

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

187

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

PubMed

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 × 10(16) W/cm(2) were successfully imaged. Analyzing this image, we found that electrons were emitted from an area of 3 ?m in diameter. At higher laser intensity of 10(18) W/cm(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. PMID:21198016

Inoue, Shunsuke; Tokita, Shigeki; Nishoji, Toshihiko; Masuno, Shinichiro; Otani, Kazuto; Hashida, Masaki; Sakabe, Shuji

2010-12-01

188

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

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

189

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

NASA Technical Reports Server (NTRS)

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

Snyder, Steve

1996-01-01

190

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.; Séguin, F. H.; Frenje, J. A.; Froula, D. H.; Petrasso, R. D.

2012-11-01

191

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

SciTech Connect

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

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

1996-03-01

192

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

DOEpatents

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

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

1985-01-01

193

Electron energy transport in ion waves and its relevance to laser-produced plasmas  

Microsoft Academic Search

Electron energy transport in plasmas is examined in the context of ion waves which are intermediate between collisionless isothermal ion acoustic waves and collisional adiabatic sound waves. The conductivity is found to be much less than the Spitzer-Ha¨rm result for wavelengths less than 1000 electron mean free paths. This is expected to be relevant to laser-produced ablating plasmas in which

A. R. Bell

1983-01-01

194

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

Microsoft Academic Search

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

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

1997-01-01

195

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

Microsoft Academic Search

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

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

2001-01-01

196

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

Microsoft Academic Search

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

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

1997-01-01

197

Study of the plasma produced from laser ablation of a KTP crystal  

Microsoft Academic Search

Optical emission spectra of the plasma produced by 1.06?m Nd:YAG laser irradiation of a potassium titanium phosphate (KTP) crystal in vacuum and in air were recorded and analyzed in a spatially resolved manner. Electron temperatures and densities in the plasma in vacuum were determined with the Boltzmann plot method using five Ti(II) emission lines and the Stark-broadened linewidths of neutral

Minju Ying; Yueyuan Xia; Yuming Sun; Qingming Lu; Mingwen Zhao; Xiangdong Liu

2003-01-01

198

Studies of a strongly coupled plasma produced in a capillary discharge  

SciTech Connect

We have carried out an experiment measuring the properties of a strongly coupled (/Gamma/ /approximately/ 0.8) plasma produced in a capillary discharge. Using an analytical model and some 1-D MHD calculations along with the measurements, we were able to determine the density, temperature, strong coupling parameter /Gamma/, and the resistivity of this plasma. We then compared our resistivity measurements to various theories. 5 refs., 5 figs.

Benage, J.F. Jr.; Jones, L.A.; Trainor, R.J. Jr.; Shanahan, W.R.; Shepherd, R.L.; Nothwang, D.P.

1989-01-01

199

Efficient laser-produced plasma extreme ultraviolet sources using grooved Sn targets  

SciTech Connect

An efficient extreme ultraviolet (EUV) generation method has been developed with the use of a CO{sub 2} laser-produced plasma from a grooved target. A approx5% conversion efficiency from laser to 13.5 nm photons was obtained with the use of grooves in a tin target or by repeated laser pulse shots at the same target position. Modeling studies proved that the groove target controls the hydrodynamic expansion of the plasma leading to confinement which prevents the plasma escaping from the EUV production zone.

Harilal, S. S.; Sizyuk, T.; Sizyuk, V.; Hassanein, A. [School of Nuclear Engineering and Center for Materials Under Extreme Environment, Purdue University, 400 Central Drive, West Lafayette, Indiana 47907 (United States)

2010-03-15

200

Silicon surface periodic structures produced by plasma flow induced capillary waves  

SciTech Connect

Silicon single crystal surface modification by the action of nitrogen quasistationary compression plasma flow generated by a magnetoplasma compressor is studied. It has been found that highly oriented silicon periodic cylindrical shape structures are produced during a single pulse surface treatment. The periodical structure formation can be related to the driven capillary waves quenched during fast cooling and resolidification phase of the plasma flow interaction with silicon surface. These waves are induced on the liquid silicon surface due to the compression plasma flow intrinsic oscillations.

Dojcinovic, I. P.; Kuraica, M. M.; Obradovic, B. M.; Puric, J. [Faculty of Physics, University of Belgrade, P.O. Box 368, 11001 Belgrade (Serbia) and Center for Science and Technology Development, Obilicev Venac 26, 11001 Belgrade (Serbia)

2006-08-14

201

Time evolution of collisionless shock in counterstreaming laser-produced plasmas.  

PubMed

We investigated the time evolution of a strong collisionless shock in counterstreaming plasmas produced using a high-power laser pulse. The counterstreaming plasmas were generated by irradiating a CH double-plane target with the laser. In self-emission streaked optical pyrometry data, steepening of the self-emission profile as the two-plasma interaction evolved indicated shock formation. The shock thickness was less than the mean free path of the counterstreaming ions. Two-dimensional snapshots of the self-emission and shadowgrams also showed very thin shock structures. The Mach numbers estimated from the flow velocity and the brightness temperatures are very high. PMID:21635040

Kuramitsu, Y; Sakawa, Y; Morita, T; Gregory, C D; Waugh, J N; Dono, S; Aoki, H; Tanji, H; Koenig, M; Woolsey, N; Takabe, H

2011-04-29

202

Time Evolution of Collisionless Shock in Counterstreaming Laser-Produced Plasmas  

NASA Astrophysics Data System (ADS)

We investigated the time evolution of a strong collisionless shock in counterstreaming plasmas produced using a high-power laser pulse. The counterstreaming plasmas were generated by irradiating a CH double-plane target with the laser. In self-emission streaked optical pyrometry data, steepening of the self-emission profile as the two-plasma interaction evolved indicated shock formation. The shock thickness was less than the mean free path of the counterstreaming ions. Two-dimensional snapshots of the self-emission and shadowgrams also showed very thin shock structures. The Mach numbers estimated from the flow velocity and the brightness temperatures are very high.

Kuramitsu, Y.; Sakawa, Y.; Morita, T.; Gregory, C. D.; Waugh, J. N.; Dono, S.; Aoki, H.; Tanji, H.; Koenig, M.; Woolsey, N.; Takabe, H.

2011-04-01

203

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

204

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

NASA Astrophysics Data System (ADS)

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

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

1985-12-01

205

Optical properties of analogs of Titan's aerosols produced by dusty plasma  

NASA Astrophysics Data System (ADS)

Analogs of Titan's aerosols are produced in the laboratory as grains in a gas mixture, or as layers on a substrate. This production procedure enables the methane-nitrogen mixture composition to be changed. The aim of this paper is to understand the variations observed on the linear polarization of the scattered light as a function of the production conditions. The influence of the concentration of methane injected in the plasma will be discussed and compared with the previous work of Hadamcik et al. (2009a). The diameter of the grains are measured by SEM-FEG images. The decrease of absorption with increasing wavelength, measured by spectroscopic ellipsometry on layers, is observed for a decreasing initial methane ratio and analyzed in terms of an increasing `amine' content in the materials. The phase function parameters of the linear polarization of the scattered light are discussed in terms of the diameters of the aggregates and of the constituent grains, and the variation of the refractive indices (mainly absorption). The polarization is found to be highly correlated with the constituent grain size. Finally, the experimental results are compared to polarization measurements from space of the Titan's atmosphere.

Hadamcik, E.; Renard, J.-B.; Mahjoub, A.; Gautier, T.; Carrasco, N.; Cernogora, G.; Szopa, C.

2013-10-01

206

Preliminary measurements of x-ray and neutron emission from laser-produced plasmas.  

PubMed

Two Nd-glass laser systems have been assembled for producing high-temperature plasmas. The smaller laser, which gives subnanosecond pulses of about 5 J, has been used primarily for x-ray studies. The spectrum above 2 keV is being explored using Bragg reflection from a cylindrically curved graphite crystal. Line radiation appears to be present in the spectra measured for laser-produced plasmas of lead and gold. Plasma temperatures implied by x-ray transmission measurements are found to vary with absorber thickness. Temperatures of a few tens of keV, inferred from thick-absorber measurements of low-Z plasmas, suggest the operation of anomalous heating mechanisms. A second glass laser system, involving face-pumped disks 14 cm in diameter, is also in use for plasma-heating experiments and has led to the production of D-D neutrons. This system has been used to produce pulses of several tens of joules in a few nanoseconds for recent experiments. A calibrated plastic scintillator with two photomultipliers is used f r neutron detection. Targets of CD(2) have produced total yields of more than 10(4) neutrons. Effective neutron production appears to require laser pulses longer than 2 nsec and to be accompanied by a large reflected pulse. PMID:20111506

Mead, S W; Kidder, R E; Swain, J E; Ranier, F; Petruzzi, J

1972-02-01

207

Enhancement of extreme ultraviolet emission from a laser-produced-lithium plasma by use of dual laser pulses  

Microsoft Academic Search

The use of dual laser pulses, a lithium plasma source produces unambiguously defined line emission at 13.5 nm with almost no off-band components, which minimize unnecessary heating of EUV optics. A plasma hydrodynamic calculation evaluated the plasma expansion time of 80 ns, within which the plasma density decreased to the critical density of the 1064-nm laser pulse.

T. Higashiguchi; C. Rajyaguru; M. Koga; K. Kawasaki; W. Sasaki; S. Kubodera

2005-01-01

208

Initiation of fibrinolysis in alpha 2-plasmin inhibitor deficient plasma. Role of fibrin  

SciTech Connect

Plasmin activity and fibrin degradation products (FDP) are found in alpha 2-plasmin inhibitor (alpha 2-PI) deficient plasma only when clotted, but are not found when the plasma is not clotted. To determine whether fibrin itself could initiate fibrinolysis without activating coagulation enzymes, fibrin monomers were prepared and added to alpha 2-PI deficient plasma. The addition of fibrin monomers resulted in the generation of plasmin activity, a marked increase in FDP concentration, and the release of /sup 125/I from /sup 125/I-labeled fibrin monomers. Replenishment of the deficient plasma with purified alpha 2-PI abolished the effects of fibrin monomers on the initiation of fibrinolysis. Neither development of plasmin activity, increase of FDP, nor release of /sup 125/I was observed. These findings indicate that fibrinolysis can be induced by fibrin itself without activation of coagulation cascade and the induction of fibrinolysis is efficiently blocked by alpha 2-PI.

Ichinose, A.; Aoki, N.

1986-03-15

209

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

210

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

DOEpatents

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

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

1992-01-01

211

Plasma Density in a Planar Current Sheet Produced under High-Pressure He-filling  

NASA Astrophysics Data System (ADS)

Formation of current sheets (CS) in 2D magnetic fields with a null-line is usually accompanied by effective plasma compression into planar sheets and in a significant increase in the electron concentration as compared with the initial plasma density. We have demonstrated recently that CS formation is also possible under high-pressure He-filling (300 mTorr), if the radial gradient of magnetic field was strong enough. Now we report the results of spectroscopic measurements on the time evolution of electron concentrations in different regions of CS. In addition, we observed the decay in the He-Ne laser (632.8 nm) intensity because of its refraction in the plasma sheet. So a gradient of electron concentration was obtained. Experiments were carried out with the device CS-3D. Plasma emission from the central part of the CS plasma was analyzed with the standard monochromator and the detector MORS-3 (CCD-line array combined with a microchannel plate). The profiles of He II and He I spectral lines have been recorded at successive stages of the CS evolution and processed using special codes. Plasma density at the CS middle plane increased up to 10E17 per cc, the value exceeded about ten times the initial atomic concentration. Supported by INTAS (grant 96-456) and by RFBR (grant 96- 02-18546).

Kunze, H.-J.; Busher, St.; Frank, A. G.; Kyrie, N. P.

1998-11-01

212

Time-resolved backside optical probing of picosecond-laser-pulse-produced plasma in solid materials  

SciTech Connect

We report on pump-probe measurements of reflectivity and transmissivity of a plasma produced in transparent solid materials. The plasma is created by irradiating uncoated transparent planar glass targets with 1.0-ps FWHM laser pulses at a peak intensity of 2.0[times]10[sup 13] W/cm[sup 2]. Time-resolved measurements using a probe light pulse incident from the backside are presented, revealing two competing mechanisms: one is highly absorptive due to a bulk underdense plasma formed behind the target surface, and the other is highly reflective due to an overdense plasma layer at the surface. A simple self-consistent and analytical model, similar to the avalanche model, is proposed, leading to both time-dependent and time-integrated solutions to the evolution of plasma density profiles and characteristics of high-intensity-laser-pulse propagation and absorption in the transparent material. Calculations of the probe light interacting with this plasma show that excellent agreement with experimental measurements can only be obtained by including a contribution from the bulk plasma formed behind the surface. Experimental measurements with Au-coated targets are also shown to illustrate elimination of the bulk plasma.

Vu, B.V. (Department of Applied Science, University of California at Davis, Livermore, California 94550 (United States) Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)); Landen, O.L.; Szoke, A. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))

1993-04-01

213

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

NASA Astrophysics Data System (ADS)

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

Pasko, V. P.

2011-12-01

214

A comparison of the emissions, densities, temperatures, and debris features of laser-produced plasmas  

NASA Astrophysics Data System (ADS)

Tin and lithium plasmas emit efficiently in the in-band region (13.5 nm with 2% bandwidth) necessary for extreme ultraviolet (EUV) lithography. A detailed comparison of the atomic and ionic debris, as well as the emission features of tin and lithium plasmas has been conducted under identical experimental conditions. Planar slabs of pure tin and lithium were irradiated with 1064 nm, 9 ns neodymium-doped yttrium aluminum garnet (Nd:YAG) laser pulses for producing plasmas. A suite of diagnostics were used to analyze the emission and debris features, including optical emission spectroscopy (OES), a Faraday cup, an EUV pinhole camera, a power tool for the absolute measurement of EUV conversion efficiency (CE), etc. The results show that tin plasmas provide a CE nearly twice that of lithium. However, the kinetic energies of tin ions are considerably higher, though with a lower flux. OES studies have shown that the kinetic energies of neutral species are substantially lower compared to that of the charged particle species. Laser-produced lithium plasmas were also studied in closer detail with 2D OES, conventional 1D OES to determine the electron density throughout the entire plasma from the Stark broadening of the spectral line emissions, along with Nomarski interferometry. The electron temperatures of both neutral and singly-ionized species were estimated through a comparison of the line intensities by using the Boltzmann plot method. These results were then compared to previous studies of tin plasmas under similar conditions. Lithium plasma density was also evaluated using 2D OES in air, argon, and helium buffer gas environments of different pressures. These studies were then repeated along several planes perpendicular to the target surface, to evaluate any radial dependence on lithium plasma electron density.

Coons, Ryan William

215

Steady-state hot-ion plasma produced by crossed electric and magnetic fields  

NASA Technical Reports Server (NTRS)

Results of initial diagnostics on the Lewis Research Center hot-ion-plasma source (HIP-1) are reported. The mirror-contained plasma was heated by applying a radial electric field similar to that used in the ORNL burnout experiments. An electrostatic neutral particle analyzer was used to make a parametric study of ion energy distributions in both hydrogen and euterium plasmas. Ion temperatures as high as 2 keV were measured in plasmas with electron densities greater than 10 to 12th power/cu cm. The performance of the device was found to be extremely sensitive to a magnetic field. There are indications that ion heating was reduced when the size of the Larmor orbit was larger than the region of a strong radial electric field.

Sigman, D. R.; Reinmann, J. J.

1973-01-01

216

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

SciTech Connect

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

Heidrich, J. E.

1981-01-01

217

Laser produced plasma clouds as a source and obstacle for multi-ion Alfven wave propagation  

NASA Astrophysics Data System (ADS)

We present results on the interaction of Alfven waves and energetic, laser-produced plasmas (LPP's). The experiment consists of a large, ambient, magnetized plasma, within which the carbon LPP is created. The LPP is generated using a turn-key Nd:YAG (1064nm, 1J, 10ns) laser. The background plasma is generated by the Large Plasma Device (LAPD) at UCLA. The background species is helium, n=10^12 cm-3, D=60cm, L=1660cm cylinder. The LPP acts as a source of energetic carbon ions: 10^15 particles, v=10^7 cm/s = 0.1vA whose expansion is directed primarily along the background magnetic field; the resulting cloud is of interest for two reasons: (1) the carbon cyclotron motions act as an electric dipole antenna, which radiates shear Alfven waves in the He plasma, which outrun the cloud expansion. (2) the relatively slow expansion of the LPP compared to the Alfven speed produces a spatially localized region of a two-ion species plasma which can act as a barrier for externally launched shear Alfven waves due to the ion-ion hybrid resonance layer in the cloud. Wave field measurements will be presented of both outgoing and incoming shear Alfven waves to the carbon cloud. Comparisons of the cyclotron emission are made to predictions by the OSIRIS PIC code.

Vincena, S.; Gekelman, W.; Tsung, F.

2010-11-01

218

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

219

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

Microsoft Academic Search

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

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

1995-01-01

220

Laser-intensity scaling experiments in long-scalelength, laser-produced plasmas  

Microsoft Academic Search

An experimental technique is demonstrated that allows variation of the average laser intensity by more than two orders of magnitude while producing much smaller changes in the other parameters that determine the laser--plasma interactions. By irradiating exploding-foil targets with 0.35 ..mu..m laser light in flat-topped pulses of variable duration, the high-power Nova laser (Rev. Sci. Instrum. 57, 2101 (1986)) produced

R. P. Drake; P. E. Young; E. A. Williams; Kent Estabrook; W. L. Kruer; B. F. Lasinski; C. B. Darrow; H. A. Baldis; T. W. Johnston

1988-01-01

221

Prepulse Effect for Recombining Plasma Produced by Ultrashort High-Intensity Lasers  

NASA Astrophysics Data System (ADS)

We compare the space-resolved characteristics of carbon plasmas produced using a single ultrashort high-intensity laser pulse (>1019 W/cm2) of less than 800 fs duration and those using a combination of a 100 ps duration prepulse and an ultrashort laser pulse. Profiles of electron density and electron temperature as functions of position from the original target surface are derived from the measured one-dimensional space-resolved soft X-ray spectra. The electron density was estimated from the Inglis-Teller limit and from a comparison of the experimental and the calculated profiles of Lyman series lines. The electron density gradually increases up to the critical density of the incident laser light near the target surface, and the density gradient is much steeper when the plasma is produced using the single ultrashort pulse. The electron temperature was estimated from the intensity ratio of the H-like Ly-? line to the He-like He-? line and that of the H-like Ly-? line to its satellite lines. The plasmas produced using the prepulse additionally are relatively uniform with moderate electron density and temperature, and a larger portion of the K-shell lines from carbon ions is produced in the recombining phase, rather than in the heating phase. With a suitable choice of prepulses, the spatial and temporal profiles of the plasma density and temperature can be controlled, which can facilitate applications of the laser-produced plasmas to various kinds of research, such as producing a gain medium for X-ray lasers.

Choi, Il Woo; Daido, Hiroyuki; Sakaya, Noriyuki; Tohyama, Yusuke; Izumi, Nobuhiko; Kodama, Ryosuke; Kitagawa, Yoneyoshi; Tanaka, Kazuo A.; Mima, Kunioki

2001-03-01

222

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

223

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

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

224

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

SciTech Connect

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 (1957)) for large ion velocity gradients. As examples, escape probability is applied to model the effect of optically thick line trapping in both exploding foil and ablating massive slab targets. Compared to detailed numerical calculations for the line transfer in these targets, the escape probability gives quite accurate estimates. This can be understood in terms of the large Doppler shifts in the line profiles that are generated by the ion velocity in the plasmas.

Lee, Y.T.; London, R.A.; Zimmerman, G.B. (Lawrence Livermore National Laboratory, Livermore, CA (USA)); Hagelstein, P.L. (Massachusetts Institute of Technology, Cambridge, MA (USA))

1990-11-01

225

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

226

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

227

Emission analysis of expanding laser produced lithium plasma plume in presence of ambient gas  

Microsoft Academic Search

Atomic analysis of the emission from laser-produced plasma from bulk lithium (Li) block has been made. The observed changes in the emission from lithium neutral and ionic species have been explained by considering various atomic processes. We demonstrate that the excitation process in case of neutral lithium Li (I) is electron impact excitation whereas for singly ionized lithium Li (II),

H. C. Joshi; V. Prahlad; R. K. Singh; Ajai Kumar

2009-01-01

228

Active-Passively Mode-Locked Dye Laser for Diagnosis of Laser-Produced Plasmas.  

National Technical Information Service (NTIS)

In this report an active-passively mode-locked, flashlamp-pumped dye laser for diagnosis of laser-produced plasmas is described. This dye laser system used as a pulsed light source for high-speed photography of laser-target experiments was synchronized to...

Y. L. Teng R. Fedosejevs R. Sigel

1981-01-01

229

Experimental and theoretical study of the expansion of a metallic vapour plasma produced by laser  

Microsoft Academic Search

The interaction between a metallic plasma produced by laser ablation and an ambient gas (argon, air and nitrogen) at atmospheric pressure is studied. The experimental results are compared with theoretical ones given by numerical simulation. Aluminium and copper targets are used. The uniform repartition of iron impurities included in the target (1.6% for Al and 2% for Cu) is warranted

A. Gomes; A. Aubreton; J. J. Gonzalez; S. Vacquié

2004-01-01

230

An Inverted Plasma Sheath for the Simulation of the Extraction of Volume Produced H-  

Microsoft Academic Search

For the extraction of positive ions from plasmas well established computer programs are available, which are based on the Bohm sheath theory. In general the results of such simulations agree very well with experimental data. The situation is completely different, however, for the simulation of the extraction of volume produced H- ions. An open question so far has been, if

Reinard Becker

2002-01-01

231

Ballistic Pendula for Measuring the Momentum of a Laser-Produced Plasma.  

National Technical Information Service (NTIS)

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. (ERA citation 08:003825)

J. Grun B. H. Ripin

1982-01-01

232

Shock formation in supersonic cluster jets and its effect on axially modulated laser-produced plasma waveguides.  

PubMed

We examine the generation of axially modulated plasmas produced from cluster jets whose supersonic flow is intersected by thin wires. Such plasmas have application to modulated plasma waveguides. By appropriately limiting shock waves from the wires, plasma axial modulation periods can be as small as 70 ?m, with plasma structures as narrow as 45 µm. The effect of shocks is eliminated with increased cluster size accompanied by a reduced monomer component of the flow. PMID:23842374

Yoon, S J; Goers, A J; Hine, G A; Magill, J D; Elle, J A; Chen, Y-H; Milchberg, H M

2013-07-01

233

Effect of a transverse magnetic field on the plume emission in laser-produced plasma: An atomic analysis  

NASA Astrophysics Data System (ADS)

We have investigated the effect of varying transverse magnetic field on the plasma plume emission of laser-produced lithium plasma. Two atomic transitions for lithium neutral Li (I) and two for Li ion LI (II) are taken for the study. It has been found that for Li (I), the emission from 670.8 nm transition (2s 2S 1/2?2p 2P 3/2'1/2) shows initial enhancement and then subsequent decrease for higher fields. Of course, the overall intensity is increased for all the fields when compared to the case of without field. On the other hand, for 610.3 nm (2p 2P 1/2?3d 2P 3/2'5/2), there is continuous decrease in intensity. Interestingly, for Li (II) transitions also, after an initial increase in intensity up to 0.08 Ta decrease is observed. From the atomic analysis, we find that for 670.8 nm line, the cause of initial enhancement is increase in electron impact excitation whereas for decreased intensity, increased field-induced ionization appears to be responsible mechanism. However, for 610.3 nm line, decrease in intensity appears to be due to decreased recombination. For Li (II), 478.8 nm (3p 1P 1?4d 1D 2) and 548.4 nm (2s 3S 1?2p 3P 2,1,0) transitions, initial increase appears to be due to increased confinement (increase in plasma density) and subsequent decrease in intensity with increase in field due to decreased recombination.

Joshi, H. C.; Kumar, Ajai; Singh, R. K.; Prahlad, V.

2010-05-01

234

System to continuously produce carbon fiber via microwave assisted plasma processing  

DOEpatents

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

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

2010-11-02

235

Fusion plasmas produced by femtosecond laser irradiation of clusters in a megagauss magnetic field  

NASA Astrophysics Data System (ADS)

Interactions of intense femtosecond lasers with atomic clusters can create plasmas with high density (10^19 cm-3) and high average ion energies (10 keV) and significant numbers (10^7) of DD fusion neutrons can be produced. We have built and are testing a 2 MA driver to create a 200 T field that can be used on the Texas Petawatt laser to create a magnetized hot, dense deuterium plasma with a high neutron yield. A cooled gas jet will be used to produce deuterium clusters with radius ˜ 10 nm. The magnetic field is produced by a 10 capacitor (100 kV) low inductance bank that discharges through a 1 cm diameter coil in vacuum. First experiments will be done on the 2 J, 120 fs GHOST laser; later experiments are scheduled on the 180 J, 160 fs Texas Petawatt. Details and status of components will be presented.

Bengtson, Roger; Lewis, Sean; Quevedo, Hernan; Wisher, Matthew; Kellog, Jeffery; Stolzfus, Brian; Struve, Kenneth; Waugh, Caleb

2011-11-01

236

Plasma Discharge Initiation of Explosives in Rock Blasting Application: A Case Study  

NASA Astrophysics Data System (ADS)

A plasma discharge initiation system for the explosive volumetric combustion charge was designed, investigated and developed for practical application. Laboratory scale experiments were carried out before conducting the large scale field tests. The resultant explosions gave rise to less noise, insignificant seismic vibrations and good specific explosive consumption for rock blasting. Importantly, the technique was found to be safe and environmentally friendly.

Jae-Ou, Chae; Young-Jun, Jeong; V, M. Shmelev; A, A. Denicaev; V, M. Poutchkov; V, Ravi

2006-07-01

237

Current initiation in low-density foam z-pinch plasmas  

SciTech Connect

Low density agar and aerogel foams were tested as z-pinch loads on the SATURN accelerator. In these first experiments, we studied the initial plasma conditions by measuring the visible emission at early times with a framing camera and 1-D imaging. At later time, near the stagnation when the plasma is hotter, x-ray imaging and spectral diagnostics were used to characterize the plasma. Filamentation and arcing at the current contacts was observed. None of the implosions were uniform along the z-axis. The prime causes of these problems are believed to be the electrode contacts and the current return configuration and these are solvable. Periodic phenomena consistent with the formation of instabilities were observed on one shot, not on others, implying that there may be a way of controlling instabilities in the pinch. Many of the issues involving current initiation may be solvable. Solutions are discussed.

Derzon, M.; Nash, T.; Allshouse, G. [and others

1996-07-01

238

Current initiation in low-density foam z-pinch plasmas  

SciTech Connect

Low density agar and aerogel foams were tested as z-pinch loads on the Saturn accelerator to study current flow initiation. In these first experiments, we studied the initial plasma conditions by measuring the visible emission at early times with a framing camera and a streaked one-dimensional imaging system. Later, near the stagnation when the plasma is hotter, x-ray imaging and spectral diagnostics were used to characterize the plasma. Filamentation and arcing at the current contacts were observed. Bright implosion features were also observed. Increasing the early time conductivity, by coating the target with a high-z layer and by providing a low-current prepulse, is the most important factor in obtaining good coupling to the machine. None of the pinches were uniform along the z axis. The prime causes of these problems are believed to be the electrode contacts and the current return configuration. Solutions are discussed. {copyright} {ital 1997 American Institute of Physics.}

Derzon, M.S.; Nash, T.J.; Allshouse, G.O.; Antolak, A.J.; Deeney, C.; Hurst, M.; McGurn, J.S.; Muron, D.J.; Seaman, J.F. [Sandia National Laboratories, Alburquerque, New Mexico 87185-1196 (United States)] [Sandia National Laboratories, Alburquerque, New Mexico 87185-1196 (United States); MacFarlane, J. [Fusion Technology Institute, University of Wisconsin at Madison, Madison, Wisconsin 53706-1687 (United States)] [Fusion Technology Institute, University of Wisconsin at Madison, Madison, Wisconsin 53706-1687 (United States); Demiris, T.; Hrubesh, L.; Lewis, H.; Ryutov, D. [Lawrence Livermore National Laboratory, Livermore, California 94550-0622 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94550-0622 (United States); Barber, T.; Gilliland, T.; Jobe, D.; Lazier, S. [K-tech Corp., Albuquerque, New Mexico, 87110-7403 (United States)] [K-tech Corp., Albuquerque, New Mexico, 87110-7403 (United States)

1997-01-01

239

Estimation of the initial amplitude of plasma bubble seed perturbation from ionograms  

NASA Astrophysics Data System (ADS)

This work gives the description of an experimental method for the calculation of the initial amplitude of plasma bubble seed perturbation in the bottomside F layer from ionograms. The observations show that after sunset the ionograms exhibit irregularities in the base of the F trace. In the context of the plasma depletion in the bottomside F-layer, the irregularities in ionograms can be seen like isodensity contour in evolution (in space and time). The initial amplitudes, calculated using the methodology, vary between 0.03 and 0.08. The ionograms analyzed were obtained from the station of Cachimbo (9.5°S, 54.8°W) during COPEX campaign in Brazil. The methodology can be useful for application in numerical simulation of plasma bubbles in which actual ionospheric parameters are used.

Carrasco, A. J.; Batista, I. S.

2012-04-01

240

Debris measurement at the intermediate focus of a laser-assisted discharge-produced plasma light source  

NASA Astrophysics Data System (ADS)

For extreme ultraviolet light lithography to be a viable process for the future development of computer chips, it is necessary that clean photons are produced at the intermediate focus (IF). To measure the flux at the IF, the Center for Plasma-Material Interactiosn (CPMI) at the University of Illinois at Urbana-Champaign has developed a Sn IF flux emission detector (SNIFFED) apparatus that is capable of measuring charged and neutral particle flux at the IF. Results will be presented that diagnose debris produced at the IF, as well as methods by which this debris can be mitigated. Advanced Materials Research Center, AMRC, International SEMATECH Manufacturing Initiative, and ISMI are servicemarks of SEMATECH, Inc. SEMATECH, and the SEMATECH logo are registered servicemarks of SEMATECH, Inc. All other servicemarks and trademarks are the property of their respective owners.

Sporre, J.; Surla, V.; Neumann, M. J.; Ruzic, D. N.; Ren, L.; Goodwin, F.

2010-03-01

241

Novel approach to produce polymerized hydrocarbon coatings using dielectric barrier controlled atmospheric pressure glow discharge plasma  

NASA Astrophysics Data System (ADS)

Conventionally, low-pressure (<1 Torr) electrical discharges are used for material processing and thin-film deposition. These schemes suffer mainly due to the high cost of equipment and the complexity of operations. The atmospheric pressure glow discharge plasma is developed using a threaded styled electrode in different configurations, and these reactors are used to produce plasma polymerized coatings, required on plane substrates as self-supporting films to obtain membranes for blocking holes in cavities, and on microballoon targets, which are used as fuel containers for inertial confinement fusion, to avoid DT gas permeation. Helium gas is used as the supporting gas for formation and stabilization of atmospheric pressure glow discharge plasma reactors. Ethylene and acetylene gases are used as monomers to produce plasma polymerized hydrocarbon films. These films are characterized using scanning electron microscopy. Plasma polymerized coatings of thickness 100 nm-10 ?m with a smooth surface finish (rms<100 nm) are deposited successfully. The surface finish is further improved using a postdischarge configuration. Preliminary results are very encouraging but further progress is to be made in this area. We are also planning to extend this technique for C:H coating of microballoons, which are used as fuel containers in inertial confinement fusion.

Mishra, K. K.; Khardekar, R. K.; Singh, Rashmi; Pant, H. C.

2002-09-01

242

A NEW CLASS OF THIN FILM HYDROGELS PRODUCED BY PLASMA POLYMERIZATION  

PubMed Central

A simple, direct route to preparation of surface immobilized hydrogel films is described. Specifically, low pressure RF pulsed plasma polymerization of 1-amino-2-propanol and 2-(ethylamino)ethanol monomers produced thin hydrogel films deposited on substrates located in the plasma reactor. The successful syntheses were carried out under plasma conditions which not only yield the hydrogel but are also sufficiently energetic to produce films strongly grafted to the substrates. The polymer films obtained exhibit the thermoresponsive property of hydrogels, as shown by film color change with temperature. Additional evidence for the phase transition properties of these films was obtained using water contact angle and capillary rise measurements. The plasma polymerization approach provides an unusually simple route to synthesis of hydrogels in which the films are pin-hole free and are of easily controlled thickness. An important added advantage, particularly for applications involving biomaterials, is the conformal property of the plasma generated polymer films. The results obtained suggest that this approach should be applicable to a variety of other monomers and, based on differences observed with the present two monomers, suggest synthesis of films which exhibit a range of phase transition temperatures.

Bhattacharyya, Dhiman; Pillai, Karthikeyan; Chyan, Oliver M. R.; Tang, Liping; Timmons, Richard B.

2008-01-01

243

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

DOEpatents

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

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

2004-10-19

244

Interferometry Results from Initial Experiments on the Plasma Liner Experiment (PLX)  

NASA Astrophysics Data System (ADS)

The Plasma Liner Experiment (PLX) is exploring and demonstrating the feasibility of forming HED and potentially MIF relevant imploding spherical ``plasma liners'' that can reach peak pressures ˜ 0.1 Mbar at stagnation. Liners will be formed via merging of 30 dense, high Mach number plasma jets (M ˜ 10-35, v ˜ 50 km/s, jet diameter ˜ 5 cm) in spherically convergent geometry. Determining ne during liner formation, convergence, and stagnation, in comparison to simulation, is imperative for understanding the underlying plasma dynamics and for optimizing the liner formation and implosion. Simulations predict a wide parameter range for ne over the liner evolution, from densities of 10^22 - 10^26 m-3. A primary density diagnostic is an 8-chord, fiber-optic, heterodyne, 561 nm interferometer. This poster overviews the interferometer design, and will present results from initial experiments including single jet propagation and two jet merging.

Merritt, Elizabeth; Lynn, Alan; Gilmore, Mark; Hsu, Scott

2011-11-01

245

Prospect on the Atomic and Molecular Processes in Plasmas 5. Recent Topics in Experiments 5.2 Recent Progress in Research on Laser-Produced-Plasma  

Microsoft Academic Search

This article reviews recent topics in the research on laser produced plasma. Specifically, the experimental results that are closely related to atomic physics and their data base are introduced. Key issues include the ultra-short-pulse laser plasma, the plasmas that exist far from equilibrium condition, the study of basic scientific phenomena in a large-scale experimental laser system.

Hitoki Yoneda

1999-01-01

246

The diagnostics of ultra-short pulse laser-produced plasma  

NASA Astrophysics Data System (ADS)

Since the invention of the laser, coherent light has been used to break down solid or gaseous material and transform it into a plasma. Over the last three decades two things have changed. Due to multiple advancements and design of high power lasers it is now possible to increase the electric and magnetic field strength that pushed the electron motion towards the regime of relativistic plasma physics. Moreover, due to the short pulse duration of the driving laser the underlying physics has become so transient that concepts like thermal equilibrium (even a local one) or spatial isotropy start to fail. Consequently short pulse laser-driven plasmas have become a rich source of new phenomena that we are just about beginning to explore. Such phenomena, like particle acceleration, nuclear laser-induced reactions, the generation of coherent secondary radiation ranging from THz to high harmonics and the production of attosecond pulses have excited an enormous interest in the study of short pulse laser plasmas. The diagnostics of such ultra-short pulse laser plasmas is a challenging task that involves many and different techniques compared to conventional laser-produced plasmas. While this review cannot cover the entire field of diagnostics that has been developed over the last years, we will try to give a summarizing description of the most important techniques that are currently being used.

Roth, Markus

2011-09-01

247

Stigmatic observations of laser-produced plasmas with a grazingincidence spectrograph.  

PubMed

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 microm over a region of 1-mm extension and spectral resolution of approximately 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 stigmatic condition in the range 10-300 A. Examples of observations of a beryllium plasma are shown. PMID:19687844

Jannitti, E; Nicolosi, P; Tondello, G

1979-06-01

248

Strong reduction of nonlocal electron heat transport in magnetized laser produced plasma  

NASA Astrophysics Data System (ADS)

We present a direct measurement of the reduction of nonlocal heat transport in laser-produced plasma by applying large external magnetic fields (> 10 T). Imaging Thomson scattering measurements of the electron temperature profile show confinement of the heat wave transverse to a high-power laser beam resulting in strong local heating. The electron temperature increases from 200 eV to 800 eV when a 12 Tesla magnetic field is applied. We find agreement with hydrodynamic modeling (using LASNEX) when including a magnetic field model that self-consistently evolves the fields in the plasma.

Divol, Laurent; Froula, D. H.; Ross, J. S.; Davis, P.; Pollock, B. B.; Edwards, M. J.; Town, R. P. J.; Price, D.; Glenzer, S. H.; Offenberger, A. A.; James, A. N.; Tynan, G. R.

2006-10-01

249

Stark profiles of forbidden and allowed transitions in a dense, laser produced helium plasma.  

NASA Technical Reports Server (NTRS)

Comparisons of experimental and theoretical Stark profiles of the allowed 2(1)P-3(1)D helium line at 6678 A and of the forbidden 2(1)P-3(1)P component at 6632 A in a dense plasma were carried out. The plasma was produced by optical breakdown of helium by means of a repetitive, high power CO2 laser. The allowed line shows good agreement with conventional theory, but discrepancies are found around the centre of the forbidden component. When normally neglected ion motions are taken into consideration, the observed discrepancies are partially removed. Tables of the Stark profiles for the pair of lines are given.

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

1972-01-01

250

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

251

Initial energy density of gluons produced in very-high-energy nuclear collisions  

PubMed

In very-high-energy nuclear collisions, the initial energy of produced gluons per unit area per unit rapidity, (dE/L2)/deta, is equal to f(g(2)&mgr;L) (g(2)&mgr;)(3)/g(2), where &mgr;(2) is proportional to the gluon density per unit area of the colliding nuclei. For an SU(2) gauge theory, a nonperturbative computation of f(g(2)&mgr;L) shows that it varies rapidly for small g(2)&mgr;L but varies only by approximately 25%, from 0.208+/-0.004 to 0.257+/-0. 005, for a wide range 35.36- 296.98 in g(2)&mgr;L. This includes the range relevant for collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). Extrapolating to SU(3), we estimate dE/deta for Au-Au collisions in the central region at RHIC and LHC. PMID:10990673

Krasnitz; Venugopalan

2000-05-01

252

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

253

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

254

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 at an angle of 64{degree} from the normal. 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{percent} 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. {copyright} {ital 1997 American Institute of Physics.}

Glenzer, S.H.; Back, C.A.; Estabrook, K.G.; MacGowan, B.J. [L-399, Lawrence Livermore National Laboratory, University of California, P. O. Box 808, California 94551 (United States)] [L-399, Lawrence Livermore National Laboratory, University of California, P. O. Box 808, California 94551 (United States)

1997-01-01

255

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

NASA Technical Reports Server (NTRS)

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

Koopman, D. W.

1972-01-01

256

Structure of the plasma fireball produced by a CO2 laser.  

NASA Technical Reports Server (NTRS)

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

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

1971-01-01

257

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

258

Time-resolved visible spectroscopy of laser-produced lithium plasmas  

NASA Astrophysics Data System (ADS)

We have measured time-resolved visible spectra emitted from a plasma formed when the output from a dye laser irradiates solid lithium. Such a plasma has potential as a source of lithium ions for ion-driven inertial confinement fusion, and it also provides a useful source for developing diagnostics. The laser delivered 0.5 Joules onto a 2 to 7 mm diameter spot, with a 900-ns pulse length. Experiments were performed with the wavelength tuned to the Li I 2s-2p resonance line at 6708 A and off resonance at 6728 A. The target was a 500 to 1000 A thick Li film, vacuum evaporated in situ onto a substrate. The light from the plasma was coupled into the entrance slit of a 1-m Czerny-Turner spectrometer, and the output from the spectrometer was focused onto the input slit of a steak camera. The electron density was obtained from Stark broadened widths of Li I 2p-4d, 2p-5d, 2p-4s, and H I 2p-4d. An irradiance of 2 x 10(6) W/sq cm at 6708 A resulted in a peak electron density of 3.9 x 10(17)/cu cm. The density decreased at lower irradiance, with an intensity threshold of 5 x 10(5) W/sq cm for producing an ionized plasma. The threshold for producing a plasma was higher with the laser tuned off resonance, although high density lithium plasmas could still be formed at relatively lower laser irradiance.

Bailey, J.; Tisone, G. C.; Hurst, M. J.; Morrison, R. L.; Bieg, K. W.

259

The expansion velocities of laser-produced plasmas determined from extreme ultraviolet spectral line profiles  

NASA Technical Reports Server (NTRS)

The expansion of laser-produced plasma is determined from the shapes of spectral lines of highly ionized iron emitted in the extreme ultraviolet. The plasmas were produced by focusing the pulse from a Nd:glass laser onto solid planar targets, and spectra were recorded with a high-resolution grazing-incidence spectrograph. From the Doppler broadening of lines of Fe XX and Fe XXI, expansion velocities of about 830 km/s were determined. The relative time-averaged ion abundances of Fe XVIII, Fe XIX, Fe XX, and Fe XXI are estimated for three different spectra. The abundances do not differ by more than a factor of 4 for any of the spectra.

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

1977-01-01

260

Characterization of Fast Ion and Neutral Debris from Laser-Produced Lithium Plasmas  

NASA Astrophysics Data System (ADS)

Emissions of fast ion and neutral debris from laser-produced lithium plasmas have been investigated. We found that Li+, Li2+, and Li3+ ion energy spectra look similar. The peak positions and maximum energies in their energy spectra were about 700-800 eV and about 800-900 eV, respectively, which were much lower than those of such high-Z targets as Xe and Sn. These indicate that most of the fast Li+ and Li2+ ions were produced by the recombination of Li3+ ions while the plasma expanded, and that they were not accelerated to a high energy range as much as the high-Z targets. We did not observe any fast neutral Li atoms. These results suggest that the use of the Li target for the extreme ultraviolet (EUV) source would be advantageous for practical applications.

Sekioka, Tsuguhisa; Nagano, Akihisa; Ohtani, Nobuyuki; Miyamoto, Shuji; Amano, Sho; Inoue, Takahiro; Mochizuki, Takayasu

2007-03-01

261

Modification of semiconductor materials with the use of plasma produced by low intensity repetitive laser pulses  

SciTech Connect

This work reports experiments concerning specific application of laser-produced plasma at IPPLM in Warsaw. A repetitive pulse laser system of parameters: energy up to 0.8 J in a 3.5 ns-pulse, wavelength of 1.06 {mu}m, repetition rate of up to 10 Hz, has been employed in these investigations. The characterisation of laser-produced plasma was performed with the use of 'time-of-flight' ion diagnostics simultaneously with other diagnostic methods. The results of laser-matter interaction were obtained in dependence on laser pulse parameters, illumination geometry and target material. The modified SiO{sub 2} layers and sample surface properties were characterised with the use of different methods at the Middle-East Technological University in Ankara and at the Warsaw University of technology. The production of the Ge nanocrystallites has been demonstrated for annealed samples prepared in different experimental conditions.

Wolowski, J.; Rosinski, M.; Badziak, J.; Czarnecka, A.; Parys, P. [Institute of Plasma Physics and Laser Microfusion, Association EURATOM-IPPLM, 23 Hery St. 01-497 Warsaw (Poland); Turan, R.; Yerci, S. [Middle East Technical University, Ankara (Turkey)

2008-03-19

262

Initial development of hybrid plasma jet generator of O2(1?) for DOIL  

NASA Astrophysics Data System (ADS)

The initial stage in development of hybrid plasma jet generator of singlet oxygen O2(1?) for a discharge oxygen-iodine laser (DOIL) is presented. This novel type of generator is based on a fast mixing of hybrid argon plasma jet of DC electric arc and RF discharge with a neutral molecular oxygen stream. Arc plasma jets have a much higher density of electrons than RF plasma jets to compensate the electro-negativity of oxygen and they can be operated at a higher pressure for an efficient supersonic expansion cooling in DOIL. An RF discharge is applied to the DC arc plasma jet at the hollow anode of the plasmatron to switch it from a hot-spot mode to a diffusive mode. That is advantageous with the use of aluminum anode, which has a lower melting point and a significantly lower rate of O2(1?) quenching compared to a standard copper anode in a gas plasmatron. An enhanced non-equilibrium in the plasma jet caused by the RF discharge and neutral oxygen injection is desirable for an efficient O2(1?) generation. Preliminary calculations on the equilibrium composition of O2-Ar mixture suggest keeping the arc temperature well down to prevent an excessive dissociation of the molecular oxygen.

Schmiedberger, Josef; Rohlena, Karel; Filip, Petr; Gregor, Jan; Hrabovský, Milan; Krenek, Petr; Jirásek, Vít; Kodymová, Jarmila

2008-10-01

263

Emission analysis of expanding laser produced lithium plasma plume in presence of ambient gas  

NASA Astrophysics Data System (ADS)

Atomic analysis of the emission from laser-produced plasma from bulk lithium (Li) block has been made. The observed changes in the emission from lithium neutral and ionic species have been explained by considering various atomic processes. We demonstrate that the excitation process in case of neutral lithium Li (I) is electron impact excitation whereas for singly ionized lithium Li (II), radiative recombination is the dominant mechanism. We also show that the ionized species are dominant in the LPP plume.

Joshi, H. C.; Prahlad, V.; Singh, R. K.; Kumar, Ajai

2009-09-01

264

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

Microsoft Academic Search

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

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

2003-01-01

265

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

Microsoft Academic Search

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

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

1977-01-01

266

Characterization of Fast Ion and Neutral Debris from Laser-Produced Lithium Plasmas  

Microsoft Academic Search

Emissions of fast ion and neutral debris from laser-produced lithium plasmas have been investigated. We found that Li+, Li2+, and Li3+ ion energy spectra look similar. The peak positions and maximum energies in their energy spectra were about 700-800 eV and about 800-900 eV, respectively, which were much lower than those of such high-Z targets as Xe and Sn. These

Tsuguhisa Sekioka; Akihisa Nagano; Nobuyuki Ohtani; Shuji Miyamoto; Sho Amano; Takahiro Inoue; Takayasu Mochizuki

2007-01-01

267

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

Microsoft Academic Search

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

William Whitty; Jean-Paul Mosnier

1998-01-01

268

Optical emission spectroscopy and modeling of plasma produced by laser ablation of titanium oxides  

Microsoft Academic Search

In the present study, the time evolution of electron number density, of electron, atom and ion temperatures, of plasma produced by KrF excimer laser ablation of titanium dioxide and monoxide targets, are investigated by temporally and spatially resolved optical emission spectroscopy over a wide range of laser fluence from 1.7 to 6 J cm?2, oxygen pressures of 10?2–10?1 torr and

A. De Giacomo; V. A. Shakhatov; O. De Pascale

2001-01-01

269

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

Microsoft Academic Search

Time-resolved, 2D images of x-ray emission from thin, laser-irradiated titanium foils are presented. The foils are irradiated with 0.35 mum light at intensities of 1×1015 W\\/cm2 which produces a plasma with electron densities <=1022 cm-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

D. S. Montgomery; O. L. Landen; R. P. Drake; K. G. Estabrook; H. A. Baldis; S. H. Batha; K. S. Bradley; R. J. Procassini

1994-01-01

270

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

Microsoft Academic Search

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

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

2006-01-01

271

X-ray emission from KrF laser-produced Al plasmas  

Microsoft Academic Search

A laser-produced plasma experiment using a high-power electron-beam-pumped KrF laser generating up to 200 J in a 50-ns pulse is described. Solid Al targets were irradiated in vacuum at peak irradiance of 3 x 10 to the 13th W\\/sq cm, and X-ray spectra in the 0.53-0.92 nm range were recorded which show intense emission of the resonance spectra of Al

Y. Matsumoto; M. J. Shaw; F. Oneil; J. P. Partanen; M. H. Key; R. Eason; I. N. Ross; E. M. Hodgson; Y. Sakagami

1985-01-01

272

Few femtosecond, few kiloampere electron bunch produced by a laser-plasma accelerator  

Microsoft Academic Search

Particle accelerators driven by the interaction of ultraintense and ultrashort laser pulses with a plasma can generate accelerating electric fields of several hundred gigavolts per metre and deliver high-quality electron beams with low energy spread, low emittance and up to 1GeV peak energy. Moreover, it is expected they may soon be able to produce bursts of electrons shorter than those

O. Lundh; J. Lim; C. Rechatin; L. Ammoura; A. Ben-Ismaïl; X. Davoine; G. Gallot; J.-P. Goddet; E. Lefebvre; V. Malka; J. Faure

2011-01-01

273

A simple x?ray microscope for photographing laser produced plasmas  

Microsoft Academic Search

We have built two simple x?ray microscopes and have used these instruments to take x?ray pictures of laser produced plasmas. The sensitive range is 0.2 ?8 keV with greatest sensitivity from approximately 0.5?2 keV. For low energy x rays the resolution is better than that which can be obtained with a pinhole camera.

F. D. Seward; T. M. Palmieri

1975-01-01

274

A simple X-ray microscope for photographing laser produced plasmas  

Microsoft Academic Search

Two simple X-ray microscopes have been built and used to take X-ray pictures of laser-produced plasmas. The sensitive range is 0.2-8 keV with greatest sensitivity at approximately 0.5-2 keV. For low-energy X rays the resolution is better than that which can be obtained with a pinhole camera.

F. D. Seward; T. M. Palmieri

1975-01-01

275

Resonant third harmonic generation in a laser produced thin foil plasma  

Microsoft Academic Search

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 2omega, 4k, where

Sukhdeep Kaur; A. K. Sharma

2008-01-01

276

A Historical Review of the Geomagnetic Storm-Producing Plasma Flows from the Sun  

NASA Astrophysics Data System (ADS)

The concept of geomagnetic storm-producing solar plasma flows has evolved and advanced considerably over the last 100 years or so. This particular field of study began in an effort to understand geomagnetic disturbances and the aurora. The purpose of this paper is try to follow the ways in which early concepts evolved to later ones, not to review each concept in detail. It is fascinating to see a step-by-step buildup of these concepts, from the earliest idea of flow of solar electrons to coronal mass ejections (CMEs). The time line, though tentative, of the studies of geomagnetic storm-producing plasma flows is presented. The author hopes that this paper will serve young researchers in particular to consider how they plan to advance further this scientific field. There is still much uncertainty about geomagnetic storm-producing solar plasma flows. Some of the major questions are listed from the point of view of a geophysicist in the summary sections by grouping them in terms of the quiet-time solar wind, solar streams from corona holes and CMEs associated with solar flares.

Akasofu, Syun-Ichi

2011-12-01

277

X-ray spectroscopy of laser-produced plasmas using a von Hamos spectrograph  

NASA Astrophysics Data System (ADS)

The design and characteristics of a von Hamos spectrograph are considered. Efficiency of the von Hamos mica crystal spectrograph is absolutely calibrated using laser-produced plasmas as an x-ray source and a p-i-n diode as a detector. The value of integrated reflectivity of the mica crystal is also determined in the same spectral bands and diffraction orders: 5.5 - 11 angstrom (first order), 2.6 - 5.0 angstrom (second order), 1.84 - 3.22 angstrom (third order), 1.84 - 2.65 angstrom (fourth order), 1.84 - 1.92 angstrom (fifth order). The von Hamos spectrograph is used for x-ray spectroscopy and radiometry of laser-produced plasmas. The spectrograph possesses several advantages of interest: high spectral resolution ((lambda) /(delta) (lambda) up to 3000), a direct registration of one or two dimensional source images (spatial resolution up to 10 micrometers) and a high detecting efficiency over a wide spectral range. Focused intensities could be 10(superscript 2) - 10(superscript 3) times higher than those of flat crystal spectrographs. This type of spectrograph is ideal for the recording of the wide-range x-ray spectra of low intensity sources such as the femtosecond laser-produced plasma, micropinch, electron beam ion trap (EBIT), and others.

Shevelko, A. P.

1998-06-01

278

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

279

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

Microsoft Academic Search

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

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

1979-01-01

280

Magnetic probe measurements of the initial phase in a plasma focus device  

Microsoft Academic Search

Measurements with magnetic probes performed in the initial phase of a plasma focus device (30 kV, 0741-3335\\/39\\/9\\/004\\/img1) in the pressure range 0.5 - 5 mbar deuterium are presented, and an interpretation of the obtained signals is given, which includes a procedure for disentangling the effect of variations in the discharge current from the signals. Thick current sheaths, essentially filling all

H. Bruzzone; D. Grondona

1997-01-01

281

High-resolution X-ray focusing concave (elliptical) curved crystal spectrograph for laser-produced plasma  

NASA Astrophysics Data System (ADS)

The X-ray spectrum emitted from laser-produced plasma contains plentiful information. X-ray spectrometer is a powerful tool for plasma diagnosis and studying the information and evolution of the plasma. X-ray concave (elliptical) curved crystals analyzer was designed and manufactured to investigate the properties of laser-produced plasma. The experiment was carried out on Mianyang Xingguang-II Facility and aimed at investigating the characteristics of a high density iron plasma. Experimental results using KAP, LIF, PET, and MICA curved crystal analyzers are described, and the spectra of Au, Ti laser-produced plasma are shown. The focusing crystal analyzer clearly gave an increase in sensitivity over a flat crystal.

Xiao, Shali; Pan, Yingjun; Zhong, Xianxin; Xiong, Xiancai; Yang, Guohong; Liu, Zongli; Ding, Yongkun

2004-08-01

282

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

NASA Astrophysics Data System (ADS)

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

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

2008-07-01

283

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

284

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

SciTech Connect

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 produce with this dual-injection spray process and compared to coatings sprayed with a conventional plasma spray process. X-ray diffraction revealed very little change in the carbide phase composition of dual-injection coatings as compared to the original composition of the carbide spray powder. Conversely, the conventionally sprayed coatings showed significant transformation of the WC phase to the less desirable W{sub 2}C phase, and secondary oxy- carbide phases were also clearly evident. Porosity in the dual- injection coatings was consistently less than 2%, as measured by image analysis of polished metallographic samples. Microhardness results for the dual injection coatings also compared very favorably with values for the conventional coatings. Preliminary results from an ongoing abrasive wear study indicate that the dual-injection coatings are more wear resistant than the conventional coatings, but further research is needed. 6 refs., 3 figs., 3 tabs.

Lenling, W.J. (Fisher-Barton, Inc., Watertown, WI (USA)); Smith, M.F.; Henfling, J.A. (Sandia National Labs., Albuquerque, NM (USA))

1990-01-01

285

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

NASA Astrophysics Data System (ADS)

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

O'Shay, Joseph Fred

286

Laser-intensity scaling experiments in long-scalelength, laser-produced plasmas  

SciTech Connect

An experimental technique is demonstrated that allows variation of the average laser intensity by more than two orders of magnitude while producing much smaller changes in the other parameters that determine the laser--plasma interactions. By irradiating exploding-foil targets with 0.35 ..mu..m laser light in flat-topped pulses of variable duration, the high-power Nova laser (Rev. Sci. Instrum. 57, 2101 (1986)) produced plasmas with electron temperatures of order 1 keV and with scale lengths of the (radial and axial) electron-density gradients of order 1000 laser wavelengths. By using a constant target thickness and systematically decreasing the pulse length and spot size as laser intensity increased, the changes in the temperature and in the scale lengths were minimized. The time-resolved spectrum of the Raman-scattered light was used to measure both the electron temperature and the maximum density of the expanding plasmas. In this paper, these measurements are compared to both 1-D models and 2-D simulations. The expected trends of slower burnthrough and lower temperature with lower laser intensity were observed. However, the inferred temperatures are lower and the burnthrough of the target (at high laser intensities) is slower than the modeling predicts. Possible sources of these discrepancies are discussed.

Drake, R.P.; Young, P.E.; Williams, E.A.; Estabrook, K.; Kruer, W.L.; Lasinski, B.F.; Darrow, C.B.; Baldis, H.A.; Johnston, T.W.

1988-06-01

287

Electron Density Measurements from Stark Broadened Emission in a Sodium Plasma Produced by Laser Resonance Saturation.  

NASA Astrophysics Data System (ADS)

Electron Stark broadening of the 4^2 D-3^2P multiplet transition in a sodium plasma produced by laser resonance saturation has provided a means of undertaking the first spatial measurements of the free electron density across and along the plasma channel created in sodium vapor of density 10^ {15}-5 x 10^{16} cm^{-3}. From these measurements and measurements of the neutral sodium density within a heat sandwich oven, we are able to deduce the corresponding electron temperature. These temperatures compare favourably with the electron temperature estimated from a Boltzmann analysis of line intensities and suggest that a highly ionized (>10%) plasma of electron temperature <6000K can be produced within 100 ns of laser excitation from a laser of modest power (10^6-10^7 Wcm^{-2}). The experimental results are in reasonable agreement with a recently developed 3-dimensional model which predicts a decrease in the degree of ionization along the path of the laser beam as a result of significant depletion of laser energy. These experimental results demonstrate that this LIBORS code is capable of predicting the 3-dimensional nature of this new mode of laser ionization with reasonable accuracy, and may also explain the low electron temperatures and free electron densities observed by other research teams.

Cappelli, Mark Antony

288

Tests for Krook model for nonlocal heat transport in laser produced plasmas  

NASA Astrophysics Data System (ADS)

A Krook model has recently been proposed [1] for solving the problem of electron energy transport in laser produced plasmas. In this work, we report on comparisons of this model with 1) a more complete Fokker-Planck model and 2) an experiment performed at NRL [2]. A simple test problem solved with a Fokker-Planck code was first considered by Matte and Virmont [3]. It consists of a pure heat transport problem in a uniform plasma slab between two thermostatic walls at different temperatures. The normalized slab length (L/? where ? is the average electron mean free path) varies from order 1 to a few hundreds. The comparison with experiment involves the back side temperature measurement behind a 58 ?m plastic foil after the passage of a laser-produced shock wave. Results from these two comparisons will be presented and outline for further work will be discussed. [1] W.Manheimer, D.Colombant and V.Goncharov, submitted to Phys. of Plasmas [2] E.McLean et al., Optics Comm. 166, 141 (1999) [3] J.P.Matte and J. Virmont, Phys. Rev. Letters 49, 1936 (1982)

Colombant, D.; Manheimer, W.; Keskinen, M.; Goncharov, V.

2007-11-01

289

Using Plasma Viral Load to Guide Antiretroviral Therapy Initiation to Prevent HIV-1 Transmission  

PubMed Central

Background Current WHO guidelines recommend antiretroviral therapy (ART) initiation at CD4 counts ?350 cells/µL. Increasing this threshold has been proposed, with a primary goal of reducing HIV-1 infectiousness. Because the quantity of HIV-1 in plasma is the primary predictor of HIV-1 transmission, consideration of plasma viral load in ART initiation guidelines is warranted. Methods Using per-sex-act infectivity estimates and cross-sectional sexual behavior data from 2,484 HIV-1 infected persons with CD4 counts >350 enrolled in a study of African heterosexual HIV-1 serodiscordant couples, we calculated the number of transmissions expected and the number potentially averted under selected scenarios for ART initiation: i) CD4 count <500 cells/µL, ii) viral load ?10,000 or ?50,000 copies/mL and iii) universal treatment. For each scenario, we estimated the proportion of expected infections that could be averted, the proportion of infected persons initiating treatment, and the ratio of these proportions. Results Initiating treatment at viral load ?50,000 copies/mL would require treating 19.8% of infected persons with CD4 counts >350 while averting 40.5% of expected transmissions (ratio 2.0); treating at viral load ?10,0000 copies/mL had a ratio of 1.5. In contrast, initiation at CD4 count <500 would require treating 41.8%, while averting 48.4% (ratio 1.1). Conclusion Inclusion of viral load in ART initiation guidelines could permit targeting ART resources to HIV-1 infected persons who have a higher risk of transmitting HIV-1. Further work is needed to estimate costs and feasibility.

Murnane, Pamela M.; Hughes, James P.; Celum, Connie; Lingappa, Jairam R.; Mugo, Nelly; Farquhar, Carey; Kiarie, James; Wald, Anna; Baeten, Jared M.

2012-01-01

290

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

291

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

SciTech Connect

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

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

2010-10-15

292

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

SciTech Connect

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

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

2013-09-21

293

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

SciTech Connect

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

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

1997-04-15

294

Doppler-shift decoupling of radiation reabsorption in expanding laser-produced plasmas  

NASA Astrophysics Data System (ADS)

The influence of radiation reabsorption on the level populations of ions in an expanding laser-produced plasma of intermediate density is investigated by starting with the system of rate equations for the population densities coupled with the line-radiation transport equation, including the dynamical Doppler effect due to the differential macroscopic velocity field. An integral equation describing the effect of Lyman-alpha radiation reabsorption on the spatial behavior of the population density of the upper resonance level is derived. Assuming a sufficiently large velocity gradient so that the Doppler-induced frequency shift dominates the linewidth and after asymptotically evaluating the frequency integral involved in the kernel, a simplified integral equation exhibiting the reduction of radiation reabsorption by Doppler decoupling is obtained. In particular, in the case of a cylindrical, radially expanding laser plasma, this Fredholm equation for the reabsorption-influenced population density is discussed.

Brunner, W.; John, R. W.

295

Tin laser-produced plasma source modeling at 13.5 nm for extreme ultraviolet lithography  

SciTech Connect

Extreme ultraviolet lithography semiconductor manufacturing requires a 13.5 nm light source. Laser-produced plasma emission from Sn V-Sn XIV ions is one proposed industry solution. The effect of laser pulse width and spatial profile on conversion efficiency is analyzed over a range of power densities using a two-dimensional radiative magnetohydrodynamic code and compared to experiment using a 1.064 {mu}m, neodymium:yttrium aluminium garnet laser on a planar tin target. The calculated and experimental conversion efficiencies and the effects of self-absorption in the plasma edge are compared. Best agreement between theory and experiment is found for an 8.0 ns Gaussian pulse.

White, J.; O'Sullivan, G. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Zakharov, S.; Choi, P. [EPPRA SAS, Villebon sur Yvette 91140 (France); Zakharov, V. [Keldysh Institute of Applied Mathematics RAS, Moscow 125047 (Russian Federation); Nishimura, H.; Fujioka, S.; Nishihara, K. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-Oka, Suita, Osaka 565-0871 (Japan)

2008-04-14

296

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

297

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

PubMed

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 ~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)]. PMID:23126856

Morita, T; Sakawa, Y; Kuramitsu, Y; Dono, S; Ide, T; Shibata, S; Aoki, H; Tanji, H; Sano, T; Shiroshita, A; Waugh, J N; Gregory, C D; Woolsey, N C; Takabe, H

2012-10-01

298

Spectroscopic study of emission coal mineral plasma produced by laser ablation  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

299

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

NASA Astrophysics Data System (ADS)

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

Whitty, William; Mosnier, Jean-Paul

1998-05-01

300

Spectroscopic analysis of the excitation transfer from background air to diffusing aluminum laser produced plasma  

SciTech Connect

During the relaxation of the plasma plume generated by laser ablation of an aluminum target, a pronounced intensity enhancement is observed at the central wavelength of the 396.15 nm self-reversed resonant line. This spectral special feature is analyzed and related to the interaction of the plasma edge with the background air excited by the shockwave, prompt electrons, and extreme ultraviolet radiation produced at the earliest times of the ablation. In this article, the electron density, the aluminum ground state, and resonant level populations are determined from the fitting of the 396.15 nm calculated line profile to the experimental one at two background pressures (100 and 1000 Pa). The evolution of these densities is derived from experiments performed at delays, after the laser pulse arrival, ranging from 120 to 180 ns.

Ribiere, M.; Cheron, B. G. [Coria UMR 6614, CNRS, Avenue de l'Universite, 76801 Saint Etienne du Rouvray (France); Karabourniotis, D. [Department of Physics, Institute of Plasma Physics, University of Crete, 71003 Heraklion (Greece)

2009-04-15

301

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

SciTech Connect

The time and space-integrated emission spectra measurements have been performed in plasma produced by 308 nm wavelength XeCl laser radiation (I{sub L}=(4-10){center_dot}10{sup 12} W/cm{sup 2}, {tau}=10 ns) and by 248 nm wavelength KrF laser pulse train radiation I{sub L}=5{center_dot}10{sup 15} W/cm{sup 2}, {tau}=7 ps, 16 pulses in train) on (CF{sub n} plane target. The lines' shapes and intensities modeling of Lyman series and He-like ion resonance series of fluorine up to n=7 by fitting experimental data shows the considerable difference of plasma formation features for these two sets of the laser pulse parameters.

Magunov, A.; Faenov, A.; Skobelev, I.; Pikuz, T.; Batani, D.; Milani, M.; Conti, A.; Masini, A.; Costato, M.; Pozzi, A.; Turcu, E.; Allot, R.; Lisi, N.; Koenig, M.; Benuzzi, A.; Flora, F.; Letardi, T.; Palladino, L.; Reale, A. [Multicharged Ions Spectra Data Center, VNIIFTRI, Mendeleevo, 141570 (Russian Federation); Dipartimento di Fisica, Universita di Milano (Italy); Istituto Nazionale di Fisica Nucleare, Sezione. di Milano (Italy); Dipartimento di Fisica, Univerista di Milano (Italy); Dipartimento di Fisica, Universita di Modena (Italy); Rutherford Appleton Laboratory (United Kingdom); LULl, Ecole Polytechnique (France); Dipartimento Innovazione, Settore INN-FIS, CRE ENEA, Frascati (Italy); Dipartimento di Fisica, Universita dell' Aquila, e INFN G. Coll. LNGS, Assergi (Italy)

1997-01-05

302

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

SciTech Connect

The time and space-integrated emission spectra measurements have been performed in plasma produced by 308 nm wavelength XeCl laser radiation (I{sub L}=(4{minus}10){center_dot}10{sup 12} W/cm{sup 2}, {tau}=10 ns) and by 248 nm wavelength KrF laser pulse train radiation (I{sub L}=5{center_dot}10{sup 15} W/cm{sup 2}, {tau}=7 ps, 16 pulses in train) on CF{sub n} plane target. The lines` shapes and intensities modeling of Lyman series and He-like ion resonance series of fluorine up to n=7 by fitting experimental data shows the considerable difference of plasma formation features for these two sets of the laser pulse parameters.

Magunov, A.; Faenov, A.; Skobelev, I.; Pikuz, T. [Multicharged Ions Spectra Data Center, VNIIFTRI, Mendeleevo, 141570 (Russia); Batani, D.; Milani, M.; Conti, A. [Dipartimento di Fisica, Universita di Milano (Italy)]|[Istituto Nazionale di Fisica Nucleare, Sezione. di Milano (Italy); Masini, A. [Dipartimento di Fisica, Univerista di Milano (Italy); Costato, M.; Pozzi, A. [Dipartimento di Fisica, Universita di Modena (Italy); Turcu, E.; Allot, R.; Lisi, N. [Rutherford Appleton Laboratory (United Kingdom); Koenig, M.; Benuzzi, A. [LULl, Ecole Polytechnique (France); Flora, F.; Letardi, T. [Dipartimento Innovazione, Settore INN-FIS, CRE ENEA, Frascati (Italy); Palladino, L.; Reale, A. [Dipartimento di Fisica, Universita dell Aquila, e INFN G. Coll. LNGS, Assergi (Italy)

1997-01-01

303

Voluntary Environmental and Social Initiatives in Supply Networks - The Case of a Global Machinery Producer  

Microsoft Academic Search

Purpose: This paper investigates the use of voluntary envir onmental and social initiatives in a global business-to-business (B2B) engineering and t echnology company and its supply network. The research question of the study is the following : Why and how do B2B companies implement voluntary environmental and social initiatives in t heir supply networks? The theoretical basis of the article

Arno Kourula; Gyöngyi Kovács; Asta Salmi

304

Start broadened profiles with self-consistent radiation transfer and atomic kinetics in plasmas produced by high intensity lasers  

SciTech Connect

Spectral line shapes and line strengths have long been used to diagnose plasma temperatures and densities. In dense plasmas, the additional broadening due to Stark effects give additional information about the plasma density. We present calculations that are self-consistent in that the radiation fields of the line transitions and the atomic kinetics are iterated to convergence. Examples are given for simple plasmas with temperature gradients, density gradients, and velocity fields. Then a more complex example of a laser produced plasma is presented.

Olson, G.L.; Comly, J.C.; La Gattuta, J.K.; Kilcrease, D.P.

1993-01-01

305

Start broadened profiles with self-consistent radiation transfer and atomic kinetics in plasmas produced by high intensity lasers  

SciTech Connect

Spectral line shapes and line strengths have long been used to diagnose plasma temperatures and densities. In dense plasmas, the additional broadening due to Stark effects give additional information about the plasma density. We present calculations that are self-consistent in that the radiation fields of the line transitions and the atomic kinetics are iterated to convergence. Examples are given for simple plasmas with temperature gradients, density gradients, and velocity fields. Then a more complex example of a laser produced plasma is presented.

Olson, G.L.; Comly, J.C.; La Gattuta, J.K.; Kilcrease, D.P.

1993-03-01

306

Self-focusing and ion wave generation in laser-produced plasmas  

NASA Astrophysics Data System (ADS)

Two-dimensional hydrodynamic simulations of laser light self-focusing in a hydrogen plasma are presented. The simulation code includes a model for laser beam propagation which accounts for inverse bremsstrahlung absorption, refraction, diffraction, and ponderomotive forces. A Gaussian hot spot, superimposed upon a collimated, spatially uniform laser beam, is used to initiate self-focusing. Intense filaments provide a driving source for ion waves near the axis of the laser beam. The radially propagating ion waves cause spatiotemporal modulations of the flux where it is initially uniform, as well as the more usual focusing that occurs along the axis. Some of the factors affecting the generation of the ion waves are considered. In particular, the effect of changing the amplitude and width of the imposed nonuniformity is investigated. The intensity thresholds for thermal and ponderomotively driven self-focusing have also been determined by artificially turning the ponderomotive force on and off.

Rankin, R.; Marchand, R.; Capjack, C. E.

1988-08-01

307

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

PubMed

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

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

2010-04-15

308

Bolometric Measurements of ECH Produced Plasmas in the Large Helical Device  

NASA Astrophysics Data System (ADS)

During the first operational cycle of the Large Helical Device measurements using metal film bolometers were made of the power radiated from the ECH (84 GHz, <350 kW, <500 ms) produced plasmas. Bolometers were installed in three ports, which are approximately evenly spaced in toroidal angle. Two of the ports are located near the outboard horizontal mid-plane and contain 4 channels each. One of these has a wide-angle view of the plasma, with no collimation besides the vessel walls. The other one views the plasma through a pinhole with the array oriented toroidally. At the third location a twenty-channel array was installed at a lower port viewing the core plasma and lower inboard divertor leg cross-section from below. A double layer of copper grids with a spacing of ?/4 was successfully used to shield the bolometers from the unabsorbed microwaves. The steady-state portion of the discharge was characterized by an uninverted signal profile which was flat, indicating that the radiation was localized near the plasma edge. Discharges typically terminated through radiation collapse, during which the total radiated power sharply increased and the signal profile became sharply peaked indicating a flat or possibly peaked radiation profile. This peak in the bolometer signal profile was observed to move with the magnetic axis when the magnetic configuration was changed. As the seven-week experimental campaign proceeded, radiation levels were seen to decrease as the stored energy and density increased indicating the effectiveness of periodic discharge cleaning and Titanium gettering in reducing impurities in the machine.

Peterson, B. J.; Sudo, S.; Sato, M.; Kawahata, K.; Morita, S.; Sakakibara, S.; Kubo, S.; Idei, H.; Shimozuma, T.; Tanaka, K.; Goto, M.; Yamada, H.; Komori, A.; 1st LHD Experimental Team

1998-11-01

309

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

310

Parameterization of x-ray production in laser-produced plasmas  

SciTech Connect

A simple and algebraically tractable model is developed for the efficiency of x-ray production in a certain spectral region by laser driven plasmas. The model is used as a interpolation/extrapolation device for experimental and theoretical results from three different target concepts. These tests indicate that it is of use in its intended capacity. Certain relationships between independent parameters and scaling laws also result from this construction. Most notable among these is the prediction that the efficiency for producing line radiation in a certain narrow energy range scales like the inverse square of this energy.

Peek, J.M.

1980-10-01

311

A parameterization of X-ray production in laser-produced plasmas  

NASA Astrophysics Data System (ADS)

A simple and algebraically tractable model was developed for the efficiency of X-ray production in a certain spectral region by laser driven plasmas. The model was used as an interpolation/extrapolation device for experimental and theoretical results from three different target concepts. Results indicate that it is of use in its intended capacity. Certain relationships between independent parameters and scaling laws also result from this construction. Most notable among these is the prediction that the efficiency for producing line radiation in a certain narrow energy range scales like the inverse square of this energy.

Peek, J. M.

1980-10-01

312

Cylindrical stationary striations in surface wave produced plasma columns of argon  

SciTech Connect

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

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

2007-12-15

313

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

PubMed

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

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

2007-04-01

314

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

Microsoft Academic Search

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

D. S. Montgomery; O. L. Landen; R. P. Drake; K. G. Estabrook; H. A. Baldis; S. H. Batha; K. S. Bradley; R. J. Procassini

1994-01-01

315

Observation of stimulated Compton scattering from resonant electrons in a laser-produced plasma  

SciTech Connect

An experimental study of stimulated Compton scattering (SCS) from resonant electrons in a laser-produced plasma is reported. Up to 1.9 kJ of 350-nm laser light was used to irradiate 3-{mu}m-thick CH targets in 1.3 to 3.3-ns pulses at intensities up to 1.3{times}10{sup 15} W/cm{sup 2}. SCS was detected by making time-resolved measurements of the emission near 420 nm. The measurements are compared to the results of theoretical modeling.

Drake, R.P.; Baldis, H.A.; Berger, R.L.; Kruer, W.L.; Williams, E.A.; Estabrook, K.; Johnston, T.W.; Young, P.E. (Lawrence Livermore National Laboratory, Livermore, California 94550 (US) National Research Council, Ottawa, Ontario, Canada K1A0R6 KMS Fusion, Inc., Ann Arbor, Michigan 48105 Institut National de la Recherche Scientifique-Energie, Varennes, Quebec, Canada J3X1S2)

1990-01-22

316

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

NASA Astrophysics Data System (ADS)

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

Nayak, B. B.

2012-01-01

317

Aplicacion de los plasmas generados por laser a la determinacion de carbono en aceros. (Application of laser-produced-plasmas to determination of carbon content in steel).  

National Technical Information Service (NTIS)

This paper describes an analytical method to determine carbon content in solid and molten steel. It is based on the study of the emission spectrum from a Nd-YAG laser produced plasma. The light emitted from the plasma is focused to the entrance slit of a ...

M. Ortiz C. Aragon J. A. Aguilera J. Campos

1994-01-01

318

Excimer laser produced plasmas in copper wire targets and water droplets  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

319

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

PubMed

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

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

2014-09-01

320

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

SciTech Connect

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

Chen Ming [School of Physics, Shandong University, Jinan 250100 (China); Liu Xiangdong; Zhao Mingwen [School of Physics, Shandong University, Jinan 250100 (China); State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Chen Chuansong; Man Baoyuan [College of Physics and Electronics, Shandong Normal University, Jinan 250014 (China)

2009-07-15

321

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

NASA Astrophysics Data System (ADS)

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

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

2009-07-01

322

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

Microsoft Academic Search

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

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

1998-01-01

323

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

NASA Astrophysics Data System (ADS)

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

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

2005-06-01

324

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

SciTech Connect

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

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

2007-12-14

325

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

NASA Astrophysics Data System (ADS)

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

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

2006-05-01

326

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 Alfvén 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

327

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

328

Study on hydrogen retention produced from reaction of FLiNaK in ECR plasma  

NASA Astrophysics Data System (ADS)

In this study, hydrogen retention from the interaction between an electron cyclone resonance (ECR) plasma and a molten salt, has been experimentally investigated. FLiNaK, which is comprised of LiF (46.5 mol%), NaF (11.5 mol%), and KF (42 mol%), has been used as a molten salt. The molten salt was prepared at the base pressure of 2 x 10-6 torr and 500^oC which is above the melting point. However, the chamber pressure was increased up to 3 x 10^5 mTorr owing to the outgassing from the mixture. The experiments have been perfromed at the working pressure of 1 mTorr at different reaction times. The electron temperature and the ion density in hydrogen ECR plasma were measured by making use of Langmuir probe. Retention of hydrogen in FLiNaK was investigated by means of TDS (Thermal Desorption Spectrometry) method. The chemical species produced from the interaction between the plasma and the molten salt by an optical emission spectroscopy (OES) and a residual gas analyzer (RGA) have been also observed.

Park, Hyunjae; Choi, Yong-Sup; Lho, Taiheop

2011-11-01

329

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

330

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

SciTech Connect

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

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

2013-09-07

331

An Inverted Plasma Sheath for the Simulation of the Extraction of Volume Produced H-  

NASA Astrophysics Data System (ADS)

For the extraction of positive ions from plasmas well established computer programs are available, which are based on the Bohm sheath theory. In general the results of such simulations agree very well with experimental data. The situation is completely different, however, for the simulation of the extraction of volume produced H- ions. An open question so far has been, if there will be a saddle point of potentials in the extraction path or there will be an inverted sheath. No simple theory existed so far for the formation of an inverted sheath, connecting the quasi-neutral plasma in a self-consistent manner with the field provided by the positive extraction voltage. Based on the formulation of the space charge of the virtual cathode, caused by reflected protons in the extraction aperture, a linear model for an inverted plasma sheath will be presented, which allows to discuss the influence of most physical processes in the formation and extraction of H- and may become the basis of a correct simulation program.

Becker, Reinard

2002-11-01

332

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

333

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

334

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

NASA Astrophysics Data System (ADS)

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

Ouart, Nicholas D.

335

Stimulated Raman scattering in a laser-produced plasma heated by laser at wavelength of 0.53 ?m  

Microsoft Academic Search

Stimulated Raman scattering (SRS) has been studied in a plasma produced by a second harmonic Nd-glass laser irradiating a limited mass target, which does not burn through during the interaction time. It is assumed that flat density regions form and move through an expanding plasma, and the SRS results have been analyzed on that basis. The SRS spectrum cut-offs are

E. A. Bolkhovitinov; V. Yu. Bychenkov; M. O. Koshevoi; M. V. Osipov; A. A. Rupasov; A. S. Shikanov; V. T. Tikhonchuk; A. V. Kilpio; N. G. Kiselev; D. G. Kochiev; P. P. Pashinin; E. V. Shashkov; Y. A. Suchkov

1995-01-01

336

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

337

Convective mechanism for inhibition of heat conduction in laser produced plasmas  

SciTech Connect

In laser-produced plasmas, the laser energy is absorbed only below and up to the critical density. For laser fusion applications, this energy must be transported beyond the corona via electron thermal conduction towards colder, higher density regions of the target to heat up material and cause ablation, which in turn generates an inward pressure to compress the fusion fuel. If the heat conduction is inhibited, the consequences will be a weaker ablation and therefore a weaker implosion. For many years now, the inhibition of heat conduction, i.e., the reduction of heat conduction relative to classical conduction, in laser-produced plasmas at relevant irradiances has been apparent from the large body of experimental evidence. Many mechanisms, such as dc magnetic fields, ion acoustic turbulence, and Weibel instabilities, have been proposed to be the cause of inhibition of heat conduction. Even improved calculations of the classical heat flux have been carried out to solve this problem. Nevertheless, no single one of the above mentioned mechanisms can explain the large inhibition observed in the experiments.

Lee, P.H.Y.; Willi, O.; Trainor, R.J.

1984-06-27

338

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

339

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

PubMed

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

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

2010-12-01

340

Plasma immunoreactive gamma melanotropin in patients with idiopathic hyperaldosteronism, aldosterone-producing adenomas, and essential hypertension.  

PubMed Central

A non-ACTH aldosterone-stimulating factor(s) has been implicated in the pathogenesis of idiopathic hyperaldosteronism (IHA). Although this factor has not been fully characterized, some evidence suggests that it may be related to a pro-gamma-melanotropin (pro-gamma-MSH), derived from the NH2-terminal region of pro-opiomelanocortin. In the present study, plasma immunoreactive (IR-) gamma-MSH levels at 0800 h in patients with IHA were evaluated (90 +/- 17 fmol/ml; range: 13-173 fmol/ml) and found to be significantly higher (P less than 0.05) than those in subjects with aldosterone-producing adenomas (33 +/- 8 fmol/ml), essential hypertension (33 +/- 6 fmol/ml), and normotensive controls (19 +/- 2 fmol/ml). Seven of nine IHA subjects had circulating IR-gamma-MSH levels above the normal range (greater than 35 fmol/ml). In plasmas sampled at 1200 h, IR-gamma-MSH was significantly higher in patients with IHA (95 +/- 26 fmol/ml) and adenomas (63 +/- 23 fmol/ml), as compared with essential hypertensives (31 +/- 6 fmol/ml) and normotensives (19 +/- 3 fmol/ml). Mean plasma IR-ACTH, plasma cortisol, and urinary cortisol levels did not differ significantly between any of these groups. In order to evaluate the effect of a pro-gamma-MSH in vitro, adrenal adenoma tissue was obtained from two patients, one with elevated IR-gamma-MSH (61 fmol/ml) and a second with low IR-gamma-MSH (12 fmol/ml). Aldosterone secretion by dispersed adenoma cells from the former, but not the latter, underwent a fourfold dose-dependent (10(-14)-10(-9) M) increase in response to human Lys-gamma 3-MSH. These data suggest that a pro-gamma-MSH may be implicated as a pathogenic factor in a subset of patients with primary aldosteronism, particularly among those differentially diagnosed as having IHA. Images

Griffing, G T; Berelowitz, B; Hudson, M; Salzman, R; Manson, J A; Aurrechia, S; Melby, J C; Pedersen, R C; Brownie, A C

1985-01-01

341

Note: Characterization of the plasma parameters of a capillary discharge-produced plasma channel waveguide to guide an intense laser pulse  

SciTech Connect

We demonstrated the production of an optical waveguide in a capillary discharge-produced plasma using a cylindrical capillary. Plasma parameters of its waveguide were characterized by use of both a Nomarski laser interferometer and a hydrogen plasma line spectrum. A space-averaged maximum temperature of 3.3 eV with electron densities of the order of 10{sup 17} cm{sup -3} was observed at a discharge time of 150 ns and a maximum discharge current of 400 A. An ultrashort, intense laser pulse was guided by use of this plasma channel.

Higashiguchi, Takeshi; Yugami, Noboru [Department of Advanced Interdisciplinary Sciences and Center for Optical Research and Education (CORE), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kanagawa, Saitama 332-0012 (Japan); Hikida, Masafumi; Terauchi, Hiromitsu; Bai Jinxiang [Department of Advanced Interdisciplinary Sciences and Center for Optical Research and Education (CORE), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Kikuchi, Takashi [Department of Electrical Engineering, Nagaoka University of Technology, Kami-tomiokamachi 1603-1, Nagaoka, Niigata 940-2188 (Japan); Tao Yezheng [Center for Energy Research, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0438 (United States)

2010-04-15

342

Particle Simulation of Laser-Produced Plasmas on the Basis of Analytic Magnetohydrodynamic Solutions.  

NASA Astrophysics Data System (ADS)

Inertial confinement fusion experiments using laser beams have reported the emission of hot electrons in large quantities. This phenomenon has been one of the major hindrances to the efficient compression of a thermonuclear target. This, however, leads to the speculation of a number of non-fusion applications and an alternative fusion confinement approach. The non-fusion applications include the study of magnetic shock propagation in conductors, laser-triggered fast switches, solid state physics in the highly nonlinear optical regime, pulse-shape detectors, compact high voltage ion accelerators, LDLC (Laser Driven Liner Compression), laser-driven propulsion, direct conversion of laser energy, and astrophysical experiments. The alternative fusion concept that has recently received serious attention is the magnetically-insulated inertial confinement fusion (MICF) proposed by Hasegawa. Successful achievement of these goals however requires a thorough understanding of the problems related to the transport of hot electrons. This work is, therefore, intended to study the transport of hot electrons in the presence of the self-generated magnetic field, which is known to alter the heat transport properties drastically. For effective analysis of the hot electron transport problem, a particle simulation code is developed based on an analytic self-similar model of the laser-produced plasma that includes the self-generated magnetic field. The code is thus capable of predicting various time-dependent transport properties of a laser-produced plasma with computational speeds two orders-of-magnitude faster than existing codes. The code developed in this work can also compute the evolution of plasma parameters over a long period of time. The results of this code calculation are in excellent agreement with those of previous work. Similar analysis is used to characterize the confinement properties of MICF. It is shown that the use of an MICF scheme would allow for two orders-of-magnitude improvement in energy confinement time over the conventional ICF scheme.

Kim, Keeman

343

Stopping Power Measurement of 225 keV\\/u Oxygen Ions in Laser-Produced Lithium Hydride Plasma  

Microsoft Academic Search

We experimentally investigated the stopping power of 225 keV\\/u oxygen ions in laser-produced lithium hydride (LiH) plasma. The plasma target was produced by irradiation of a small LiH pellet with a Q-switched Nd-glass laser. We have developed a system to measure the energy loss of projectile ions in the target with a time-of-flight method. We found that the measured stopping

Akira SAKUM; Takeshi WATANABE; Kyo SHIBATA; Jun HASEGAWA; Masao OGAWA; Yoshiyuki OGURI

1999-01-01

344

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

345

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

NASA Astrophysics Data System (ADS)

Current challenges in the development of efficient laser produced plasma sources for the next generation extreme ultraviolet lithography (EUVL) are increasing EUV power and maximizing lifetime and therefore, reducing cost of devices. Mass-limited targets such as small tin droplets are considered among the best choices for cleaner operation of the optical system because of lower mass of atomic debris produced by the laser beam. The small diameter of droplets, however, decreases the conversion efficiency (CE) of EUV photons emission, especially in the case of CO2 laser, where laser wavelength has high reflectivity from the tin surface. We investigated ways of improving CE in mass-limited targets. We considered in our modeling various possible target phases and lasers configurations: from solid/liquid droplets subjected to laser beam energy with different intensities and laser wavelength to dual-beam lasers, i.e., a pre-pulse followed by a main pulse with adjusted delay time in between. We studied the dependence of vapor expansion rate, which can be produced as a result of droplet heating by pre-pulse laser energy, on target configuration, size, and laser beam parameters. As a consequence, we studied the influence of these conditions and parameters on the CE and debris mass accumulation. For better understanding and more accurate modeling of all physical processes occurred during various phases of laser beam/target interactions, plasma plume formation and evolution, EUV photons emission and collection, we have implemented in our heights package state-of-the art models and methods, verified, and benchmarked against laboratory experiments in our CMUXE center as well as various worldwide experimental results.

Sizyuk, T.; Hassanein, A.

2012-08-01

346

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

PubMed

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

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

2013-07-01

347

Development of CO2 laser produced Xe plasma EUV light source for microlithography  

NASA Astrophysics Data System (ADS)

A CO2 laser driven Xe droplet plasma is presented as a light source for EUV lithography. A short-pulse TEA CO2 master oscillator power amplifier system and a pre-pulse Nd:YAG laser were used for initial experiment with 0.6% of CE from a Xe jet. A target technology is developed for high average power experiments based on a Xe droplet at 100kHz. Magnetic field ion mitigation is shown to work well in the pre-pulsed plasma combined with a CO2 laser main pulse. This result is very promising with respect to collector mirror lifetime extension by magnetic field mitigation. A master oscillator power amplifier (MOPA) CO2 laser system is under development with a few kW and 100 kHz repetition rate with less than 15ns laser pulse width using a waveguide Q-switched CO2 laser oscillator and RF-excited fast axial flow CO2 laser amplifiers.

Mizoguchi, Hakaru; Endo, Akira; Ariga, Tatsuya; Miura, Taisuke; Hoshino, Hideo; Ueno, Yoshifumi; Nakano, Masaki; Komori, Hiroshi; Sumitani, Akira; Abe, Tamotsu; Suganuma, Takashi; Soumagne, Georg; Someya, Hiroshi; Takabayashi, Yuichi; Toyoda, Koichi

2006-04-01

348

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

SciTech Connect

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

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

2013-05-15

349

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

NASA Astrophysics Data System (ADS)

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

Hassanein, A.; Sizyuk, T.

2013-05-01

350

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

351

Stable dense plasma jets produced at laser power densities around 1014 W/cm2  

NASA Astrophysics Data System (ADS)

The results of investigations are presented that are connected with defocused laser beam-planar target interaction. Following the very large focus laser-plasma interaction experiments on the Nova [H. T. Powell, J. A. Caird, J. E. Murray, and C. E. Thompson, 1991 ICF Annual Report UCRL-LR-105820-91, p. 163 (1991)] and GEKKO-XII [C. Yamanaka, Y. Kato, Y. Izawa, K. Yoshida, T. Yamanaka, T. Sasaki, T. Nakatsuka, J. Kuroda, and S. Nakai, IEEE J. Quantum Electron. QE-17, 1639 (1981)] lasers, as well as on the National Ignition Facility (NIF) laser [W. J. Hogan, E. I. Moses, B. E. Warner, M. S. Sorem, and J. M. Soures, Nucl. Fusion 41, 567 (2001)] with generation of high Mach number jets, this paper is devoted to similar jet generation with very detailed measurements of density profiles by using high-power lasers at large focus conditions. The experiment was carried out with target materials of different mass densities (Al, Cu, Ag, Ta, and Pb) using the Prague Asterix Laser System (PALS) iodine laser [K. Jungwirth, A. Cejnarova, L. Juha, B. Kralikowa, J. Krasa, E. Krousky, P. Krupickova, L. Laska, K. Masek, A. Prag, O. Renner, K. Rohlena, B. Rus, J. Skala, P. Straka, and J. Ullschmied, Phys. Plasmas 8, 2495 (2001)]. The investigations were conducted for the laser radiation energy of 100 J at two wavelengths of 1.315 and 0.438 ?m (the first and third harmonics of laser radiation), pulse duration of 0.4 ns, and a focal spot radius of 300 ?m. Most of the experimental data were obtained by means of a three-frame laser interferometer and an x-ray streak camera; the crater parameters were obtained by using the crater replica technique. These investigations have shown that stable dense plasma jets can be produced in a simple configuration of laser beam-planar target interaction, provided that a proper target material is used.

Kasperczuk, A.; Pisarczyk, T.; Borodziuk, S.; Ullschmied, J.; Krousky, E.; Masek, K.; Rohlena, K.; Skala, J.; Hora, H.

2006-06-01

352

Structure and surface correlations to the optical properties of nonthermal plasma-produced silicon nanoparticles  

NASA Astrophysics Data System (ADS)

Nanomaterials have diverse capabilities to enable new technology and to deepen our understanding of our world, providing exciting prospects for scientists and the public alike in a vast span of uses. In the past decade, however, the potential held by nanotechnology has been reframed in the context of helping to slow global climate change and to alter the ways in which we use our energy to reflect more efficient technology and renewable energy sources. Silicon is a standout material in this new framework: as a nanomaterial, silicon can emit light when exposed to an applied voltage or ultraviolet optical excitation source. Silicon nanocrystals also exhibit size-dependent light emission, due to quantum confinement. This thesis is an exploration of the synthesis and processing parameters that affect the optical performance of silicon nanocrystals produced in a nonthermal plasma reactor. The efficiency of this light emission is sensitive to both synthesis environment and post-synthesis treatment. The work presented here is an attempt to deepen our understanding of the effects of different reactor and treatment parameters on the light emission efficiency from silicon nanoparticles, such that the luminescence behavior of the nanoparticles can be specifically engineered. Being able to fine-tune the structure, surface, and optical characteristics of the silicon nanocrystals is key in maximizing their use in luminescence applications. For all of the experiments described here, a nonthermal plasma flow-through reactor has been used to create the silicon nanoparticles. Silane gas is dissociated in the plasma and fragments come together to form silicon clusters, then grow to create nanoparticles. The nanoparticles were collected from the reactor for further processing, characterization, and experiments. The first discovery in this project was that by adjusting the power to the plasma reactor, the crystallinity of the silicon particles can be tuned: low power results in amorphous silicon nanoparticles, and high power yields crystalline nanoparticles. Even more important, the crystallinity of a nanoparticle ensemble relates directly to the photoluminescence (PL) efficiency, or quantum yield, from the ensemble: crystalline silicon nanoparticle samples, after alkyl functionalization, exhibit PL efficiencies of 40% or greater, while amorphous samples emit light with very poor efficiency (<2%). Additional studies of the plasma reactor revealed the importance of injecting a flow of hydrogen gas into the afterglow of the plasma, which turns out to have dramatic implications for the ultimate PL quantum yields of the nanocrystals. This injection scheme was systematically studied by varying the injected gas and its position. Hydrogen injected directly into the plasma afterglow was found to be vital for achieving high quantum-yield silicon nanocrystals, likely due to a reduction in surface trap states due to additional hydrogen passivation at the nanocrystal surface. Further investigations into the nanocrystal surface and how it relates to PL quantum yield showed that the photoluminescence from silicon nanocrystals is not only dependent on synthesis parameters, but also on processing temperatures and procedures following synthesis. While the highest PL efficiencies are found for silicon nanocrystals capped with alkyl chains, the PL efficiency of a nanocrystal ensemble can also be improved simply by heating the sample to temperatures between 150-200° C. This heating step also leads to a change in the hydride structure at the nanocrystal surface, which appears to be brought about by the effusion of silyl (or disilane) groups. Finally, details of the construction of a silicon-nanocrystal-based LED will be discussed. The LED project is part of a collaboration, and while the majority of device-specific aspects of the project were carried out in the lab of Professor R. Holmes by his Ph.D. student Kai-Yuan Cheng, the processing and alterations made to the nanocrystals used in the LED were all the responsibility of the author. The details of the pr

Anthony, Rebecca Joy

353

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

SciTech Connect

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

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

2013-07-15

354

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

355

Using a Z-pinch precursor plasma to produce a cylindrical, hotspot ignition, ICF  

NASA Astrophysics Data System (ADS)

We show that if the same precursor plasma that exists in metal wire arrays can be generated with a Deuterium-Tritium plasma then this precursor provides an ideal target for a cylindrical magneto-inertial ICF scheme. The precursor is generated from a fraction of the mass of the array which arrives on the axis early in time and remains confined at high density by the inertia of further material bombarding the axis. Later on, the main implosion of the DT Z-pinch produces a dense, low temperature shell which compressively heats the precursor target to high temperatures and tamps its expansion. The azimuthal magnetic field in the hotspot is sufficient to reduce the Larmor radius for the alpha particles to much less than the hotspot size, which dramatically reduces the ?R required for ignition. A computational analysis of this approach is presented, including a study of the thermonuclear burn wave propagation. The robustness of the scheme with respect to instabilities, confinement time and drive parameters is examined. The results indicate that a high energy gain can be achieved using Z-pinches with 50-100 MA currents and a few hundred nanosecond rise-times. This work was partially supported by the U.S. Department of Energy through cooperative agreement DE-FC03-02NA00057.

Chittenden, Jeremy

2005-10-01

356

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

357

Dynamics of laser produced silver plasma under film deposition conditions studied using optical emission spectroscopy  

NASA Astrophysics Data System (ADS)

Laser produced plasma from silver is generated using a Q-switched Nd:YAG laser. Optical emission spectroscopy is used to carry out time of flight (TOF) analysis of atomic particles. An anomalous double peak profile in the TOF distribution is observed at low pressure. A collection of slower species emerge at reduced pressure below 4 × 10 -3 mbar and this species has a greater velocity spread. At high pressure the plasma expansion follows the shockwave model with cylindrical symmetry whereas at reduced pressure it shows unsteady adiabatic expansion (UAE). During UAE the species show a parabolic increases in the expansion time with radial distance whereas during shock wave expansion the exponent is less than one. The angular distribution of the ablated species in the plume is obtained from the measurement of optical density of thin films deposited on to glass substrates kept perpendicular to the plume. There is a sharp variation in the film thickness away from the film centre due to asymmetries in the plume.

Issac, Riju C.; Vasudevan Pillai, K.; Harilal, S. S.; Varier, Geetha K.; Bindhu, C. V.; Gopinath, Pramod; Radhakrishnan, P.; Nampoori, V. P. N.; Vallabhan, C. P. G.

1998-02-01

358

Fast ion emission from the plasma produced by the PALS laser system  

NASA Astrophysics Data System (ADS)

This paper presents the results of studies of fast ion emission from the multiply charged high-Z number plasma generated using the PALS high-energy iodine laser system (?1.2 kJ, 0.4 ns) at the PALS Research Center in Prague. The properties of the emitted ion streams were investigated using ion collectors located at various angles with respect to the target normal and an electrostatic energy analyser. The x-ray emission from the plasma was measured using semiconductor detectors. Different groups of ions (slow, thermal and fast) were observed in the ion collector signals. Ion current densities higher than 80 mA cm-2 at ~1 m from the target were demonstrated. The charge velocity distribution, ion current density and angular distribution of ion charge emission, as well as total charge and average ion energy were obtained from these signals. Using the electrostatic ion-energy analyser, the emission of highly charged heavy ions (Ta52+, Ag38+) with energies up to 7 MeV for Ta ions was demonstrated. The dependence of ion stream parameters on the experimental conditions is discussed. We also report the results of preliminary experiments on the direct implantation of laser-produced ions into various materials.

Wolowski, J.; Badziak, J.; Boody, F. P.; Hora, H.; Hnatowicz, V.; Jungwirth, K.; Krása, J.; Láska, L.; Parys, P.; Pecina, V.; Pfeifer, M.; Rohlena, K.; Ryc, L.; Ullschmied, J.; Woryna, E.

2002-07-01

359

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

360

Recombination effects during expansion into vacuum in laser produced Sn plasma  

SciTech Connect

The distance over which the charge state distribution evolves during the expansion of laser produced Sn plasma in vacuum is investigated experimentally. This distance is found to be less than 6 cm with a planar target irradiated by a 1.064 mum laser at 8.3x10{sup 11} W/cm{sup 2} but greater than 60 cm when a 10.6 mum laser at 2.5x10{sup 10} W/cm{sup 2} is used. The difference is attributed to the laser wavelength dependence of the coronal electron density and the subsequent recombination processes during expansion. Important implications to the extreme ultraviolet x-ray source application are discussed specifically.

Burdt, Russell A.; Ueno, Yoshifumi; Tao Yezheng; Yuspeh, Sam; Tillack, Mark S.; Najmabadi, Farrokh [Center for Energy Research, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093 (United States)

2010-07-26

361

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

362

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

SciTech Connect

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

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

2010-05-12

363

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

364

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

365

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

NASA Astrophysics Data System (ADS)

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

Saito, Tetsuji; Akiyama, Tomoya

2014-05-01

366

Potential effects of Plasma on the Development of Laser Produced Craters  

SciTech Connect

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

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

2006-04-07

367

Moisture resistant and anti-reflection optical coatings produced by plasma polymerization of organic compounds  

NASA Technical Reports Server (NTRS)

The need for protective coatings on critical optical surfaces, such as halide crystal windows or lenses used in spectroscopy, has long been recognized. It has been demonstrated that thin, one micron, organic coatings produced by polymerization of flourinated monomers in low temperature gas discharge (plasma) exhibit very high degrees of moisture resistence, e.g., hundreds of hours protection for cesium iodide vs. minutes before degradation sets in for untreated surfaces. The index of refraction of these coatings is intermediate between that of the halide substrate and air, a condition for anti-reflection, another desirable property of optical coatings. Thus, the organic coatings not only offer protection, but improved transmittance as well. The polymer coating is non-absorbing over the range 0.4 to 40 microns with an exception at 8.0 microns, the expected absorption for C-F bonds.

Hollahan, J. R.; Wydeven, T.

1975-01-01

368

Elliptically-bent crystal spectrograph for X-ray diagnosis of laser-produced plasmas  

NASA Astrophysics Data System (ADS)

In order to measure spatially and temporarily resolved laser-produced plasma X-ray spectra in 0.2-2 nm region, a novel two-channel elliptically-bent crystal spectrograph has been developed. Dispersive elements are LiF, PET, Mica, and KAP crystals, which cover Bragg angles in the range of 30-67.5 degrees. Eccentricity and focal distance of twin ellipses are 0.9586 and 1350 mm, respectively. Spatially resolved spectrum is photographically recorded with an X-ray film or X-CCD camera in one channel, and temporarily resolved one is photographically recorded with an X-ray streak camera in another channel, thus spatially and temporarily resolved spectra can be simultaneously obtained. Spectral images were acquired with X-CCD and PET in SHENGUANG-II laser facility, and experimental results show that the spectral resolution of the spectrograph is about 0.002 nm.

Xiong, Xiancai; Zhong, Xianxin; Xiao, Shali; Yang, Guohong; Gao, Jie

2004-01-01

369

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

370

Systems and methods for imaging using radiation from laser produced plasmas  

DOEpatents

In particular embodiments, the present disclosure provides systems and methods for imaging a subject using radiation emitted from a laser produced plasma generating by irradiating a target with a laser. In particular examples, the target includes at least one radiation enhancing component, such as a fluor, cap, or wire. In further examples, the target has a metal layer and an internal surface defining an internal apex, the internal apex of less than about 15 .mu.m, such as less than about 1 .mu.m. The targets may take a variety of shapes, including cones, pyramids, and hemispheres. Certain aspects of the present disclosure provide improved imaging of a subject, such as improved medical images of a radiation dose than typical conventional methods and systems.

Renard-Le Galloudec, Nathalie (Reno, NV) [Reno, NV; Cowan, Thomas E. (Reno, NV) [Reno, NV; Sentoku, Yasuhiko (Reno, NV) [Reno, NV; Rassuchine, Jennifer (Reno, NV) [Reno, NV

2009-06-30

371

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

372

Layered composites made from bimetallic strips produced by plasma spraying of TiAl on niobium  

NASA Astrophysics Data System (ADS)

The production and structure of a multilayer TiAl/Nb composite material made from bimetallic TiAl/Nb strips fabricated by plasma spraying of TiAl granules onto niobium plates are studied. Here, 3-mm-and 2-mm-thick plates of a layered composite material (LCM) are produced by hot isostatic pressing of a stack of 35 bimetallic plates followed by hot rolling (the total degree of reduction is 78.6 and 85.7%, respectively). The LCM consists of discontinuous TiAl layers separated by niobium layers, and the adhesion between the layers is good. Diffusional intermediate layers form at the TiAl/Nb interfaces in the 3-mm-thick LCM and consist of the following two solid solutions: an ?2-Ti3Al-based solid solution contains up to 28 at % Nb, and a niobiumbased solid solution contains up to 27 at % Ti and 32 at % Al. The diffusional intermediate layers in the 2-mmthick LCM plates consist of an ?2-Ti3Al-based solid solution with up to 16.0 at % Nb; a ?-Ti3Al2Nb-or Ti4Al3Nb-based solid solution with 51.5 at % Ti, 32 at % Al, and 16.5 at % Nb; and a niobium-based solid solution with up to 22 at % Ti and 30.5 at % Al. When a bimetallic TiAl/Nb strip is fabricated by plasma spraying of granules of the Ti-48 at % Al alloy, this alloy is depleted of aluminum to 42 45 at %, and the fraction of the ?2-Ti3Al phase in the sprayed layer increases. When the LCM is produced by hot isostatic pressing followed by hot rolling, the layer of plain niobium (Nb1) dissolves up to 5 at % Ti and 7 at % Al.

Burmistrov, V. I.; Antonova, A. V.; Povarova, K. B.; Bannykh, I. O.

2007-12-01

373

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

NASA Astrophysics Data System (ADS)

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

Manuel, Mario J.-E.

374

Absorption spectroscopy of an expanding laser produced lithium plasma in the extreme ultraviolet using the Dual Laser Plasma technique  

Microsoft Academic Search

We describe the essential features of the Dual Laser Plasma (DLP) vacuum ultraviolet photoabsorption spectroscopy technique and the characteristics of our DLP apparatus. We show that the time- and space-resolved capabilities of this technique are suited to the monitoring of the dynamics of expanding plasma plumes in the regime used for pulsed laser deposition of materials. Examples of spectra showing

William Whitty; John Costello; Eugene Kennedy; Christopher Moloney; Jean-Paul Mosnier

1998-01-01

375

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

Microsoft Academic Search

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

R. W. Short; A. Simon

1997-01-01

376

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: 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

377

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

NASA Astrophysics Data System (ADS)

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

Yazdanpanah, J.; Anvari, A.

2014-02-01

378

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

SciTech Connect

The plasma-puff triggering mechanism based on a hypocycloidal pinch geometry was investigated to determine the optimal operating conditions for the azimuthally uniform surface flashover which initiates plasma-puff under wide range of fill gas pressure of Ar, He and N2. The optimal fill gas pressure for the azimuthally uniform plasma-puff was about 120 mTorr and 450 Torr for He and N2, and between 120 mTorr and 5 Torr for Ar. The inverse pinch switch was triggered with the plasma-puff and the switching capability under various electrical parameters and working gas pressures of Ar, He and N2 was determined. It was also shown that the azimuthally uniform switching discharges were dependent on the type of fill gas and its fill pressure. A new concept of plasma-focus driven plasma-puff was also discussed in comparison with the hypocycloidal pinch plasma-puff triggering. The main discharge of inverse pinch switch with plasma-focus driven plasma-puff trigger is found to be more azimuthally uniform than that with hypocycloidal pinch plasma-puff trigger in a gas pressure region between 80 mTorr and 1 Torr.

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

1990-09-01

379

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

NASA Astrophysics Data System (ADS)

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

Weeks, Tyler; Shevelko, Alexander

2005-05-01

380

Measurement of growth rates and temporal behavior of stimulated Raman scattering in a CO2-laser-produced plasma  

Microsoft Academic Search

The stimulated-Raman-scattering instability in a CO2-laser-produced plasma is studied by picosecond-resolution Thomson scattering. The instability first appears near 0.25n\\/nc and is observed to propagate to lower densities at the group velocity of electron plasma waves. Temporal growth rates are measured over the whole investigated density range (0.15<=n\\/nc<=0.25) and are found to be 5 times smaller than absolute rates theoretically predicted

G. McIntosh; H. Houtman; J. Meyer

1986-01-01

381

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

382

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

Microsoft Academic Search

Absolute x-ray calibration of laser-produced plasmas was performed using a focusing crystal von Hamos spectrometer. The plasmas were created by an Nd-YAG laser (0.53 mum\\/200 mJ\\/3 ns\\/10 Hz) on massive solid targets (Mg, Cu, Zn, Sn, Mo, Ta, Ti, Steel). Cylindrical mica crystal (radius of curvature R=20 mm) and a CCD linear array detector (Toshiba model TCD 1304AP) were used

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

2005-01-01

383

Study of a colliding laser-produced plasma by analysis of time- and space-resolved image spectra  

SciTech Connect

The interaction of two counterpropagating laser-produced plasmas was studied using simultaneous imaging and spectroscopic techniques. Spectrally filtered time-gated intensified charge coupled device imaging was used to obtain information about the spatial dynamics and temporal evolution of the collision process, while time-resolved imaging spectroscopy was used to determine the spatial and temporal distributions of electron temperature and density within the interaction region. We examine specifically the interaction of plasmas whose parameters match those typically used in pulsed laser deposition of thin films. These low temperature plasmas are highly collisional leading to the creation of a pronounced stagnation layer in the interaction region.

Luna, H.; Kavanagh, K. D.; Costello, J. T. [NCPST, Dublin City University, Glasnevin, Dublin 9 (Ireland); School of Physical Science, Dublin City University, Glasnevin, Dublin 9 (Ireland)

2007-02-01

384

A review on calcium phosphate coatings produced using a sputtering process--an alternative to plasma spraying.  

PubMed

New promising techniques for depositing hydroxyapatite (HA) and calcium phosphate (CaP) coatings on medical devices are continuously being investigated. Given the vast number of experimental deposition process currently available, this review will focus only on CaP and/or HA coatings produced using the sputtering process. This review will discuss the characterization of sputtered CaP coatings before and after post-deposition treatments and tissue responses to some of the characterized coating surfaces. From the studies observed in the literature, current research on sputtered CaP coatings has shown some promises that may eliminate some of the problems associated with the plasma-spraying process. It has been generally accepted that sputtered HA and CaP coatings improve bone strength and initial osseointegration rate. However, optimal coating properties required to achieve maximal bone response are yet to be reported. As such, the use of well-characterized sputtered CaP and/or HA surfaces in the evaluation of biological responses should be well documented to avoid controversial results. In addition, future investigations of the sputtering process should include clinical trials, to continue the understanding of bone responses to coated-implant surfaces of different properties, and the possibility of coupling sputtered HA and CaP coatings with growth factors. PMID:15262475

Yang, Yunzhi; Kim, Kyo-Han; Ong, Joo L

2005-01-01

385

Absorption spectroscopy of an expanding laser produced lithium plasma in the extreme ultraviolet using the Dual Laser Plasma technique  

NASA Astrophysics Data System (ADS)

We describe the essential features of the Dual Laser Plasma (DLP) vacuum ultraviolet photoabsorption spectroscopy technique and the characteristics of our DLP apparatus. We show that the time- and space-resolved capabilities of this technique are suited to the monitoring of the dynamics of expanding plasma plumes in the regime used for pulsed laser deposition of materials. Examples of spectra showing the spatial and temporal evolution of a lithium plasma expanding in vacuum are presented. A model based on a self-similar expansion for the plume is developed and used to analyse the shape of absorption lines. Measurements in the photoionisation continuum of Li + are also presented.

Whitty, William; Costello, John; Kennedy, Eugene; Moloney, Christopher; Mosnier, Jean-Paul

1998-05-01

386

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

Microsoft Academic Search

A 6 nsec 1010 W\\/cm2 ruby laser pulse irradiates a grating with spacing in the 6–35 ?m range. The expansion of the plasma above the surface is observed using interferometry and shadowgraphy. The plasma is found to be modulated with n˜\\/n up to 8%. Such a plasma can be used to accelerate charged particles.

M. Laberge; J. Meyer

1990-01-01

387

Fine tuning of IRF-4 expression by SWAP-70 controls the initiation of plasma cell development.  

PubMed

The generation of plasma cells (PCs) is key for proper humoral immune responses. The transcription factors IRF-4 and BLIMP-1 (B-lymphocyte induce maturation protein-1) control PC commitment, but the underlying regulatory mechanisms are incompletely understood. Here we have identified SWAP-70 as being critically involved in Toll-like receptor (TLR)-triggered PC differentiation. Upon activation through various TLRs, Swap-70(-/-) B cells were activated and proliferated normally. However, expression of BLIMP-1 was markedly reduced and PC differentiation was impaired. Four hours of LPS stimulation were sufficient to drive PC differentiation, and SWAP-70 was required during this initial period. Swap-70(-/-) B cells pre-activated in vitro failed to efficiently differentiate into PCs upon adoptive transfer into recipient mice. Re-introduction of SWAP-70 into Swap-70(-/-) B cells rescued their development into PCs, and SWAP-70 over-expression in wild-type (WT) B cells increased PC generation. In the absence of SWAP-70, IRF-4 protein levels were reduced and the IRF-4(high) B220(+) CD138(-) compartment, including PC precursors, was strongly diminished. Ectopic expression of SWAP-70 increases IRF-4 protein levels and PC differentiation in WT and Swap-70(-/-) B cells, and IRF-4 over-expression in Swap-70(-/-) B cells elevates PC differentiation to WT levels. Thus, in a dose-dependent manner, SWAP-70 controls IRF-4 protein expression and thereby regulates the initiation of PC differentiation. PMID:21728176

Chopin, Michaël; Chacón-Martínez, Carlos Andrés; Jessberger, Rolf

2011-10-01

388

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

389

Behavior of debris from laser-produced plasma for extreme ultraviolet light source measured by laser imaging technique  

SciTech Connect

The behavior of debris generated from a laser-produced plasma (LPP) for the extreme ultraviolet light source at 13.5 nm has been studied using a laser induced fluorescence (LIF) imaging system. Tin (Sn) LPPs were produced by irradiating a flat Sn plate and Sn thin films perpendicularly with a Nd:YAG laser beam. When a thin Sn film was used as a target material, the depletion of the Sn atoms was clearly observed along the Nd:YAG laser beam. The LIF system was also used for visualizing the sputtering process of a mirror substrate by the fast ions generated from the plasma.

Tanaka, Hiroki; Hashimoto, Yuki; Tamaru, Kouji; Takahashi, Akihiko; Okada, Tatsuo [Department of Electrical and Electronic Systems Engineering, Graduate School of Information Science and Electrical Engineering, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan)

2006-10-30

390

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

391

Initial plasma-filled backward-wave oscillator experiments using a cathode-mounted plasma prefill source  

Microsoft Academic Search

The introduction of plasma into the slow-wave structure (SWS) of a backward-wave oscillator (BWO) has been shown to increase microwave power output and generation efficiency, as well as provide several other benefits. Researchers at Niigata University in Japan have performed a linear analysis that has shown that the optimal plasma-filled BWO configuration is one in which the plasma is confined

Chris Grabowski; J. M. Gahl; Edl Schamiloglu

1998-01-01

392

An experimental investigation of refraction-induced distortions in harmonic-light images of laser-produced plasmas  

SciTech Connect

In this paper the results of a simple experiment designed to study refraction-induced distortion of images of narrow-band-light-emitting regions in a laser-produced plasma are described. Source regions were formed by relaying the image of a backlit pinhole array into the plasma (25 {mu}m-diam. pinhole; 30-ps, 0.25-{mu}m backlighter beam). Images of these source regions were recorded on film and compared with and without plasma present. Refraction effects, evidenced by translation of the apparent pinhole locations and blurring of the pinhole spots, are compared for different plasma sizes and for different delays of the backlighter pulse with respect to the plasma-production laser pulse. These results were then compared with expectations based on numerical raytraces through a plasma-density profile derived from a hydrodynamic simulation of our exploding-foil plasma. The significance of these results in the imaging of harmonic and half-harmonic light as a plasma-density diagnostic is discussed. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48.

Darrow, C.; Montgomery, D.S.; Estabrook, K.; Drake, R.P. (Lawrence Livermore National Laboratory, Box 808, Livermore, California 94550 (USA)); Busch, G.E.; Gabl, E.F. (KMS Fusion Inc., 3621 South State Road, Ann Arbor, Michigan 48106 (USA))

1990-04-15

393

Space-resolved spectra of laser-produced plasmas in the XUV  

NASA Technical Reports Server (NTRS)

The design and imaging properties of an XUV (extreme ultraviolet, 200-550 A) normal-incidence slitless spectrograph, the spectrum obtained from laser-generated plasmas, and the monochromatic plasma images are described. The electron temperature of the plasmas, electron density as a function of position in the plasma, and the thickness of material penetrated by the laser pulse are determined. Elements from Z = 6 to Z = 28 were investigated, in addition to Nb. Secondary plasma-emission regions were observed 2-3 mm from the flat (thick or thin) targets. Time-integrated photographs of the expanding plasmas were recorded by the slitless spectrograph. A technique for obtaining time-resolved images of the plasmas in picosecond time intervals is proposed, and problems in the design of a stigmatic XUV spectrograph are discussed.

Feldman, U.; Doschek, G. A.; Prinz, D. K.; Nagel, D. J.

1976-01-01

394

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

395

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

SciTech Connect

Silicon nitride films were synthesized at 170 deg. C by using inductively coupled plasma chemical vapor deposition under three microwave power conditions of 500, 800, and 1000 W. The chemical, physical and electrical properties of the deposited silicon nitride films were characterized by Fourier transform infrared, wet etching, atomic force microscopy, ellipsometry, J-V, and C-V measurements of metal-insulator-semiconductor. The microwave power for film deposition is found to play an important role at the films' properties. A high microwave power reduces the retention of hydrogen in a form of Si-H and N-H atomic bonds. The microwave power significantly affects the density of pin holes; the 800 W film has the lowest density of pin holes. In general, the low-temperature silicon nitride films possess better surface roughness than the conventional silicon nitride films produced at higher temperatures. The low-temperature silicon nitride films exhibit an abrupt breakdown, a characteristic of avalanche breakdown. The variation in breakdown strength is correlated with the change in pin-hole density, and the 800 W silicon nitride film possesses the highest breakdown strength. The microwave power has limited influences on leakage current and resistivity of the films. All the low-temperature silicon nitride films are characterized by high-density fixed charges and interface charge traps, of which both densities vary slightly with the microwave power for film deposition.

Xu, Q.; Ra, Y.; Bachman, M.; Li, G. P. [Space Science Center, Morehead State University, Morehead, Kentucky 40351 (United States); BMR Technology Corp., Placentia, California 92870 (United States); Department of Electrical Engineering and Computer Science, University of California, Irvine, California 92697 (United States)

2009-01-15

396

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

SciTech Connect

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

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

2013-10-15

397

Space resolved XUV and NUV spectra from a KrF laser-produced plasma.  

NASA Astrophysics Data System (ADS)

We use a KrF laser that generates pulses of 10^15 watt/cm^2 when focused onto graphite and boron nitride targets. We study the emitted light of the laser produced plasmas in the XUV and near UV region of the spectrum. For the XUV we use a 1-m grazing incidence spectrograph equipped with a crossed slit that allows us to measure the space resolved spectra of CVI, CV, BV, BIV. Line profiles will be shown together with 1D simulations. In the NUV we do polarization spectroscopy to measure the Zeeman splitting on n=2,? n=0 ; lines of helium-like carbon and boron ions. We measured simultaneously the ? ; and ? components of the lines, with a 0.5; Å resolution, to discriminate against Stark and Doppler broadening. We used a 2D Peltier-cooled intensified CCD in order to optimize our signal to noise ratio, as compared with former measurements(APS Bulletin,38^th) DPP,9p33, 1996. Results of the measured magnetic field, as a function of distance from the target surface, as infered from the measured line profiles including Stark and Doppler broadening, will be discussed. E.J.Iglesias-Perm.Address.Universidad-Simón- Bolívar,Venezuela

Iglesias, E. J.; Griem, H. R.; Elton, R.; Welch, B. L.

1997-11-01

398

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

NASA Astrophysics Data System (ADS)

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.

2008-10-01

399

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

400

A prospective study of endothelial activation biomarkers, including plasma angiopoietin-1 and angiopoietin-2, in Kenyan women initiating antiretroviral therapy  

PubMed Central

Background HIV-1-related inflammation is associated with increased levels of biomarkers of vascular adhesion and endothelial activation, and may increase production of the inflammatory protein angiopoietin-2 (ANG-2), an adverse prognostic biomarker in severe systemic infection. We hypothesized that antiretroviral therapy (ART) initiation would decrease endothelial activation, reducing plasma levels of ANG-2. Methods Antiretroviral-naïve Kenyan women with advanced HIV infection were followed prospectively. Endothelial activation biomarkers including soluble intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1), and E-selectin, and plasma ANG-2 and angiopoietin-1 (ANG-1) were tested in stored plasma samples from 0, 6, and 12 months after ART initiation. We used Wilcoxon matched-pairs signed rank tests to compare endothelial activation biomarkers across time-points, generalized estimating equations to analyze associations with change in log10-transformed biomarkers after ART initiation, and Cox proportional-hazards regression to analyze associations with mortality. Results The 102 HIV-1-seropositive women studied had advanced infection (median CD4 count, 124 cells/?L). Soluble ICAM-1 and plasma ANG-2 levels decreased at both time-points after ART initiation, with concomitant increases in the beneficial protein ANG-1. Higher ANG-2 levels after ART initiation were associated with higher plasma HIV-1 RNA, oral contraceptive pill use, pregnancy, severe malnutrition, and tuberculosis. Baseline ANG-2 levels were higher among five women who died after ART initiation than among women who did not (median 2.85 ng/mL [inter-quartile range (IQR) 2.47–5.74 ng/mL] versus median 1.32 ng/mL [IQR 0.35–2.18 ng/mL], p?=?0.01). Both soluble ICAM-1 and plasma ANG-2 levels predicted mortality after ART initiation. Conclusions Biomarkers of endothelial activation decreased after ART initiation in women with advanced HIV-1 infection. Changes in plasma ANG-2 were associated with HIV-1 RNA levels over 12 months of follow-up. Soluble ICAM-1 and plasma ANG-2 levels represent potential biomarkers for adverse outcomes in advanced HIV-1 infection.

2013-01-01

401

Changing patterns of plasma membrane-associated filaments during the initial phases of polymorphonuclear leukocyte adherence  

PubMed Central

By utilizing a combination of several ultrastructural techniques, we have been able to demonstrate differences in filament organization on the adherent plasma membranes of spreading and mobile PMN as well as within the extending lamellipodia. To follow the subplasmalemmal filaments of this small amoeboid cell during these kinetic events, we sheared off the upper portions of cells onto glass and carbon surfaces for 30 s--5 min. The exposed adherent membranes were immediately fixed and processed for high-resolution SEM or TEM. Whole cells were also examined by phase contrast microscopy, SEM, and oriented thin sections. Observed by SEM, the inner surface of nonadherent PMN membranes is free of filaments, but within 30 s of attachment to the substrate a three- dimensional, interlocking network of globular projections and radiating microfilaments--i.e., a subplasmalemmal filament complex--is consistently demonstrable (with or without postfixation in OsO4). Seen by TEM, extending lamellipodia contain a felt of filamentous and finely granular material, distinct from the golbule/filament complex of the adjacent adherent membrane. In the spread cell, this golbule-filament complex covers the entire lower membrane and increases in filament- density over the next 2--3 min. By 3--5 min after plating, as the PMN rounds up before the initiation of amoeboid movements, another pattern emerges--circumferential bands of anastomosing filament bundles in which thick, short filaments resembling myosin are found. This work provides structural evidence on the organization of polymerized contractile elements associated with the plasma membrane during cellular adherence.

1979-01-01

402

High-energy electrons produced in subpicosecond laser-plasma interactions from subrelativistic laser intensities to relativistic intensities  

Microsoft Academic Search

The characteristics of the forward hot electrons produced by subpicosecond laser-plasma interactions are studied for different laser polarizations at laser intensities from subrelativistic to relativistic. The peak of the hot electron beam produced by p-polarized laser beam shifts to the laser propagation direction from the target normal direction as the laser intensity reaches the relativistic. For s-polarized laser pulse, hot

Y. T. Li; J. Zhang; Z. M. Sheng; J. Zheng; Z. L. Chen; R. Kodama; T. Matsuoka; M. Tampo; K. A. Tanaka; T. Tsutsumi; T. Yabuuchi

2004-01-01

403

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

404

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

PubMed

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

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

2010-10-15

405

Characterization of a UV VUV light source based on a gas-target ns-laser-produced plasma  

NASA Astrophysics Data System (ADS)

We report measurements of the temporal and spatial evolution of plasmas, produced on gaseous targets by focused ns-Nd:YAG laser. Characterization of the UV-VUV light source includes time-resolved visualization of the spatial growth and the spectroscopic signatures of plasmas produced on pulsed, supersonic jets of helium, argon, nitrogen and xenon gases into a vacuum chamber. Photon fluxes of up to 10 12 photons cm -2 nm -1/pulse have been measured in the wavelength region 100-260 nm within the first 30 ns following the laser pulse. Also discussed for comparison are plasma signatures in helium, argon and nitrogen gases at standard temperature and pressure. The results indicate availability of photon fluxes, at typical laser repetition rates, that are at least one order of magnitude higher than those achieved from commercial c.w. lamp light sources.

Di Palma, Tonia M.; Borghese, Antonio

2007-01-01

406

Plasma polymerization of cobalt tetraphenylporphyrin and the functionalities of the thin films produced  

Microsoft Academic Search

Thin films were prepared for the first time from cobalt tetraphenylporphyrin (CoTPP) by plasma polymerization at different r.f. powers. They had cross-linked structures in which the porphyrin ring structure of CoTPP monomer was retained to different extents. Studies by use of a sandwich type device of Au\\/plasma polymerized CoTPP thin film\\/ITO glass revealed that plasma polymerized CoTPP thin films had

Kenji Nakamura; Masato Watanabe; Ming Zhou; Motoi Fujishima; Masahiro Tsuchiya; Tetsuya Handa; Shigeru Ishii; Hiromichi Noguchi; Kunihiro Kashiwagi; Yasuhiko Yoshida

1999-01-01

407

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

408

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

409

Analysis of mono-atomic ions in individual fluid inclusions by laser-produced plasma emission spectroscopy  

Microsoft Academic Search

The analysis of mono-atomic ions in individual fluid inclusions was investigated using emission spectroscopy of a laser-produced plasma. The first step was the application of this technique to the analysis of major cations (Ca ++ , Mg ++ , Na + , and K + ) contained in macroscopic electrolyte solutions before applying the method to synthetic individual fluid inclusions.

M. C. Boiron; J. Dubessy; N. Andre; A. Briand; J. L. Lacour; P. Mauchien; J. M. Mermet

1991-01-01

410

Extreme ultraviolet emission from a laser-produced lithium plasma by use of quasi mass-limited target  

Microsoft Academic Search

Usage of two laser pulses is an efficient way to produce EUV emission, since a density and temperature of a plasma formed by the first laser pulse are regulated by the second laser pulse. By adjusting the delay of the second pulse, one could maximize the EUV emission at 13.5 nm. A mass-limited lithium aqueous target with several tens mum

Takeshi Higashiguchi

2005-01-01

411

Diamond Like Carbon Coating Produced by Plasma Source Ion Implantation as a Corrosion Barrier for Steels in Marine Environments  

Microsoft Academic Search

A36 steel samples coated with diamond like carbon (DLC) produced by plasma source ion implantation (PSII) were examined in ASTM artificial ocean water (ASTM AOW). To evaluate the coating's susceptibility to breakdown in a marine environment, electrochemical impedance spectroscopy experiments were conducted on coated samples immersed in ASTM AOW for a 2 month period. Results determined that while the coating

R. Scott Lillard; Darryl Butt; Michael Nastasi; Kevin Walter

412

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

NASA Astrophysics Data System (ADS)

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

Luo, Xiaoyu

413

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

NASA Technical Reports Server (NTRS)

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

Kim, Yong W.

1990-01-01

414

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

415

A comparison of the emissions, densities, temperatures, and debris features of laser-produced plasmas  

Microsoft Academic Search

Tin and lithium plasmas emit efficiently in the in-band region (13.5 nm with 2% bandwidth) necessary for extreme ultraviolet (EUV) lithography. A detailed comparison of the atomic and ionic debris, as well as the emission features of tin and lithium plasmas has been conducted under identical experimental conditions. Planar slabs of pure tin and lithium were irradiated with 1064 nm,

Ryan William Coons

2010-01-01

416

Space-resolved soft X-ray emission from laser produced lithium plasma  

Microsoft Academic Search

Space-resolved emission spectroscopy was used to study the evolution of 13.5 nm line intensity and electron temperature of the plasma generated by laser ablation of lithium target. Two emitting regions were observed, their intensities depending on laser fluency. Plasma image is discussed in the frame of a Gaussian model of particle expansion.

P. Nica; S. Miyamoto; S. Amano; T. Inoue; A. Shimoura; T. Mochizuki

2007-01-01

417

Spatially resolved spectra of resonantly pumped laser produced plasmas of lithium  

Microsoft Academic Search

Spatially resolved visible spectra emitted from a plasma formed by focusing the output of a flashlamp pumped dye laser onto solid targets of lithium have been recorded. The effects of laser wavelength on plasma formation have been analyzed by tuning the laser to the first resonance transition in lithium at 6708 Å and comparing the results with those obtained at

Tom McCormack; Gerry O'Sullivan

1999-01-01

418

Space-resolved soft X-ray emission from laser produced lithium plasma  

NASA Astrophysics Data System (ADS)

Space-resolved emission spectroscopy was used to study the evolution of 13.5 nm line intensity and electron temperature of the plasma generated by laser ablation of lithium target. Two emitting regions were observed, their intensities depending on laser fluency. Plasma image is discussed in the frame of a Gaussian model of particle expansion.

Nica, P.; Miyamoto, S.; Amano, S.; Inoue, T.; Shimoura, A.; Mochizuki, T.

2007-10-01

419

High density collimated beams of relativistic ions produced by petawatt laser pulses in plasmas  

Microsoft Academic Search

Under optimal interaction conditions ions can be accelerated up to relativistic energies by a petawatt laser pulse in both underdense and overdense plasmas. Two-dimensional particle in cell simulations show that the laser pulse drills a channel through an underdense plasma slab due to relativistic self-focusing. Both ions and electrons are accelerated in the head region of the channel. However, ion

Y. Sentoku; T. V. Liseikina; T. Zh. Esirkepov; F. Califano; N. M. Naumova; Y. Ueshima; V. A. Vshivkov; Y. Kato; K. Mima; K. Nishihara; F. Pegoraro; S. V. Bulanov

2000-01-01

420

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

421

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

Microsoft Academic Search

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

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

1998-01-01

422

Development of a visible framing camera diagnostic for the study of current initiation in z-pinch plasmas  

Microsoft Academic Search

The authors assembled and tested a visible framing camera system to take 5 ns FWHM images of the early time emission from a z-pinch plasma. This diagnostic was used in conjunction with a visible streak camera allowing early time emissions measurements to diagnose current initiation. Individual frames from gated image intensifiers were proximity coupled to charge injection device (CID) cameras

D. J. Muron; M. J. Hurst; M. S. Derzon

1996-01-01

423

Development of a visible framing camera diagnostic for the study of current initiation in z-pinch plasmas  

Microsoft Academic Search

We assembled and tested a visible framing camera system to take 5 ns FWHM images of the early time emission from a z-pinch plasma. This diagnostic was used in conjunction with a visible streak camera allowing early time emissions measurements to diagnose current initiation. Individual frames from gated image intensifiers were proximity coupled to charge injection device cameras and read

D. J. Muron; M. J. Hurst; M. S. Derzon

1997-01-01

424

Modeling of ultrashort pulse propagation and nonlinear plasma formation in transparent Kerr media using realistic initial conditions  

Microsoft Academic Search

Ultrashort laser pulses tightly focused provide intensity sufficient to initialize nonlinear ionization processes. Thus a plasma is generated in the focal region eventually resulting in optical breakdown. The deterministic character of this nonlinear interaction enables the generation of precise and highly reproducible material alteration. To gain better spatial precision applications have recently evolved strongly towards tight focusing of ultrashort pulses

C. L. Arnold; W. Ertmer; H. Lubatschowski

2007-01-01

425

Propagation of charge-exchange plasma produced by an ion thruster  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

426

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

427

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

428

Molecular Gas Dynamical Analysis of Initial Combustion Enhancement Due to a Plasma Torch in Supersonic Shear Flow  

NASA Astrophysics Data System (ADS)

The 1st report clarified the superiority of the atomic oxygen injected from a plasma torch with the diffusive mode operation for initiating supersonic combustion. In this paper the features of combustion enhancement by various combinations of plasma mole flux and heat flux are investigated. The effectiveness of each combination is evaluated by H2O production efficiency. A molecular dynamical numerical simulation technique with the reactional molecular collision model is applied for the analysis of multi-species reaction system. The results of parametric study show that the effect of atomic oxygen plasma is attributed to the mole flux, whilst the strong dependence on the heat flux is observed for the atomic hydrogen plasma.

Obata, Shigeo; Nagashima, Toshio

429

Absolute x-ray calibration of laser-produced plasmas using a CCD linear array and a focusing crystal spectrometer  

NASA Astrophysics Data System (ADS)

Absolute x-ray calibration of laser-produced plasmas was performed using a CCD linear array and a focusing crystal spectrometer. The plasmas were created by a Nd glass laser and a high repetition rate Nd-YAG laser. A commercial CCD was used for x-ray detection. The CCD linear array has 3724 pixels giving a total length of approximately 30 mm. First the CCD detector was absolutely calibrated using laser- produced plasmas and an FE55 isotope source. The sensitivity of the detector was about two orders of magnitude higher than x-ray photographic film. The CCD detector was used for monitoring the absolute x-ray yield, for finding the optical focal position, for estimating the flux density on the target and for measuring the electron temperature of the plasma. In combination with a focusing von Hamos spectrometer the detector was used for absolute spectral measurements and determination of the plasma parameters. This spectrometer is promising for absolute spectral measurements of x-ray radiation of low-intensity sources and for numerous practical applications.

Shevelko, Alexander P.; Knight, Larry V.; Wang, Quan; Yakushev, Oleg F.

2001-11-01

430

Characterization of hydrogen microwave plasmas produced by elementary sources in matrix configuration  

NASA Astrophysics Data System (ADS)

In a previous study, a planar plasma reactor comprising 4 × 3 elementary microwave plasma sources distributed according to a square lattice matrix configuration was first characterized with argon. In this work, the objective is to characterize these so-called matrix plasmas with hydrogen in view of surface processing applications. In the absence of a static magnetic field, hydrogen plasmas can be sustained uniformly in the medium pressure range from 10 to 70 Pa. Using a cylindrical Langmuir probe, plasma density and electron temperature have been investigated at a distance of 20 mm from the source plane as functions of pressure and microwave power. The results show that the electron temperature Te is of the order of 1.2 eV and that plasma densities up to a few 1011 cm-3 can be reached. Under the same experimental conditions, optical emission spectroscopy measurements have been performed in order to determine the gas temperature and the degree of dissociation of hydrogen. The gas temperature, calculated from the ?-Fulcher Q branch emission band (2-2) d\\,^{3}\\Pi_u^{-}a\\,^{3}\\Sigma _g , varies from 600 to 850 K ± 50 K. The degree of dissociation has also been determined by using a spectroscopic method based on emission line intensities of H?, H? and H2 (2-2) d\\,^{3}\\Pi_u^{-}a\\,^{3}\\Sigma_g (N = 1) species. The maximum degree of dissociation of 50% has been obtained for the operating conditions corresponding to the highest plasma density.

Rayar, M; LeQuoc, H; Lacoste, A; Latrasse, L; Pelletier, J

2009-05-01

431

Mass spectrometric study of discharges produced by a large-area dual-frequency-dual-antenna inductively coupled plasma source  

NASA Astrophysics Data System (ADS)

An energy-resolved quadrupole mass spectrometer is used to investigate the time-averaged ion energy distribution (IED) of positive ionic species in an Ar/CF4 (90%/10%) discharge produced by dual-frequency-dual-antenna, next-generation large-area inductively coupled plasma source. The operating pressure is 10 mTorr. Two radio frequencies of 2 MHz (low frequency) and 13.56 MHz (high frequency) are used to initiate and sustain the discharge. The orifice of the mass spectrometer was 100 µm in diameter and placed at 30 mm below the ICP source and 20 mm outside the discharge volume. It is observed that both of the frequencies have significant effect on IEDs of all prominent discharge species. The evolution of IEDs with power shows that the discharge undergoes a mode transition (E to H) as the applied power is increased.