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1

Time-dependent electron temperature diagnostics for high-power aluminum z-pinch plasmas  

SciTech Connect

Time-resolved x-ray pinhole photographs and time-integrated radially-resolved x-ray crystal-spectrometer measurements of azimuthally-symmetric aluminum-wire implosions suggest that the densest phase of the pinch is composed of a hot plasma core surrounded by a cooler plasma halo. The slope of the free-bound x-ray continuum, provides a time-resolved, model-independent diagnostic of the core electron temperature. A simultaneous measurement of the time-resolved K-shell line spectra provides the electron temperature of the spatially averaged plasma. Together, the two diagnostics support a 1-D Radiation-Hydrodynamic model prediction of a plasma whose thermalization on axis produces steep radial gradients in temperature, from temperatures in excess of a kilovolt in the core to below a kilovolt in the surrounding plasma halo.

Sanford, T.W.L.; Nash, T.J.; Mock, R.C. [and others

1996-08-01

2

Variation of high-power aluminum-wire array Z-pinch dynamics with wire number, array radius, and load mass  

SciTech Connect

A systematic study of annular aluminum-wire z-pinches on the Saturn accelerator shows that the quality of the implosion, including the radiated power, increases with wire number. Radiation magnetohydrodynamic (RMEC) xy simulations suggest that the implosion transitions from that of individual wire plasmas to that of a continuous plasma shell when the interwire spacing is reduced below {approximately} 1.4 mm. In the plasma-shell regime, the experimental implosions exhibit 1D- and 2D-code characteristics as evidenced by the presence of a strong first and a weak second radiation pulse that correlates with a strong and weak radial convergence. In this regime, many of the radiation and plasma characteristics are in agreement with those simulated by 2D-RMHC rz simulations. Moreover, measured changes in the radiation pulse width with variations in array mass and radius are consistent with the simulations and are explained by the development of 2D fluid motion in the rz plane. Associated variations in the K-shell yield are qualitatively explained by simple K-shell radiation scaling models.

Sanford, T.W.L.; Mock, R.C.; Marder, B.M. [and others

1997-06-01

3

Experimental astrophysics with high power lasers and Z pinches  

SciTech Connect

With the advent of high energy density (HED) experimental facilities, such as high-energy lasers and fast Z-pinch, pulsed-power facilities, mm-scale quantities of matter can be placed in extreme states of density, temperature, and/or velocity. This has enabled the emergence of a new class of experimental science, HED laboratory astrophysics, wherein the properties of matter and the processes that occur under extreme astrophysical conditions can be examined in the laboratory. Areas particularly suitable to this class of experimental astrophysics include the study of opacities relevant to stellar interiors; equations of state relevant to planetary interiors; strong shock driven nonlinear hydrodynamics and radiative dynamics, relevant to supernova explosions and subsequent evolution; protostellar jets and high Mach-number flows; radiatively driven molecular clouds and nonlinear photoevaporation front dynamics; and photoionized plasmas relevant to accretion disks around compact objects, such as black holes and neutron stars.

Remington, B A; Drake, R P; Ryutov, D D

2004-12-10

4

Wire number breakthrough for high-power annular z pinches and some characteristics at high wire number  

NASA Astrophysics Data System (ADS)

Characteristics of annular wire array z pinches as a function of wire number and at high wire number are reviewed. The data, taken primarily using aluminum wires on Saturn, are comprehensive. The experiments have provided important insights into the features of wire-array dynamics critical for high X-ray power generation, and have initiated a renaissance in z pinches when high numbers of wires are used. In this regime, for example, radiation environments characteristic of those encountered during the early pulses required for indirect-drive ICF ignition on the NIF have been produced in hohlraums driven by X rays from a z pinch, and are commented on here.

Sanford, T. W. L.

2001-10-01

5

Wire-number effects on high-power annular z-pinches and some characteristics at high wire number  

SciTech Connect

Characteristics of annular wire-array z-pinches as a function of wire number and at high wire number are reviewed. The data, taken primarily using aluminum wires on Saturn are comprehensive. The experiments have provided important insights into the features of wire-array dynamics critical for high x-ray power generation, and have initiated a renaissance in z-pinches when high numbers of wires are used. In this regime, for example, radiation environments characteristic of those encountered during the early pulses required for indirect-drive ICF ignition on the NIF have been produced in hohlraums driven by x-rays from a z-pinch, and are commented on here.

SANFORD,THOMAS W. L.

2000-05-23

6

Differential phase shift interferometer for measuring axisymmetric gas distributions for high-power Z-pinch research  

Microsoft Academic Search

A sensitive interferometer [B. V. Weber and S. F. Fulghum, Rev. Sci. Instrum. 68, 1227 (1997)] with 10-5-wave phase resolution is used to measure gas distributions from axisymmetric, supersonic nozzles employed in high power Z-pinch experiments. The line-integrated gas density, N??ndx, is measured as a function of time at one distance, z, from the nozzle and one distance, y, from

B. V. Weber; S. J. Stephanakis; B. Moosman

1999-01-01

7

Differential phase shift interferometer for measuring axisymmetric gas distributions for high-power Z-pinch research  

NASA Astrophysics Data System (ADS)

A sensitive interferometer [B. V. Weber and S. F. Fulghum, Rev. Sci. Instrum. 68, 1227 (1997)] with 10-5-wave phase resolution is used to measure gas distributions from axisymmetric, supersonic nozzles employed in high power Z-pinch experiments. The line-integrated gas density, N??ndx, is measured as a function of time at one distance, z, from the nozzle and one distance, y, from the axis. The (y,z) region of interest is scanned shot to shot. The N(y) data are analyzed to find radial density distributions via Abel inversion: n(r)=-(1/?)?r?[(dN/dy)/?y2-r2 ]dy. Error propagation based on the uncertainty in N results in larger relative uncertainties in n, especially near the axis. The precision may be improved using a modified version of this interferometer, where the reference beam is moved into the gas, a small distance (1-2 mm) from the scene beam. The phase difference is then a direct measurement of dN/dy, reducing the error introduced by numerically differentiating N. These two techniques are compared using two nozzles with different density distributions from DECADE Module 2 Z-pinch experiments.

Weber, B. V.; Stephanakis, S. J.; Moosman, B.

1999-01-01

8

Implosion characteristics and applications of combined tungsten-aluminum Z-pinch planar arrays  

NASA Astrophysics Data System (ADS)

An exploration of the implosion properties and X-ray radiation pulses from tungsten-based planar wire array Z-pinch experiments is presented, with an emphasis on loads mixed with aluminum. These experiments were carried out on Zebra, the 1.0 MA pulse power generator at the Nevada Terawatt Facility. A suite of diagnostics was used to study these plasmas, including X-ray and EUV Si diodes, optical imaging, laser shadowgraphy, and time-gated and time-integrated X-ray pinhole imagers and spectrometers. Specifically, loads with relatively large inter-wire gaps where tungsten is placed in the center of a planar configuration composed primarily of aluminum showed unusual characteristics. These loads are shown to generate a "bubbling" effect in which plasma from the ablation of outer aluminum wires is temporarily hindered from converging at the center of the array where the tungsten wire is located. Reproduction of these experiments with variations to load geometry, materials, and mass distribution are also presented and discussed in an attempt to better understand the phenomenon. In addition, a theoretical model has also been applied to better understand the dynamics of the implosions of these loads. Applications of this effect to radiation pulse shaping, particularly with multi-planar arrays, are also discussed.

Osborne, G. C.; Kantsyrev, V. L.; Esaulov, A. A.; Safronova, A. S.; Weller, M. E.; Shrestha, I.; Williamson, K. M.; Shlyaptseva, V. V.

2013-12-01

9

X-ray absorption spectroscopy of aluminum z-pinch plasma with tungsten backlighter planar wire array source  

SciTech Connect

Absorption features from K-shell aluminum z-pinch plasmas have recently been studied on Zebra, the 1.7 MA pulse power generator at the Nevada Terawatt Facility. In particular, tungsten plasma has been used as a semi-backlighter source in the generation of aluminum K-shell absorption spectra by placing a single Al wire at or near the end of a single planar W array. All spectroscopic experimental results were recorded using a time-integrated, spatially resolved convex potassium hydrogen phthalate (KAP) crystal spectrometer. Other diagnostics used to study these plasmas included x-ray detectors, optical imaging, laser shadowgraphy, and time-gated and time-integrated x-ray pinhole imagers. Through comparisons with previous publications, Al K-shell absorption lines are shown to be from much lower electron temperature ({approx}10-40 eV) plasmas than emission spectra ({approx}350-500 eV).

Osborne, G. C.; Kantsyrev, V. L.; Safronova, A. S.; Esaulov, A. A.; Weller, M. E.; Shrestha, I.; Shlyaptseva, V. V. [Physics Department, University of Nevada, Reno, Reno, Nevada 89557 (United States); Ouart, N. D. [Naval Research Laboratory, Washington, D.C. 20375 (United States)

2012-10-15

10

X-ray absorption spectroscopy of aluminum z-pinch plasma with tungsten backlighter planar wire array source.  

PubMed

Absorption features from K-shell aluminum z-pinch plasmas have recently been studied on Zebra, the 1.7 MA pulse power generator at the Nevada Terawatt Facility. In particular, tungsten plasma has been used as a semi-backlighter source in the generation of aluminum K-shell absorption spectra by placing a single Al wire at or near the end of a single planar W array. All spectroscopic experimental results were recorded using a time-integrated, spatially resolved convex potassium hydrogen phthalate (KAP) crystal spectrometer. Other diagnostics used to study these plasmas included x-ray detectors, optical imaging, laser shadowgraphy, and time-gated and time-integrated x-ray pinhole imagers. Through comparisons with previous publications, Al K-shell absorption lines are shown to be from much lower electron temperature (?10-40 eV) plasmas than emission spectra (?350-500 eV). PMID:23126925

Osborne, G C; Kantsyrev, V L; Safronova, A S; Esaulov, A A; Weller, M E; Shrestha, I; Shlyaptseva, V V; Ouart, N D

2012-10-01

11

X-ray absorption spectroscopy of aluminum z-pinch plasma with tungsten backlighter planar wire array sourcea)  

NASA Astrophysics Data System (ADS)

Absorption features from K-shell aluminum z-pinch plasmas have recently been studied on Zebra, the 1.7 MA pulse power generator at the Nevada Terawatt Facility. In particular, tungsten plasma has been used as a semi-backlighter source in the generation of aluminum K-shell absorption spectra by placing a single Al wire at or near the end of a single planar W array. All spectroscopic experimental results were recorded using a time-integrated, spatially resolved convex potassium hydrogen phthalate (KAP) crystal spectrometer. Other diagnostics used to study these plasmas included x-ray detectors, optical imaging, laser shadowgraphy, and time-gated and time-integrated x-ray pinhole imagers. Through comparisons with previous publications, Al K-shell absorption lines are shown to be from much lower electron temperature (˜10-40 eV) plasmas than emission spectra (˜350-500 eV).

Osborne, G. C.; Kantsyrev, V. L.; Safronova, A. S.; Esaulov, A. A.; Weller, M. E.; Shrestha, I.; Shlyaptseva, V. V.; Ouart, N. D.

2012-10-01

12

Opacity and gradients in aluminum wire array z-pinch implosions on the Z pulsed power facility  

SciTech Connect

Aluminum wire array z pinches imploded on the Z generator are an extremely bright source of 1–2?keV radiation, with close to 400?kJ radiated at photon energies >1?keV and more than 50?kJ radiated in a single line (Al Ly-?). Opacity plays a critical role in the dynamics and K-shell radiation efficiency of these pinches. Where significant structure is present in the stagnated pinch this acts to reduce the effective opacity of the system as demonstrated by direct analysis of spectra. Analysis of time-integrated broadband spectra (0.8–25?keV) indicates electron temperatures ranging from a few 100?eV to a few keV are present, indicative of substantial temperature gradients.

Ampleford, D. J., E-mail: damplef@sandia.gov; Hansen, S. B.; Jennings, C. A.; Jones, B.; Coverdale, C. A.; Harvey-Thompson, A. J.; Rochau, G. A.; Dunham, G.; Moore, N. W.; Harding, E. C.; Cuneo, M. E. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Chong, Y.-K.; Clark, R. W.; Ouart, N.; Thornhill, J. W.; Giuliani, J.; Apruzese, J. P. [Naval Research Laboratory, Washington, DC 20375 (United States)] [Naval Research Laboratory, Washington, DC 20375 (United States)

2014-03-15

13

Opacity and gradients in aluminum wire array z-pinch implosions on the Z pulsed power facility  

NASA Astrophysics Data System (ADS)

Aluminum wire array z pinches imploded on the Z generator are an extremely bright source of 1-2 keV radiation, with close to 400 kJ radiated at photon energies >1 keV and more than 50 kJ radiated in a single line (Al Ly-?). Opacity plays a critical role in the dynamics and K-shell radiation efficiency of these pinches. Where significant structure is present in the stagnated pinch this acts to reduce the effective opacity of the system as demonstrated by direct analysis of spectra. Analysis of time-integrated broadband spectra (0.8-25 keV) indicates electron temperatures ranging from a few 100 eV to a few keV are present, indicative of substantial temperature gradients.

Ampleford, D. J.; Hansen, S. B.; Jennings, C. A.; Jones, B.; Coverdale, C. A.; Harvey-Thompson, A. J.; Rochau, G. A.; Dunham, G.; Moore, N. W.; Harding, E. C.; Cuneo, M. E.; Chong, Y.-K.; Clark, R. W.; Ouart, N.; Thornhill, J. W.; Giuliani, J.; Apruzese, J. P.

2014-03-01

14

Development of a Z-pinch-driven ICF hohlraum concept on Z  

Microsoft Academic Search

Summary form only given. Recent development of high power Z-pinches (>150 TW) on the Z driver has permitted the study of high-temperature, radiation-driven hohlraums. Three complementary, Z-pinch source-hohlraum-ICF capsule configurations are being developed to harness the X-ray output of these Z-pinch's. These are the dynamic-hohlraum, static-wall hohlraum, and Z-pinch-driven hohlraum concepts. Each has different potential strengths and concerns. In this

M. E. Cuneo; R. A. Vesey; L. E. Ruggles; W. W. Simpson; M. Vargas; D. L. Hanson; T. Nash; G. A. Chandler; J. R. Asay; C. A. Hall; C. Deeney; R. B. Spielman; J. H. Hammer; A. Toor; O. Landen; J. Koch

1999-01-01

15

Explosive Z Pinch  

E-print Network

We propose an explanation for the recently observed powerful contained explosion in a Z pinch experiment performed at Sandia National Laboratories. Our arguments are based on the assumption that a pure SU(2) Yang-Mills theory of scale $\\sim 0.5 $MeV is responsible for the emergence of the electron and its neutrino.

Francesco Giacosa; Ralf Hofmann; Markus Schwarz

2006-04-20

16

Radiating Shock Properties in the Z-pinch Dynamic Hohlraum  

Microsoft Academic Search

The Z-pinch dynamic hohlraum is a high-power x-ray source used for a variety of high energy-density physics applications including high temperature opacity measurements and inertial confinement fusion (ICF). The system consists of a tungsten wire-array Z pinch that implodes onto a low-density CH2 foam launching a radiating shock that heats the hohlraum to radiation temperatures >200 eV. The temperature and

Gregory A. Rochau; J. E. Bailey; Y. Maron; G. Chandler; V. Fisher; R. Lemke; J. Macfarlane; K. Peterson; S. Slutz; E. Stambulchik

2009-01-01

17

Z-Pinch Fusion Propulsion  

NASA Technical Reports Server (NTRS)

Fusion-based nuclear propulsion has the potential to enable fast interplanetary transportation. Shorter trips are better for humans in the harmful radiation environment of deep space. Nuclear propulsion and power plants can enable high Ispand payload mass fractions because they require less fuel mass. Fusion energy research has characterized the Z-Pinch dense plasma focus method. (1) Lightning is form of pinched plasma electrical discharge phenomena. (2) Wire array Z-Pinch experiments are commonly studied and nuclear power plant configurations have been proposed. (3) Used in the field of Nuclear Weapons Effects (NWE) testing in the defense industry, nuclear weapon x-rays are simulated through Z-Pinch phenomena.

Miernik, Janie

2011-01-01

18

Experimental investigation of the properties and phase state of thick aluminum surfaces pulsed to megagauss level magnetic field in a Z-pinch geometry  

NASA Astrophysics Data System (ADS)

Thermal transformation to plasma of an aluminum surface pulsed to multi-megagauss magnetic field is observed to occur when the surface field reaches a threshold level of 2.2 MG. Magnetic field (B) is pulsed on the surface of cylindrical metallic rods. Rods are thick ---with radii (R) exceeding the magnetic field penetration depth (deltaB). Ohmic heating is confined to a skin layer, with deltaB determined by diffusion and hydrodynamic processes. Initial rod diameters (D0) ranging from 2.00 to 0.50 mm are pulsed with 1.0 MA peak current by the Zebra z-pinch. Due to Zebra's high transmission line impedance (1.9 ohm), the current waveform is insensitive to D0. The Zebra current, I( t), consistently rises exponentially to 100 kA (with rise time tau=13 ns), and then linearly from 100 to 900 kA for 70 ns, with dI/d t = 1.1x1013 A/s, to a maximum current of 1.0 MA. By altering D0, a variety of magnetic field and current density profiles are examined. For D0 of 2.00 and 0.50 mm, magnetic field rise rates ?B/? t) vary from 30 and 80 MG/mus, and peak surface fields reach 1.5 and 4 MG, respectively. Novel contact configurations and load surface profiles mitigate plasma formation from contact arcing or electric-field-driven electron avalanche, ensuring that plasma forms thermally---a result of ohmic or compression heating. Aluminum plasma is observed through a variety of independently measured phenomena. First, for rod surfaces pulsed above the magnetic field threshold (Bs > Bthreshold = 2.2 MG), multi-eV brightness temperatures (TBB) are observed, clearly indicating plasma for aluminum. For example, peak TBB reach 20 and 36 eV for 1.00 and 0.50 mm rods, respectively. Plasma forms at lower current and reaches higher temperatures as D0 is decreased. Second, aluminum ion species are distinguished via extreme ultraviolet (EUV) spectroscopy. Line spectra from Al3+ and Al4+ ions are obtained. The average ion charge and line ratios depend strongly upon temperature, and taking the ratio of line intensities results in an estimated peak plasma temperature of 15+/-1 eV for 1.00-mm-diameter rods. Third, EUV photon flux consistent with multi-eV temperature is recorded by Al or Si/Zr filtered photodiodes sensitive to photon energies from 16 to 73 eV, or 60 to 100 eV, respectively. Fourth, magnetohydrodynamic (MHD) instabilities form. Instability development depends on the conductivity of the low density expanding surface material. High resistivity vapor interacts weakly with magnetic field; therefore, flute instabilities are attributed to surface plasma. For those rods which do not reach B threshold = 2.2 MG, no evidence of surface plasma is obtained. For 2.00-mm-diameter rods, which reach peak surface field of only 1.7 MG, surface temperatures remain cool (peak TBB = 0.7 eV), no EUV emission can be measured, and even while carrying 1.0 MA of current, and after significant radial expansion, no surface instability is observed. The experiment offers the first detailed study of plasma formation by pulsed magnetic field on a thick metallic surface carrying a skin current. The magnetic field threshold for plasma formation, surface brightness temperature, radial expansion velocity, instability growth, and ionization state have been measured. The effects of hardware design, load geometry, Al alloy, and surface smoothness have been carefully examined, creating a dataset that can be used for the design of practical systems. The experiment has achieved thermal, uniform, and symmetric plasma formation, providing a meaningful comparison for MHD simulations.

Awe, Thomas J.

19

Z-Pinch Fusion for Energy Applications  

SciTech Connect

Z pinches, the oldest fusion concept, have recently been revisited in light of significant advances in the fields of plasma physics and pulsed power engineering. The possibility exists for z-pinch fusion to play a role in commercial energy applications. We report on work to develop z-pinch fusion concepts, the result of an extensive literature search, and the output for a congressionally-mandated workshop on fusion energy held in Snowmass, Co July 11-23,1999.

SPIELMAN,RICK B.

2000-01-01

20

Development of a Z-pinch-driven ICF hohlraum concept on Z  

SciTech Connect

Recent development of high power z-pinches (> 150 MW) on the Z driver has permitted the study of high-temperature, radiation-driven hohlraums. Three complementary, Z-pinch source-hohlraum-ICF capsule configurations are being developed to harness the x-ray output of these Z-pinch's. These are the dynamic-hohlraum, static-wall hohlraum, and Z-pinch-driven hohlraum concepts. Each has different potential strengths and concerns. In this paper, the authors report on the first experiments with the Z-pinch-driven hohlraum (ZPDH) concept. A high-yield ICF capsule design for this concept appears feasible, when driven by z-pinches from a 60 MA-class driver. Initial experiments characterize the behavior of the spoke array on Z-pinch performance and x-ray transmission, and the uniformity of radiation flux incident on a foam capsule in the secondary, for a single-sided drive. Measurements of x-ray wall re-emission power and spectrum, radiation temperatures, spoke-plasma location, and drive uniformity will be presented and compared with 0-D energetics, 2-D Lasnex rad-hydro, and 3-D radiosity calculations of energy transport and drive uniformity.

Cuneo, M.E.; Porter, J.L. Jr.; Vesey, R.A. [and others

1999-07-01

21

Radiating Shock Properties in the Z-pinch Dynamic Hohlraum  

NASA Astrophysics Data System (ADS)

The Z-pinch dynamic hohlraum is a high-power x-ray source used for a variety of high energy-density physics applications including high temperature opacity measurements and inertial confinement fusion (ICF). The system consists of a tungsten wire-array Z pinch that implodes onto a low-density CH2 foam launching a radiating shock that heats the hohlraum to radiation temperatures >200 eV. The temperature and density evolution of this shock have been inferred through the measurement of time- and space-resolved line emission from Si atoms locally doped in the CH2 foam. The observed emission spectra are analyzed through comparison to collisional-radiative calculations that include a detailed treatment of line-shapes and the effect of non-local radiation on the atomic level populations. As a complement to the detailed spectral data, the radial and azimuthal distribution of the axially directed shock emission is recorded with time-gated x-ray pinhole images that provide information on the spatial profile of the shock conditions. Together with broadband x-ray power measurements, these data provide a comprehensive suite of information to determine the shock dynamics and associated energetics of the Z-pinch dynamic hohlraum.

Rochau, Gregory A.; Bailey, J. E.; Maron, Y.; Chandler, G.; Fisher, V.; Lemke, R.; MacFarlane, J.; Peterson, K.; Slutz, S.; Stambulchik, E.

2009-09-01

22

Radiating Shock Properties in the Z-pinch Dynamic Hohlraum  

SciTech Connect

The Z-pinch dynamic hohlraum is a high-power x-ray source used for a variety of high energy-density physics applications including high temperature opacity measurements and inertial confinement fusion (ICF). The system consists of a tungsten wire-array Z pinch that implodes onto a low-density CH{sub 2} foam launching a radiating shock that heats the hohlraum to radiation temperatures >200 eV. The temperature and density evolution of this shock have been inferred through the measurement of time- and space-resolved line emission from Si atoms locally doped in the CH{sub 2} foam. The observed emission spectra are analyzed through comparison to collisional-radiative calculations that include a detailed treatment of line-shapes and the effect of non-local radiation on the atomic level populations. As a complement to the detailed spectral data, the radial and azimuthal distribution of the axially directed shock emission is recorded with time-gated x-ray pinhole images that provide information on the spatial profile of the shock conditions. Together with broadband x-ray power measurements, these data provide a comprehensive suite of information to determine the shock dynamics and associated energetics of the Z-pinch dynamic hohlraum.

Rochau, Gregory A.; Bailey, J. E.; Chandler, G.; Lemke, R.; Peterson, K.; Slutz, S. [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Maron, Y.; Fisher, V.; Stambulchik, E. [Weizmann Institute, Rehovot (Israel); MacFarlane, J. [Prism Computational Sciences, Madison, Wisconsin 53704 (United States)

2009-09-10

23

The physics of fast Z pinches  

SciTech Connect

The spectacular progress made during the last few years in reaching high energy densities in fast implosions of annular current sheaths (fast Z pinches) opens new possibilities for a broad spectrum of experiments, from x-ray generation to controlled thermonuclear fusion and astrophysics. Presently Z pinches are the most intense laboratory X ray sources (1.8 MJ in 5 ns from a volume 2 mm in diameter and 2 cm tall). Powers in excess of 200 TW have been obtained. This warrants summarizes the present knowledge of physics that governs the behavior of radiating current-carrying plasma in fast Z-pinches. This survey covers essentially all aspects of the physics of fast Z pinches: initiation, instabilities of the early stage, magnetic Rayleigh-Taylor instability in the implosion phase, formation of a transient quasi-equilibrium near the stagnation point, and rebound. Considerable attention is paid to the analysis of hydrodynamic instabilities governing the implosion symmetry. Possible ways of mitigating these instabilities are discussed. Non-magnetohydrodynamic effects (anomalous resistivity, generation of particle beams, etc.) are summarized. Various applications of fast Z pinches are briefly described. Scaling laws governing development of more powerful Z pinches are presented. The survey contains 52 figures and nearly 300 references.

Ryutov, D.D. [Lawrence Livermore National Lab., CA (United States); Derzon, M.S.; Matzen, M.K. [Sandia National Labs., Albuquerque, NM (United States)

1998-07-01

24

The Physics of Fast Z Pinches  

SciTech Connect

The spectacular progress made during the last few years in reaching high energy densities in fast implosions of annular current sheaths (fast Z pinches) opens new possibilities for a broad spectrum of experiments, from x-ray generation to controlled thermonuclear fusion and astrophysics. Presently Z pinches are the most intense laboratory X ray sources (1.8 MJ in 5 ns from a volume 2 mm in diameter and 2 cm tall). Powers in excess of 200 TW have been obtained. This warrants summarizing the present knowledge of physics that governs the behavior of radiating current-carrying plasma in fast Z pinches. This survey covers essentially all aspects of the physics of fast Z pinches: initiation, instabilities of the early stage, magnetic Rayleigh-Taylor instability in the implosion phase, formation of a transient quasi-equilibrium near the stagnation point, and rebound. Considerable attention is paid to the analysis of hydrodynamic instabilities governing the implosion symmetry. Possible ways of mitigating these instabilities are discussed. Non-magnetohydrodynamic effects (anomalous resistivity, generation of particle beams, etc.) are summarized. Various applications of fast Z pinches are briefly described. Scaling laws governing development of more powerful Z pinches are presented. The survey contains 36 figures and more than 300 references.

RYUTOV,D.D.; DERZON,MARK S.; MATZEN,M. KEITH

1999-10-25

25

Z and Z-Pinch IFE  

NASA Astrophysics Data System (ADS)

Rapid development of z-pinch loads on the Z accelerator at SNL has led to radiative powers of up to 280 TW in 4 ns with a total radiated x-ray energy of 1.8 MJ, making Z the most powerful, multi-module, synchronized pulsed power accelerator in the world. Demonstration of a single-shot, high-yield fusion target is a goal of the z-pinch ICF program at SNL. Demonstration of a rep-rated z-pinch power plant for energy is a goal of z-pinch IFE development. Z-pinch IFE exploits the advantages of using high-yield targets (a few GJ) at low rep-rate (0.1 Hz), with a Recyclable Transmission Line (RTL) to provide the necessary standoff between the fusion target and the pulsed power accelerator. Results of recent experiments on Z, computer simulations of high-yield targets, experiments on Saturn to test candidate RTL materials and low-mass RTL's, experiments on Z and RHEPP to test candidate first-wall materials, and present z-pinch power plant studies will be presented.

Olson, Craig

2002-04-01

26

Ionization dynamics of a single wire z-pinch  

NASA Astrophysics Data System (ADS)

This thesis explored the ionization dynamics of a single wire z-pinch. Experiments were conducted on fine wires of aluminum, copper, silver, and tungsten ranging in diameter from 7.5--50mum with lengths of 2.5cm. These wires were subjected to a pulsed current of ˜2kA, 500ns half-cycle from a spark-gap triggered, negatively-charged capacitor bank discharge. The results of this thesis are divided into three parts which cover the entire dynamic evolution of the wires during the first ˜500ns of the current pulse. The first part examined surface impurity evolution and its contribution to the voltage collapse and initial plasma formation. It was discovered that hydrocarbon impurities contribute significantly to the initial plasma formation, for all wires studied, and that high ionization states of carbon (CIII and CIV) are present at the point of the voltage collapse. The second portion of the thesis dealt with laser imaging and the observation of instability growth at the core/corona boundary of expanding z-pinch wire plasmas. From the increased sensitivity of the resonant XeCl excimer laser diagnostics, it was determined that, for aluminum wires, these instabilities were consistent with a hydrodynamic Rayleigh-Taylor instability of a decelerating plasma plume front. The third portion of the thesis focused on potential seeding mechanisms for instability growth in single wire z-pinches and their relevance to wire array experiments. It was observed in copper wires that do pre-heating of wires caused surface alterations due to recrystallization. It was also discovered, during the course of these studies, that electrical current pulses on the timescale of the experimental pulse (500ns half-cycle) could also alter the surface structure of copper wires and lead to coronal instabilities. Finally, preliminary investigations into the possibility of crystal/grain growth behavior in tungsten wires is given, along with the idea of using potassium doped tungsten wires as a means of compensating for this behavior in pure tungsten. The experiments in this thesis were designed with the intention of aiding in the overall understanding of z-pinch wire physics and in particular the pre-pulse conditions on larger wire array experiments, such as the Z-machine at Sandia National Laboratories. The information in this thesis is directed towards supporting ongoing modeling efforts to help establish the initial conditions for individual wires on wire arrays, with the overall goal of being able to better predict wire array behavior. (Abstract shortened by UMI.)

Johnston, Mark Darren

27

Spectral Unfolds of Tungsten Z Pinches and Z-Pinch Driven Hohlraum Radiation Sources*  

NASA Astrophysics Data System (ADS)

We have measured the sub-keV spectral output from tungsten Z pinches^1 and from tungsten Z-pinch driven hohlraums^2 on the 7-MA Saturn accelerator. A primary detector system consists of a set of filtered x-ray diode detectors. The broad spectral response of the individual detectors requires a spectral unfold of their response to obtain the source flux. With these detectors we have inferred peak x-ray powers from these Z-pinch sources of 62 TW. Fluxes from hohlraums driven by these Z pinches yield a measured peak equivalent brightness temperature of 85 eV. The unfolded spectral output from these sources as a function of source parameters and hohlraum geometry will be presented. We will begin z-pinch experiments this summer using the 16-MA PBFA-Z accelerator^3. The PBFA-Z driver should be able to produce output powers > 150 TW and hohlraums with radiation temperatures > 100 eV. The scaling obtained from preliminary measurements on the PBFA-Z accelerator will also be presented. 1 C. Deeney et. al., this conference. 2 J. L. Porter et. al., this conference. 3 R.B. Spielman et. al., Proc. Beams 96. *This work performed by Sandia National Laboratories is supported by the U.S. Department of Energy under contract DE-AC04-94AL85000

Chandler, G. A.; Fehl, D. L.; Torres, J. A.; Deeney, C.; Porter, J. L.; Olson, R. E.; Spielman, R. B.

1996-11-01

28

Hohlraum Energetics of Z-pinch-driven ICF Target Configurations  

NASA Astrophysics Data System (ADS)

The Z accelerator has produced z-pinch x-ray powers and energies of up to 290 TW and 2 MJ, respectively with wall plug to x-ray energy generation efficiencies of 15%. This has created great interest in the ICF applications of z-pinches for high yield where large absorbed capsule energies are required. A z-pinch target is comprised of three parts: the pinch implosion region, the fusion capsule, and the enclosing hohlraum case. Three distinct z-pinch targets have already been proposed: the so-called 1) z-pinch-driven hohlraum, 2) static-walled hohlraum, and 3) dynamic hohlraums. We report on the results of hohlraum energetics modeling of these target configurations and comparisons of the strengths and weaknesses of each approach. The issues considered are capsule ignition criteria, radiation transport symmetry and efficiency, and z-pinch x-ray power scaling.

Mehlhorn, T. A.; Vesey, R. A.; Olson, R. E.

1998-11-01

29

Preliminary Results of a 10 kJ Z-Pinch  

Microsoft Academic Search

Preliminary results obtained on 10 kJ Z-pinch device developed at the Plasma and Electrical Discharge Laboratory in the University of Castilla-La Mancha are presented. The device called ENERGU-1 is composed by 8 capacitors (0.5 ?F, 75 kV, 20 nH) connected in parallel to a discharge chamber by means of one high power plane transmission line by mean of 8 spark-gaps

O. D. Corta´zar; A. R. Piriz; G. Rodri´guez Prieto; D. H. H. Hoffmann; N. A. Tahir

2008-01-01

30

Preliminary Results of a 10 kJ Z-Pinch  

Microsoft Academic Search

Preliminary results obtained on 10 kJ Z-pinch device developed at the Plasma and Electrical Discharge Laboratory in the University of Castilla-La Mancha are presented. The device called ENERGU-1 is composed by 8 capacitors (0.5 muF, 75 kV, 20 nH) connected in parallel to a discharge chamber by means of one high power plane transmission line by mean of 8 spark-gaps

O. D. Cortázar; A. R. Piriz; G. Rodríguez Prieto; D. H. H. Hoffmann; N. A. Tahir

2008-01-01

31

Applications of high-power diode lasers for aluminum welding  

NASA Astrophysics Data System (ADS)

Industries worldwide are confronted with the need for an increased use of aluminum alloys in various applications. Therefore the requirements result in the necessity for a multitude of joining and welding innovations. Applications of modern aluminum alloys are not constricted to common components anymore. In fact, they are used in ever more complex lightweight structures. However, this complexity has to be fulfilled by a higher geometric flexibility in laser welding and represents a major challenge for new approaches in working lightweight structures. The present work includes the welding of aluminum utilizing Bifocal Hybrid Laser Welding (BHLW) and a 6 kW high power diode laser (HPDL) for welding. The welding setups allow for welded butt- and fillet-welds of tubes under consideration of the hardly fusion weldable alloy AA6060. Welded joints of AA6060 are investigated metallographically in regard to the influence of process parameters like intensity and the interconnected penetration. The weldability is characterized by qualitative investigations of the microstructure as well as the mechanical behavior under quasistatic loading. The investigations result in an adequate welding process for AA6060.

Huber, Sonja; Merzkirch, Matthias; Zaeh, Michael F.; Schulze, Volker

2009-02-01

32

Z: A Precision 200-TW, 2-MJ Z-Pinch X-Ray Source  

NASA Astrophysics Data System (ADS)

Recent experiments on Sandia National Laboratories' Z facility have demonstrated z-pinch x-ray sources with record powers and energies. We have measured x-ray powers greater than 200 TW with x-ray energies of 2 MJ in a single 7.5 ns FWHM pulse. These dramatic results are made possible by the development of pulsed power drivers that deliver currents up to 20 MA with a current risetime of 100 ns. Z stores 11.4 MJ in its 36 Marx generators, couples 5 MJ to the output water transmission lines in a 60 TW, 105 ns pulse, and delivers 3.0 MJ and 50 TW of electrical energy to the z-pinch load. Overall efficiencies from stored energy to x-rays is measured to be 15%. The z-pinch plasma is created using cylindrical wire arrays. These wire arrays consist of 90-300 tungsten, aluminum, or titanium wires. Typical wire array dimensions are 1.75 to 5.0 cm diameters and 1 to 2 cm lengths. These wire arrays have total masses in the range of 2-5 mg/cm. The z-pinch creates a reproducible x-ray source that is tunable in spectrum and pulse duration. We have demonstrated reproducibility in x-ray performance in the 5-10% range shot-to-shot. We describe some of the fundamental z-pinch physics issues, including wire initiation, the magneto-Rayleigh-Taylor instability, and fundamental plasma properties, that restrict our ability to attain even higher x-ray powers.

Spielman, Rick B.

1997-11-01

33

Study of Wire Contact Resistance in Single and Multiwire Z-Pinch Experiments  

Microsoft Academic Search

Contact resistance of single and multi-wire array z-pinch has been measured for aluminum, stainless steel, and tungsten wires; diameters ranged from 7.5 to 30.5 micron. DC contact resistance in these experiments accounted for approximately 80% of load resistance, and resistance measurements varied from wire-to-wire by up to 15%. These DC measurements show that the resistance is highly dependent on both

M. R. Gomez; J. Zier; W. Tang; D. M. French; R. M. Gilgenbach; Y. Y. Lau; M. E. Cuneo; M. D. Johnston; M. G. Mazarakis; T. A. Mehlhorn

2007-01-01

34

Multichannel vacuum arc discharge used for Z-pinch formation  

NASA Astrophysics Data System (ADS)

Results are presented from experimental studies of the implosion dynamics and radiative characteristics of an aluminum Z-pinch formed from a plasma shell (PS). The PS with an initial diameter of 4 cm was produced with the help of a multichannel vacuum arc discharge and formed due to the evaporation of the electrode material in ten parallel arc discharges. The PS composition depended on the electrode material in the arc discharge. The described experiments were performed with aluminum electrodes. The total arc current was 80 kA. The PS implosion was provided by an IMRI-5 high-current generator with a current amplitude of 450 kA and rise time of 500 ns. The PS implosion resulted in the formation of a 0.2-cm-diameter plasma column with an electron temperature of 700-900 eV and average ion density of (5-8) × 1017 cm-3. The maximum radiation power per unit length in aluminum K-lines reached 300 MW/cm, the duration of the radiation pulse being 20 ns.

Rousskikh, A. G.; Baksht, R. B.; Zhigalin, A. S.; Oreshkin, V. I.; Chaikovsky, S. A.; Labetskaya, N. A.

2012-08-01

35

Z-pinch driven fusion energy  

SciTech Connect

The Z machine at Sandia National Laboratories (SNL) is the most powerful multi-module synchronized pulsed-power accelerator in the world. Rapid development of z-pinch loads on Z has led to outstanding progress in the last few years, resulting in radiative powers of up to 280 TW in 4 ns and a total radiated x-ray energy of 1.8 MJ. The present goal is to demonstrate single-shot, high-yield fusion capsules. Pulsed power is a robust and inexpensive technology, which should be well suited for Inertial Fusion Energy, but a rep-rated capability is needed. Recent developments have led to a viable conceptual approach for a rep-rated z-pinch power plant for IFE. This concept exploits the advantages of going to high yield (a few GJ) at low rep-rate ({approximately} 0.1 Hz), and using a Recyclable Transmission Line (RTL) to provide the necessary standoff between the fusion target and the power plant chamber. In this approach, a portion of the transmission line near the capsule is replaced after each shot. The RTL should be constructed of materials that can easily be separated from the liquid coolant stream and refabricated for a subsequent shots. One possibility is that most of the RTL is formed by casting FLiBe, a salt composed of fluorine, lithium, and beryllium, which is an attractive choice for the reactor coolant, with chemically compatible lead or tin on the surface to provide conductivity. The authors estimate that fusion yields greater than 1 GJ will be required for efficient generation of electricity. Calculations indicate that the first wall will have an acceptable lifetime with these high yields if blast mitigation techniques are used. Furthermore, yields above 5 GJ may allow the use of a compact blanket direct conversion scheme.

SLUTZ,STEPHEN A.; OLSON,CRAIG L.; ROCHAU,GARY E.; DERZON,MARK S.; PETERSON,P.F.; DEGROOT,J.S.; JENSEN,N.; MILLER,G.

2000-05-30

36

Chemically etched modulation in wire radius for wire array Z-pinch perturbation studies  

SciTech Connect

A technique for manufacturing wires with imposed modulation in radius with axial wavelengths as short as 1 mm is presented. Extruded aluminum 5056 with 15 {mu}m diameter was masked and chemically etched to reduce the radius by {approx}20% in selected regions. Characterized by scanning electron microscopy, the modulation in radius is a step function with a {approx}10 {mu}m wide conical transition between thick and thin segments, with some pitting in etched regions. Techniques for mounting and aligning these wires in arrays for fast z-pinch experiments will be discussed. Axially mass-modulated wire arrays of this type will allow the study of seeded Rayleigh-Taylor instabilities in z pinches, corona formation, wire initiation with varying current density in the wire core, and correlation of perturbations between adjacent wires. This tool will support magnetohydrodynamics code validation in complex three-dimensional geometries, and perhaps x-ray pulse shaping.

Jones, B.; Deeney, C.; McKenney, J.L.; Garrity, J.E.; Lobley, D.K.; Martin, K.L.; Griego, A.E.; Ramacciotti, J.P.; Bland, S.N.; Lebedev, S.V.; Bott, S.C.; Ampleford, D.J.; Palmer, J.B.A.; Rapley, J.; Hall, G. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); MPCL/Ktech Corp., Albuquerque, New Mexico 87123 (United States); Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)

2004-11-01

37

Chemically etched modulation in wire radius for wire array Z-pinch perturbation studies.  

SciTech Connect

A technique for manufacturing wires with imposed modulation in radius with axial wavelengths as short as 1 mm is presented. Extruded aluminum 5056 with 15 {micro}m diameter was masked and chemically etched to reduce the radius by {approx}20% in selected regions. Characterized by scanning electron microscopy, the modulation in radius is a step function with a {approx}10 {micro}m wide conical transition between thick and thin segments, with some pitting in etched regions. Techniques for mounting and aligning these wires in arrays for fast z-pinch experiments will be discussed. Axially mass-modulated wire arrays of this type will allow the study of seeded Rayleigh-Taylor instabilities in z pinches, corona formation, wire initiation with varying current density in the wire core, and correlation of perturbations between adjacent wires. This tool will support magnetohydrodynamics code validation in complex three-dimensional geometries, and perhaps x-ray pulse shaping.

Bland, Simon Nicholas (Blackett Laboratory, Imperial College, London, UK); Lebedev, S. V. (Blackett Laboratory, Imperial College, London, UK); Hall, G. (Blackett Laboratory, Imperial College, London, UK); Ramacciotti, J. P. (MPCL/Ktech Corp., Albuquerque, New Mexico); Griego, A. E. (MPCL/Ktech Corp., Albuquerque, New Mexico); Lobley, Dennis Keith (MPCL/Ktech Corp., Albuquerque, New Mexico); Martin, K. L. (MPCL/Ktech Corp., Albuquerque, New Mexico); Ampleford, David J. (Blackett Laboratory, Imperial College, London, UK); McKenney, John Lee; Bott, S. C. (Blackett Laboratory, Imperial College, London, UK); Garrity, James Emmett (MPCL/Ktech Corp., Albuquerque, New Mexico); Jones, B.; Rapley, J. (Blackett Laboratory, Imperial College, London, UK); Deeney, Christopher; Palmer, J. B. A. (Blackett Laboratory, Imperial College, London, UK)

2004-06-01

38

Z-Pinch Experiments with Styrofoam Fibres and Plasmajets  

NASA Astrophysics Data System (ADS)

Z-pinch plasmas created from fibres are less prone to macroscopic instabilities than predicted by ideal MHD theory. However, solid fibre experiments at the pulseline KALIF (2 MV, 900 kA) gave disappointing results with respect to driver-load coupling and pinch plasma confinement. High power discharges led to current leaks and plasma expansion presumably due to lacking initial conductivity and compressibility. Therefore two alternative schemes have been investigated: Solid fibres were replaced by styrofoam fibres with about 1 % solid density and plasmajets of a deuterium-argon mixture. Analyses of the experimental results showed no major differences between styrofoam and solid fibres. However, the plasmajet experiments resulted in significant improvements with respect to the initial discharge behaviour. Unfortunately, severe pinch disruptions about 40 ns after discharge initiation prevented pinch formation and confinement. The high electric field of the pulseline KALIF and the low density of the jet plasma (E/n > 10-15 Vm2) resulted in runaway electrons and plasma erosion rather than in magnetic confinement to the pinch.

Stein, S.; Decker, G.; Kies, W.; Röwekamp, P.; Ziethen, G.; Baumung, K.; Bluhm, H.; Ratajczak, W.; Rusch, D.; Bayley, J. M.

1994-03-01

39

Progress in Z-pinch inertial fusion energy.  

SciTech Connect

The goal of z-pinch inertial fusion energy (IFE) is to extend the single-shot z-pinch inertial confinement fusion (ICF) results on Z to a repetitive-shot z-pinch power plant concept for the economical production of electricity. Z produces up to 1.8 MJ of x-rays at powers as high as 230 TW. Recent target experiments on Z have demonstrated capsule implosion convergence ratios of 14-21 with a double-pinch driven target, and DD neutron yields up to 8x10exp10 with a dynamic hohlraum target. For z-pinch IFE, a power plant concept is discussed that uses high-yield IFE targets (3 GJ) with a low rep-rate per chamber (0.1 Hz). The concept includes a repetitive driver at 0.1 Hz, a Recyclable Transmission Line (RTL) to connect the driver to the target, high-yield targets, and a thick-liquid wall chamber. Recent funding by a U.S. Congressional initiative for $4M for FY04 is supporting research on RTLs, repetitive pulsed power drivers, shock mitigation, full RTL cycle planned experiments, high-yield IFE targets, and z-pinch power plant technologies. Recent results of research in all of these areas are discussed, and a Road Map for Z-Pinch IFE is presented.

Weed, John Woodruff

2010-03-01

40

The ZaP Flow Z-Pinch Project  

SciTech Connect

The results from the ZaP experiment are consistent with the theoretical predictions of sheared flow stabilization. Z pinches with a sheared flow are generated in the ZaP experiment using a coaxial accelerator coupled to an assembly region. The current sheet in the accelerator initially acts as a snowplow. As the Z pinch forms, plasma formation in the accelerator transits to a deflagration process. The plasma exits the accelerator and maintains the flow in the Z pinch. During the quiescent period in the magnetic mode activity at z=0 cm, a stable Z pinch is seen on the axis of the assembly region. The evolution of the axial velocity profile shows a large velocity shear is measured at the edge of the Z pinch during the quiescent period. The velocity shear is above the theoretical threshold. As the velocity shear decreases towards 0.1kV{sub A}, the predicted stability threshold, the quiescent period ends. The present understanding of the ZaP experiment shows that it may be possible for the Z pinch to operate in a steady state if the deflagration process can be maintained by constantly supplying neutral gas or plasma to the accelerator.

Shumlak, U.; Nelson, B. A.

2005-09-01

41

Experimental Investigation of Sheared Flow Stabilization of Z-pinches  

NASA Astrophysics Data System (ADS)

The wire array z-pinch is an efficient x-ray source [1] which has been proposed for use in indirect drive inertial confinement fusion schemes [2]. The z-pinch can become a more efficient x-ray source if its stability is improved. Cylindrical wire array z-pinch experiments where the Rayleigh-Taylor instability was suppressed showed increased x-ray yield and power [1]; however the pressure driven MHD instabilities (sausage and kink instabilities) were still present and possibly limited the x-ray production of the pinch. Linear MHD calculations of z-pinch stability with an axial velocity shear predict that a supersonic axial flow with a radial gradient is capable of stabilizing the MHD instabilities [3][4][5]. A sheared flow can be introduced to a pinch by using a conical wire array with a fine metallic wire on axis [6]. The wire on axis will carry a fraction of the total current during the implosion which will cause the center wire to create a conducting plasma column while a flow passes over it. This presentation will compare the experimental results of a z-pinch with and without a sheared flow. From this comparison it will be shown that the sheared flow in these experiments has a stabilizing effect on the MHD instabilities present in the z-pinch plasma column.

Martinez, David

42

Z-Pinch Pulsed Plasma Propulsion Technology Development  

NASA Technical Reports Server (NTRS)

Fusion-based propulsion can enable fast interplanetary transportation. Magneto-inertial fusion (MIF) is an approach which has been shown to potentially lead to a low cost, small reactor for fusion break even. The Z-Pinch/dense plasma focus method is an MIF concept in which a column of gas is compressed to thermonuclear conditions by an axial current (I approximates 100 MA). Recent advancements in experiments and the theoretical understanding of this concept suggest favorable scaling of fusion power output yield as I(sup 4). This document presents a conceptual design of a Z-Pinch fusion propulsion system and a vehicle for human exploration. The purpose of this study is to apply Z-Pinch fusion principles to the design of a propulsion system for an interplanetary spacecraft. This study took four steps in service of that objective; these steps are identified below. 1. Z-Pinch Modeling and Analysis: There is a wealth of literature characterizing Z-Pinch physics and existing Z-Pinch physics models. In order to be useful in engineering analysis, simplified Z-Pinch fusion thermodynamic models are required to give propulsion engineers the quantity of plasma, plasma temperature, rate of expansion, etc. The study team developed these models in this study. 2. Propulsion Modeling and Analysis: While the Z-Pinch models characterize the fusion process itself, propulsion models calculate the parameters that characterize the propulsion system (thrust, specific impulse, etc.) The study team developed a Z-Pinch propulsion model and used it to determine the best values for pulse rate, amount of propellant per pulse, and mixture ratio of the D-T and liner materials as well as the resulting thrust and specific impulse of the system. 3. Mission Analysis: Several potential missions were studied. Trajectory analysis using data from the propulsion model was used to determine the duration of the propulsion burns, the amount of propellant expended to complete each mission considered. 4. Vehicle Design: To understand the applicability of Z-Pinch propulsion to interplanetary travel, it is necessary to design a concept vehicle that uses it -- the propulsion system significantly impacts the design of the electrical, thermal control, avionics and structural subsystems of a vehicle. The study team developed a conceptual design of an interplanetary vehicle that transports crew and cargo to Mars and back and can be reused for other missions. Several aspects of this vehicle are based on a previous crewed fusion vehicle study -- the Human Outer Planet Exploration (HOPE) Magnetized Target Fusion (MTF) vehicle. Portions of the vehicle design were used outright and others were modified from the MTF design in order to maintain comparability.

Polsgrove, Tara; Adams, Robert B.; Fabisinski, Leo; Fincher, Sharon; Maples, C. Dauphne; Miernik, Janie; Percy, Tom; Statham, Geoff; Turner, Matt; Cassibry, Jason; Cortez, Ross; Santarius, John

2010-01-01

43

High density Z pinch formed from a solid deuterium fiber  

SciTech Connect

Experiments in which 250 kA have been passed through a z-pinch column formed from a thin fiber of cryogenic solid deuterium have demonstrated unexpectedly stable behavior. It has been shown that it is possible to maintain a z pinch in near radial equilibrium while it is ohmically heated from 16/sup 0/K to several hundred eV. These results have motivated an effort to increase the plasma current to 1 MA and above, giving the potential of producing reactor-relevant plasmas capable of significant thermonuclear burn. Such a megamp experiment has been designed, partially fabricated, and successfully tested with an existing generator.

Hammel, J.E.; Scudder, D.W.

1987-01-01

44

Measurements of Z-pinch plasma parameters with crystal spectroscopy on PBFAZ and SATURN  

SciTech Connect

The authors have used a spatially-resolved time-integrated convex crystal spectrometer to measure spectra above 1 keV on the pulsed power machines PBFAZ and SATURN. They observe a tungsten M absorption edge from tungsten z-pinches on PBFAZ. From the energy shift and depth of the edge they infer the z-pinch halo plasma electron temperature and rho*r to be 150 eV and 0.00018 g/sq cm. The slope of the tungsten spectrum indicates a 700 eV core electron temperature on PBFAZ, up from a 350 eV slope measured on the smaller accelerator SATURN. In contrast to tungsten pinches on SATURN, for an array consisting of aluminum wires coated with potassium chloride, they have measured the core electron temperature by three independent techniques to be 1,200 eV. These three techniques are the aluminum K-shell free-bound continuum slope, the ratio of isoelectronic helium-alpha lines in potassium and chlorine, and the ratio or Lyman to helium alpha in chloride.

Nash, T.; Deeney, C.; Sanford, T.W.L. [Sandia National Labs., Albuquerque, NM (United States)] [and others

1997-12-31

45

High Power Selective Laser Melting (HP SLM) of Aluminum Parts  

NASA Astrophysics Data System (ADS)

Selective Laser Melting (SLM) is one of the Additive Manufacturing (AM) technologies that enables the production of light weight structured components with series identical mechanical properties without the need for part specific tooling or downstream sintering processes, etc. Especially aluminum is suited for such eco-designed components due to its low weight and superior mechanical and chemical properties. However, SLM's state-of-the-art process and cost efficiency is not yet suited for series-production. In order to improve this efficiency it is indispensable to increase the build rate significantly. Thus, aluminum is qualified for high build rate applications using a new prototype machine tool including a 1 kW laser and a multi-beam system.

Buchbinder, D.; Schleifenbaum, H.; Heidrich, S.; Meiners, W.; Bültmann, J.

46

High Power Selective Laser Melting (HP SLM) of Aluminum Parts  

Microsoft Academic Search

Selective Laser Melting (SLM) is one of the Additive Manufacturing (AM) technologies that enables the production of light weight structured components with series identical mechanical properties without the need for part specific tooling or downstream sintering processes, etc. Especially aluminum is suited for such eco-designed components due to its low weight and superior mechanical and chemical properties. However, SLM's state-of-the-art

D. Buchbinder; H. Schleifenbaum; S. Heidrich; W. Meiners; J. Bültmann

2011-01-01

47

Adaptive Wavelet Techniques in Fast Z Pinch Research  

Microsoft Academic Search

Various theoretical models describing aspects of Z pinch dynamics involve disperate space scales whose resolution is numerically challenging. We have been exploring adaptive wavelet techniques which could be the best possible answer to the question of tiling relevant sections of phase space efficiently. MHD, Vlasov and kinetic models including collisions can all benefit from the prospect of maximally compact operator

Bedros B. Afeyan; M. R. Douglas; R. B. Spielman

1999-01-01

48

Wire array z-pinch insights for high x-ray power generation  

SciTech Connect

The discovery that the use of very large numbers of wires enables high x-ray power to be generated from wire-array z-pinches represents a breakthrough in load design for large pulsed power generators, and has permitted high temperatures to be generated in radiation cavities on Saturn. In this paper, changes in x-ray emission characteristics as a function of wire number, array mass, and load radius, for 20-mm-long aluminum arrays on Saturn that led to these breakthrough hohlraum results, are discussed and compared with a few related emission characteristics of high-wire-number aluminum and tungsten arrays on Z. X=ray measurement comparisons with analytic models and 2-D radiation-magnetohydrodynamic (RMHC) code simulations in the x-y and r-z planes provide confidence in the ability of the models and codes to predict future x-ray performance with very-large-number wire arrays.

Sanford, T.W.L.; Mock, R.C.; Nash, T.J. [and others

1998-08-01

49

Wire array z-pinch insights for high X-ray power generation  

SciTech Connect

The discovery that the use of very large numbers of wires enables high x-ray power to be generated from wire-array z-pinches represents a breakthrough in load design for large pulsed power generators, and has permitted high temperatures to be generated in radiation cavities on Saturn and Z. In this paper, changes in x-ray emission characteristics as a function of wire number, array mass, and load radius, for 20-mm-long aluminum arrays on Saturn that led to these breakthrough hohlraum results, are discussed and compared with a few related emission characteristics of high-wire-number aluminum and tungsten arrays on Z. X-ray measurement comparisons with analytic models and 2-D radiation-magnetohydrodynamic (RMHC) code simulations in the x-y and r-z planes provide confidence in the ability of the models and codes to predict future x-ray performance with very-large-number wire arrays.

Sanford, T.W.L.; Marder, B.M.; Desjarlais, M.P. [and others

1998-12-31

50

Study of Wire Contact Resistance in Single and Multi-wire Z-Pinch Experiments  

NASA Astrophysics Data System (ADS)

Contact resistance of single and multi-wire array z-pinch has been measured for aluminum, stainless steel, and tungsten wires; diameters ranged from 7.5 to 30.5 micron. DC contact resistance in these experiments accounted for approximately 80% of load resistance, and resistance measurements varied from wire-to-wire by up to 15%. These DC measurements show that the resistance is highly dependent on both the wire material and the mass of the wire weights (0.8 g to 3.6 g). Marx pulses of 120 kV, 18 kA, 150 ns risetime were applied to the z-pinch. Wire plasma expansion velocity was measured using a streak camera, and expansion profile of the wires was determined using laser schlieren imaging. Electron temperature of individual wire plasmas is being determined by visible/UV spectra. Results will be presented of several methods being explored to reduce the contact resistance. *This work was supported by U. S. DoE through Sandia National Laboratories award number 240985 to the University of Michigan. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

Gomez, M. R.; Zier, J.; Tang, W.; French, D. M.; Gilgenbach, R. M.; Lau, Y. Y.; Cuneo, M. E.; Johnston, M. D.; Mazarakis, M. G.; Mehlhorn, T. A.

2007-11-01

51

An Inertial-Fusion Z-Pinch Power Plant Concept  

SciTech Connect

With the promising new results of fast z-pinch technology developed at Sandia National Laboratories, we are investigating using z-pinch driven high-yield Inertial Confinement Fusion (ICF) as a fusion power plant energy source. These investigations have led to a novel fusion system concept based on an attempt to separate many of the difficult fusion engineering issues and a strict reliance on existing technology, or a reasonable extrapolation of existing technology, wherever possible. In this paper, we describe the main components of such a system with a focus on the fusion chamber dynamics. The concept works with all of the electrically-coupled ICF proposed fusion designs. It is proposed that a z-pinch driven ICF power system can be feasibly operated at high yields (1 to 30 GJ) with a relatively low pulse rate (0.01-0.1 Hz). To deliver the required current from the rep-rated pulse power driver to the z-pinch diode, a Recyclable Transmission Line (RTL) and the integrated target hardware are fabricated, vacuum pumped, and aligned prior to loading for each power pulse. In this z-pinch driven system, no laser or ion beams propagate in the chamber such that the portion of the chamber outside the RTL does not need to be under vacuum. Additionally, by utilizing a graded-density solid lithium or fluorine/lithium/beryllium eutectic (FLiBe) blanket between the source and the first-wall the system can breed its own fuel absorb a large majority of the fusion energy released from each capsule and shield the first-wall from a damaging neutron flux. This neutron shielding significantly reduces the neutron energy fluence at the first-wall such that radiation damage should be minimal and will not limit the first-wall lifetime. Assuming a 4 m radius, 8 m tall cylindrical chamber design with an 80 cm thick spherical FLiBe blanket, our calculations suggest that a 20 cm thick 6061-T6 Al chamber wall will reach the equivalent uranium ore radioactivity level within 100 years after a 30 year plant operation. The implication of this low radioactivity is that a z-pinch driven power plant may not require deep geologic waste storage.

DERZON,MARK S.; ROCHAU,GARY E.; DEGROOT,J.; OLSON,CRAIG L.; PETERSON,P.; PETERSON,R.R.; SLUTZ,STEPHEN A.; ZAMORA,ANTONIO J.

2000-12-15

52

Azimuthal structure in wire-array Z pinch experiments  

Microsoft Academic Search

Nested wire-array loads on Z with a high degree of azimuthal symmetry in the outside current-return-shell (which surrounds a z pinch) exhibit a 6±2 azimuthal mode structure in the axial X-ray emission near stagnation when the pinch is viewed from above through a small radiation-exit-hole in the anode. MACH3 numerical simulations show that if a low-number mode like 6 does

Thomas W. L. Sanford; Norman F. Roderick; Raymond C. Mock; Kenneth W. Struve; Darrell L. Peterson

2002-01-01

53

Neon photoionization experiments driven by Z-pinch radiation  

Microsoft Academic Search

Present-day Z-pinch experiments generate ?2×1021erg\\/s peak power, ?6ns full-width at half-maximum X-ray bursts that provide new possibilities to study radiation-heated matter. This source is being used to investigate the production of plasmas in which photoionization dominates collisional ionization. Spectroscopic measurements of such plasmas can serve to benchmark atomic physics models of the photoionized plasmas. Beyond intrinsic interest in the atomic

J. E. Bailey; D. Cohen; G. A. Chandler; M. E. Cuneo; M. E. Foord; R. F. Heeter; D. Jobe; P. Lake; D. A. Liedahl; J. J. MacFarlane; T. J. Nash; D. Nielson; R. Smelser; W. A. Stygar

2001-01-01

54

Evaluation of a Z-pinch-driven ICF Concept  

NASA Astrophysics Data System (ADS)

We are developing a technique for driving static-walled hohlraums with x-rays from a z-pinch radiation source. In this ICF concept, radiation from z-pinch stagnation provides the x-ray input on both ends of a cylindrical hohlraum containing a low density, low-Z fill; high-Z symmetry shields; and a 1-2 mm diameter cryogenic DT-filled capsule. Numerical simulations indicate that a 60 MA Z-pinch driver would be required to achieve ignition conditions. In order to gain preliminary understanding of the hohlraum concept and to test our numerical simulations, we have performed a series of hohlraum experiments with a scaled down, single-sided drive at the 20 MA level in the SNL Z-facility. In these experiments, the hohlraums (6 mm diameter and 7 mm long) have been successfully heated to radiation temperatures in the range of 80-100 eV. Experiments to date include investigations of hohlraum diagnostic hole closure, axial temperature gradients, pulse shaping, azimuthal symmetry, and radiation transport in capsule / shine shield configurations. The ignition concept, the experimental results, and the shortcomings and successes of the numerical simulations will be discussed in this presentation.

Olson, R. E.; Chandler, G. A.; Sanford, T. W. L.; Alberts, T. E.; Derzon, M. S.; Fehl, D. L.; Gilliland, T. L.; Hebron, D. E.; Jobe, D. O.; Lash, J. S.; Leeper, R. J.; McGuire, E. J.; McGurn, J. S.; Mills, J. A.; Nash, T. J.; Ruggles, L.; Struve, K. W.; Stygar, W. A.; Torres, J. A.; Vargas, M.; Vesey, R..

1998-11-01

55

X-ray power increase from symmetrized wire-array z-pinch implosions  

SciTech Connect

A systematic experimental study of annular aluminum-wire z-pinches on the Saturn accelerator shows that, for the first time, the measured spatial characteristics and x-ray powers can approach those of two-dimensional, radiation-magneto-hydrodynamic simulations when large numbers of wires are used. Calculations show that the implosion begins to transition from that of individual plasma wires to that of a continuous plasma shell, when the circumferential gap between wires in the array is reduced below 1.4+1.3/-0.7 mm. This calculated gap coincides with the measured transition of 1.4 {+-}0.4 mm between the observed regimes of slow and rapid improvement in power output with decreasing gap. In the plasma shell regime, x-ray powers in excess of a factor of three over that generated in the plasma-wire region are measured.

Sanford, T.W.L.; Allshouse, G.O.; Marder, B.M. [and others

1996-08-01

56

Z-Pinch fusion-based nuclear propulsion  

NASA Astrophysics Data System (ADS)

Fusion-based nuclear propulsion has the potential to enable fast interplanetary transportation. Due to the great distances between the planets of our solar system and the harmful radiation environment of interplanetary space, high specific impulse (Isp) propulsion in vehicles with high payload mass fractions must be developed to provide practical and safe vehicles for human space flight missions. The Z-Pinch dense plasma focus method is a Magneto-Inertial Fusion (MIF) approach that may potentially lead to a small, low cost fusion reactor/engine assembly [1]. Recent advancements in experimental and theoretical understanding of this concept suggest favorable scaling of fusion power output yield [2]. The magnetic field resulting from the large current compresses the plasma to fusion conditions, and this process can be pulsed over short timescales (10-6 s). This type of plasma formation is widely used in the field of Nuclear Weapons Effects testing in the defense industry, as well as in fusion energy research. A Z-Pinch propulsion concept was designed for a vehicle based on a previous fusion vehicle study called "Human Outer Planet Exploration" (HOPE), which used Magnetized Target Fusion (MTF) [3] propulsion. The reference mission is the transport of crew and cargo to Mars and back, with a reusable vehicle. The analysis of the Z-Pinch MIF propulsion system concludes that a 40-fold increase of Isp over chemical propulsion is predicted. An Isp of 19,436 s and thrust of 3812 N s/pulse, along with nearly doubling the predicted payload mass fraction, warrants further development of enabling technologies.

Miernik, J.; Statham, G.; Fabisinski, L.; Maples, C. D.; Adams, R.; Polsgrove, T.; Fincher, S.; Cassibry, J.; Cortez, R.; Turner, M.; Percy, T.

2013-02-01

57

High energy density Z-pinch plasmas using flow stabilization  

NASA Astrophysics Data System (ADS)

The ZaP Flow Z-Pinch research project[1] at the University of Washington investigates the effect of sheared flows on MHD instabilities. Axially flowing Z-pinch plasmas are produced that are 100 cm long with a 1 cm radius. The plasma remains quiescent for many radial Alfvén times and axial flow times. The quiescent periods are characterized by low magnetic mode activity measured at several locations along the plasma column and by stationary visible plasma emission. Plasma evolution is modeled with high-resolution simulation codes - Mach2, WARPX, NIMROD, and HiFi. Plasma flow profiles are experimentally measured with a multi-chord ion Doppler spectrometer. A sheared flow profile is observed to be coincident with the quiescent period, and is consistent with classical plasma viscosity. Equilibrium is determined by diagnostic measurements: interferometry for density; spectroscopy for ion temperature, plasma flow, and density[2]; Thomson scattering for electron temperature; Zeeman splitting for internal magnetic field measurements[3]; and fast framing photography for global structure. Wall stabilization has been investigated computationally and experimentally by removing 70% of the surrounding conducting wall to demonstrate no change in stability behavior.[4] Experimental evidence suggests that the plasma lifetime is only limited by plasma supply and current waveform. The flow Z-pinch concept provides an approach to achieve high energy density plasmas,[5] which are large, easy to diagnose, and persist for extended durations. A new experiment, ZaP-HD, has been built to investigate this approach by separating the flow Z-pinch formation from the radial compression using a triaxial-electrode configuration. This innovation allows more detailed investigations of the sheared flow stabilizing effect, and it allows compression to much higher densities than previously achieved on ZaP by reducing the linear density and increasing the pinch current. Experimental results and scaling analyses will be presented. In addition to studying fundamental plasma science and high energy density physics, the ZaP and ZaP-HD experiments can be applied to laboratory astrophysics.

Shumlak, U.; Golingo, R. P.; Nelson, B. A.; Bowers, C. A.; Doty, S. A.; Forbes, E. G.; Hughes, M. C.; Kim, B.; Knecht, S. D.; Lambert, K. K.; Lowrie, W.; Ross, M. P.; Weed, J. R.

2014-12-01

58

Thermal Analysis of the Z-Pinch Power Plant Concept  

SciTech Connect

In this work, a preliminary thermal model for the Z-Pinch Power Plant is presented. This power plant utilizes fusion energy to generate electric energy in the GW range. The Z-Pinch Technology consists of compressing high-density plasma to produce X-rays to indirectly heat to ignition a deuterium/tritium fusion capsule. This ignition releases a minimum of 3 GJ every 10 seconds. The thermal energy generated is absorbed by the primary cycle fluid, and it is later used to power a Brayton or Rankine cycle. An advanced heat exchanger is used as the interface between the two cycles. This heat exchanger plays an important role in power plant performance. Three fluids (Flibe, Pb-17Li, and Li) were used for the plant performance analysis. The thermodynamic properties of the selected fluids determine the maximum operating temperature of the power cycles. Model results show that high temperatures (over 1000 deg. C) are developed in the primary cycle as needed to efficiently run the secondary cycle. The results of the performance parametric study demonstrated that the Brayton cycle exhibits better performance characteristics than the Rankine cycle for this type of application.

Modesto, M.A.; Lindgren, E.R.; Morrow, C.W. [Sandia National Laboratories (United States)

2005-04-15

59

Z pinch driven inertial confinement fusion target physics research at Sandia National Laboratories  

Microsoft Academic Search

Three hohlraum concepts are being pursued at Sandia National Laboratories (SNL) to investigate the possibility of using pulsed power driven magnetic implosions (Z pinches) to drive targets capable of fusion yields in the range 200-1000 MJ. This research is being conducted on SNL's Z facility, which is capable of driving peak currents of 20 MA in various Z pinch load

R. J. Leeper; T. E. Alberts; J. R. Asay; P. M. Baca; K. L. Baker; S. P. Breeze; G. A. Chandler; D. L. Cook; G. W. Cooper; C. Deeney; M. S. Derzon; M. R. Douglas; D. L. Fehl; T. Gilliland; D. E. Hebron; M. J. Hurst; D. O. Jobe; J. W. Kellogg; J. S. Lash; S. E. Lazier; M. K. Matzen; D. H. McDaniel; J. S. McGurn; T. A. Mehlhorn; A. R. Moats; R. C. Mock; D. J. Muron; T. J. Nash; R. E. Olson; J. L. Porter; J. P. Quintenz; P. V. Reyes; L. E. Ruggles; C. L. Ruiz; T. W. L. Sanford; F. A. Schmidlapp; J. F. Seamen; R. B. Spielman; M. A. Stark; K. W. Struve; W. A. Stygar; D. R. Tibbetts-Russell; J. A. Torres; M. Vargas; T. C. Wagoner; C. Wakefield; J. H. Hammer; D. D. Ryutov; M. Tabak; S. C. Wilks; R. L. Bowers; K. D. McLenithan; D. L. Peterson

1999-01-01

60

Tungsten Z-Pinch Long Implosions on the Saturn Generator  

SciTech Connect

Recent success on the Saturn and Z accelerators at Sandia National Laboratories have demonstrated the ability to scale z-pinch parameters to increasingly larger current pulsed power facilities. Next generation machines will require even larger currents (>20 MA), placing further demands on pulsed power technology. To this end, experiments have been carried out on Saturn operating in a long pulse mode, investigating the potential of lower voltages and longer implosion times while still maintaining pinch fidelity. High wire number, 25 mm diameter tungsten arrays were imploded with implosion times ranging from 130 to 240 ns. The results were comparable to those observed in the Saturn short pulse mode, with risetimes on the order of 4.5 to 6.5 ns. Experimental data will be presented, along with two dimensional radiation magnetohydrodynamic simulations used to explain and reproduce the experiment.

DOUGLAS,MELISSA R.; DEENEY,CHRISTOPHER; SPIELMAN,RICK B.; COVERDALE,CHRISTINE A.; RODERICK,N.F.; HAINES,M.G.

1999-11-05

61

Shrapnel Formation in a Z-Pinch Power Plant  

NASA Astrophysics Data System (ADS)

The mainline z-pinch IFE power plant design has a recyclable transmission line (RTL) that drives a fusion capsule with output energy in the range of about 3 GJ. The deposition of this energy will result in the RTL close to the target being transformed to high temperature plasma. The RTL farther away from the fusion capsule will be converted to liquid and shrapnel. The shrapnel is composed of droplets, aerosols, liquid, and solid metal. Continuum theory and molecular dynamics calculations are being used to quantify the shrapnel production as a result of spallation driven by shock reflection. The study will also focus on the essential issue of the defect content in the RTL material. We are developing scaling laws that show which sections of the RTL are turned into plasma, droplets, aerosols, liquid, and solid metal. We are also evaluating the effects of post-shot EMP, plasma, droplets, and shrapnel up the RTL.

de Groot, John

2005-10-01

62

Magnetic Flux Compression with a Gas Puff Z Pinch.  

NASA Astrophysics Data System (ADS)

The dynamics of a hollow gas puff z pinch imploding with a trapped, initially uniform, axial magnetic field is studied on the 0.45 MA, 1.2 mu s rise-time U.C. Irvine z pinch. The primary purpose is to ascertain the feasibility of producing short pulsed ultrahigh magnetic fields with this geometry. Data is taken primarily for Ne and Kr plasmas with a pulsed (7 ns) interferometer, twin pinhole cameras, x-ray diodes, and axial and azimuthal magnetic probes. The spatiotemporal behavior of the plasma is mapped by numerically processed interference patterns. Significant differences between Kr and Ne are recorded with this diagnostic. Kr implodes as a thinner shell which appears more disrupted by spatial nonuniformities of scale-length order 1 mm. Kr, though, achieves a much higher state of compression than Ne. Kr implosions with an initial axial magnetic field of 0.5 T are inferred to produce a field of 150 T at maximum compression assuming the axial magnetic flux interior to the plasma column is conserved during the implosion. This is an order of magnitude higher than can be similarly inferred for Ne implosions. The assumption of flux conservation is reasonably justified for Ne by correlation with on-axis magnetic probe measurements, although the field for Kr rises too quickly for the probe to respond. To help explain these results, the significance of such effects as Rayleigh -Taylor and MHD instabilities, radiation cooling, resistive flux diffusion, and plasma end-loss on flux compression performance are inferred from the data and studied with the help of simple theoretical models.

Ruden, Edward Lee

63

Instability heating of solid-fiber Z pinches  

NASA Astrophysics Data System (ADS)

The Los Alamos High Density Z Pinch-II (HDZP-II) facility is used to study the dynamics of z-pinch plasmas generated from solid fibers of deuterated polyethylene CD(sub 2) with a range in radii of 3-60 microns. HDZP-II is a pulsed-power generator that delivers a current that rises to 700 kA in 100 ns through an inductive load. A multiframe circular schlieren records the evolution of the shape and size of the plasma on seven images taken at 10-ns intervals. These circular-schlieren images show very strong m=0 instability at the onset of current and a rapid radial expansion of the plasma. No higher-order instabilities are observed. An interferometer is used to infer the electron density and electron line density, giving a measure of the fraction of plasma contained within the outline of the circular-schlieren image at one time during the multiframe sequence. A three-channel x-ray crystal-reflection spectrometer provides the time-resolved, spatially-averaged electron temperature. The magnitude of the x-ray emission at these energies also gives qualitative information about the electron temperature and density at late times. A lower bound on the ion temperature is inferred from the particle pressure needed to balance the magnetic field pressure. The ion temperature rose above that of the electrons, strongly suggesting an additional heating term that puts energy directly into the ions. An ion heating term is proposed to explain the observed rapid radial expansion and elevated ion temperatures. This heating term is based on the assumption that the observed m=0 instabilities reconnect, enclosing magnetic flux which degenerates into turbulence in the plasma. A 0-D simulation is developed to investigate the relevance of different physical models to the data presented.

Riley, R. A., Jr.

1994-02-01

64

Z-Pinch Wire-Electrode Contact Resistance Studies Using Weighted and Soft Metal Gasket Contacts*  

NASA Astrophysics Data System (ADS)

The contact made between z-pinch wires and electrodes has a significant effect on both the energy deposited in the wires and the uniformity of the expansion profile of the wires. We have shown that using soft metal gaskets can improve wire-electrode contact significantly over typical weighted contacts. Images of wire expansion profile and wire plasma emission will be presented for single and double wire shots on a 16 kA, 100 kV 4-stage Marx bank with 150 ns risetime. Bench resistance measurements for aluminum, stainless steel, and tungsten wires with diameters ranging from 7.5 um to 30 um will be presented. These measurements utilized both soft metal gasket contacts (gaskets include: indium, silver, aluminum, tin, and lead) and double-ended wire weight contacts (weights ranged from 0.4 g to 1.9 g). *This research was supported by U. S. DoE through Sandia National Laboratories award document numbers 240985, 768225, 790791 and 805234 to the University of Michigan. MRG supported by NNSA Fellowship and JCZ supported by NPSC Fellowship sponsored by Sandia National Labs.

Gomez, M. R.; Zier, J. C.; Thurtell, A. F.; French, D. M.; Gilgenbach, R. M.; Tang, W.; Lau, Y. Y.

2008-11-01

65

The effect of load thickness on Rayleigh-Taylor mitigation in high velocity, annular z pinch implosion  

SciTech Connect

Numerical calculations have been performed to investigate the role that load thickness may play in the performance of fast annular z pinch implosions. In particular, the effects of load thickness on the mitigation of the magnetically-driven Rayleigh-Taylor (RT) instability and energy coupling between the load and generator are addressed. using parameters representative of the Z accelerator [R.B.Spielman et al., Phys.Plasmas, 5, 2105 (1998)] at Sandia National Laboratories, two dimensional magnetohydrodynamic (MHD) simulations show that increased shell thickness results in lower amplitude, slightly longer wavelength RT modes. In addition, there appears to be an optimum in load velocity which is directly associated with the thickness of the sheath and subsequent RT growth. Thin, annular loads, which should couple efficiently to the accelerator, show a large reduction in implosion velocity due to extreme RT development and increased load inductance. As a consequence, thicker loads on the order of 5 mm, couple almost as efficiently to the generator since the RT growth is reduced. This suggests that z-pinch loads can be tailored for different applications, depending on the need for uniformity or high powers.

DOUGLAS,MELISSA R.; DEENEY,CHRISTOPHER; RODERICK,NORMAN F.

2000-05-16

66

X-ray imaging measurements of capsule implosions driven by a Z-pinch dynamic hohlraum.  

PubMed

The radiation and shock generated by impact of an annular tungsten Z-pinch plasma on a 10-mm diam 5-mg/cc CH(2) foam are diagnosed with x-ray imaging and power measurements. The radiative shock was virtually unaffected by Z-pinch plasma instabilities. The 5-ns-duration approximately 135-eV radiation field imploded a 2.1-mm-diam CH capsule. The measured radiation temperature, shock radius, and capsule radius agreed well with computer simulations, indicating understanding of the main features of a Z-pinch dynamic-hohlraum-driven capsule implosion. PMID:12190409

Bailey, J E; Chandler, G A; Slutz, S A; Bennett, G R; Cooper, G; Lash, J S; Lazier, S; Lemke, R; Nash, T J; Nielsen, D S; Moore, T C; Ruiz, C L; Schroen, D G; Smelser, R; Torres, J; Vesey, R A

2002-08-26

67

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.

68

A non-LTE kinetic model for quick analysis of K-shell spectra from Z-pinch plasmas  

NASA Astrophysics Data System (ADS)

Analyzing and modeling K-shell spectra emitted by low-to moderate-atomic number plasma is a useful and effective way to retrieve temperature density of z-pinch plasmas. In this paper, a non-LTE population kinetic model for quick analysis of K-shell spectra was proposed. The model contains ionization stages from bare nucleus to neutral atoms and includes all the important atomic processes. In the present form of the model, the plasma is assumed to be both optically thin and homogeneous with constant temperature and density, and only steady-state situation is considered. According to the detailed calculations for aluminum plasmas, contours of ratios of certain K-shell lines in electron temperature and density plane as well as typical synthesized spectra were presented and discussed. The usefulness of the model is demonstrated by analyzing the spectrum from a neon gas-puff Z-pinch experiment performed on a 1 MA pulsed-power accelerator.

Li, J.; Huang, X. B.; Cai, H. C.; Yang, L. B.; Xie, W. P.; Duan, S. C.

2014-12-01

69

Preliminary experiments on the production of high photon energy continuum radiation from a Z-pinch at the Z accelerator  

NASA Astrophysics Data System (ADS)

Traditionally, the generation of multi-keV x-ray radiation from Z-pinch plasmas has focused on K-shell emissions from moderate Z materials. While this approach has worked well, it requires increasingly higher energies be coupled to each ion to produce substantial output as the photon energy increases. An alternate approach to generating multi-keV radiation, proposed in Ref. 1, utilizes lower Z materials than are necessary to generate the appropriate K-shell lines, but tailors the Z-pinch load to overheat the plasma in order to enhance the recombination radiation that is generated. Initial experiments have been performed at the Z Accelerator to evaluate the level of recombination radiation that can be generated through the tailoring of initial load radius and mass with Aluminum and Titanium wire arrays. In this paper, the results of these experiments will be presented. Measurements of yield were made for several photon energy ranges and spectra were collected to evaluate the high energy continuum. These results will be compared with simulations and theoretical predictions to evaluate the feasibility of an overheated plasma for generating higher photon energy emissions. This work is supported by the Defense Threat Reduction Agency and the Department of Energy. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AI85000. *Ktech Corporation [1] A.L. Velikovich, et. al., Phys. Plasmas 8, 4509 (2001).

Coverdale, C. A.; Deeney, C.; Harper-Slaboscewica, V. J.; Lepell, P. D.; Velikovich, A. L.; Davis, J.; Oreshkin, V. I.

2003-10-01

70

Indirect-drive ICF target concepts for the X-1 Z-pinch facility  

Microsoft Academic Search

The authors describe designs of hohlraums and capsules for both ignition (â¼1--10 MJ) and high yield (up to â¼200 MJ) Z-pinch driven indirect-drive ICF concepts. Two potential Z-pinch hohlraum configurations: (1) the static wall or on-axis hohlraum; and (2) the imploding liner or dynamic hohlraum are considered. Both concepts involve cryogenic, DT-filled capsules (â¼2--4 mm in diameter) with Be or

R. E. Olson; G. A. Chandler; M. S. Derzon

1999-01-01

71

Measurements of Z-pinch plasma parameters with crystal spectroscopy on PBFAZ and SATURN  

Microsoft Academic Search

Summary form only given. We have used a spatially-resolved time-integrated convex crystal spectrometer to measure spectra above 1 keV on the pulsed power machines PBFAZ and SATURN. We observe a tungsten M absorption edge from tungsten Z-pinches on PBFAZ. From the energy shift and depth of the edge we infer the Z-pinch halo plasma electron temperature and rho*r to be

T. Nash; C. Deeney; T. W. L. Sanford; G. A. Chandler; R. B. Spielman; D. Jobe; J. Seaman; T. K. Gilliland; J. McGurn; J. MacFarlane; J. P. Apruzese; K. G. Whitney; P. E. Pulsifier; J. Davis; B. Failor; P. D. LePell; B. Whitton; J. C. Riordan; E. Yadlowsky

1997-01-01

72

The importance of EBIT data for Z-pinch plasma diagnostics  

Microsoft Academic Search

The results from the last six years of x-ray spectroscopy and spectropolarimetry of high energy density Z-pinch plasmas complemented by experiments with the electron beam ion trap (EBIT) at the Lawrence Livermore National Laboratory (LLNL) are presented. The two topics discussed are the development of M-shell x-ray W spectroscopic diagnostics and K-shell Ti spectropolarimetry of Z-pinch plasmas. The main focus

A S Safronova; V L Kantsyrev; P Neill; U I Safronova; D A Fedin; N D Ouart; M F Yilmaz; G Osborne; I Shrestha; K Williamson; T Hoppe; C Harris; P Beiersdorfer; S Hansen

2007-01-01

73

Effects of an axial magnetic field on Z-pinch plasmas for extreme ultraviolet sources  

Microsoft Academic Search

This paper describes the effect of an axial magnetic field (Bz) on plasma pinch dynamics and on the extreme ultraviolet (EUV) emission property of a compact Z-pinch device for EUV sources. The Z-pinch xenon plasma was driven by a pulse current with an amplitude of 27 kA and duration of 150 ns in an alumina tube with a diameter of

Sunao Katsuki; Akihiro Kimura; Yoshihiro Kondo; Hiroyuki Horita; Takao Namihira; Takashi Sakugawa; Hidenori Akiyama

2006-01-01

74

Soldered Contact and Current Risetime Effects on Negative Polarity Wire Array Z-pinches  

SciTech Connect

The Cornell University COBRA pulser is a nominal 1 MA machine, capable of driving up to 32 wire cylindrical Z-pinch arrays. COBRA can operate with variable current risetimes ranging from 100 ns to 200 ns (short and long pulse, respectively). Wires are typically strung with a 'press' contact to the electrode hardware, where the wire is loosely pulled against the hardware and held there to establish electrical contact. The machine is normally negative, but a bolt-on convolute can be used to modify the current path and effectively produce positive polarity operation at the load.Previous research with single wires on a 1-5 kA pulser has shown that soldering the wire, thereby improving the wire/electrode contact, and operating in positive polarity can improve the energy deposition into the wire and enhance wire core expansion. Negative polarity showed no difference. Previous experiments on the negative polarity, 20 MA, 100 ns Z accelerator have shown that improving the contact improved the x-ray yield.Cornell data were collected on 16-wire Aluminum Z-pinch arrays in negative polarity. Experiments were conducted with both short and long current pulses with soldered and no-soldered wire/electrode contacts. The initiation, ablation, implosion and stagnation phases were compared for these four conditions. Time dependent x-ray signals were measured using diodes and diamond detectors. An inductive voltage monitor was used to infer minimum current radius achieved, as defined by a uniform shell of current moving radially inward, producing a time dependent inductance. Total energy data were collected with a metal-strip bolometer. Self-emission data were collected by an XUV 4-frame camera and an optical streak camera.In negative polarity and with short pulses, soldering appeared to produce a smaller radius pinch and decrease variations in the x-ray pulse shape. The bolometer, laser backlighter, 4-frame and streak cameras showed negligible differences in the initiation ablation and implosion phases. X-ray yield was increased with soldered arrays in negative polarity with long pulses. The bolometer also showed a 50% increase in radial power emitted for soldered arrays. 4-frame images showed soldered arrays have a more pronounced 'Christmas Tree' effect originating from the cathode. The inductive voltage monitor showed, with both long and short pulses, that soldered and no-solder arrays reached the same minimum current radius at the same time. However, with long pulses soldered arrays radiate x-rays at the time of minimum current radius while no-solder array x-ray output is delayed by {approx}20 ns, resulting in decreased x-ray yield.

Chalenski, D. A.; Kusse, B. R.; Greenly, J. B.; Blesener, I. C.; McBride, R. D.; Hammer, D. A.; Knapp, P. F. [Cornell University Laboratory of Plasma Studies, 439 Rhodes Hall, Ithaca, NY 14853 (United States)

2009-01-21

75

PBFA Z: A 20-MA z-pinch driver for plasma radiation sources  

SciTech Connect

Sandia National Laboratories is completing a major modification to the PBFA-II facility. PBFA Z will be a z-pinch driver capable of delivering up to 20 MA to a z-pinch load. It optimizes the electrical coupling to the implosion energy of z pinches at implosion velocities of {approximately} 40 cm/{mu}s. Design constraints resulted in an accelerator with a 0.12-{Omega} impedance, a 10.25-nH inductance, and a 120-ns pulse width. The design required new water transmission lines, insulator stack, and vacuum power feeds. Current is delivered to the z-pinch load through four, self-magnetically-insulated vacuum transmission lines and a double post-hole convolute. A variety of design codes are used to model the power flow. These predict a peak current of 20 MA to a z-pinch load having a 2-cm length, a 2-cm radius, and a 15--mg mass, coupling 1.5 MJ into kinetic energy. We present 2-D Rad-Hydro calculations showing MJ x-ray outputs from tungsten wire-array z pinches.

Spielman, R.B.; Breeze, S.F.; Deeney, C. [and others

1996-07-01

76

Recyclable Transmission Line (RTL) Concept for Z-Pinch IFE*  

NASA Astrophysics Data System (ADS)

The Recyclable Transmission Line (RTL) concept for IFE uses a recyclable material for the magnetically-insulated transmission line that connects the pulsed power accelerator to the z-pinch fusion target. The RTL may be made of frozen coolant (e.g., Flibe) or a material that is easily separable from the coolant (e.g., low activation ferritic steel). Initial experiments on Saturn at the 10 MA level have already shown excellent electrical turn-on for several candidate RTL materials, and demonstrated high electrical conductivities for thin low-mass RTLs. The present RTL baseline is a 50 kg ferritic steel RTL operating in a 10-20 Torr background chamber pressure. Initial results of investigations are presented on the RTL structural strength (buckling analysis); post-shot RTL formation of schrapnel/plasma; vacuum and electrical RTL connections to the power feed; post-shot effects up the RTL (EMP, schrapnel, etc.); activation and waste stream analysis; study of mechanical properties of foam Flibe; handling of sheer mass of RTLs (one-day storage supply, etc.); and RTL manufacturing and recycling system design.

Olson, C. L.; Slutz, S. A.; Rochau, G. E.; Morrow, C. W.; Kammer, D. C.; Fatenejad, M.; El-Guebaly, L. A.; de Groot, J. S.; Peterson, P. F.

2003-10-01

77

Diagnostics for Z-pinch implosion experiments on PTS  

NASA Astrophysics Data System (ADS)

The preliminary experiments of wire array implosion were performed on PTS, a 10 MA z-pinch driver with a 70 ns rise time. A set of diagnostics have been developed and fielded on PTS to study pinch physics and implosion dynamics of wire array. Radiated power measurement for soft x-rays was performed by multichannel filtered x-ray diode array, and flat spectral responses x-ray diode detector. Total x-ray yield was measured by a calibrated, unfiltered nickel bolometer which was also used to obtain pinch power. Multiple time-gated pinhole cameras were used to produce spatial-resolved images of x-ray self-emission from plasmas. Two time-integrated pinhole cameras were used respectively with 20-?m Be filter and with multilayer mirrors to record images produced by >1-keV and 277±5 eV self-emission. An optical streak camera was used to produce radial implosion trajectories, and an x-ray streak camera paired with a horizontal slit was used to record a continuous time-history of emission with one-dimensional spatial resolution. A frequency-doubled Nd:YAG laser (532 nm) was used to produce four frame laser shadowgraph images with 6 ns time interval. We will briefly describe each of these diagnostics and present some typical results from them.

Ren, X. D.; Huang, X. B.; Zhou, S. T.; Zhang, S. Q.; Dan, J. K.; Li, J.; Cai, H. C.; Wang, K. L.; Ouyang, K.; Xu, Q.; Duan, S. C.; Chen, G. H.; Wang, M.; Feng, S. P.; Yang, L. B.; Xie, W. P.; Deng, J. J.

2014-12-01

78

Theoretical z -pinch scaling relations for thermonuclear-fusion experiments.  

PubMed

We have developed wire-array z -pinch scaling relations for plasma-physics and inertial-confinement-fusion (ICF) experiments. The relations can be applied to the design of z -pinch accelerators for high-fusion-yield (approximately 0.4 GJ/shot) and inertial-fusion-energy (approximately 3 GJ/shot) research. We find that (delta(a)/delta(RT)) proportional (m/l)1/4 (Rgamma)(-1/2), where delta(a) is the imploding-sheath thickness of a wire-ablation-dominated pinch, delta(RT) is the sheath thickness of a Rayleigh-Taylor-dominated pinch, m is the total wire-array mass, l is the axial length of the array, R is the initial array radius, and gamma is a dimensionless functional of the shape of the current pulse that drives the pinch implosion. When the product Rgamma is held constant the sheath thickness is, at sufficiently large values of m/l, determined primarily by wire ablation. For an ablation-dominated pinch, we estimate that the peak radiated x-ray power P(r) proportional (I/tau(i))(3/2)Rlphigamma, where I is the peak pinch current, tau(i) is the pinch implosion time, and phi is a dimensionless functional of the current-pulse shape. This scaling relation is consistent with experiment when 13 MA < or = I < or = 20 MA, 93 ns < or = tau(i) < or = 169 ns, 10 mm < or = R < or = 20 mm, 10 mm < or = l < or = 20 mm, and 2.0 mg/cm < or = m/l < or = 7.3 mg/cm. Assuming an ablation-dominated pinch and that Rlphigamma is held constant, we find that the x-ray-power efficiency eta(x) congruent to P(r)/P(a) of a coupled pinch-accelerator system is proportional to (tau(i)P(r)(7/9 ))(-1), where P(a) is the peak accelerator power. The pinch current and accelerator power required to achieve a given value of P(r) are proportional to tau(i), and the requisite accelerator energy E(a) is proportional to tau2(i). These results suggest that the performance of an ablation-dominated pinch, and the efficiency of a coupled pinch-accelerator system, can be improved substantially by decreasing the implosion time tau(i). For an accelerator coupled to a double-pinch-driven hohlraum that drives the implosion of an ICF fuel capsule, we find that the accelerator power and energy required to achieve high-yield fusion scale as tau(i)0.36 and tau(i)1.36, respectively. Thus the accelerator requirements decrease as the implosion time is decreased. However, the x-ray-power and thermonuclear-yield efficiencies of such a coupled system increase with tau(i). We also find that increasing the anode-cathode gap of the pinch from 2 to 4 mm increases the requisite values of P(a) and E(a) by as much as a factor of 2. PMID:16196715

Stygar, W A; Cuneo, M E; Vesey, R A; Ives, H C; Mazarakis, M G; Chandler, G A; Fehl, D L; Leeper, R J; Matzen, M K; McDaniel, D H; McGurn, J S; McKenney, J L; Muron, D J; Olson, C L; Porter, J L; Ramirez, J J; Seamen, J F; Speas, C S; Spielman, R B; Struve, K W; Torres, J A; Waisman, E M; Wagoner, T C; Gilliland, T L

2005-08-01

79

Fusion burn dynamics in dense Z-pinch (DZP)  

SciTech Connect

The fusion burn dynamics and energy yield of the dense Z-pinch (DZP) are examined using a profile-averaged, zero-dimensional, time dependent model. A range of conditions (fuel, line density, voltage, fusion-product heating, enthalpy endloss, density and temperature profiles, current rise rate, electrode impurities) are examined. Magneto-hydrodynamic stability is assumed, and initial conditions are based on those ideally existing after the melting and ionization of a solid fiber of fusion fuel. Plasma conditions required of neutron sources for materials testing ({dot S}{sub n} {ge} 10{sup 19} n/s) and for possible commercial power production (ratio of fusion energy yield to energy input, Q{sub p} {approx equal} 15, lower values if reversible recovery of a fraction of the magnetic energy is possible) are described. If f{sub B} {approx gt} 0.8 fractional fuel burnup is possible in a nominal 800-ns DT discharge (200-ns current-rise phase at 20 MV/m followed by a 500-ns constant-current crowbarred phase), reactor-relevant values of Q{sub p} may be possible. For the simpler (and shorter) constant-voltage discharge (e.g., no voltage crowbar) the value of Q{sub p} is in the range 5--10 for discharges below 200-ns duration. Smaller levels of fuel burnup, shorter discharges, or generally lower levels of Q{sub p} will require a reversible energy transfer system to meet reactor energy-balance requirements. Imposition of a plasma current rise-time constraint that may be needed for stable plasma operation (e.g., I > 10{sup 12} A/s) will burnup, Q{sub p} and discharge time to an extent where reversible energy/transfer system will be required to meet reactor energy- balance requirements. 25 refs.

Krakowski, R.A.

1990-04-01

80

PBFA Z: A 60-TW/5-MJ Z-pinch driver  

NASA Astrophysics Data System (ADS)

PBFA Z, a new 60-TW/5-MJ electrical accelerator located at Sandia National Laboratories, is now the world's most powerful z-pinch driver. PBFA Z stores 11.4 MJ in its 36 Marx generators, couples 5 MJ into a 60-TW/105-ns FWHM pulse to the 120-m? water transmission lines, and delivers 3.0 MJ and 50 TW of electrical energy to the z-pinch load. Depending on load parameters, we attain peak load currents of 16-20 MA with a current rise time of ˜105 ns with wire-array z-pinch loads. We have extended the x-ray performance of tungsten wire-array z pinches from earlier Saturn experiments. Using a 2-cm-radius, 2-cm-long tungsten wire array with 240, 7.5-?m diameter wires (4.1-mg mass), we achieved an x-ray power of 210 TW and an x-ray energy of 1.9 MJ. Preliminary spectral measurements suggest a mostly optically-thick, Planckian-like radiator below 1000 eV. Data indicate ˜100 kJ of x rays radiated above 1000 eV. An intense z-pinch x-ray source with an overall coupling efficiency greater than 15% has been demonstrated.

Spielman, R. B.; Deeney, C.; Chandler, G. A.; Douglas, M. R.; Fehl, D. L.; Matzen, M. K.; McDaniel, D. H.; Nash, T. J.; Porter, J. L.; Sanford, T. W. L.; Seamen, J. F.; Stygar, W. A.; Struve, K. W.; Breeze, S. P.; McGurn, J. S.; Torres, J. A.; Zagar, D. M.; Gilliland, T. L.; Jobe, D. O.; McKenney, J. L.; Mock, R. C.; Vargas, M.; Wagoner, T.; Peterson, D. L.

1997-05-01

81

Axial x-ray backlighting of wire-array Z-pinches using X pinches  

NASA Astrophysics Data System (ADS)

For the first time, a geometry has been developed to allow for an axial imaging system for wire-array Z-pinch experiments that produce high-resolution x-ray images. The new geometry required a significant redesign of the electrode hardware. Calibrated areal density measurements of the Z-pinch plasma including wire cores, coronal plasma, streaming plasma, and the precursor were obtained. The system used eight-wire molybdenum (Mo) X pinches in series with and directly below the Z-pinch axis to provide micron-scale x-rays sources for point-projection radiography. The images formed on the x-ray sensitive film had a 15 mm diameter field of view at the center height of the array and a magnification of about 7.5:1. Titanium (Ti) filters in front of the film transmitted radiation in the spectral range of 3-5 keV. For calibration, a separate film with the same thickness Ti filter was placed the same distance from the X pinch. This film had an unobstructed path that bypasses the Z-pinch but included step wedges for calibration of the Z-pinch plasma. The step wedges had thicknesses of tungsten (W) ranging from 0.015 to 1.1 ?m to obtain areal density measurements of the W plasma from the wire-array. Images had subnanosecond temporal resolution and about 10 ?m spatial resolution.

Blesener, I. C.; Greenly, J. B.; Pikuz, S. A.; Shelkovenko, T. A.; Vishniakou, S.; Hammer, D. A.; Kusse, B. R.

2009-12-01

82

On the possibility of neutron generation in an imploding TiD2 puff Z pinch  

NASA Astrophysics Data System (ADS)

Simulation of implosion of a TiD2 puff Z pinch is reported. The Z pinch is supposed to be produced by the plasma flow generated by a vacuum arc, as described by Rousskikh et al. [Phys. Plasmas 18, 092707 (2011)]. To simulate the implosion, a one-dimensional two-temperature radiative magnetohydrodynamics code was used. The simulation has shown that neutrons are generated during the implosion of a TiD2 puff Z pinch due to thermalization of the pinch plasma stagnated on axis. It has been shown that the necessary condition for neutron generation is that the ion temperature must be substantially higher than the electron temperature. For a pinch current of 1 MA, the predicted yield of "thermal" neutrons is 2.5 × 109 neutrons/shot.

Baksht, Rina B.; Oreshkin, Vladimir I.; Rousskikh, Alexander G.

2013-08-01

83

Measurement and Control of Current Waveform in an Ablative Z-Pinch Pulsed Plasma Thruster"  

E-print Network

in series with a 100nH inductor. The circuit used for the simulation is a simple RLC circuit with the three elements in series and a switch used to close the circuit after the 38F capacitor is initialized Current Ringing in the AZPPT2 Circuit Abstract The second Ablative Z-Pinch Pulsed Plasma Thruster AZPPT2

Choueiri, Edgar

84

Prediction of Z-Pinch Implosion Shape from Gas Jet Nozzle Geometry  

Microsoft Academic Search

A technique for predicting the shape of Z-pinch implosions based on gas jet nozzle geometry has been developed and tested against data from argon gas experiments on BLACKJACK 5. The prediction technique involves use of a code which calculates the gas distribution, as a function of nozzle geometry and initial gas input pressure, at the start of the implosion. The

E. Waisman; R. Ingermanson; H. Murphy; N. Loter; W. Rix

1994-01-01

85

Low mass recyclable transmission lines for Z-pinch driven inertial fusion  

NASA Astrophysics Data System (ADS)

Recyclable transmission lines (RTLs) are being studied as a means to repetitively drive Z pinches. Minimizing the mass of the RTL should also minimize the reprocessing costs. Low mass RTLs could also help reduce the cost of a single shot facility such as the proposed X-1 accelerator and make Z-pinch driven nuclear space propulsion feasible. Calculations are presented to determine the minimum electrode mass to provide sufficient inertia against the magnetic pressure produced by the large currents needed to drive the Z pinches. The results indicate an electrode thickness which is much smaller than the initial resistive skin depth. This suggests that the minimum electrode thickness may be not be solely determined by inertial effects, but also by the ability of the electrode to efficiently carry the current. A series of experiments have been performed to determine the ability of the electrodes to carry current as a function of the electrode thickness. The results indicate that electrodes much thinner than the initial resistive skin depth can efficiently carry large currents presumably due to the formation of a highly conducting plasma. This result implies that a transmission line with only a few tens of kilograms of material can carry the large Z-pinch currents needed for inertial fusion.

Slutz, S. A.; Olson, C. L.; Peterson, Per

2003-02-01

86

Efficient Neutron Production from a Novel Configuration of Deuterium Gas-Puff Z-Pinch  

NASA Astrophysics Data System (ADS)

A novel configuration of a deuterium z pinch has been used to generate fusion neutrons. Injecting an outer hollow cylindrical plasma shell around an inner deuterium gas puff, neutron yields from DD reactions reached Yn=(2.9±0.3)×1012 at 700 ns implosion time and 2.7 MA current. Such a neutron yield means a tenfold increase in comparison with previous deuterium gas puff experiments at the same current generator. The increase of beam-target yields was obtained by a larger amount of current assembled on the z-pinch axis, and subsequently by higher induced voltage and higher energies of deuterons. A stack of CR-39 track detectors on the z-pinch axis showed hydrogen ions up to 38 MeV. Maximum neutron energies of 15 and 22 MeV were observed by radial and axial time-of-flight detectors, respectively. The number of DD neutrons per one joule of stored plasma energy approached 5×107. This implies that deuterium gas puff z pinches belong to the most efficient plasma-based sources of DD neutrons.

Klir, D.; Kubes, P.; Rezac, K.; Cikhardt, J.; Kravarik, J.; Sila, O.; Shishlov, A. V.; Kovalchuk, B. M.; Ratakhin, N. A.; Kokshenev, V. A.; Labetsky, A. Yu.; Cherdizov, R. K.; Fursov, F. I.; Kurmaev, N. E.; Dudkin, G. N.; Nechaev, B. A.; Padalko, V. N.; Orcikova, H.; Turek, K.

2014-03-01

87

Efficient neutron production from a novel configuration of deuterium gas-puff z-pinch.  

PubMed

A novel configuration of a deuterium z pinch has been used to generate fusion neutrons. Injecting an outer hollow cylindrical plasma shell around an inner deuterium gas puff, neutron yields from DD reactions reached Y(n)=(2.9 ± 0.3) × 10(12) at 700 ns implosion time and 2.7 MA current. Such a neutron yield means a tenfold increase in comparison with previous deuterium gas puff experiments at the same current generator. The increase of beam-target yields was obtained by a larger amount of current assembled on the z-pinch axis, and subsequently by higher induced voltage and higher energies of deuterons. A stack of CR-39 track detectors on the z-pinch axis showed hydrogen ions up to 38 MeV. Maximum neutron energies of 15 and 22 MeV were observed by radial and axial time-of-flight detectors, respectively. The number of DD neutrons per one joule of stored plasma energy approached 5 × 10(7). This implies that deuterium gas puff z pinches belong to the most efficient plasma-based sources of DD neutrons. PMID:24655260

Klir, D; Kubes, P; Rezac, K; Cikhardt, J; Kravarik, J; Sila, O; Shishlov, A V; Kovalchuk, B M; Ratakhin, N A; Kokshenev, V A; Labetsky, A Yu; Cherdizov, R K; Fursov, F I; Kurmaev, N E; Dudkin, G N; Nechaev, B A; Padalko, V N; Orcikova, H; Turek, K

2014-03-01

88

UV Laser Diagnostics of the 1-MA Z-pinch Plasmas  

SciTech Connect

The 532 nm laser diagnostic set at the Zebra generator shows the details of the ablation and stagnation phases in cylindrical, planar, and star-like wire arrays but it cannot show the structure of the stagnated z-pinch and the implosion in small diameter loads, 1-3 mm in diameter. The absorption increment and the refraction angle of the 532 nm laser, when passing through the plasma, are too great to obtain quality images. An ultraviolet probing beam at the wavelength of 266 nm was developed to study small-diameter loads and to investigate the structure of the 1-MA z-pinch. The UV radiation has a much smaller absorption increment and refraction angles in plasmas than the 532 nm light and allows for better imaging of the z-pinch plasmas. Estimates showed that UV probing would be able to probe the high-density z-pinch plasma in experiments on the Zebra generator, and the early results of UV probing on the Zebra generator have shown promise.

Altemara, S. D.; Ivanov, V. V.; Astanovitskiy, A. L.; Haboub, A. [University of Nevada, Reno, NV 89557 (United States)

2009-01-21

89

Radiation from a Tungsten Z-pinch Plasma Impinging on a Gold Wall  

Microsoft Academic Search

A number of exploratory scenarios are being investigated to evaluate the feasibility of creating hohlraum like conditions suitable to drive an ICF target to ignition with the radiation produced from a tungsten multiwire nested array Z-pinch plasma. In this investigation we will focus on the axial and radial x-ray emission from the wire load impinging on a gold wall. We

J. Davis; R. W. Clark Giuliani Jr.; J. P. Apruzese; J. W. Thornhill; Y. K. Chong; P. Kepple; K. G. Whitney

2002-01-01

90

Calculation of tungsten emission spectra for mega ampere Z-pinches  

Microsoft Academic Search

Opacity effects and reabsorption in spectral lines is very important for calculation of the ionization equilibrium and radiation issue of tungsten pinch plasma. The assumption of manifold collapses with different parameters and thermalization of issued radiation gives reasonable spectra of mega ampere z-pinches.

Vladimir G. Novikov; Ilya Yu. Vichev; Anna D. Solomyannaya

2007-01-01

91

Convective Cell Formation in a Z-Pinch Plasma Science and Fusion Center  

E-print Network

Convective Cell Formation in a Z-Pinch J. Kesner Plasma Science and Fusion Center Massachusetts systems can develop convective cells when the MHD inter- change stability criterion is violated. Using the system may develop large-scale convective cells which can lead to nonlocal transport [6, 7, 8, 9, 10

92

The electric resistance and electron viscosity of Z-pinch plasma  

SciTech Connect

The electron magnetohydrodynamic equations imply that electron gas viscosity can have a significant influence on a plasma's electric resistance. For a long inhomogeneous plasma column with axial symmetry, as in a z-pinch, the viscous part of the resistance can be several orders of magnitude larger than the usual frictional resistance.

Esaulov, A. A.; Sasorov, P. V. [Institute for Theoretical and Experimental Physics B. Cheremushkinskaya St. 25, Moscow 117259 (Russian Federation)

1997-05-05

93

Recent advances in theoretical and numerical studies of wire array Z-pinch in the IAPCM  

NASA Astrophysics Data System (ADS)

Fast Z-pinch has produced the most powerful X-ray radiation source in laboratory and also shows the possibility to drive inertial confinement fusion (ICF). Recent advances in wire-array Z-pinch researches at the Institute of Applied Physics and Computational Mathematics are presented in this paper. A typical wire array Z-pinch process has three phases: wire plasma formation and ablation, implosion and the MRT instability development, stagnation and radiation. A mass injection model with azimuthal modulation coefficient is used to describe the wire initiation, and the dynamics of ablated plasmas of wire-array Z-pinches in (r, ?) geometry is numerically studied. In the implosion phase, a two-dimensional(r, z) three temperature radiation MHD code MARED has been developed to investigate the development of the Magneto-Rayleigh-Taylor(MRT) instability. We also analyze the implosion modes of nested wire-array and find that the inner wire-array is hardly affected before the impaction of the outer wire-array. While the plasma accelerated to high speed in the implosion stage stagnates on the axis, abundant x-ray radiation is produced. The energy spectrum of the radiation and the production mechanism are investigated. The computational x-ray pulse shows a reasonable agreement with the experimental result. We also suggest that using alloyed wire-arrays can increase multi-keV K-shell yield by decreasing the opacity of K-shell lines. In addition, we use a detailed circuit model to study the energy coupling between the generator and the Z-pinch implosion. Recently, we are concentrating on the problems of Z-pinch driven ICF, such as dynamic hohlraum and capsule implosions. Our numerical investigations on the interaction of wire-array Z-pinches on foam convertors show qualitative agreements with experimental results on the "Qiangguang I" facility. An integrated two-dimensional simulation of dynamic hohlraum driven capsule implosion provides us the physical insights of wire-array plasma acceleration, shock generation and production, hohlraum formation, radiation ablation and fuel compression.

Ding, Ning; Zhang, Yang; Xiao, Delong; Wu, Jiming; Huang, Jun; Yin, Li; Sun, Shunkai; Xue, Chuang; Dai, Zihuan; Ning, Cheng; Shu, Xiaojian; Wang, Jianguo; Li, Hua

2014-12-01

94

Plasma channel and Z-pinch dynamics for heavy ion transport  

SciTech Connect

A self stabilized, free standing, z-pinch plasma channel has been proposed to deliver the high intensity heavy ion beam from the end of a driver to the fuel target in a heavy ion inertial fusion power plant. The z-pinch relaxes emittance and energy spread requirements requiring a lower cost driver. A z-pinch transport would reduce the number of beam entry port holes to the target chamber from over a hundred to four as compared to neutralized ballistic focusing thus reducing the driver hardware exposure to neutron flux. Experiments where a double pulse discharge technique is used, z-pinch plasma channels with enhanced stability are achieved. Typical parameters are 7 kV pre-pulse discharge and 30 kV main bank discharge with 50 kA of channel current in a 7 torr background gas atmosphere. This work is an experimental study of these plasma channels examining the relevant physics necessary to understand and model such plasmas. Laser diagnostics measured the dynamical properties of neutrals and plasma. Schlieren and phase contrast techniques probe the pre-pulse gas dynamics and infrared interferometry and faraday effect polarimetry are used on the z-pinch to study its electron density and current distribution. Stability and repeatability of the z-pinch depend on the initial conditions set by the pre-pulse. Results show that the z-pinch channel is wall stabilized by an on-axis gas density depression created by the pre-pulse through hydrodynamic expansion where the ratio of the initial gas density to the final gas density is > 10/1. The low on-axis density favors avalanching along the desired path for the main bank discharge. Pinch time is around 2 s from the main bank discharge initiation with a FWHM of {approx} 2 cm. Results also show that typical main bank discharge plasma densities reach 10{sup 17} cm{sup -3} peak on axis for a 30 kV, 7 torr gas nitrogen discharge. Current rise time is limited by the circuit-channel inductance with the highest contribution to the impedance due to the plasma. There is no direct evidence of surface currents due to high frequency skin effects and magnetic field experiments indicate that > 70% of the current carried by the channel is enclosed within FWHM of the channel. Code-experiment benchmark comparisons show that simulations capture the main mechanisms of the channel evolution, but complete atomic models need to be incorporated.

Ponce-Marquez, David

2002-07-09

95

Characterization of plasma expansion dynamics in a high power diode with a carbon-fiber-aluminum cathode  

SciTech Connect

Thermal plasma expansion is characterised during the operation of a high power diode with an explosive emission carbon-fiber-aluminum cathode driven by a 250?kV, 150?ns accelerating pulse. It is found that a quasi-stationary state of plasma expansion is obtained during the main part of the accelerating pulse and the whole plasma expansion exhibits an “U”-shape velocity evolution. A theoretical model describing the dynamics of plasma expansion is developed, which indicates that the plasma expansion velocity is determined by equilibrium between the diode current density and plasma thermal electron current density.

Ju, J.-C., E-mail: jujinchuan@126.com [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Laboratoire de Physique des Gaz et des Plasmas, CNRS-Université Paris-Sud, Orsay 91405 (France); Liu, L.; Cai, D. [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

2014-06-09

96

Advances in experimental spectroscopy of Z-pinch plasmas and applications  

NASA Astrophysics Data System (ADS)

Recent advances in experimental work on plasma spectroscopy of Z-pinches are presented. The results of experiments on the 1.7 MA Z-pinch Zebra generator at UNR with wire arrays of various configurations and X-pinches are overviewed. A full x-ray and EUV diagnostic set for detailed spatial and temporal monitoring of such plasmas together with theoretical support from relativistic atomic structure and non-LTE kinetic codes used in the analysis are discussed. The use of a variety of wire materials in a broad range from Al to W provided an excellent opportunity to observe and study specific atomic and plasma spectroscopy features. In addition, the applications of such features to fusion and astrophysics will be considered.

Kantsyrev, V. L.; Safronova, A. S.; Safronova, U. I.; Shrestha, I.; Weller, M. E.; Osborne, G. C.; Shlyaptseva, V. V.; Wilcox, P. G.; Stafford, A.

2012-06-01

97

Z-Pinch Driven Inertial Confinement Fusion Target Physics Research at Sandia National Laboratories  

SciTech Connect

Three hohlraum concepts are being pursued at Sandia National Laboratories (SNL) to investigate the possibility of using pulsed power driven magnetic implosions (z-pinches) to drive high gain targets capable of yields in the range of 200-1000 MJ. This research is being conducted on SNL'S.Z facility that is capable of driving peak currents of 20 MA in z-pinch loads producing implosion velocities as high as 7.5X 107 cm/s, x-ray energies approaching 2 MJ, and x-ray powers exceeding 200 TW. This paper will discuss each of these hohlraum concepts and will overview the experiments that have been conducted on these systems to date.

Alberts, T.E.; Asay, J.R.; Baca, P.M.; Baker, K.L.; Breeze, S.P.; Chandler, G.A.; Cook, D.L.; Cooper, G.W.; Deeney, C.; Derzon, M.S.; Douglas, M.R.; Fehl, D.L.; Gilliland, T.; Hebron, D.E.; Hurst, M.J.; Jobe, D.O.; Kellogg, J.W.; Lash, J.S.; Lazier, S.E.; Leeper, R.J.; Matzen, M.K.; McDaniel, D.H.; McGurn, J.S.; Mehlhorn, T.A.; Moats, A.R.; Mock, R.C.; Muron, D.J.; Nash, T.J.; Olson, R.E.; Porter, J.L.; Quintenz, J.P.; Reyers, P.V.; Ruggles, L.E.; Ruiz, C.L.; Sandford, T.W.L.; Schmidlapp, F.A.; Seamen, J.F.; Spielman, R.B.; Stark, M.A.; Struve, K.W.; Stygar, W.A.; Tibbetts-Russell, D.R.; Torres, J.A.; Vargas, M.; Wagoner, T.C.; Wakefield, C.

1998-10-27

98

Studies of Hot Spots in Wire-Array Z-Pinches and X-Pinches  

NASA Astrophysics Data System (ADS)

Wire array Z-pinches and X-pinches radiate in both the soft (sub-keV) and hard (multi-keV) x-ray ranges. Hot spots are brief and intense x-ray bursts at localized small points within a Z- or X-pinch. Experiments have been carried out on the 1MA COBRA and 0.5 MA XP pulsed-power generators to investigate the temporal development, spatial structure, and x-ray emission structure of the hot spots in X-pinches and Z-pinches made from multiple fine metal wires. A Kentech x-ray streak camera and diamond photoconducting diodes (PCDs) with various filters were used to study the time evolution of the energy distribution emitted from the hot spots. Time integrated self emission pinhole images with various filters and time-gated four frame MCP images were used to study the spatial structure of hot spot x-ray emission.

Bell, Kate; Shelkovenko, Tatiana; Pikuz, Sergey; Hammer, David; Douglass, Jonathan; McBride, Ryan; Greenly, John

2007-11-01

99

Study of the stability of Z-pinch implosions with different initial density profiles  

SciTech Connect

Stability of metal-puff Z pinches was studied experimentally. Experiments were carried out on a facility producing a load current up to 450 kA with a rise time of 450?ns. In a metal-puff Z pinch, the plasma shell is produced due to evaporation of the electrode material during the operation of a vacuum arc. In the experiment to be reported, a single-shell and a shell-on-jet pinch load with magnesium electrodes were used. Two-dimensional, 3 ns gated, visible-light images were taken at different times during the implosion. When the shell was formed from a collimated plasma flow with small radial divergence, Rayleigh–Taylor (RT) instability typical of gas-puff implosions was recorded. The RT instability was completely suppressed in a mode where the initial density distribution of the shell approached a tailored density profile [A. L. Velikovich et al., Phys. Rev. Lett. 77, 853 (1996)].

Rousskikh, A. G.; Zhigalin, A. S.; Labetskaya, N. A.; Chaikovsky, S. A.; Yushkov, G. Yu. [Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk (Russian Federation)] [Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk (Russian Federation); Oreshkin, V. I.; Batrakov, A. V. [Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk (Russian Federation) [Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk (Russian Federation); Tomsk Polytechnic University, Tomsk (Russian Federation); Baksht, R. B. [Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk (Russian Federation) [Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk (Russian Federation); Tel-Aviv University, Tel Aviv (Israel)

2014-05-15

100

Measurement of emission diameter as a function of time on foam z- pinch plasmas  

SciTech Connect

We have developed a streaked imaging capability to make time-resolved measurements of the emission size for low density foam z-pinches. By lens coupling visible emission from the z-pinch target to an array of fiber optics we obtained the emission profile in the visible as a function of time with radial resolution of 300 {mu}m. To measure the emission at temperatures greater than {approx}40 eV the source was slit-imaged or pin-hole imaged onto an x-ray filtered scintillator. Non-uniformities in both visible and x-ray emission were observed. We describe the diagnostics, the image unfold process, and results from the instrument for both visible and x-ray measurements.

Lazier, S.E.; Barber, T.L. [Ktech Corp., Albuquerque, NM (United States); Derzon, M.S.; Kellogg, J.W.

1996-05-14

101

Exploring Ways to Improve Predictive Capability of Z-Pinch Calculations  

SciTech Connect

For some time 2-dimensional RMHD (radiation magneto-hydrodynamic) calculations of radiating z-pinches have been made to agree with integral data (current wave form, yield and power). For these calculations, the agreement with detailed data, such as time-resolved x-ray images, is generally not as good. Correctly modeling the physics of z-pinches, including detailed data, is needed to have true predictive capability. To address this problem, the authors first determine which integral data are most sensitive to the details in the models. With this information, they investigate aspects of the pinch, to which the data is sensitive, using non-standard techniques. For example, the pinch is calculated in (x,y)-geometry to investigate how a non-symmetric implosion affects the simulated data.

Matuska, W.; Aubrey, J.; Bowers, R.; Lee, H.; Peterson, D.; Deeney, C.; Derzon, M.; Nash, T.

1998-10-19

102

Mitigation of end-effects in wire array z-pinches through hardware modification  

NASA Astrophysics Data System (ADS)

Symmetry is a crucial factor for various applications of wire array z-pinches, including Inertial Confinement Fusion and K- shell x-ray source development. Previous work has shown that a non-uniformity is initiated near the cathode wire contact of a z-pinch. An imploding bubble expands axially until it stagnates prematurely on axis prior to the main x-ray pulse, leading to regions near the cathode in which no x-ray output is present at peak emission. The effects of such non-uniformities are likely to be particularly significant for the large initial load diameters used to achieve appropriate plasma conditions for K- shell emission from mid-Z elements at facilities such as Z. We discuss experiments on the Saturn accelerator which attempt to mitigate this effect by placing a step on the cathode to obstruct the propagation of the bubble towards the axis, hence preventing the non-uniformity on axis.

Ampleford, D. J.; Jennings, C. A.; Jones, B.; Chittenden, J. P.; Lebedev, S. V.; Bland, S. N.; Bott, S. C.

2007-11-01

103

Study of the stability of Z-pinch implosions with different initial density profiles  

NASA Astrophysics Data System (ADS)

Stability of metal-puff Z pinches was studied experimentally. Experiments were carried out on a facility producing a load current up to 450 kA with a rise time of 450 ns. In a metal-puff Z pinch, the plasma shell is produced due to evaporation of the electrode material during the operation of a vacuum arc. In the experiment to be reported, a single-shell and a shell-on-jet pinch load with magnesium electrodes were used. Two-dimensional, 3 ns gated, visible-light images were taken at different times during the implosion. When the shell was formed from a collimated plasma flow with small radial divergence, Rayleigh-Taylor (RT) instability typical of gas-puff implosions was recorded. The RT instability was completely suppressed in a mode where the initial density distribution of the shell approached a tailored density profile [A. L. Velikovich et al., Phys. Rev. Lett. 77, 853 (1996)].

Rousskikh, A. G.; Zhigalin, A. S.; Oreshkin, V. I.; Labetskaya, N. A.; Chaikovsky, S. A.; Batrakov, A. V.; Yushkov, G. Yu.; Baksht, R. B.

2014-05-01

104

Spectroscopic Characterization and Laser Imaging of Wires and Impurities in Z-Pinch Discharges *  

NASA Astrophysics Data System (ADS)

Experiments measure the composition of the coronal plasma surrounding metal z-pinch wires with emphasis on determining the presence and importance of impurities in the discharge. A single wire Z-pinch with a 2 kA, 500 ns (half-cycle) exhibits hydrodynamics of the early-time coronal plasma. Diagnostics include OES with gated ICCD or PM tube and non/resonant laser imaging. Temporally and spatially resolved OES data show that C and H play a major role in coronal plasma and current. At the time of current discontinuity and voltage collapse, C+ and C++ line emission dominate spectra (for Al, W, Cu, Ag wires). Effects of wire cleaning on coronal plasma behavior are presented. These experiments are directed towards improving the understanding of coronal plasmas in Sandia's Z-machine and validating ALEGRA radiation-MHD models of wire initiation. [11pt]Research supported by DOE through a Sandia National Laboratories subcontract to University of Michigan.

Johnston, M. D.; Gilgenbach, R. M.; Strickler, T. S.; Lau, Y. Y.; Jones, M. C.; Mehlhorn, T. A.; Cuneo, M. E.

2003-10-01

105

The Physics of the Dense Z-Pinch in Theory and in Experiment With Application to Fusion Reactor  

Microsoft Academic Search

A new generation of Z-pinches employing high voltage, high current pulsed lines as power sources produce dense hot plasmas with enhanced stability properties. Three methods of Z-pinch formation are currently in use: (1) cylindrical collapse and compression of a pre-ionised gas; (2) laser initiation and Joule heating of a gas embedded pinch, and (3) hollow gas puff and subsequent collapse

M G Haines

1982-01-01

106

A New High Current Fast 100ns LTD Based Driver for Z-pinch IFE at Sandia  

Microsoft Academic Search

Sandia is actively pursuing the development of new accelerators based on the novice technology of linear transformer driver (LTD). LTD based drivers are currently considered for many applications including future very high current Z-pinch drivers like ZX and z-pinch IFE (inertial fusion energy). LTD is a new method for constructing high-current, high-voltage pulsed accelerators. The salient feature of the approach

M. G. Mazarakis; C. L. Olson

2005-01-01

107

Mach2 Simulations of Kr Shell Deuterium Target Z-Pinches  

NASA Astrophysics Data System (ADS)

Mach2 Simulations of Kr shell onto Deuterium target Z-pinches were performed and are compared to UC Irvine's experimental results of such load configurations. The two load configurations tested were: a 4 cm dia. Kr hollow gas shell liner with either a 1.7 cm dia. D2 hollow gas shell or solid gas jet target, with axial magnetic fields ranging from 0 to 2 kG.

Rahman, Haffiz; Ney, Paul; van Drie, Alan

2001-10-01

108

Efficient K-shell emission in a Z pinch with axial magnetic field  

Microsoft Academic Search

Summary form only given, as follows. An axial magnetic field is known to produce a stabilizing effect on Z-pinch implosions by introducing magnetic shear that suppresses the RT instability. For this mechanism to be effective, Bz has to become comparable to the self-generated azimuthal magnetic field of the pinch. Experiments made some years ago have confirmed the above-mentioned stabilization. Early

V. I. Oreshkin; L. I. Rudakov; J. Davis; R. W. Clark; A. L. Velikovich

2001-01-01

109

Spatially and temporally resolved EUV emissions from SATURN Z-pinches  

Microsoft Academic Search

Summary form only given, as follows. EUV emissions can be used to measure several Z-pinch parameters. We have measured implosion velocity from Doppler splitting of lines and estimated electron temperature during run-in from the mean ionization state of line emissions. In an argon pinch we measure an electron temperature of 100 eV before stagnation. To date doppler split lines have

T. J. Nash; S. Breeze; R. Mock; D. Jobe

1995-01-01

110

Shock Mitigation using Compressible Two-Phase Jets for Z-Pinch IFE Reactor Applications  

Microsoft Academic Search

Compressible liquid\\/gas jets offer the opportunity to limit and mitigate the mechanical consequences of rapid heating\\/evaporation of the protective jets in a high-yield, low repetition rate Inertial Fusion Energy (IFE) system such as the Z-Pinch IFE reactor. In this investigation, experiments have been conducted to quantify the extent by which a two-phase jet can attenuate a shock wave. The experiments

C. C. Lascar; D. L. Sadowski; S. I. Abdel-Khalik

2005-01-01

111

Modeling of Dopant Spectral Emission in Z-Pinch Dynamic Hohlraum Experiments  

Microsoft Academic Search

X-ray spectra have been obtained from Si-doped low-density foams in dynamic hohlraum z-pinch experiments at Sandia National Laboratories. The purpose of the dopants is to provide spectroscopy signatures for constraining the time-dependent conditions within the hohlraum. In these experiments, ˜ 16 - 18 MA of current is delivered to a load comprised of a tungsten wire array which surrounds a

Joseph Macfarlane; G. A. Rochau

2005-01-01

112

X-ray spectroscopy of z-pinches in implosions of wire arrays with combined materials  

Microsoft Academic Search

Summary form only given. Time-resolved laser-probe diagnostics and gated X-ray imaging of star-like wire array Z-pinch implosions have shown implosion characteristics that are more stable than those of other types of wire arrays on the Zebra generator. Here, we study the plasma conditions achieved in star-like wire arrays implosions using time-integrated and spatially-resolved X-ray spectroscopy. To this end, spectroscopic data

P. Hakel; R. C. Mancini; V. V. Ivanov; A. Haboub; J. M. Kindel

2009-01-01

113

Modeling X-ray data for the Saturn z-pinch machine  

Microsoft Academic Search

Summary form only given, as follows. A wealth of XRD and time dependent X-ray imaging data exist for the Saturn z-pinch machine, where the load is either a tungsten wire array or a tungsten wire array which implodes onto a SiO2 foam. Also, these pinches have been modeled with a 2-D RMHD Eulerian computer code. In the paper we start

W. Matuska; D. Peterson; C. Deeney; M. Derzon

1997-01-01

114

Simulation of Dopant Spectral Emission in Z-Pinch Dynamic Hohlraum Experiments  

Microsoft Academic Search

Summary form only given. We report on the analysis of X-ray spectra obtained from doped low-density foams in dynamic hohlraum Z-pinch experiments at Sandia National Laboratories. In these experiments, ~16-18 MA of current is delivered to a load comprised of a tungsten wire array which surrounds a low-density cylindrical CH foam. The foam is doped with ~1% SiO2 to provide

J. J. MacFarlane; I. E. Golovkin; P. R. Woodruff; J. E. Bailey; G. A. Rochau; K. Peterson

2005-01-01

115

Analysis of Radiatively-Heated Thin Foils in Z-Pinch Hohlraum Experiments  

Microsoft Academic Search

Z-pinch experiments are performed at the Z pulsed-power facility at Sandia National Laboratories (SNL) to study physics issues related to high energy density plasmas and inertial confinement fusion. In recent Z experiments, time-resolved x-ray crystal spectroscopy has been used [Bailey, et. al., this meeting] to record inner-shell K-alpha spectra from a thin tamped Al foil located in a slot in

J. J. Macfarlane; J. E. Bailey; G. A. Chandler; T. J. Nash; M. S. Derzon; C. Deeney; M. R. Douglas; R. B. Spielman

1999-01-01

116

Spectral Analysis of Tracer Emission and Absorption Lines in Z-Pinch Dynamic Hohlraum Experiments  

Microsoft Academic Search

Spectroscopic analysis of tracer absorption and emission lines is reported for a nested tungsten (W) wire array z-pinch containing an on-axis CH foam with an embedded, thin Al-Mg tracer. The absorption and emission of radiation from the W plasma, the tracer, and the foam are studied with the goal of determining plasma parameters, such as electron temperatures, W composition along

J. J. Macfarlane; K. A. Park; A. R. Thomas-Cramer; J. E. Bailey; G. A. Chandler; P. Lake; T. A. Mehlhorn; T. J. Nash; G. A. Rochau S; S. A. Slutz; R. A. Vesey

2001-01-01

117

Spectral Analysis of Tracer Emission and Absorption Lines in Z-Pinch Dynamic Hohlraum Experiments  

Microsoft Academic Search

Spectroscopic analysis of tracer absorption and emission lines is reported for a nested tungsten (W) wire array z-pinch containing an on-axis CH foam with an embedded, thin Al-Mg tracer. The absorption and emission of radiation from the W plasma, the tracer, and the foam are studied with the goal of determining plasma parameters, such as electron temperatures, W composition along

Joseph Macfarlane; Jim Bailey; Greg Rochau; Tom Nash; Gordon Chandler; Tom Sanford; Tom Mehlhorn; Igor Golovkin; Pam Woodruff

2002-01-01

118

Generation and anisotropy of neutron emission from a condensed Z-pinch  

NASA Astrophysics Data System (ADS)

The paper presents results of measurements of neutron emission generated in the constriction of a fast Z-pinch at the S-300 facility (2 MA, 100 ns). An increased energy concentration was achieved by using a combined load the central part of which was a microporous deuterated polyethylene neck with a mass density of 100 mg/cm3 and diameter of 1-1.5 mm. The neck was placed between two 5-mm-diameter agar-agar cylinders. The characteristics of neutron emission in two axial and two radial directions were measured by the time-of-flight method. The neutron spectrum was recovered from the measured neutron signals by the Monte Carlo method. In all experiments, the spatiotemporal characteristics of plasma in the Z-pinch constriction were measured by means of the diagnostic complex of the S-300 facility, which includes frame photography in the optical, VUV, and soft X-ray (SXR) spectral regions; optical streak imaging; SXR detection; and time-integrated SXR photography. The formation of hot dense plasma in the Z-pinch constriction was accompanied by the generation of hard X-ray (with photon energies E > 30 keV), SXR (with photon energies E > 1 keV and duration of 2-4 ns), and neutron emission. Anisotropy of the neutron energy distribution in the axial direction was revealed. The mean neutron energies measured in four directions at angles of 0° (above the anode), 90°, 180° (under the cathode), and 270° with respect to the load axis were found to be of 2.1 ± 0.1, 2.5 ± 0.1, 2.6 ± 0.2, and 2.4 ± 0.1 MeV, respectively. For a 1-mm-diameter neck, the maximum integral neutron yield was 6 × 109 neutrons. The anisotropy of neutron emission for a Z-pinch with a power-law distribution of high-energy ions is calculated.

Bakshaev, Yu. L.; Bryzgunov, V. A.; Vikhrev, V. V.; Volobuev, I. V.; Dan'ko, S. A.; Kazakov, E. D.; Korolev, V. D.; Klír, D.; Mironenko-Marenkov, A. D.; Pimenov, V. G.; Smirnova, E. A.; Ustroev, G. I.

2014-06-01

119

Radiative signatures of Z-pinch plasmas at UNR: from X-pinches to wire arrays  

NASA Astrophysics Data System (ADS)

University-scale Z-pinch generators are able to produce High Energy Density (HED) plasmas in a broad range of plasma parameters under well-controlled and monitored experimental conditions suitable for radiation studies. The implosion of X-pinch and wire array loads at a 1 MA generator yields short (1-20 nsec) x-ray bursts from one or several bright plasma spots near the wire cross point (for X-pinches) or along and near Z-pinch axis (for wire arrays). Such X- and Z-pinch HED plasma with scales from a few µm to several mm in size emits radiation in a broad range of energies from 10 eV to 0.5 MeV and is subject of our studies during the last ten years. In particular, the substantial number of experiments with very different wire loads was performed on the 1 MA Zebra generator and analyzed: X-pinch, cylindrical, nested, and various types of the novel load, Planar Wire Arrays (PWA). Also, the experiments at an enhanced current of 1.5-1.7 MA on Zebra using Load Current Multiplier (LCM) were performed. This paper highlights radiative signatures of X-pinches and Single and Double PWAs which are illustrated using the new results with combined wire loads from two different materials.

Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Safronova, U. I.; Shlyaptseva, V. V.; Shrestha, I.; Osborne, G. C.; Weller, M. E.; Stafford, A.; Lorance, M.; Chuvatin, A. S.

2014-08-01

120

Z pinch driven inertial confinement fusion target physics research at Sandia National Laboratories  

NASA Astrophysics Data System (ADS)

Three hohlraum concepts are being pursued at Sandia National Laboratories (SNL) to investigate the possibility of using pulsed power driven magnetic implosions (Z pinches) to drive targets capable of fusion yields in the range 200-1000 MJ. This research is being conducted on SNL's Z facility, which is capable of driving peak currents of 20 MA in various Z pinch load configurations that produce implosion velocities as high as 7.5 × 107cm/s, X ray energies of 1-2 MJ and X ray powers of 100-250 TW. The first concept, denoted dynamic hohlraum, has achieved a temperature of 180 +/- 14 eV in a configuration suitable for driving capsules. In addition, this concept has also achieved a temperature of 230 +/- 18 eV in an arrangement suitable for driving an external hohlraum. The second concept, denoted static walled hohlraum, has achieved temperatures of ~80-100 eV. Experimental investigation of the third concept, denoted Z pinch driven hohlraum, has recently begun. The article discusses each of these hohlraum concepts and provides an overview of the experiments that have been conducted on these systems to date.

Leeper, R. J.; Alberts, T. E.; Asay, J. R.; Baca, P. M.; Baker, K. L.; Breeze, S. P.; Chandler, G. A.; Cook, D. L.; Cooper, G. W.; Deeney, C.; Derzon, M. S.; Douglas, M. R.; Fehl, D. L.; Gilliland, T.; Hebron, D. E.; Hurst, M. J.; Jobe, D. O.; Kellogg, J. W.; Lash, J. S.; Lazier, S. E.; Matzen, M. K.; McDaniel, D. H.; McGurn, J. S.; Mehlhorn, T. A.; Moats, A. R.; Mock, R. C.; Muron, D. J.; Nash, T. J.; Olson, R. E.; Porter, J. L.; Quintenz, J. P.; Reyes, P. V.; Ruggles, L. E.; Ruiz, C. L.; Sanford, T. W. L.; Schmidlapp, F. A.; Seamen, J. F.; Spielman, R. B.; Stark, M. A.; Struve, K. W.; Stygar, W. A.; Tibbetts-Russell, D. R.; Torres, J. A.; Vargas, M.; Wagoner, T. C.; Wakefield, C.; Hammer, J. H.; Ryutov, D. D.; Tabak, M.; Wilks, S. C.; Bowers, R. L.; McLenithan, K. D.; Peterson, D. L.

1999-09-01

121

Study of micro-pinches in wire-array Z pinches  

SciTech Connect

Bright and hot areas with a high plasma density and temperature are observed in all kinds of Z pinches. We studied bright radiating spots produced by micro-pinches in cylindrical and planar wire-arrays at the 1 MA Zebra pulsed power generator using an x-ray streak camera synchronized with laser diagnostics, x-ray time-gated pinhole camera, and spectroscopy. Hot spots with extremely dense and relatively hot plasma arise during the collapse of the micro-pinches. These hot spots radiate a continuum spectrum with energy >2.5 keV. Typical micro-pinches in Al wire arrays generate x-ray bursts with durations of 0.4–1 ns in the soft x-ray range and 0.1–0.4 ns in the keV range. UV two-frame shadowgraphy shows spatial correlation of hot spots with the collapse and explosion of micro-pinches. Micro-pinches typically occur at the necks of the Z pinch, but can demonstrate a variety of parameters and different dynamics. An analysis of x-ray streak images shows that micro-pinches can generate >20% of the x-ray energy in some types of wire-array Z pinches.

Ivanov, V. V.; Papp, D.; Anderson, A. A.; Talbot, B. R.; Astanovitskiy, A. L.; Nalajala, V.; Dmitriev, O. [Department of Physics, University of Nevada, Reno, Nevada 89557 (United States)] [Department of Physics, University of Nevada, Reno, Nevada 89557 (United States); Chittenden, J. P.; Niasse, N. [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)] [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom); Pikuz, S. A.; Shelkovenko, T. A. [P.N. Lebedev Physical Institute, Moscow 119991 (Russian Federation)] [P.N. Lebedev Physical Institute, Moscow 119991 (Russian Federation)

2013-11-15

122

Radiative cooling of two-component wire-array Z-pinch plasma  

SciTech Connect

Wire-array two-component Z-pinch plasmas containing Al and other elements were studied experimentally and the observations interpreted with the help of theoretical modeling. Special attention was given to achieving reproducible implosions. Cascading implosions in star wire arrays mix components during the implosion phase and implosion dynamics were not affected by changes in concentration. A reduction in Al K-shell radiation and an increase in soft x-ray radiation emission were observed in Al-W plasma with 84% concentration of Al ions compared to only-Al plasma. Plasma with 84% of Al ions has radiative properties like those of W Z-pinches. The analysis of Al K-shell x-ray spectra with a collisional-radiative atomic kinetics model shows a drop of the electron temperature from 400?eV in pure Al plasma to below 300?eV in the Al-W mix. Al-Au Z-pinches present radiation features similar to Al-W plasma. This is indicative of a similar plasma cooling effect due to the presence of a high-Z element.

Ivanov, V. V.; Mancini, R. C.; Papp, D.; Hakel, P.; Durmaz, T. [Department of Physics, University of Nevada, Reno, Nevada 89557 (United States); Florido, R. [Department of Physics, University of Nevada, Reno, Nevada 89557 (United States); Departamento de Física, Universidad de Las Palmas de Gran Canaria, 35017 Las Palmas de Gran Canaria (Spain)

2014-08-15

123

Study of micro-pinches in wire-array Z pinches  

NASA Astrophysics Data System (ADS)

Bright and hot areas with a high plasma density and temperature are observed in all kinds of Z pinches. We studied bright radiating spots produced by micro-pinches in cylindrical and planar wire-arrays at the 1 MA Zebra pulsed power generator using an x-ray streak camera synchronized with laser diagnostics, x-ray time-gated pinhole camera, and spectroscopy. Hot spots with extremely dense and relatively hot plasma arise during the collapse of the micro-pinches. These hot spots radiate a continuum spectrum with energy >2.5 keV. Typical micro-pinches in Al wire arrays generate x-ray bursts with durations of 0.4-1 ns in the soft x-ray range and 0.1-0.4 ns in the keV range. UV two-frame shadowgraphy shows spatial correlation of hot spots with the collapse and explosion of micro-pinches. Micro-pinches typically occur at the necks of the Z pinch, but can demonstrate a variety of parameters and different dynamics. An analysis of x-ray streak images shows that micro-pinches can generate >20% of the x-ray energy in some types of wire-array Z pinches.

Ivanov, V. V.; Papp, D.; Anderson, A. A.; Talbot, B. R.; Astanovitskiy, A. L.; Nalajala, V.; Dmitriev, O.; Chittenden, J. P.; Niasse, N.; Pikuz, S. A.; Shelkovenko, T. A.

2013-11-01

124

Correlations Between Wire Morphology and Plasma Instability Development in Single and Multiwire Z-Pinches  

NASA Astrophysics Data System (ADS)

Moderate current rise (8-30 A/ns at current start) wire z-pinch experiments have been performed at the University of Michigan to study the early time behavior of single and multiwire (2-6) z-pinches. Effects of wire morphology on the development of plasma instabilities have been explored. Initial experiments included DC heating copper wires in vacuum prior to the z-pinch shot in order to induce grain boundary dislocations and grain growth in the metal. During the discharge, we applied laser shadowgraphy techniques to observe the plasma structures that develop in the exploding wire. We have observed a correlation between heating-induced grain discontinuities and development of instabilities after 100`s of ns. Currently, we are diagnosing tungsten wire discharges and applying the same techniques to observe if similar phenomena exist. Investigations concern tungsten wires with different grain boundary structures e.g., pure W vs. K-doped W (lighting wire). Emission spectroscopy diagnoses plasma composition.\\$*Research supported by US DOE through a Sandia National Lab contract to the University of Michigan. T.S. Strickler received a DOE Fusion Technology Fellowship.

Strickler, T. S.; Johnston, M. D.; Gilgenbach, R. M.; Lau, Y. Y.; Jones, M. C.; Mehlhorn, T. A.; Cuneo, M. E.

2004-11-01

125

Radiation characteristics and implosion dynamics of tungsten wire array Z-pinches on the YANG accelerator  

NASA Astrophysics Data System (ADS)

We investigated the radiation characteristics and implosion dynamics of low-wire-number cylindrical tungsten wire array Z-pinches on the YANG accelerator with a peak current 0.8-1.1 MA and a rising time ~ 90 ns. The arrays are made up of (8-32) × 5 ?m wires 6/10 mm in diameter and 15 mm in height. The highest X-ray power obtained in the experiments was about 0.37 TW with the total radiation energy ~ 13 kJ and the energy conversion efficiency ~ 9% (24 × 5 ?m wires, 6 mm in diameter). Most of the X-ray emissions from tungsten Z-pinch plasmas were distributed in the spectral band of 100-600 eV, peaked at 250 and 375 eV. The dominant wavelengths of the wire ablation and the magneto-Rayleigh—Taylor instability were found and analyzed through measuring the time-gated self-emission and laser interferometric images. Through analyzing the implosion trajectories obtained by an optical streak camera, the run-in velocities of the Z-pinch plasmas at the end of the implosion phase were determined to be about (1.3-2.1) × 107 cm/s.

Huang, Xian-Bin; Yang, Li-Bing; Li, Jing; Zhou, Shao-Tong; Ren, Xiao-Dong; Zhang, Si-Qun; Dan, Jia-Kun; Cai, Hong-Chun; Duan, Shu-Chao; Chen, Guang-Hua; Zhang, Zheng-Wei; Ouyang, Kai; Li, Jun; Zhang, Zhao-Hui; Zhou, Rong-Guo; Wang, Gui-Lin

2012-05-01

126

Influence of induced axial magnetic field on plasma dynamics and radiative characteristics of Z pinches  

SciTech Connect

The influence of an induced axial magnetic field on plasma dynamics and radiative characteristics of Z pinches is investigated. An axial magnetic field was induced in a novel Z-pinch load: a double planar wire array with skewed wires (DPWAsk), which represents a planar wire array in an open magnetic configuration. The induced axial magnetic field suppressed magneto-Rayleigh-Taylor (MRT) instabilities (with m = 0 and m = 1 instability modes) in the Z-pinch plasma. The influence of the initial axial magnetic field on the structure of the plasma column at stagnation was manifested through the formation of a more uniform plasma column compared to a standard double planar wire array (DPWA) load [V. L. Kantsyrev et al., Phys. Plasmas 15, 030704 (2008)]. The DPWAsk load is characterized by suppression of MRT instabilities and by the formation of the sub-keV radiation pulse that occurs before the main x-ray peak. Gradients in plasma parameters along the cathode-anode gap were observed and analyzed for DPWAsk loads made from low atomic number Z (Al) and mid-Z (brass) wires.

Kantsyrev, V. L.; Esaulov, A. A.; Safronova, A. S.; Osborne, G. C.; Shrestha, I.; Weller, M. E.; Stafford, A.; Shlyaptseva, V. V. [Physics Department, University of Nevada, Reno, Nevada 89557 (United States); Velikovich, A. L. [Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States); Rudakov, L. I. [Icarus Research Inc., Bethesda, Maryland 20824 (United States); Williamson, K. M. [Physics Department, University of Nevada, Reno, Nevada 89557 (United States); Plasma Engineering Research Laboratory, Texas A and M University, Corpus Christi, TX 78412 (United States)

2011-10-15

127

Radiative cooling of two-component wire-array Z-pinch plasma  

NASA Astrophysics Data System (ADS)

Wire-array two-component Z-pinch plasmas containing Al and other elements were studied experimentally and the observations interpreted with the help of theoretical modeling. Special attention was given to achieving reproducible implosions. Cascading implosions in star wire arrays mix components during the implosion phase and implosion dynamics were not affected by changes in concentration. A reduction in Al K-shell radiation and an increase in soft x-ray radiation emission were observed in Al-W plasma with 84% concentration of Al ions compared to only-Al plasma. Plasma with 84% of Al ions has radiative properties like those of W Z-pinches. The analysis of Al K-shell x-ray spectra with a collisional-radiative atomic kinetics model shows a drop of the electron temperature from 400 eV in pure Al plasma to below 300 eV in the Al-W mix. Al-Au Z-pinches present radiation features similar to Al-W plasma. This is indicative of a similar plasma cooling effect due to the presence of a high-Z element.

Ivanov, V. V.; Mancini, R. C.; Papp, D.; Hakel, P.; Durmaz, T.; Florido, R.

2014-08-01

128

Plasma dynamics and generation of hard radiations in experiments with cylindrical Z-pinches  

SciTech Connect

A survey of experimental studies on the generation of hard ionizing radiations from dynamic cylindrical Z-pinches is presented. Comprehensive experimental data do not confirm the hypothesis that charged particles responsible for the generation of hard radiations (neutrons and X-rays) are accelerated in short-scale Z-pinch necks (m = 0). Analysis of the experimental data indicates that, in discharges in pure hydrogen and deuterium, these particles are most probably accelerated in the axial direction along H{sub {phi} {approx}} 0 lines by the induction electric field generated during the initiation of the secondary near-wall breakdown, which disconnects the pinch from the power supply. In discharges excited in heavy gases and at high initial current growth rates (I{sub 0} {>=} 10{sup 12} A/s) in experiments with hydrogen and deuterium contaminated with admixtures arriving from the chamber wall, there is an additional acceleration mechanism related to the growth of the resistance of a radiatively cooled Z-pinch.

Matveev, Yu. V. [Academy of Sciences of Abkhazia, Sukhum Physicotechnical Institute, Abkhazia (Georgia)

2010-03-15

129

Characterization of diagnostic hole-closure in Z-pinch driven hohlraums  

SciTech Connect

In this article we investigate the partial closure of diagnostic holes in Z-pinch driven hohlraums. These hohlraums differ from current laser-driven hohlraums in a number of ways such as their larger size, greater x-ray drive energy, and lower temperature. Although the diameter of the diagnostic holes on these Z-pinch driven hohlraums can be much greater than their laser-driven counterparts, 4 mm in diameter or larger, radiation impinges on the wall material surrounding the hole for the duration of the Z pinch, nearly 100 ns. This incident radiation causes plasma to ablate from the hohlraum walls surrounding the diagnostic hole and partially obscure this diagnostic hole. This partial obscuration reduces the effective area over which diagnostics view the hohlraum's radiation. This reduction in area can lead to an underestimation of the wall temperature when nonimaging diagnostics such as x-ray diodes and bolometers are used to determine power and later to infer a wall temperature. In this article we describe the techniques used to characterize the hole-closure in these hohlraums and present the experimental measurements of this process. (c) 2000 American Institute of Physics.

Baker, K. L. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Porter, J. L. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Ruggles, L. E. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Chandler, G. A. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Deeney, Chris [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Vargas, M. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Moats, Ann [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Struve, Ken [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Torres, J. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); McGurn, J. S. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] (and others) [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)

2000-02-01

130

Reliable Copper and Aluminum Connections for High Power Applications in Electromobility  

NASA Astrophysics Data System (ADS)

Investigations concerning the growth of intermetallic phases during the heat input both at the diffusion annealing of copper aluminum roll claddings and the subsequent welding process of copper-aluminum connections by using roll cladded inserts are compared to the analytical determination of phase growth. The temperature distribution in the cladding interface has been determined by thermal simulation, in order to calculate the growth of the intermetallic phases. A comparison between the width of the phases in the analytical calculation and the experiment is achieved. In consideration of high welding speeds, the energy input during the welding process is appraised in order to grade the growth of intermetallic phases. Furthermore the prevention of damage in the roll cladding interface by means of unadapted material thicknesses or welding parameters can be assessed analytically and numerically. The numerical simulations can determine the critical thickness of the roll cladding to avoid damage like exceeding growth of intermetallic phases.

Hofmann, Konstantin; Holzer, Matthias; Hugger, Florian; Roth, Stephan; Schmidt, Michael

131

Aluminum Nitride-An Alternative Ceramic Substrate for High Power Applications in Microcircuits  

Microsoft Academic Search

The development of more complex integrated circuits (IC's) with larger chip sizes and greater power generation IC's, emitter-coupled logic (ECL) circuits, very large-scale integration (VLSI), and laser diodes requires new packaging schemes with improved thermal management. From the limited number of some ten nonmetallic inorganic solids known from the literature to have thermal conductivities greater than 100 W\\/m°K, aluminum nitride

W. Werdecker; F. Aldinger

1984-01-01

132

Development of UV Laser Probing Diagnostics for the Investigation of DenseZ Pinch Plasmas  

NASA Astrophysics Data System (ADS)

UV, 266-nm wavelength, laser probing diagnostics were developed for the investigation of the dense plasma on the 1-MA pulsed power generator, Zebra, located at the University of Nevada, Reno. These new diagnostics complemented the 532-nm laser probing diagnostics, which were not highly applicable for a z-pinch with an electron density higher than 1019 cm -3, due to strong absorption and refraction of the beam as it passes through the plasma. The UV laser diagnostics, shadowgraphy and interferometry, have been successfully tested at the ablation, implosion, stagnation, and dissipation phases of wire-array z-pinches. Probing simultaneously with 266-nm and 532-nm light has shown that the UV laser probes deeper into the z-pinch plasma, with higher resolution. The UV laser probe enjoys a significant advantage over the 532-nm laser probe, because the inverse bremsstrahlung absorption increment and refraction in the plasma column is proportional to the wavelength squared. For interferometry, the phase shift of the laser beam is proportional to the wavelength. UV interferometry was employed to measure the plasma density profile up to an electron density of 1·2x1020 cm -3. A high resolution laser probing channel was developed for further study of the dense z-pinch plasma. Specially designed anode and cathode plates allowed installation of the objective lens inside of the vacuum chamber. A spatial resolution of 4 microns was achieved with UV. Instabilities in the dense plasma pinch were directly observed. The micro-structure of the dense pinch was unfolded for the first time. Micro-pinches, small-scale and mid-scale instabilities, large kink and sausage instabilities, and breaks in the plasma column were studied with UV high resolution shadowgraphy and interferometry. To investigate the dynamics of the dense plasma, a second, time-delayed, frame was developed for the UV laser diagnostics. Large velocities, greater than 100 km/s, were measured. These demonstrate the generation of kinetic energy in the stagnation phase of the z-pinch.

Altemara, Sara D.

133

On the transparency of foam in low-density foam Z-pinch experiments  

NASA Astrophysics Data System (ADS)

Z-pinch experiments have been performed on the SATURN and Z machines at Sandia National Laboratories to study physics issues related to x-ray radiation generation and inertial confinement fusion. Some of these experiments utilize a CH foam located on-axis to convert energy to radiation and act as a radiative transfer volume. A significant issue for foam Z-pinch experiments is the transparency of the heated foam as a function of time and wavelength. Foam transparency will be important in future foam Z-pinch experiments both because it influences the time-dependent radiation field seen by an inertial confinement fusion capsule embedded in the foam, and because it is an important factor in making high-resolution spectral measurements of a capsule or tracers embedded in the foam. In this article, we describe results from simulations and experiments which address the issue of foam transparency. We discuss imaging data from one Z experiment in which x-ray emission from a half-Au/half-CH disk located at the bottom of a 1-cm-tall, 14 mg/cc TPX foam is observed. Simulation results predicting CH foam optical depths as a function of plasma conditions are presented. In addition, we present results from spectral calculations which utilize 2D magnetohydrodynamic (MHD) simulation predictions for the time-dependent foam conditions. Our results indicate that the observed x-ray framing camera images are consistent with early-time (several ns prior to stagnation) foam electron temperatures of ?30 eV, which is somewhat hotter than the foam electron temperatures predicted from the 2D MHD simulations at early times.

MacFarlane, J. J.; Derzon, M. S.; Nash, T. J.; Chandler, G. A.; Peterson, D. L.

1999-01-01

134

Grazing incidence extreme ultraviolet spectrometer fielded with time resolution in a hostile Z-pinch environment  

SciTech Connect

This recently developed diagnostic was designed to allow for time-gated spectroscopic study of the EUV radiation (4 nm < {lambda} < 15 nm) present during harsh wire array z-pinch implosions. The spectrometer utilizes a 25 {mu}m slit, an array of 3 spherical blazed gratings at grazing incidence, and a microchannel plate (MCP) detector placed in an off-Rowland position. Each grating is positioned such that its diffracted radiation is cast over two of the six total independently timed frames of the MCP. The off-Rowland configuration allows for a much greater spectral density on the imaging plate but only focuses at one wavelength per grating. The focal wavelengths are chosen for their diagnostic significance. Testing was conducted at the Zebra pulsed-power generator (1 MA, 100 ns risetime) at University of Nevada, Reno on a series of wire array z-pinch loads. Within this harsh z-pinch environment, radiation yields routinely exceed 20 kJ in the EUV and soft x-ray. There are also strong mechanical shocks, high velocity debris, sudden vacuum changes during operation, energic ion beams, and hard x-ray radiation in excess of 50 keV. The spectra obtained from the precursor plasma of an Al double planar wire array contained lines of Al IX and AlX ions indicating a temperature near 60 eV during precursor formation. Detailed results will be presented showing the fielding specifications and the techniques used to extract important plasma parameters using this spectrometer.

Williamson, K. M.; Kantsyrev, V. L.; Safronova, A. S.; Wilcox, P. G.; Cline, W.; Batie, S.; LeGalloudec, B.; Nalajala, V.; Astanovitsky, A. [Plasma Physics and Diagnostics Laboratory, Physics Department, University of Nevada, Reno, Nevada 89557 (United States)

2011-09-15

135

On the transparency of foam in low-density foam Z-pinch experiments  

SciTech Connect

Foam Z-pinch experiments have been performed on the SATURN and Z machines at Sandia National Laboratories to study physics issues related to x-ray radiation generation and inertial confinement fusion. A significant issue for foam Z-pinch experiments is the transparency of the heated foam as a function of time and wavelength. Foam transparency will be important in future foam Z-pinch experiments both because it influences the time-dependent radiation field seen by an ICF capsule embedded in the foam, and because it is an important factor in making high-resolution spectral measurements of a capsule or tracers embedded in the foam. In this paper, the authors describe results from simulations and experiments which address the issue of foam transparency. They discuss imaging data from one Z experiment in which x-ray emission from a half-Au/half-CH disk located at the bottom of a 1 cm-tall, 14 mg/cc TPX foam is observed. Simulation results predicting CH foam optical depths as a function of plasma conditions are presented. In addition, the authors present results from spectral calculations which utilize 2-D MHD simulation predictions for the time-dependent foam conditions. The results indicate that the observed x-ray framing camera images are consistent with early-time (several ns prior to stagnation) foam electron temperatures of {approx_gt} 30 eV, which is somewhat hotter than the foam electron temperatures predicted from the 2-D MHD simulations at early times.

MacFarlane, J.J. [Prism Computational Sciences, Inc., Madison, WI (United States)]|[Univ. of Wisconsin, Madison, WI (United States). Fusion Technology Inst.; Derzon, M.S.; Nash, T.J.; Chandler, G.A. [Sandia National Labs., Albuquerque, NM (United States); Peterson, D.L. [Los Alamos National Lab., NM (United States)

1998-12-31

136

Radiation energetics of inertial confinement fusion relevant wire-array z pinches  

NASA Astrophysics Data System (ADS)

The scaling of the radiation power and energy of z-pinch sources as a function of current and implosion time is of interest for z-pinch-driven, high-yield inertial confinement fusion applications [R.A. Vesey et al., Phys. Plasmas 14, 056302 (2007)]. Short implosion-time 20-mm diameter, 300-wire tungsten arrays maintain high peak x-ray powers on the 20 MA, 100-ns Z pulsed-power facility despite a reduction in peak current from 19 to 13 MA. The implosion kinetic energy is estimated using multiple diagnostics, including the first measurement of the imploding mass density profile of a wire- array z-pinch. The main radiation pulse (i.e., not including the late-time radiation) on tests with a 1-mm on-axis rod to limit the convergence may be explained solely by the kinetic energy flux. However, bare-axis tests require sub-mm convergence of the magnetic field and/or enhanced resistive heating. Sub-mm convergence is never seen in these arrays in the ˜450 eV x-ray emission characteristic of the peak of the blackbody emission. Sub-mm widths are seen only in high- energy >1 keV emission diagnostics. The latter images are characteristic of the high-energy tail in the emission spectrum that accounts for a substantial fraction of the total radiated energy and appears to be associated with small-area, high- temperature sources. The radiography and imaging data discussed here are presently being used to provide strong constraints for simulations beyond just the radiated power and energy. In collaboration with: M.E. Cuneo, S.V. Lebedev (Imperial College), R.W. Lemke, E.M. Waisman, W.A. Stygar, B. Jones, M.C. Jones, J.L. Porter, and D.F. Wenger.

Sinars, Daniel

2007-11-01

137

The importance of EBIT data for Z-pinch plasma diagnostics  

SciTech Connect

The results from the last six years of x-ray spectroscopy and spectropolarimetry of high energy density Z-pinch plasmas complemented by experiments with the electron beam ion trap (EBIT) at the Lawrence Livermore National Laboratory (LLNL) are presented. The two topics discussed are the development of M-shell x-ray W spectroscopic diagnostics and K-shell Ti spectropolarimetry of Z-pinch plasmas. The main focus is on radiation from a specific load configuration called an 'X-pinch'. X-pinches are excellent sources for testing new spectral diagnostics and for atomic modelling because of the high density and temperature of the pinch plasmas, which scale from a few {micro}m to several mm in size. They offer a variety of load configurations, which differ in wire connections, number of wires, and wire materials. In this work the study of X-pinches with tungsten wires combined with wires from other, lower-Z materials is reported. Utilizing data produced with the LLNL EBIT at different energies of the electron beam the theoretical prediction of line positions and intensity of M-shell W spectra were tested and calibrated. Polarization-sensitive X-pinch experiments at the University of Nevada, Reno (UNR) provide experimental evidence for the existence of strong electron beams in Ti and Mo X-pinch plasmas and motivate the development of x-ray spectropolarimetry of Z-pinch plasmas. This diagnostic is based on the measurement of spectra recorded simultaneously by two spectrometers with different sensitivity to the linear polarization of the observed lines and compared with theoretical models of polarization-dependent spectra. Polarization-dependent K-shell spectra from Ti X-pinches are presented and compared with model calculations and with spectra generated by a quasi-Maxwellian electron beam at the LLNL EBIT-II electron beam ion trap.

Safronova, A S; Kantsyrev, V L; Neill, P; Safronova, U I; Fedin, D A; Ouart, N D; Yilmaz, M F; Osborne, G; Shrestha, I; Williamson, K; Hoppe, T; Harris, C; Beiersdorfer, P; Hansen, S

2007-04-04

138

Time-resolved voltage measurements of Z-pinch radiation sources with a vacuum voltmeter  

SciTech Connect

A vacuum-voltmeter (VVM) was fielded on the Saturn pulsed power generator during a series of argon gas-puff Z-pinch shots. Time-resolved voltage and separately measured load current are used to determine several dynamic properties as the load implodes, namely, the inductance, L(t), net energy coupled to the load, E{sub coupled}(t), and the load radius, r(t). The VVM is a two-stage voltage divider, designed to operate at voltages up to 2 MV. The VVM is presently being modified to operate at voltages up to 6 MV for eventual use on the Z generator.

Murphy, D. P.; Allen, R. J.; Weber, B. V.; Commisso, R. J.; Apruzese, J. P. [Plasma Physics Division, Naval Research Laboratory, 4555 Overlook Ave. SW, Code 6770 Washington, DC 20375 (United States); Phipps, D. G.; Mosher, D. [L3 Communications/Titan Group, Reston, Virginia 20910 (United States)

2008-10-15

139

Spectral Analysis of Tracer Emission and Absorption Lines in Z-Pinch Dynamic Hohlraum Experiments  

NASA Astrophysics Data System (ADS)

Spectroscopic analysis of tracer absorption and emission lines is reported for a nested tungsten (W) wire array z-pinch containing an on-axis CH foam with an embedded, thin Al-Mg tracer. The absorption and emission of radiation from the W plasma, the tracer, and the foam are studied with the goal of determining plasma parameters, such as electron temperatures, W composition along the spectrometer (approximately on-axis) line-of-sight, optical depths, and effects of photoionization on atomic populations and spectra. Collisional-radiative calculations are performed using the SPECT3D spectral analysis code. We will present results of our simulations and comparisons with experimental data.

Macfarlane, Joseph; Bailey, Jim; Rochau, Greg; Nash, Tom; Chandler, Gordon; Sanford, Tom; Mehlhorn, Tom; Golovkin, Igor; Woodruff, Pam

2002-11-01

140

Characteristics of ICF Relevant Hohlraums Driven by X-Rays from a Z-Pinch  

SciTech Connect

Radiation environments characteristic of those encountered during the low-temperature foot pulse and subsequent higher-temperature early-step pulses (without the foot pulse) required for indirect-drive ICF ignition on the National ignition Facility have been produced in hohlraums driven by x-rays from a z-pinch. These environments provide a platform to better understand the dynamics of full-scale NIF hohlraums, ablator material, and capsules prior to NIF completion. Radiation temperature, plasma fill, and wall motion of these hohlraums are discussed.

BOWERS,R.L.; CHANDLER,GORDON A.; HEBRON,DAVID E.; LEEPER,RAMON J.; MATUSKA,W.; MOCK,RAYMOND CECIL; NASH,THOMAS J.; OLSON,RICHARD E.; PETERSON,D.L.; PETERSON,R.R.; RUGGLES,LAURENCE E.; RUIZ,CARLOS L.; SANFORD,THOMAS W. L.; SIMPSON,WALTER W.; VESEY,ROGER A.

1999-11-03

141

Demonstration of radiation symmetry control for inertial confinement fusion in double Z-pinch hohlraums.  

PubMed

Simulations of a double Z-pinch hohlraum, relevant to the high-yield inertial-confinement-fusion concept, predict that through geometry design the time-integrated P2 Legendre mode drive asymmetry can be systematically controlled from positive to negative coefficient values. Studying capsule elongation, recent experiments on Z confirm such control by varying the secondary hohlraum length. Since the experimental trend and optimum length are correctly modeled, confidence is gained in the simulation tools; the same tools predict capsule drive uniformity sufficient for high-yield fusion ignition. PMID:12570498

Vesey, R A; Cuneo, M E; Bennett, G R; Porter, J L; Adams, R G; Aragon, R A; Rambo, P K; Ruggles, L E; Simpson, W W; Smith, I C

2003-01-24

142

Use of spherically bent crystals to diagnose wire array z pinches  

SciTech Connect

Spherically bent mica and quartz crystals have provided time-integrated spectra and monochromatic images in self-radiation of wire array z-pinch implosions on the MAGPIE generator (1 MA, 240 ns) at Imperial College. Diagnostics based on spherically bent crystals offer higher efficiencies than those based on flat or convex dispersion elements, allowing positioning far from the pinch with good debris shielding. A mica crystal spectrometer produced an image of the pinch in each emission line with about 100 {mu}m axial resolution. Combining the results of monochromatic imaging and spectra confirmed the presence of bright spots, probably generated by energetic electrons inside the pinch.

Shelkovenko, T.A.; Pikuz, S.A.; Hammer, D.A.; Ampleford, D.J.; Bland, S.N.; Bott, S.C.; Chittenden, J.P.; Lebedev, S.V. [Laboratory of Plasma Studies, Cornell University, 369 Upson Hall, Ithaca, New York 14853 (United States); Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)

2004-10-01

143

Development of UV Two-Frame Imaging Diagnostics for Investigation of Plasma Dynamics in Z Pinches at Stagnation  

NASA Astrophysics Data System (ADS)

Two-frame laser diagnostics with high spatial resolution at the wavelength of 266nm were developed for investigation of plasma dynamics in wire arrays at the stagnation stage on the 1 MA Zebra pulsed power generator. UV diagnostics is a significant advance compared to regular diagnostics at 532nm due to smaller adsorption and refraction in dense plasma. UV diagnostics at 266nm allows for unique observations of the internal structure of dense Z pinches hidden by trailing material [1]. Evolution of m=0 necks on the pinch and development of kink instability was observed with two-frame shadowgraphy. Fast plasma motion with a velocity greater than 100km/s was observed in the Z pinch at stagnation. Plasma motion in the stagnated Z pinches may be linked to generation of kinetic energy from magnetic energy. [4pt] [1] V. V. Ivanov, J.P. Chittenden, S. D. Altemara et al., Phys. Rev. Lett. 107, 165002 (2011)

Altemara, Sara; Anderson, Austin; Papp, Daniel; Ivanov, Vladimir

2012-10-01

144

Implosion dynamics and radiation characteristics of wire-array Z pinches on the Cornell Beam Research Accelerator  

NASA Astrophysics Data System (ADS)

Experimental results are presented that characterize the implosion dynamics and radiation output of wire-array Z pinches on the 1-MA, 100-ns rise-time Cornell Beam Research Accelerator (COBRA) [J. B. Greenly et al., Rev. Sci. Instrum. 79, 073501 (2008)]. The load geometries investigated include 20-mm-tall cylindrical arrays ranging from 4to16mm in diameter, and consisting of 8, 16, or 32 wires of either tungsten, aluminum, or Invar (64% iron, 36% nickel). Diagnostics fielded include an optical streak camera, a time-gated extreme-ultraviolet framing camera, a laser shadowgraph system, time-integrated pinhole cameras, an x-ray wide-band focusing spectrograph with spatial resolution, an x-ray streak camera, a load voltage monitor, a Faraday cup, a bolometer, silicon diodes, and diamond photoconducting detectors. The data produced by the entire suite of diagnostics are analyzed and presented to provide a detailed picture of the overall implosion process and resulting radiation output on COBRA. The highest x-ray peak powers (300-500GW) and total energy yields (6-10kJ) were obtained using 4-mm-diameter arrays that stagnated before peak current. Additional findings include a decrease in soft x-ray radiation prior to stagnation as the initial wire spacing was changed from 1.6mmto785?m, and a timing correlation between the onset of energetic electrons, hard x-ray generation, and the arrival of trailing current on axis—a correlation that is likely due to the formation of micropinches. The details of these and other findings are presented and discussed.

McBride, R. D.; Shelkovenko, T. A.; Pikuz, S. A.; Hammer, D. A.; Greenly, J. B.; Kusse, B. R.; Douglass, J. D.; Knapp, P. F.; Bell, K. S.; Blesener, I. C.; Chalenski, D. A.

2009-01-01

145

Design of the PST: A Diagnostic for 1-D Imaging of Fast Z-Pinch Power Emissions  

SciTech Connect

Fast Z-pinch technology developed on the Z machine at Sandia National Laboratories can produce up to 230 TW of thermal x-ray power for applications in inertial confinement fusion (ICF) and weapons physics experiments. During implosion, these Z-pinches develop Rayleigh-Taylor (R-T) instabilities which are very difficult to diagnose and which functionally diminish the overall pinch quality. The Power-Space-Time (PST) instrument is a newly configured diagnostic for measuring the pinch power as a function of both space and time in a Z-pinch. Placing the diagnostic at 90 degrees from the Z-pinch axis, the PST provides a new capability in collecting experimental data on R-T characteristics for making meaningful comparisons to magneto-hydrodynamic computer models. This paper is a summary of the PST diagnostic design. By slit-imaging the Z-pinch x-ray emissions onto a linear scintillator/fiber-optic array coupled to a streak camera system, the PST can achieve {approximately}100 {micro}m spatial resolution and {approximately}1.3 ns time resolution. Calculations indicate that a 20 {micro}m thick scintillating detection element filtered by 1,000 {angstrom} of Al is theoretically linear in response to Plankian x-ray distributions corresponding to plasma temperatures from 40 eV to 150 eV, By calibrating this detection element to x-ray energies up to 5,000 eV, the PST can provide pinch power as a function of height and time in a Z-pinch for temperatures ranging from {approximately}40 eV to {approximately}400 eV. With these system pm-meters, the PST can provide data for an experimental determination of the R-T mode number, amplitude, and growth rate during the late-time pinch implosion.

ROCHAU,GREGORY A.; DERZON,MARK S.; CHANDLER,GORDON A.; LAZIER,STEVEN EARL

2000-08-03

146

An alternative scaling model for neutron production in Z-pinch devices  

SciTech Connect

The DD neutron yield (Y{sub n}) from z-pinches, either dense plasma foci or fast radial pinches, has been fitted for decades to the scaling model Y{sub n} {approx} {alpha}(I{sub max}){sup {delta}}, where {alpha} is a numerical scaling coefficient, I{sub max} the peak current, and 3 < {delta} < 5. The data from 12 000 pulses analyzed from eight different z-pinches presented in this paper show that Y{sub n} varies by as much as {+-}15 000% about the best fit value of the conventional scaling model with {delta} = 4. A revised scaling model derived from the reaction rate equation and a circuit model that includes the time derivative of the current dI/dt (normalized to its initial value) reduces the scatter in data from {+-}15 000% to {+-}100%. For the special case of very high normalized dI/dt, the standard deviation between the revised scaling prediction and the measured neutron yields is reduced to just {+-}30%. Implications of this revised scaling for higher current pinches are discussed.

Bures, Brian L.; Krishnan, Mahadevan [Alameda Applied Sciences Corporation, 3077 Teagarden St., San Leandro, California 94577 (United States)

2012-11-15

147

Investigation of Magnetic Field Geometry in Exploding Wire Z-Pinches via Proton Deflectometry  

NASA Astrophysics Data System (ADS)

It is often difficult to determine the configuration of B-fields within z-pinch plasma systems. Typical laser probing diagnostics are limited by the critical density, and electrical diagnostics are prone to failure as well as perturbation of the system. The use of proton beams launched by high intensity lasers, and the subsequent tracking of their deflected trajectories, will enable access to field measurements in previously inaccessible plasma densities.The experimental testing of this method is performed at the Nevada Test Facility (NTF) using the 10J 0.3ps Leopard laser coupled to the 1.6MA ZEBRA pulsed power generator. MHD simulations of the z-pinch plasmas are performed with the 3D resistive MHD code, GORGON. Protons are then injected and tracked through the plasma using the 3D PIC Large Scale Plasma code in order to produce possible proton image plane data. The first computational demonstration of protons propagating through single wire and x-pinch plasmas, along with comparison to recent experimental data will be presented.

Mariscal, Derek; Beg, Farhat; Wei, Mingsheng; Chittenden, Jeremy; Presura, Radu

2012-10-01

148

Ion probe beam experiments and kinetic modeling in a dense plasma focus Z-pinch  

NASA Astrophysics Data System (ADS)

The Z-pinch phase of a dense plasma focus (DPF) emits multiple-MeV ions in a ˜cm length. The mechanisms through which these physically simple devices generate such high energy beams in a relatively short distance are not fully understood. We are exploring the origins of these large gradients using measurements of an ion probe beam injected into a DPF during the pinch phase and the first kinetic simulations of a DPF Z-pinch. To probe the accelerating fields in our table top experiment, we inject a 4 MeV deuteron beam along the z-axis and then sample the beam energy distribution after it passes through the pinch region. Using this technique, we have directly measured for the first time the acceleration of an injected ion beam. Our particle-in-cell simulations have been benchmarked on both a kJ-scale DPF and a MJ-scale DPF. They have reproduced experimentally measured neutron yields as well as ion beams and EM oscillations which fluid simulations do not exhibit. Direct comparisons between the experiment and simulations enhance our understanding of these plasmas and provide predictive design capability for accelerator and neutron source applications.

Schmidt, A.; Ellsworth, J.; Falabella, S.; Link, A.; McLean, H.; Rusnak, B.; Sears, J.; Tang, V.; Welch, D.

2014-12-01

149

Indirect-drive ICF target concepts for the X-1 Z-pinch facility  

SciTech Connect

The authors describe designs of hohlraums and capsules for both ignition ({approximately}1--10 MJ) and high yield (up to {approximately}200 MJ) Z-pinch driven indirect-drive ICF concepts. Two potential Z-pinch hohlraum configurations: (1) the static wall or on-axis hohlraum; and (2) the imploding liner or dynamic hohlraum are considered. Both concepts involve cryogenic, DT-filled capsules ({approximately}2--4 mm in diameter) with Be or CH ablators (O, F, and Cu are currently being considered as dopants). Both types of hohlraums involve a Helium and/or CH foam fill. In the static wall hohlraum concept, the ICF capsule is isolated from the x-ray generation region. Advantages in the areas of capsule drive symmetry and diagnostic access might be gained from this arrangement. In the dynamic hohlraum, the ICF capsule has a direct view of the stagnation radiation. The potential advantage would result from the higher x-ray intensity and larger total capsule absorbed energy.

Olson, R.E.; Chandler, G.A.; Derzon, M.S. [Sandia National Labs., Albuquerque, NM (United States)] [and others

1999-03-01

150

Primary experimental results of wire-array Z-pinches on PTS  

NASA Astrophysics Data System (ADS)

The Primary Test Stand (PTS) developed at the China Academy of Engineering Physics is a multiterawatt pulsed power driver, which can deliver a ˜10 MA, 70 ns rise-time (10%-90%) current to a short circuit load and has important applications in Z-pinch driven inertial confinement fusion and high energy density physics. In this paper, primary results of tungsten wire-array Z-pinch experiments on PTS are presented. The load geometries investigated include 15-mm-tall cylindrical single and nested arrays with diameter ranging from 14.4-26.4 mm, and consisting of 132˜276 tungsten wires with 5˜10 ?m in diameter. Multiple diagnostics were fielded to determine the characteristics of x-ray radiations and to obtain self-emitting images of imploding plasmas. X-ray power up to 80 TW with ˜3 ns FWMH is achieved by using nested wire arrays. The total x-ray energy exceeds 500 kJ and the peak radiation temperature is about 150 eV. Typical velocity of imploding plasmas goes around 3˜5×107 cm/s and the radial convergence ratio is between 10 and 20.

Huang, X. B.; Zhou, S. T.; Ren, X. D.; Dan, J. K.; Wang, K. L.; Zhang, S. Q.; Li, J.; Xu, Q.; Cai, H. C.; Duan, S. C.; Ouyang, K.; Chen, G. H.; Ji, C.; Wang, M.; Feng, S. P.; Yang, L. B.; Xie, W. P.; Deng, J. J.

2014-12-01

151

PBFA II-Z: A 20-MA driver for z-pinch experiments  

SciTech Connect

Sandia is modifying the PBFA II accelerator into a dual use facility. While maintaining the present ion-beam capability, we are developing a long-pulse, high-current operating mode for magnetically-driven implosions. This option, called PBFA II-Z, will require new water transmission lines, a new insulator stack, and new magnetically-insulated transmission lines (MITLs). Each of the existing 36, coaxial water pulse-forming sections will couple to a 4.5-{Omega}, bi-plate water-transmission line. The water transmission lines then feed a four-level insulator stack. The insulators are expected to operate at a maximum, spatially-averaged electric field of {approximately}l00 kV/cm. The MITL design is based on the successful biconic Saturn design. The four ``disk`` feeds will each have a vacuum impedance of {approximately}2.0 {Omega}. The disk feeds are added in parallel using a double post-hole convolute at a diameter of 15 cm. We predict that the accelerator will deliver 20 MA to a 15-mg z-pinch load in 100 ns, making PBFA II-Z the most powerful z-pinch driver in the world providing a pulsed power and load physics scaling testbed for future 40-80-MA drivers.

NONE

1995-12-01

152

Analysis of spatially resolved Z-pinch spectra to investigate the nature of ``bright spots''  

NASA Astrophysics Data System (ADS)

Localized, intensely radiating regions are often observed in Z pinches. High resolution images of such areas have been recorded at least as far back as the 1970s. However, there is as yet no widely accepted consensus on the nature of these "bright spots" or how they are formed. This phenomenon has also been referred to "hot spots" or "micropinches." To shed further light on this issue, we have analyzed axially resolved K-shell spectra from 4 Z pinches driven by the refurbished Z generator ("ZR") at Sandia National Laboratories, and the previous version of the Z machine ("Z"). The atomic numbers of the loads varied from 13 to 29. We find that higher spatial K-shell intensity in the Al pinch correlates with density. The K-shell intensity within a copper shot taken on ZR correlates strongly with increased electron temperature, but another, somewhat less well-diagnosed copper shot from Z shows correlation with density. The bright spots in a Ti pinch correlate with neither density nor temperature, but do correlate with the product of density and diameter (proportional to opacity). This opacity correlation is also observed in the other 3 pinches.

Apruzese, J. P.; Giuliani, J. L.; Thornhill, J. W.; Coverdale, C. A.; Jones, B.; Ampleford, D. J.

2013-02-01

153

Determining the temperature and density distribution from a Z-pinch radiation source  

SciTech Connect

High temperature radiation sources exceeding one hundred eV can be produced via z-pinches using currently available pulsed power. The usual approach to compare the z-pinch simulation and experimental data is to convert the radiation output at the source, whose temperature and density distributions are computed from the 2-D MHD code, into simulated data such as a spectrometer reading. This conversion process involves a radiation transfer calculation through the axially symmetric source, assuming local thermodynamic equilibrium (LTE), and folding the radiation that reaches the detector with the frequency-dependent response function. In this paper the authors propose a different approach by which they can determine the temperature and density distributions of the radiation source directly from the spatially resolved spectral data. This unfolding process is reliable and unambiguous for the ideal case where LTE holds and the source is axially symmetric. In reality, imperfect LTE and axial symmetry will introduce inaccuracies into the unfolded distributions. The authors use a parameter optimization routine to find the temperature and density distributions that best fit the data. They know from their past experience that the radiation source resulting from the implosion of a thin foil does not exhibit good axial symmetry. However, recent experiments carried out at Sandia National Laboratory using multiple wire arrays were very promising to achieve reasonably good symmetry. For these experiments the method will provide a valuable diagnostic tool.

Matuska, W.; Lee, H.

1997-11-01

154

Optical Spectroscopy Measurements of Shock Waves Driven by Intense Z-Pinch Radiation  

SciTech Connect

Z-pinches created using the Z accelerator generate {approximately}220 TW, 1.7 MJ radiation pulses that heat large ({approximately}10 cm{sup 3}) hohlraums to 100-150 eV temperatures for times of order 10 nsec. We are performing experiments exploiting this intense radiation to drive shock waves for equation of state studies. The shock pressures are typically 1-10 Mbar with 10 nsec duration in 6-mm-diameter samples. In this paper we demonstrate the ability to perform optical spectroscopy measurements on shocked samples located in close proximity to the z-pinch. These experiments are particularly well suited to optical spectroscopy measurements because of the relatively large sample size and long duration. The optical emission is collected using fiber optics and recorded with a streaked spectrograph. Other diagnostics include VISAR and active shock breakout measurements of the shocked sample and a suite of diagnostics that characterize the radiation drive. Our near term goal is to use the spectral emission to obtain the temperature of the shocked material. Longer term objectives include the examination of deviations of the spectrum from blackbody, line emission from lower density regions, determination of kinetic processes in molecular systems, evaluation of phase transitions such as the onset of metalization in transparent materials, and characterization of the plasma formed when the shock exits the rear surface. An initial set of data illustrating both the potential and the challenge of these measurements is described.

Asay, J. Bernard, M.; Bailey, J.E.; Carlson, A.L.; Chandler, G.A.; Hall, C.A.; Hanson, D.; Johnston, R.; Lake, P.; Lawrence, J.

1999-04-09

155

Modeling of Dopant Spectral Emission in Z-Pinch Dynamic Hohlraum Experiments  

NASA Astrophysics Data System (ADS)

X-ray spectra have been obtained from Si-doped low-density foams in dynamic hohlraum z-pinch experiments at Sandia National Laboratories. The purpose of the dopants is to provide spectroscopy signatures for constraining the time-dependent conditions within the hohlraum. In these experiments, ˜ 16 - 18 MA of current is delivered to a load comprised of a tungsten wire array which surrounds a low density cylindrical CH2 foam. The z-pinch magnetic field accelerates the W plasma radially inward, reaching velocities ˜ a few x 10^7 cm/s. As the W plasma strikes the foam, a strong shock propagates through the foam, with temperatures behind the shock reaching ˜ a few x 10^2 eV. Time- and space-resolved x-ray spectra from Si K-shell lines are recorded, providing spectra from regions both within the shock and ahead of the shock. To model these spectra, we use the SPECT3D multi-dimensional collisional-radiative spectral analysis code. In this study, we investigate the influence of photopumping of Si transitions in the unshocked foam due to radiation emitted by the shocked foam region. We will present results from recent simulations, and discuss the sensitivity of the spectra to the conditions in the shocked and unshocked foam regions.

Macfarlane, Joseph; Rochau, G. A.

2005-10-01

156

Magnetic Field Measurements in Wire-Array Z-Pinches using Magneto-Optically Active Waveguides  

SciTech Connect

Understanding the magnetic field topology in wire-array Z-pinches as a function of time is of great significance to understanding these high-energy density plasmas especially for their ultimate application to stockpile stewardship and inertial confinement fusion. We are developing techniques to measure magnetic fields as a function of space and time using Faraday rotation of a single longitudinal mode (SLM) laser through a magneto-optically active bulk waveguide (multicomponent terbium borate glass) placed adjacent to, or within, the wire array in 1 MA experiments. We have measured fields >10 T with 100 ns rise times outside of a wire-array for the entire duration of the current pulse and as much as {approx}2 T inside a wire-array for {approx}40 ns from the start of current. This is the first time that such rapidly varying and large fields have been measured using these materials. In a dense Z-pinch, these sensing devices may not survive for long but may provide the magnetic field at the position of the sensor that can be used to corroborate magnetic probes, with which we compare our results.

Syed, Wasif [School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853 (United States); Laboratory of Plasma Studies, Cornell University, Ithaca, NY 14853 (United States); Blesener, Isaac; Hammer, David A. [School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853 (United States); Laboratory of Plasma Studies, Cornell University, Ithaca, NY 14853 (United States); Lipson, Michal [School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853 (United States)

2009-01-21

157

Ion debris characterization from a z-pinch extreme ultraviolet light source  

SciTech Connect

An XTREME Technologies XTS 13-35 extreme ultraviolet (EUV) light source creates a xenon z pinch that generates 13.5 nm light. Due to the near x-ray nature of light at this wavelength, extremely smooth metal mirrors for photon collection must be employed. These are exposed to the source debris. Dissolution of the z-pinch gas column results in high-energy ion and neutral release throughout the chamber that can have adverse effects on mirror surfaces. The XTREME commercial EUV emission diagnostic chamber was designed to maximize diagnostic access to the light and particulate emissions from the z pinch. The principal investigation is characterization of the debris field and the erosive effects on optics present. Light emission from the z pinch is followed by ejection of multiply charged ions and fast neutral particles that make up an erosive flux to chamber surfaces. Attenuation of this erosive flux to optical surfaces is attempted by inclusion of a debris mitigation tool consisting of foil traps and neutral buffer gas flow. Characterization of the z-pinch ejecta is performed with a spherical sector energy analyzer (ESA) that diagnoses fast ion species by energy-to-charge ratio using ion time-of-flight (ITOF) analysis. This is used to evaluate the debris tool's ability to divert direct fast ions from impact on optic surfaces. The ITOF-ESA is used to characterize both the energy and angular distribution of the direct fast ions. Xe{sup +} up to Xe{sup +4} ions have been characterized along with Ar{sup +} (the buffer gas used), W{sup +}, Mo{sup +}, Si{sup +}, Fe{sup +}, and Ni{sup +}. Energy spectra for these species from 0.5 up to 13 keV are defined at 20 deg. and 30 deg. from the pinch centerline in the chamber. Results show a drop in ion flux with angular increase. The dominant species is Xe{sup +} which peaks around 8 keV. Ion flux measured against buffer gas flow rate suggests that the direct fast ion population is significantly attenuated through increases in buffer gas flow rate. This does not address momentum transfer from scattered ions or fast neutral particles. These results are discussed in the context of other investigations on the effects of total particle flux to normal incidence mirror samples exposed for 1x10{sup 7} pulses. The samples (Si/Mo multilayer with Ru capping layer, Au, C, Mo, Pd, Ru, and Si) were exposed to the source plasma with 75% argon flow rate in the debris mitigation tool and surface metrology was performed using x-ray photoelectron spectroscopy, atomic force microscopy, x-ray reflectivity, and scanning electron microscopy to analyze erosion effects on mirrors. These results are compared to the measured direct ion debris field.

Antonsen, Erik L.; Thompson, Keith C.; Hendricks, Matthew R.; Alman, Darren A.; Jurczyk, Brian E.; Ruzic, D.N. [Plasma-Materials Interaction Group, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

2006-03-15

158

Going from nested to single wire array for 800ns implosion time Z-pinches, using microsecond prepulse technique on sphinx machine  

Microsoft Academic Search

Summary form only given. The Sphinx machine is a 6 MA, 1 mus driver based on the LTD technology, used for Z-pinch experiments. Despite the long implosion time (600 ns to 800 ns), Sphinx wire arrays with large diameter (~14 cm) have already shown to behave and to be controlled by the same physical processes as faster Z-pinches. This allowed

F. Zucchini; H. Calamy; F. Lassalle; A. Loyen; F. Hamann; P. Maury; A. Georges; J. P. Bedoch; A. Morell

2008-01-01

159

Optimal welding parameters for very high power ultrasonic additive manufacturing of smart structures with aluminum 6061 matrix  

NASA Astrophysics Data System (ADS)

Ultrasonic additive manufacturing (UAM) is a recent solid state manufacturing process that combines ad- ditive joining of thin metal tapes with subtractive milling operations to generate near net shape metallic parts. Due to the minimal heating during the process, UAM is a proven method of embedding Ni-Ti, Fe-Ga, and PVDF to create active metal matrix composites. Recently, advances in the UAM process utilizing 9 kW very high power (VHP) welding has improved bonding properties, enabling joining of high strength materials previously unweldable with 1 kW low power UAM. Consequently, a design of experiments study was conducted to optimize welding conditions for aluminum 6061 components. This understanding is critical in the design of UAM parts containing smart materials. Build parameters, including weld force, weld speed, amplitude, and temperature were varied based on a Taguchi experimental design matrix and tested for me- chanical strength. Optimal weld parameters were identi ed with statistical methods including a generalized linear model for analysis of variance (ANOVA), mean e ects plots, and interaction e ects plots.

Wolcott, Paul J.; Hehr, Adam; Dapino, Marcelo J.

2014-03-01

160

Pinch me - I'm fusing! Fusion Power - what is it? What is a z pinch? And why are z-pinches a promising fusion power technology?  

SciTech Connect

The process of combining nuclei (the protons and neutrons inside an atomic nucleus) together with a release of kinetic energy is called fusion. This process powers the Sun, it contributes to the world stockpile of weapons of mass destruction and may one day generate safe, clean electrical power. Understanding the intricacies of fusion power, promised for 50 years, is sometimes difficult because there are a number of ways of doing it. There is hot fusion, cold fusion and con-fusion. Hot fusion is what powers suns through the conversion of mass energy to kinetic energy. Cold fusion generates con-fusion and nobody really knows what it is. Even so, no one is generating electrical power for you and me with either method. In this article the author points out some basic features of the mainstream approaches taken to hot fusion power, as well as describe why z pinches are worth pursuing as a driver for a power reactor and how it may one day generate electrical power for mankind.

DERZON,MARK S.

2000-03-01

161

Theoretical and Experimental Studies of Radiation from Z-Pinch Complex Wire Arrays and Applications  

NASA Astrophysics Data System (ADS)

In the research area of high energy density plasmas an ever increasing goal is searching for higher efficient radiators, particularly in z-pinch plasmas, and their applications. This goal is a major focus of this dissertation and implements both theoretical and experimental tools in the process. The theoretical tools involve the Wire Ablation Dynamics Model (WADM) to infer z-pinch implosion characteristics and various non-local thermodynamic equilibrium (LTE) kinetic models to understand the radiative properties of plasmas, including a new model for L-shell Ag. The experimental tools includes an advanced set of diagnostics, in particular a newly developed time-gated hard x-ray spectrometer to gain an understanding as to how these plasmas radiate in time, particularly in the 0.7 - 4.4 A range. The experiments predominately took place on the 1.7 MA Zebra generator at the Nevada Terawatt Facility (NTF) at the University of Nevada, Reno (UNR). Traditional nested cylindrical wire arrays with mixed materials (brass and Al, Mo and Al) were tested to understand how the inner and outer arrays implode and radiate. Novel planar wire arrays, which have been shown to be very powerful radiation sources, arranged in single, double, and triple wire array configurations were tested with Mo and Ag materials, which have both been shown to be powerful radiators, and also mixed with Al to understand opacity effects and how a mixture of two different plasmas radiate. Radiation from the extreme ultraviolet (EUV) range has also been of recent interest due the substantial contribution into total radiation yields. Therefore EUV radiation of M-shell Cu was modeled and benchmarked with spheromak and laser-produced plasma data. Lastly, lasing gain from L-shell Ag is calculated as an application of the aforementioned model to evaluate whether lasing might be occurring in wire array z-pinches. In connection to creating a uniform plasma column to measure lasing lines, the split double planar wire array is introduced and preliminary results discussed.

Weller, Michael Eugene

162

Z-pinch vacuum hohlraum radiation symmetry control for high-performance capsule implosions, ignition, and high yield  

NASA Astrophysics Data System (ADS)

Capsule radiation symmetry is a crucial issue in the design of the double z-pinch hohlraum approach to high-yield inertial confinement fusion [1]. Recent x-ray backlit capsule experiments in double z-pinch hohlraums on Sandia National Laboratories' Z facility have demonstrated the ability to predictably control time-integrated P2 asymmetry [2], and have measured the sensitivity of P2 and P4 asymmetry to hohlraum geometric parameters (hohlraum length, case-to-capsule ratio, etc.) [3]. 2D viewfactor and radiation-hydrodynamics hohlraum/capsule simulations reproduce the Z experimental results reasonably well, giving confidence in predictions of the performance of future experiments. These same tools are being used to predict the performance of high-yield capsules (radius > 2.5 mm, yield > 400 MJ) in double z-pinch hohlraums driven by ˜20 MJ z-pinch x-ray sources. In the nearer term, time-dependent symmetry control influences the design of neutron-producing moderate convergence (Cr ˜20) capsules for Z, as well as liquid cryogenic fuel capsules for compression to densities approaching 100 g/cc for fast ignition physics experiments on ZR. 1. J. H. Hammer et al., Phys. Plas. 6, 2129 (1999). 2. G. R. Bennett et al., Phys. Plas (in press), R. A. Vesey et al., Phys. Plas. 10, 1854 (2003). 3. M. E. Cuneo et al.; G. R. Bennett et al., (this conference)

Vesey, R. A.; Cuneo, M. E.; Bennett, G. R.; Hanson, D. L.; Porter, J. L.; Ruggles, L. E.; Simpson, W. W.; Mehlhorn, T. A.; Wunsch, S. E.

2003-10-01

163

Theoretical Investigation of Radiation Characteristics of Silver Z-pinch Arrays with Applications  

NASA Astrophysics Data System (ADS)

Experiments of Ag planar wire array z-pinches have been carried out on the 1.7 MA Zebra generator at UNR and produced L-shell plasmas with electron temperatures exceeding 1.8 keV and total radiated energy upwards of 30 kJ, which is of interest for radiation physics studies. Recently, an important question about such Ag plasmas is whether lasing occurs in the Na-like and Ne-like soft x-ray range, and if so, at what gains was considered. To this end, level populations were used from modified SCRAM to calculate theoretical lasing gains for Ne-like Ag. In addition, HELIOS-CR from PRISM was utilized for 1D MHD calculations for simple cylindrical Ag configurations. The importance of the study of Ag planar wire arrays is discussed.

Weller, M. E.; Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Shrestha, I.; Osborne, G. C.; Shlyaptseva, V. V.; Keim, S. F.; Stafford, A.; Petkov, E. E.; Chuvatin, A. S.; Apruzese, J. P.; Golovkin, I. E.; Macfarlane, J. J.

2012-10-01

164

The role of Z-pinch fusion transmutation of waste in the nuclear fuel cycle.  

SciTech Connect

The resurgence of interest in reprocessing in the United States with the Global Nuclear Energy Partnership has led to a renewed look at technologies for transmuting nuclear waste. Sandia National Laboratories has been investigating the use of a Z-Pinch fusion driver to burn actinide waste in a sub-critical reactor. The baseline design has been modified to solve some of the engineering issues that were identified in the first year of work, including neutron damage and fuel heating. An on-line control feature was added to the reactor to maintain a constant neutron multiplication with time. The transmutation modeling effort has been optimized to produce more accurate results. In addition, more attention was focused on the integration of this burner option within the fuel cycle including an investigation of overall costs. This report presents the updated reactor design, which is able to burn 1320 kg of actinides per year while producing 3,000 MWth.

Smith, James Dean; Drennen, Thomas E. (Hobart & William Smith College, Geneva, NY); Rochau, Gary Eugene; Martin, William Joseph; Kamery, William (Hobart & William Smith College, Geneva, NY); Phruksarojanakun, Phiphat (University of Wisconsin, Madison, WI); Grady, Ryan (University of Wisconsin, Madison, WI); Cipiti, Benjamin B.; Wilson, Paul Philip Hood (University of Wisconsin, Madison, WI); Mehlhorn, Thomas Alan; Guild-Bingham, Avery (Texas A& M University, College Station, TX); Tsvetkov, Pavel Valeryevich (Texas A& M University, College Station, TX)

2007-10-01

165

Preliminary Results of Cone Z-Pinch Device with 5 kJ  

NASA Astrophysics Data System (ADS)

The Cone Z-Pinch Experiment with 5 kJ is designed, constructed and operated. The electric discharge takes place between an upper ring electrode and a lower pin electrode creating plasma sheath in shape of cone. The preliminary experimental results using Helium gas in discharge show that the discharge period is 35 ?s, the total system inductance is 287 nH, and the total system resistance is 15 m?. The breakdown curve shows a minimum breakdown value at 0.2 torr pressure. The cone plasma is confined by electromagnetic force and plasma inductance has its maximum value at the pinch. The plasma current has a maximum value of 53 kA at the axis of the discharge tube. The experimental results showed that a time of 2.1 ?s at least is required for the pinch to occur and that both the pinch time and the duration time decrease with increasing the charging voltage.

Abdel-kader, M. E.; Abd Al-Halim, M. A.; Shagar, A. M.; Eltayeb, H. A.; Algamal, H. A.; Saudy, A. H.

2013-10-01

166

Use of vacuum arc plasma guns for a metal puff Z-pinch system  

SciTech Connect

The performance of a metal puff Z-pinch system has been studied experimentally. In this type of system, the initial cylindrical shell 4 cm in diameter was produced by ten plasma guns. Each gun initiates a vacuum arc operating between magnesium electrodes. The net current of the guns was 80 kA. The arc-produced plasma shell was compressed by using a 450-kA, 450-ns driver, and as a result, a plasma column 0.3 cm in diameter was formed. The electron temperature of the plasma reached 400 eV at an average ion concentration of 1.85 {center_dot} 10{sup 18} cm{sup -3}. The power of the Mg K-line radiation emitted by the plasma for 15-30 ns was 300 MW/cm.

Rousskikh, A. G.; Zhigalin, A. S.; Oreshkin, V. I.; Chaikovsky, S. A.; Labetskaya, N. A. [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk 634055 (Russian Federation); Baksht, R. B. [Tel Aviv University, Electrical Discharge and Plasma Laboratory, Tel Aviv 69101 (Israel)

2011-09-15

167

Investigation of a 5 kJ conical Z-pinch discharge  

NASA Astrophysics Data System (ADS)

A conical 5 kJ Z-pinch experiment with 35 ?s discharge time was constructed and operated. Preliminary results showed that the total circuit parameters are 287 nH inductance and 13 m? total resistance. The cone plasma inductance has its maximum value at the pinch. It has been determined that the pinching time is inversely proportional to the deposited energy. Moreover, a calculated delay time of about 2.1 ?s is required for the pinch to occur and the calculated sheath velocity ranges between 1 and 11.5 cm/ ?s. Erosion of the pin electrode could potentially explain the difference between the mass of helium gas inside the cone and the calculated swept mass. The main product of the ionization process is a singly-ionized helium atom.

Abdel-kader, Mohamed E.; Abd Al-Halim, Mohamed A.; Shagar, Azza M.; Saudy, Ali H.

2014-06-01

168

Dense Plasma Focus Z-pinches for High Gradient Particle Acceleration  

SciTech Connect

The final Z-pinch stage of a Dense Plasma Focus (DPF) could be used as a simple, compact, and potentially rugged plasma-based high-gradient accelerator with fields at the 100 MV/m level. In this paper we review previously published experimental beam data that indicate the feasibility of such an DPF-based accelerator, qualitatively discuss the physical acceleration processes in terms of the induced voltages, and as a starting point examine the DPF acceleration potential by numerically applying a self-consistent DPF system model that includes the induced voltage from both macroscopic and instability driven plasma dynamics. Applications to the remote detection of high explosives and a multi-staged acceleration concept are briefly discussed.

Tang, V; Adams, M L; Rusnak, B

2009-07-24

169

Plasma density measurements in tungsten wire-array Z-pinches  

SciTech Connect

Measurements of the plasma density profile near the exploding wires in 1 MA tungsten (W) wire-array Z-pinches have been made using calibrated x-ray absorption. As many as 5 x-ray images per pulse were obtained between 65 and 160 ns after the start of the 100 ns rise time current pulse. Measured W ion densities range from above 10{sup 19}/cm{sup 3} close to the wire to {approx}10{sup 17}/cm{sup 3} about 1 mm away from the wire in the plasma stream. After accurate geometrical registration of the individual wires in each successive image in a pulse using the Genetic Algorithm, the temporal evolution of the axial modulation wavelength distribution of the ablation rate from the wires in each array and the global mass-ablation rate as a function of time are presented.

Douglass, J. D.; Hammer, D. A.; Pikuz, S. A.; Shelkovenko, T. A.; Blesener, K. S. [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States)

2012-07-15

170

Behavior of a plasma in a high-density gas-embedded Z-pinch configuration  

SciTech Connect

The theoretical analysis of a high density Z-pinch (HDZP) begins with an examination of the steady state energy balance between ohmic heating and bremsstrahlung radiation losses for a plasma column in pressure equilibrium. The model is then expanded to include the time-varying internal energy and results in a quasi-equilibrium prescription for the load current through a constant radius plasma channel. This set of current waveforms is useful in the design of experimental systems. The behavior of a plasma for physically realizable conditions is first examined by allowing adiabatic changes in the column radius. A more complete model is then developed by incorporating inertial effects into the momentum equation, and the resultant global MHD computational model is compared with more sophisticated, and costly, one- and two-dimensional computer simulations. These comparisons demonstrate the advantages of the global MHD description over previously developed zero-dimensional models.

Shlachter, J.S.

1982-05-01

171

Rep-rated Z-Pinch Power Plant Concept - Direct Energy Conversion and Shrapnel Generation*  

NASA Astrophysics Data System (ADS)

We are developing direct energy conversion schemes and shrapnel generation models to be used to optimize a high yield z-pinch IFE power plant concept. The concept uses high yield ( 10 GJ) at low rep-rate ( 0.1 Hz), with a Recyclable Transmission Line (RTL) to provide the necessary standoff between the fusion target and the power plant chamber. The RTL would be cast out of a conventional power plant coolant material (such as Li or Flibe) that can be used to absorb the fusion energy, breed tritium, and mitigate the shock to the first wall. Current results of initial work on this concept will be discussed. *Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the United States Department of Energy Under Contract DE-AC04-94AL85000.

de Groot, John S.; Gronbech-Jensen, Niels; Miller, Greg; Olsen, Craig L.; Rochau, Gary E.; Derzon, Mark S.; Slutz, Steven A.; Spielman, Rick B.; Peterson, Per F.; Rochau, Gregory A.; Pederson, Robert R.

2000-10-01

172

Imaging XUV spectroscopy of a Z-pinch plasma in the former Soviet Union  

SciTech Connect

In 1991 a group of scientists from the Angara 5 pulsed power facility at the Kurchatov Institute in Troitsk, Russia had determined the thermal emission from an implosion of xenon gas onto an annular, molybdenum doped foam liner to be 30 TW/cm{sup 2}. This represents an extremely efficient conversion of energy into a high fluence radiation field. In order to verify this claim and better understand the process of producing radiation by means of a Z-pinch plasma device, a series of experiments were proposed through a collaboration from Sandia National Laboratory, Albuquerque, Los Alamos National Laboratory, and Lawrence Livermore National Laboratory. Due to previous experience with x-ray spectroscopic measurements in the XUV region, the team from Lawrence Livermore Lab took on the task of designing, constructing, and fielding the necessary diagnostic equipment to spatially and temporally resolve plasma temperatures throughout the implosion of the high Z foam target.

Bruns, H.C.; Springer, P.T.; Emig, J.A.; Lanier, N.E.; Hernandez, J.A.

1993-08-11

173

X-ray spectroscopy of Cu impurities on NSTX and comparison with Z-pinch plasmas  

SciTech Connect

X-ray spectroscopy of mid-Z metal impurities is important in the study of tokamak plasmas and may reveal potential problems if their contribution to the radiated power becomes substantial. The analysis of the data from a high-resolution x-ray and extreme ultraviolet grating spectrometer, XEUS, installed on NSTX, was performed focused on a detailed study of x-ray spectra in the range 7-18 A. These spectra include not only commonly seen iron spectra but also copper spectra not yet employed as an NSTX plasma impurity diagnostic. In particular, the L-shell Cu spectra were modeled and predictions were made for identifying contributions from various Cu ions in different spectral bands. Also, similar spectra, but from much denser Cu plasmas produced on the UNR Z-pinch facility and collected using the convex-crystal spectrometer, were analyzed and compared with NSTX results.

Safronova, A. S.; Ouart, N. D.; Kantsyrev, V. L.; Cox, P. G.; Shlyaptseva, V.; Williamson, K. M. [University of Nevada, Reno, Nevada 89557 (United States); Lepson, J. K. [Space Sciences Laboratory, Berkeley, California 94720 (United States); Beiersdorfer, P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Stratton, B.; Bitter, M. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2010-10-15

174

Spectral Analysis of Tracer Emission and Absorption Lines in Z-Pinch Dynamic Hohlraum Experiments  

NASA Astrophysics Data System (ADS)

Spectroscopic analysis of tracer absorption and emission lines is reported for a nested tungsten (W) wire array z-pinch containing an on-axis CH foam with an embedded, thin Al-Mg tracer. The absorption and emission of radiation from the W plasma, the tracer, and the foam are studied with the goal of determining plasma parameters, such as electron temperatures, W composition along the spectrometer (approximately on-axis) line-of-sight, optical depths, and effects of photoionization on atomic populations and spectra. Collisional-radiative calculations are performed using the SPECT3D and NLTERT spectral analysis codes. We will present results of our simulations and comparisons with experimental data.

Macfarlane, J. J.; Park, K. A.; Thomas-Cramer, A. R.; Bailey, J. E.; Chandler, G. A.; Lake, P.; Mehlhorn, T. A.; Nash, T. J.; Rochau S, G. A.; Slutz, S. A.; Vesey, R. A.

2001-10-01

175

Radiation from a Tungsten Z-pinch Plasma Impinging on a Gold Wall  

NASA Astrophysics Data System (ADS)

A number of exploratory scenarios are being investigated to evaluate the feasibility of creating hohlraum like conditions suitable to drive an ICF target to ignition with the radiation produced from a tungsten multiwire nested array Z-pinch plasma. In this investigation we will focus on the axial and radial x-ray emission from the wire load impinging on a gold wall. We determine the plasma environment and characterize its properties and determine its suitability for driving targets to ignition. The modeling and simulation are carried out using a 1-D nonLTE radiation hydrodynamics model with radiation transport as well as an LTE multigroup radiation diffusion model. Wire and wall plasma dynamics and emission spectra will be compared and analyzed from these models.

Davis, J.; Giuliani, R. W. Clark, Jr.; Apruzese, J. P.; Thornhill, J. W.; Chong, Y. K.; Kepple, P.; Whitney, K. G.

2002-11-01

176

Observation of particles with energy over 100 keV in z-pinch device  

NASA Astrophysics Data System (ADS)

The high energy particles were produced at the implosion of a tungsten wire array z-pinch onto a deuterated fiber at the S-300 device (4 MA, 700 kV, 100ns; RRC Kurchatov Institute, Moscow). The FWHM of the signal in spectral window 270 eV was 35-60 ns. The hard x-rays and neutrons with the FWHM (10-30) ns were produced during the soft x-ray maximum. The neutron yield from the D-D reaction reached 108 per shot. The mean energy of neutrons determined from time-of-flight analysis in the direction back to the anode, back to the cathode and side-on was in the range of (2.2-3.1) MeV and a time delay between neutron and hard x-rays maximum was in the range of (5-20)ns.

Kubes, Pavel; Klir, Daniel; Kravarik, Jozef; Bakshaev, Yuriy L.; Blinov, Peter I.; Chernenko, Andrey S.; Danko, Sergey A.; Hongchun, Cai; Ivanov, Michail I.; Korolev, Valery D.; Korelsky, Alexander V.; Kravchenko, Elena V.; Shaskov, Andrey Y.; Ustroev, Genady I.

2005-03-01

177

Modeling x-ray data for the Saturn z-pinch machine  

SciTech Connect

A wealth of XRD and time dependent x-ray imaging data exist for the Saturn z-pinch machine, where the load is either a tungsten wire array or a tungsten wire array which implodes onto a SiO{sub 2} foam. Also, these pinches have been modeled with a 2-D RMHD Eulerian computer code. In this paper the authors start with the 2-D Eulerian results to calculate time and spatially dependent spectra using both LTE and NLTE models. Then using response functions, these spectra are converted to XRD currents and camera images, which are quantitatively compared with the data. Through these comparisons, areas of good and lesser quality agreement are determined, and areas are identified where the 2-D Eulerian code should be improved.

Matuska, W.; Peterson, D. [Los Alamos National Lab., NM (United States); Deeney, C.; Derzon, M. [Sandia National Labs., Albuquerque, NM (United States)

1997-12-31

178

Theoretical Development of M-shell Spectroscopy for Z-Pinch Plasma Diagnostics  

NASA Astrophysics Data System (ADS)

Tungsten wire explosions are being intensively studied at Sandia National Laboratories. Any available x-ray spectral data accumulated in Z experiments with appropriate theoretical modeling can lead to better understanding of plasma evolution during a wire explosion. The present work focuses on the theoretical development of M-shell spectroscopy of W ions in the spectral range from 4 up to 8 Å. The majority of line emissions in this spectral region is composed of 31 ? 41', 51? transitions. Atomic data were calculated using Cowan and MBPT codes for all isoelectronic sequences contributing into this spectral range. The non-LTE kinetic model was developed based on these atomic data. The sensitivity of this model to the number of included ions, configurations and levels, the electron density, ionization balance, and electron distribution function is discussed. The complete modeling of this spectrum allows a detailed diagnostic of a hotter plasma core in z-pinch experiments involving heavy ions.

Shlyaptseva, Alla S.; Hamasha, Safeia M.; Hansen, Stephanie B.; Ouart, Nicholas D.; Safronova, Ulyana I.

2002-12-01

179

Circuit model for the inverse Z-pinch wire array switch.  

SciTech Connect

A 0D circuit code is introduced to study the wire array switch concept introduced in. It has been implemented and researched at Imperial College. An exploding wire array, the switch, is in parallel with the load, an imploding wire array. Most of the current flows in the exploding array until it expands and becomes highly resistive. The 0D code contains simple models of Joule energy deposition and plasma expansion for W and Al wires. The purpose of the device is to produce fast Z-pinch implosion, below 100ns on MAGPIE and the Sandia Z machine. Self and mutual inductances are taken into consideration as well as the rocket model for wire ablation. The switch characteristics of the exploding array are prescribed and tuned up to agree with MAGPIE shots. The dependence of the device on the configuration of the arrays is studied and scaling to ZR conditions is explored.

Waisman, Eduardo Mario; Cuneo, Michael Edward; Harvey-Thompson, A. (The Blackett Laboratory, Imperial College, London SW7 2BW, UK); Lebedev, Sergey V. (The Blackett Laboratory, Imperial College, London SW7 2BW, UK)

2010-06-01

180

Tracer Spectroscopy for Foam-Embedded Capsules in Z-Pinch-Driven ICF Experiments  

NASA Astrophysics Data System (ADS)

We present results from spectroscopic simulations relevant to understanding the conditions in radiatively-heated foams and in the ablation region of capsules in z-pinch dynamic hohlraum ICF experiments. Tracers located on the surface of the capsule or elsewhere in the foam provide information on the time-dependent conditions at specific locations in the dynamic hohlraum system. Spectra have been obtained in experiments in which capsules were coated with a thin layer of Al, providing constraints on conditions in the ablation region as it expands into the surrounding low-density foam. In other experiments, thin Al and MgF2 tracers have been embedded in other regions of the foam, providing information on the evolution of the radiatively-heated foam. Collisional-radiative calculations are performed using the SPECT3D and PrismSPECT spectral analysis codes. We will present results of our simulations and comparisons with spectra obtained in experiments at the Sandia Z facility.

Macfarlane, J. J.; Golovkin, I. E.; Woodruff, P. R.; Bailey, J. E.; Chandler, G. A.; Mehlhorn, T. A.; Nash, T. J.; Sanford, T. W. L.; Rochau, G. A.

2003-10-01

181

Imposed Axial Mass Modulations in Wire Array Z-Pinches on MAGPIE  

NASA Astrophysics Data System (ADS)

The role of 3D effects in wire array z-pinch dynamics is a topic of increasing interest. To study 3D structure in a controlled manner, 15 ?m diameter Al wires were etched at Sandia, seeding 20% radial perturbations with variable axial wavelength. Laser shadowgram and x-ray pinhole data suggest faster ablation and earlier implosion of the low-mass segments of an 8-wire, ?=5 mm modulated array imploded on MAGPIE at Imperial College. Less mass was left behind in the low-mass regions. Similar behavior is seen in 3D MHD modeling. Modification of the x-ray pulse shape will be discussed. Coronal plasma structure matching the seeded mode was seen in early-time shadowgrams, with ?=0.5 mm radial flares (typical in MAGPIE Al arrays) superimposed. Future experiments include shorter wavelength modulations that may compete with the naturally occurring radial flares, and unique 3D geometries potentially useful for code validation.

Jones, B.; Deeney, C.; McKenney, J.; Bland, S.; Lebedev, S.; Chittenden, J.; Bott, S.; Ampleford, D.

2003-10-01

182

A Compact Soft X-Ray Microscope using an Electrode-less Z-Pinch Source  

PubMed Central

Soft X-rays (< 1Kev) are of medical interest both for imaging and microdosimetry applications. X-ray sources at this low energy present a technological challenge. Synchrotrons, while very powerful and flexible, are enormously expensive national research facilities. Conventional X-ray sources based on electron bombardment can be compact and inexpensive, but low x-ray production efficiencies at low electron energies restrict this approach to very low power applications. Laser-based sources tend to be expensive and unreliable. Energetiq Technology, Inc. (Woburn, MA, USA) markets a 92 eV, 10W(2pi sr) electrode-less Z-pinch source developed for advanced semiconductor lithography. A modified version of this commercial product has produced 400 mW at 430 eV (2pi sr), appropriate for water window soft X-ray microscopy. The US NIH has funded Energetiq to design and construct a demonstration microscope using this source, coupled to a condenser optic, as the illumination system. The design of the condenser optic matches the unique characteristics of the source to the illumination requirements of the microscope, which is otherwise a conventional design. A separate program is underway to develop a microbeam system, in conjunction with the RARAF facility at Columbia University, NY, USA. The objective is to develop a focused, sub-micron beam capable of delivering > 1 Gy/second to the nucleus of a living cell. While most facilities of this type are coupled to a large and expensive particle accelerator, the Z-pinch X-ray source enables a compact, stand-alone design suitable to a small laboratory. The major technical issues in this system involve development of suitable focusing X-ray optics. Current status of these programs will be reported. PMID:20198115

Silterra, J; Holber, W

2009-01-01

183

Effective versus ion thermal temperatures in the Weizmann Ne Z-pinch: Modeling and stagnation physics  

SciTech Connect

The difference between the ion thermal and effective temperatures is investigated through simulations of the Ne gas puff z-pinch reported by Kroupp et al. [Phys. Rev. Lett. 107, 105001 (2011)]. Calculations are performed using a 2D, radiation-magnetohydrodynamic code with Tabular Collisional-Radiative Equilibrium, namely Mach2-TCRE [Thornhill et al., Phys. Plasmas 8, 3480 (2001)]. The extensive data set of imaging and K-shell spectroscopy from the experiments provides a challenging validation test for z-pinch simulations. Synthetic visible images of the implosion phase match the observed large scale structure if the breakdown occurs at the density corresponding to the Paschen minimum. At the beginning of stagnation (?4?ns), computed plasma conditions change rapidly showing a rising electron density and a peak in the ion thermal temperature of ?1.8?keV. This is larger than the ion thermal temperature (<400?eV) inferred from the experiment. By the time of peak K-shell power (0?ns), the calculated electron density is similar to the data and the electron and ion thermal temperatures are equilibrated, as is observed. Effective ion temperatures are obtained from calculated emission line widths accounting for thermal broadening and Doppler velocity shifts. The observed, large effective ion temperatures (?4?keV) early in the stagnation of this Ne pinch can be explained solely as a combination of compressional ion heating and steep radial velocity gradients near the axis. Approximations in the modeling are discussed in regard to the higher ion thermal temperature and lower electron density early in the stagnation compared to the experimental results.

Giuliani, J. L.; Thornhill, J. W.; Dasgupta, A.; Velikovich, A. L.; Chong, Y. K.; Mehlhorn, T. A. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States)] [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Kroupp, E.; Osin, D.; Maron, Y.; Starobinets, A.; Fisher, V.; Zarnitsky, Yu.; Bernshtam, V. [Weizmann Institute of Science, Rehovot 76100 (Israel)] [Weizmann Institute of Science, Rehovot 76100 (Israel); Apruzese, J. P. [Consultant to NRL through Engility Corp., Chantilly, Virginia 20151 (United States)] [Consultant to NRL through Engility Corp., Chantilly, Virginia 20151 (United States); Fisher, A. [Falculty of Physics, Technion-Israeli Institute of Technology, Haifa (Israel)] [Falculty of Physics, Technion-Israeli Institute of Technology, Haifa (Israel); Deeney, C. [National Security Technologies, LLC, Las Vegas, Nevada 89144 (United States)] [National Security Technologies, LLC, Las Vegas, Nevada 89144 (United States)

2014-03-15

184

Magnetohydrodynamic simulation of solid-deuterium-initiated Z-pinch experiments  

SciTech Connect

Solid-deuterium-initiated Z-pinch experiments are numerically simulated using a two-dimensional resistive magnetohydrodynamic model, which includes many important experimental details, such as ``cold-start`` initial conditions, thermal conduction, radiative energy loss, actual discharge current vs. time, and grids of sufficient size and resolution to allow realistic development of the plasma. The alternating-direction-implicit numerical technique used meets the substantial demands presented by such a computational task. Simulations of fiber-initiated experiments show that when the fiber becomes fully ionized rapidly developing m=0 instabilities, which originated in the coronal plasma generated from the ablating fiber, drive intense non-uniform heating and rapid expansion of the plasma column. The possibility that inclusion of additional physical effects would improve stability is explored. Finite-Larmor-radius-ordered Hall and diamagnetic pressure terms in the magnetic field evolution equation, corresponding energy equation terms, and separate ion and electron energy equations are included; these do not change the basic results. Model diagnostics, such as shadowgrams and interferograms, generated from simulation results, are in good agreement with experiment. Two alternative experimental approaches are explored: high-current magnetic implosion of hollow cylindrical deuterium shells, and ``plasma-on-wire`` (POW) implosion of low-density plasma onto a central deuterium fiber. By minimizing instability problems, these techniques may allow attainment of higher temperatures and densities than possible with bare fiber-initiated Z-pinches. Conditions for significant D-D or D-T fusion neutron production may be realizable with these implosion-based approaches.

Sheehey, P.T.

1994-02-01

185

A compact soft X-ray microscope using an electrode-less Z-pinch source  

NASA Astrophysics Data System (ADS)

Soft X-rays (< 1Kev) are of medical interest both for imaging and microdosimetry applications. X-ray sources at this low energy present a technological challenge. Synchrotrons, while very powerful and flexible, are enormously expensive national research facilities. Conventional X-ray sources based on electron bombardment can be compact and inexpensive, but low x-ray production efficiencies at low electron energies restrict this approach to very low power applications. Laser-based sources tend to be expensive and unreliable. Energetiq Technology, Inc. (Woburn, MA, USA) markets a 92 eV, 10W(2pi sr) electrode-less Z-pinch source developed for advanced semiconductor lithography. A modified version of this commercial product has produced 400 mW at 430 eV (2pi sr), appropriate for water window soft X-ray microscopy. The US NIH has funded Energetiq to design and construct a demonstration microscope using this source, coupled to a condenser optic, as the illumination system. The design of the condenser optic matches the unique characteristics of the source to the illumination requirements of the microscope, which is otherwise a conventional design. A separate program is underway to develop a microbeam system, in conjunction with the RARAF facility at Columbia University, NY, USA. The objective is to develop a focused, sub-micron beam capable of delivering > 1 Gy/second to the nucleus of a living cell. While most facilities of this type are coupled to a large and expensive particle accelerator, the Z-pinch X-ray source enables a compact, stand-alone design suitable to a small laboratory. The major technical issues in this system involve development of suitable focusing X-ray optics. Current status of these programs will be reported. (Supported by NIH grants 5R44RR022488-03 and 5R44RR023753-03)

Horne, S. F.; Silterra, J.; Holber, W.

2009-09-01

186

Control of Rayleigh-Taylor Instability Leading to Breakeven in Staged Z-pinch  

NASA Astrophysics Data System (ADS)

In recent staged Z-pinch experiments at UCI a 2 cm radius plasma shell made from a high Z element such as Kr or Ne implodes on a Deuterium plasma column. The imploding target plasma remains remarkably uniform and stable even though the outer plasma shell becomes highly unstable. The stability of the inner surface of the liner plasma is attributed to the pealing off of a higher charge state layer from the liner plasma that then compresses the target plasma. This has been verified using a state of the art two and half dimensional radiation MHD code (MACH2). The results of this experiment and simulation showed a remarkable similarity. This code is also used to scale up the concept for the parameter regime that is similar to the Sandia Z-facility. The generator parameters that are used in these calculations are: stored energy of 2.0 MJ, with a maximum current of 18 MA and a rise time 100 ns. The outer liner plasma in this case is made from a 1 cm radius Ag wire array and the inner plasma target is a uniform DT plasma fill. Reduction in the growth of the RT-instability is further enhanced by using a smaller initial radius and a higher Z element liner. The compression ratio of the DT plasma column exceeds 200 in a very stable manner even though the outer surface becomes quite unstable. The plasma density at the peak implosion reaches ? 10^24 cm-3 with a temperature of 8 KeV. The net fusion energy produced up to peak implosion is 2.3 MJ, after which the calculations crashed due to numerical instability. Breakeven and beyond may be possible in staged Z pinch configurations provided proper optimization of parameters is performed.

Rahman, H. U.; Ney, P. H.; van Drie, A.; Wessel, F. J.; Rostoker, N.

2003-10-01

187

Z-pinches as intense x-ray sources for high energy density physics applications  

NASA Astrophysics Data System (ADS)

Fast z-pinch implosions can convert more than 10% of the stored electrical energy in a pulsed-power accelerator into x rays. These x rays are produced when an imploding cylindrical plasma, driven by the magnetic field pressure associated with very large axial currents, stagnates upon the cylindrical axis of symmetry. On the Saturn pulsed-power accelerator at Sandia National Laboratories, for example, currents of 6 to 8 MA with a risetime of less than 50 ns are driven through cylindrically-symmetric loads (typically gas jets, arrays of wires, thin foils, or low density foams), producing implosions velocities as high as 100 cm/?s and x-ray energies as high as 500 kJ. The keV component of the resulting x-ray spectrum has been used for many years as a source for material response studies. Alternatively, the x-ray output can be thermalized into a near-Planckian x-ray source by containing it within a large cylindrical radiation case (a hohlraum). These large volume ( 6000 mm^3), long-lived ( 20 ns) radiation sources have recently been used for ICF-relevant ablator physics experiments as well as astrophysical opacity and radiation-material interaction experiments. Magneto-Rayleigh-Taylor instabilities and load symmetry are critical, limiting factors in determining the assembled plasma densities and temperatures, and thus in the x-ray pulsewidths that can be produced on these accelerators. In recent experiments on the Saturn accelerator, these implosion nonuniformities have been minimized by using uniform-fill gas puff loads or by using wire arrays with as many a 192 wires. These techniques produced significant improvements in the pinched plasma quality, reproducibility, and x-ray output power. X-ray pulsewidths of less than 5 ns and peak powers of 75?10 TW have been achieved with arrays of 120 tungsten wires. These powers represent greater than a factor of three in power amplification over the electrical power of the accelerator, and are a record for x-ray powers in the laboratory. When the modification to enable z-pinch implosions on PBFA II is completed, x-ray energies in excess of 1.5 MJ at powers in excess of 150 TW should be reached. These intense x-ray sources offer the potential for performing many new basic physics and fusion-relevant experiments. *This work supported by the U.S. Department of Energy under Contract DE-AC04- 94AL85000.

Matzen, M. Keith

1996-11-01

188

Conversion of electromagnetic energy in Z-pinch process of single planar wire arrays at 1.5 MA  

SciTech Connect

The electromagnetic energy conversion in the Z-pinch process of single planar wire arrays was studied on Qiangguang generator (1.5 MA, 100?ns). Electrical diagnostics were established to monitor the voltage of the cathode-anode gap and the load current for calculating the electromagnetic energy. Lumped-element circuit model of wire arrays was employed to analyze the electromagnetic energy conversion. Inductance as well as resistance of a wire array during the Z-pinch process was also investigated. Experimental data indicate that the electromagnetic energy is mainly converted to magnetic energy and kinetic energy and ohmic heating energy can be neglected before the final stagnation. The kinetic energy can be responsible for the x-ray radiation before the peak power. After the stagnation, the electromagnetic energy coupled by the load continues increasing and the resistance of the load achieves its maximum of 0.6–1.0 ? in about 10–20?ns.

Liangping, Wang; Mo, Li; Juanjuan, Han; Ning, Guo [Northwest Institute of Nuclear Technology, Xi'an 710024 (China); Key State Laboratory of Simulation and Effect for Intense Pulse Radiation, Xi'an 710024 (China); Jian, Wu [Xi'an Jiaotong University, Xi'an 710049 (China); Aici, Qiu [Northwest Institute of Nuclear Technology, Xi'an 710024 (China); Xi'an Jiaotong University, Xi'an 710049 (China)

2014-06-15

189

Conversion of electromagnetic energy in Z-pinch process of single planar wire arrays at 1.5 MA  

NASA Astrophysics Data System (ADS)

The electromagnetic energy conversion in the Z-pinch process of single planar wire arrays was studied on Qiangguang generator (1.5 MA, 100 ns). Electrical diagnostics were established to monitor the voltage of the cathode-anode gap and the load current for calculating the electromagnetic energy. Lumped-element circuit model of wire arrays was employed to analyze the electromagnetic energy conversion. Inductance as well as resistance of a wire array during the Z-pinch process was also investigated. Experimental data indicate that the electromagnetic energy is mainly converted to magnetic energy and kinetic energy and ohmic heating energy can be neglected before the final stagnation. The kinetic energy can be responsible for the x-ray radiation before the peak power. After the stagnation, the electromagnetic energy coupled by the load continues increasing and the resistance of the load achieves its maximum of 0.6-1.0 ? in about 10-20 ns.

Liangping, Wang; Mo, Li; Juanjuan, Han; Jian, Wu; Ning, Guo; Aici, Qiu

2014-06-01

190

Stability of wire array Z-pinch in the 100 ns to 1 ?s implosion time scales  

Microsoft Academic Search

Summary form only given. Centre d'Etudes de Gramat (CEG) is now studying long implosion time (about 1?s) plasma radiation sources which are of great interest because they allow to reduce the complexity and cost of generators. Single or double shell Z-pinch sources are routinely used by other laboratories in the 100 ns regime with the well known experimental result that

F. Hamann; C. Mangeant; F. Lassalle; F. Bayol; H. Calamy

2004-01-01

191

Monochromatic x-ray backlighting of wire-array z-pinch plasmas using spherically bent quartz crystals  

Microsoft Academic Search

X-ray backlighting systems are being developed to diagnose z-pinch, inertial confinement fusion capsule, and complex hydrodynamics experiments on the 20 MA Sandia Z machine. The x-ray backlighter source is a laser-produced plasma created using the Z-Beamlet laser, a 2 TW, 2 kJ Nd:glass laser recently constructed at Sandia. As an alternative to point-projection radiography, we are investigating a different geometry

D. B. Sinars; M. E. Cuneo; G. R. Bennett; D. F. Wenger; L. E. Ruggles; M. F. Vargas; J. L. Porter; R. G. Adams; D. W. Johnson; K. L. Keller; P. K. Rambo; D. C. Rovang; H. Seamen; W. W. Simpson; I. C. Smith; S. C. Speas

2003-01-01

192

Radiation symmetry control for inertial confinement fusion capsule implosions in double Z-pinch hohlraums on Z  

NASA Astrophysics Data System (ADS)

The double Z-pinch hohlraum high-yield concept [Hammer et al., Phys. Plasmas 6, 2129 (1999)] utilizes two 63-MA Z pinches to heat separate primary hohlraums at either end of a secondary hohlraum containing the cryogenic fusion capsule. Recent experiments on the Z accelerator [Spielman et al., Phys. Plasmas 5, 2105 (1998)] at Sandia National Laboratories have developed an advanced single-sided power feed, double Z-pinch load to study radiation symmetry and pinch power balance using implosion capsules [Cuneo et al., Phys. Rev. Lett. 88, 215004 (2002)]. Point-projection x-ray imaging with the Z-Beamlet Laser mapped the trajectory and distortion of 2-mm diameter plastic ablator capsules. Using the backlit capsule distortion as a symmetry diagnostic, the ability to predictably tune symmetry at the <10% level in fluence by modifying the hohlraum geometry has been demonstrated. Systematic control of the time-integrated P2 Legendre mode asymmetry coefficient over a range of ±6% (±2% considering points nearest the optimum) was achieved by varying the length of the cylindrical secondary hohlraum containing the capsule, in agreement with viewfactor and radiation-hydrodynamics simulations.

Vesey, Roger A.; Cuneo, Michael E.; Porter, John L.; Adams, Richard G.; Aragon, Rafael A.; Rambo, Patrick K.; Ruggles, Laurence E.; Simpson, Walter W.; Smith, Ian C.; Bennett, Guy R.

2003-05-01

193

Recent experimental results on ICF target implosions by Z-pinch radiation sources and their relevance to ICF ignition studies  

NASA Astrophysics Data System (ADS)

Inertial confinement fusion capsule implosions absorbing up to 35 kJ of x-rays from a ~220 eV dynamic hohlraum on the Z accelerator at Sandia National Laboratories have produced thermonuclear D D neutron yields of (2.6±1.3) × 1010. Argon spectra confirm a hot fuel with Te ~ 1 keV and ne ~ (1 2) × 1023 cm-3. Higher performance implosions will require radiation symmetry control improvements. Capsule implosions in a ~70 eV double-Z-pinch-driven secondary hohlraum have been radiographed by 6.7 keV x-rays produced by the Z-beamlet laser (ZBL), demonstrating a drive symmetry of about 3% and control of P2 radiation asymmetries to ±2%. Hemispherical capsule implosions have also been radiographed in Z in preparation for future experiments in fast ignition physics. Z-pinch-driven inertial fusion energy concepts are being developed. The refurbished Z machine (ZR) will begin providing scaling information on capsule and Z-pinch in 2006. The addition of a short pulse capability to ZBL will enable research into fast ignition physics in the combination of ZR and ZBL-petawatt. ZR could provide a test bed to study NIF-relevant double-shell ignition concepts using dynamic hohlraums and advanced symmetry control techniques in the double-pinch hohlraum backlit by ZBL.

Mehlhorn, T. A.; Bailey, J. E.; Bennett, G.; Chandler, G. A.; Cooper, G.; Cuneo, M. E.; Golovkin, I.; Hanson, D. L.; Leeper, R. J.; MacFarlane, J. J.; Mancini, R. C.; Matzen, M. K.; Nash, T. J.; Olson, C. L.; Porter, J. L.; Ruiz, C. L.; Schroen, D. G.; Slutz, S. A.; Varnum, W.; Vesey, R. A.

2003-12-01

194

Quasi-steady accelerator operation on the ZAP flow Z-pinch  

NASA Astrophysics Data System (ADS)

The ZaP Flow Z-Pinch Experiment utilizes sheared flows to stabilize an otherwise unstable equilibrium. The sheared flows are maintained by streaming high velocity plasma parallel to the pinch. Previous operations of the machine show depletion of the accelerator's neutral gas supply late in the pulse leading to pinch instability. The current distribution in the accelerator exhibits characteristic modes during this operation, which is corroborated by interferometric signals. The decrease in density precipitates a loss of plasma quiescence in the pinch, which occurs on a timescale related to the flow velocity from the plasma source. To abate the depletion, the geometry of the accelerator is altered to increase the neutral gas supply. The design creates a standing deflagration front in the accelerator that persists for the pulse duration. The new operating mode is characterized by the same diagnostics as the previous mode. The lessons learned in the accelerator operations have been applied to the design of a new experiment, ZaP-HD. This work was supported by grants from the Department of Energy and the National Nuclear Security Administration.

Hughes, M. C.; Shumlak, U.; Golingo, R. P.; Nelson, B. A.; Ross, M. P.

2014-12-01

195

Model of enhanced energy deposition in a Z-pinch plasma  

SciTech Connect

In numerous experiments, magnetic energy coupled to strongly radiating Z-pinch plasmas exceeds the thermalized kinetic energy, sometimes by a factor of 2-3. An analytical model describing this additional energy deposition based on the concept of macroscopic magnetohydrodynamic (MHD) turbulent pinch heating proposed by Rudakov and Sudan [Phys. Reports 283, 253 (1997)] is presented. The pinch plasma is modeled as a foam-like medium saturated with toroidal ''magnetic bubbles'' produced by the development of surface m=0 Rayleigh-Taylor and MHD instabilities. As the bubbles converge to the pinch axis, their magnetic energy is converted to thermal energy of the plasma through pdV work. Explicit formulas for the average dissipation rate of this process and the corresponding contribution to the resistance of the load, which compare favorably to the experimental data and simulation results, are presented. The possibility of using this enhanced (relative to Ohmic heating) dissipation mechanism to power novel plasma radiation sources and produce high K-shell yields using long current rise time machines is discussed. (c) 2000 American Institute of Physics.

Velikovich, A. L. [Radiation Hydrodynamics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States)] [Radiation Hydrodynamics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States); Davis, J. [Radiation Hydrodynamics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States)] [Radiation Hydrodynamics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States); Thornhill, J. W. [Radiation Hydrodynamics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States)] [Radiation Hydrodynamics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States); Giuliani, J. L. Jr. [Radiation Hydrodynamics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States)] [Radiation Hydrodynamics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States); Rudakov, L. I. [Advanced Power Technologies, Inc., Washington, D.C. 20037 (United States)] [Advanced Power Technologies, Inc., Washington, D.C. 20037 (United States); Deeney, C. [Sandia National Laboratories, Albuquerque, New Mexico 87545 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87545 (United States)

2000-08-01

196

The role of Z-pinches and related configurations in magnetized target fusion  

SciTech Connect

The use of a magnetic field within a fusion target is now known as Magnetized Target Fusion in the US and as MAGO (Magnitnoye Obzhatiye, or magnetic compression) in Russia. In contrast to direct, hydrodynamic compression of initially ambient-temperature fuel (e.g., ICF), MTF involves two steps: (a) formation of a warm, magnetized, wall-confined plasma of intermediate density within a fusion target prior to implosion; (b) subsequent quasi-adiabatic compression and heating of the plasma by imploding the confining wall, or pusher. In many ways, MTF can be considered a marriage between the more mature MFE and ICF approaches, and this marriage potentially eliminates some of the hurdles encountered in the other approaches. When compared to ICF, MTF requires lower implosion velocity, lower initial density, significantly lower radial convergence, and larger targets, all of which lead to substantially reduced driver intensity, power, and symmetry requirements. When compared to MFE, MTF does not require a vacuum separating the plasma from the wall, and, in fact, complete magnetic confinement, even if possible, may not be desirable. The higher density of MTF and much shorter confinement times should make magnetized plasma formation a much less difficult step than in MFE. The substantially lower driver requirements and implosion velocity of MTF make z-pinch magnetically driven liners, magnetically imploded by existing modern pulsed power electrical current sources, a leading candidate for the target pusher of an MTF system.

Lindemuth, I.R.

1997-07-10

197

Preradiation studies for non-thermal Z-pinch wire load experiments on Saturn  

SciTech Connect

The implosion dynamics of compact wire arrays on Saturn are explored as a function of wire mass m, wire length {ell}, wire radii R, and radial power-flow feed geometry using the ZORK code. Electron losses and the likelihood of arcing in the radial feed adjacent the wire load are analyzed using the TWOQUICK and CYLTRAN codes. The physical characteristics of the implosion and subsequent thermal radiation production are estimated using the LASNEX code in one dimension. These analyses show that compact tungsten wire arrays with parameters suggested by D. Mosher and with a 21-nH vacuum feed geometry satisfy the empirical scaling criterion I/(M/{ell}) {approximately} 2 MA/(mg/cm) of Mosher for optimizing non-thermal radiation from z pinches, generate low electron losses in the radial feeds, and generate electric fields at the insulator stack below the Charlie Martin flashover limit thereby permitting full power to be delivered to the load. Under such conditions, peak currents of {approximately}5 MA can be delivered to wire loads {approximately}20 ns before the driving voltage reverses at the insulator stack, potentially allowing the m = 0 instability to develop with the subsequent emission of non-thermal radiation as predicted by the Mosher model.

Sanford, T.W.L.; Humphreys, D.R.; Poukey, J.W.; Marder, B.M.; Halbleib, J.A.; Crow, J.T.; Spielman, R.B. [Sandia National Labs., Albuquerque, NM (United States); Mock, R.C. [Ktech Corp., Albuquerque, NM (United States)

1994-06-01

198

Analyzing Spatially Resolved Z-pinch Spectra to Determine the Nature of ``Bright Spots''*  

NASA Astrophysics Data System (ADS)

Wire array Z-pinch implosions which access the K-shell stages of their load elements are usually characterized by spatially nonuniform emission. But, is the existence of the ``bright spots'' due to density enhancement, higher temperature, or some combination of the two? Does the answer vary with atomic number of the load? To investigate this issue we have analyzed spatially resolved spectra from Cu and Al pinches driven by the Z generator. Correlation studies and regression analyses from the derived conditions are employed in order to infer the cause(s) of the local enhancements of K-shell powers. [4pt] *Work supported by U. S. Department of Energy, National Nuclear Security Administration. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE's NNSA under contract DE-AC04-94AL85000. JPA is a consultant to NRL through L3 Communications, Chantilly, VA 20151

Apruzese, J. P.; Giuliani, J. L.; Thornhill, J. W.; Ampleford, D. J.; Jones, B.; Coverdale, C. A.

2011-11-01

199

Construction and Initial Tests of MAIZE: 1 MA LTD-Driven Z-Pinch *  

NASA Astrophysics Data System (ADS)

We report construction and initial testing of a 1-MA Linear Transformer Driver (LTD), The Michigan Accelerator for Inductive Z-pinch Experiments, (MAIZE). This machine, the first of its type to reach the USA, is based on the joint HCEI, Sandia Laboratories, and UM development effort. The compact LTD uses 80 capacitors and 40 spark gap switches, in 40 ``bricks'', to deliver 1 MA, 100 kV pulses with 70 ns risetime into a matched resistive load. Test results will be presented for a single brick and the full LTD. Design and construction will be presented of a low-inductance MITL. Experimental research programs under design and construction at UM include: a) Studies of Magneto-Raleigh-Taylor Instability of planar foils, and b) Vacuum convolute studies including cathode and anode plasma. Theory and simulation results will be presented for these planned experiments. Initial experimental designs and moderate-current feasibility experiments will be discussed. *Research supported by U. S. DoE through Sandia National Laboratories award document numbers 240985, 768225, 790791 and 805234 to the UM. MRG supported by NNSA Fellowship and JCZ supported by NPSC Fellowship / Sandia National Labs.

Gilgenbach, R. M.; Gomez, M. R.; Zier, J. C.; Tang, W.; French, D. M.; Lau, Y. Y.; Mazarakis, M. G.; Cuneo, M. E.; Johnston, M. D.; Oliver, B. V.; Mehlhorn, T. A.; Kim, A. A.; Sinebryukhov, V. A.

2008-11-01

200

Computational investigation of the limits to Pease-Braginskii collapse of a Z-pinch  

SciTech Connect

This dissertation investigates the one-dimensional limits to such a radiation enhanced collapse through the use of a Lagrangian simulation code, LASNEX. The code includes the effects of a wide range of phenomena - opacity, ionization, experimentally determined equations of state, magnetic effects on transport coefficients, and external electrical circuits. Special attention was given to the magnetic field subroutines. They were revised to include ion acoustic and lower hybrid drift induced resistivity and to increase accuracy and efficiency. The magnetic pressure term was differenced in a manner that eliminates any influence of zone size, allowing large, low density zones outside the plasma column. In these large zones, magnetic flux and energy were determined by direct integration instead of summation to increase overall conservation. With these changes, the computational timesteps were determined by phenomena in the plasma instead of the Alfven velocity in the low density region. These modifications improved the accuracy of the code on Z-pinch problems by a factor of 10-100 depending on the minimum pinch radius reached.

Nielsen, P.D.

1981-06-01

201

New compact hohlraum configuration research at the 1.7 MA Z-pinch generator  

NASA Astrophysics Data System (ADS)

A new compact Z-pinch x-ray hohlraum design with parallel-driven x-ray sources was experimentally demonstrated in a full configuration with a central target and tailored shine shields (to provide a symmetric temperature distribution on the target) at the 1.7 MA Zebra generator. This presentation reports on the joint success of two independent lines of research. One of these was the development of new sources - planar wire arrays (PWAs). PWAs turned out to be a prolific radiator. Another success was the drastic improvement in energy efficiency of pulsed-power systems, such as the Load Current Multiplier (LCM). The Zebra/LCM generator almost doubled the plasma load current to 1.7 MA. The two above-mentioned innovative approaches were used in combination to produce a new compact hohlraum design for ICF, as jointly proposed by SNL and UNR. Good agreement between simulated and measured radiation temperature of the central target is shown. Experimental comparison of PWAs with planar foil liners (PFL) - another viable alternative to wire array loads at multi-MA generators show promising data. Results of research at the University of Nevada Reno allowed for the study of hohlraum coupling physics at University-scale generators. The advantages of new hohlraum design applications for multi-MA facilities with W or Au double PWAs or PFL x-ray sources are discussed.

Kantsyrev, V. L.; Chuvatin, A. S.; Rudakov, L. I.; Velikovich, A. L.; Shrestha, I. K.; Esaulov, A. A.; Safronova, A. S.; Shlyaptseva, V. V.; Osborne, G. C.; Astanovitsky, A. L.; Weller, M. E.; Stafford, A.; Schultz, K. A.; Cooper, M. C.; Cuneo, M. E.; Jones, B.; Vesey, R. A.

2014-12-01

202

Role of Z-pinches in magnetic reconnection in space plasmas  

NASA Astrophysics Data System (ADS)

abstract-type="normal"> A widely accepted scenario of magnetic reconnection in collisionless space plasmas is the breakage of magnetic field lines in X-points. In laboratory, reconnection is commonly studied in pinches, current channels embedded into twisted magnetic fields. No model of magnetic reconnection in space plasmas considers both null-points and pinches as peers. We have performed a particle-in-cell simulation of magnetic reconnection in a three-dimensional configuration where null-points are present initially, and Z-pinches are formed during the simulation along the lines of spiral null-points. The non-spiral null-points are more stable than spiral ones, and no substantial energy dissipation is associated with them. On the contrary, turbulent magnetic reconnection in the pinches causes the magnetic energy to decay at a rate of ~1.5% per ion gyro period. Dissipation in similar structures is a likely scenario in space plasmas with large fraction of spiral null-points.

Olshevsky, Vyacheslav; Lapenta, Giovanni; Markidis, Stefano; Divin, Andrey

2015-01-01

203

Analysis of Radiatively-Heated Thin Foils in Z-Pinch Hohlraum Experiments  

NASA Astrophysics Data System (ADS)

Z-pinch experiments are performed at the Z pulsed-power facility at Sandia National Laboratories (SNL) to study physics issues related to high energy density plasmas and inertial confinement fusion. In recent Z experiments, time-resolved x-ray crystal spectroscopy has been used [Bailey, et. al., this meeting] to record inner-shell K-alpha spectra from a thin tamped Al foil located in a slot in the return current can (i.e., at the hohlraum boundary). Using the pinch as a backlighter, the spectrograph views the tungsten pinch x-ray radiation through the Al foil. Spectral diagnostics of this type can be used to help constrain measurements of the pinch radiation power, the hohlraum radiation temperature, and can also be used in experiments to measure radiation flow in various materials. We discuss results from our analysis of these experiments, in which we perform 3-D view factor, 1-D radiation-hydrodynamics, and 1-D collisional-radiative equilibrium simulations.

Macfarlane, J. J.; Bailey, J. E.; Chandler, G. A.; Nash, T. J.; Derzon, M. S.; Deeney, C.; Douglas, M. R.; Spielman, R. B.

1999-11-01

204

Tungsten wire-array Z-pinch experiments at 200 TW and 2 MJ  

NASA Astrophysics Data System (ADS)

Here Z, a 60 TW/5 MJ electrical accelerator located at Sandia National Laboratories, has been used to implode tungsten wire-array Z pinches. These arrays consisted of large numbers of tungsten wires (120-300) with wire diameters of 7.5 to 15 ?m placed in a symmetric cylindrical array. The experiments used array diameters ranging from 1.75 to 4 cm and lengths from 1 to 2 cm. A 2 cm long, 4 cm diam tungsten array consisting of 240, 7.5 ?m diam wires (4.1 mg mass) achieved an x-ray power of ˜200 TW and an x-ray energy of nearly 2 MJ. Spectral data suggest an optically thick, Planckian-like radiator below 1000 eV. One surprising experimental result was the observation that the total radiated x-ray energies and x-ray powers were nearly independent of pinch length. These data are compared with two-dimensional radiation magnetohydrodynamic code calculations.

Spielman, R. B.; Deeney, C.; Chandler, G. A.; Douglas, M. R.; Fehl, D. L.; Matzen, M. K.; McDaniel, D. H.; Nash, T. J.; Porter, J. L.; Sanford, T. W. L.; Seamen, J. F.; Stygar, W. A.; Struve, K. W.; Breeze, S. P.; McGurn, J. S.; Torres, J. A.; Zagar, D. M.; Gilliland, T. L.; Jobe, D. O.; McKenney, J. L.; Mock, R. C.; Vargas, M.; Wagoner, T.; Peterson, D. L.

1998-05-01

205

Numerical simulations of Z-Pinch experiments to create supersonic differentially-rotating plasma flows  

NASA Astrophysics Data System (ADS)

Recently, it was proposed that a small number of plasma jets produced by lasers could be used to generate a plasma configuration relevant to some features of astrophysical accretion disc physics. We propose complementary experimental configurations which employ converging flows generated in a cylindrical wire array Z- pinch modified to produce a rotating plasma. In this paper we present 3D MHD simulations using the code GORGON which show how this approach can be implemented at the MAGPIE facility at Imperial College, London. We will present the general scenario and the results of a parametric study relating the parameters of the array with the features of the resulting plasma. In particular, we will show how a rotating plasma cylinder or ring, with typical rotation velocity 30 Km/s and Mach number 8 is formed, and how, after about 1-2 revolutions, the material of the plasma ring is ejected in a pair of thermally driven, conical outflows propagating along the rotation axis. We will discuss to what aspects of the physics of accretion discs, the results of such experiments could be relevant. We will also consider the effects of different magnetic configurations, which further expand the possibility to relate the experiments with the astrophysical discs. Experimental implementation of some of these setups is currently in progress on MAGPIE.

Bochi, Matteo; Ummels, Sebastiaan; Chittenden, Jeremy; Lebedev, Sergey

2011-11-01

206

X-ray Diode Measurements of Z-pinch Driven Internal Loads on Z  

NASA Astrophysics Data System (ADS)

We are pursuing the concept of Z-pinch driven internal targets or 'dynamic' hohlraums for ICF and high energy density physics applications. Utilizing the Z accelerator at Sandia National Laboratories we implode tungsten wires on internal targets at 40 cm/?s with the ultimate goal of generating a high temperature, long lived radiation environment. Nominal parameters for the Z accelerator are a 20 MA peak current with a 100 ns risetime. Wire arrays are configured utilizing 30 and 40 mm diameters, 1-2 cm long with 2.4-2.75 mg/cm. Initial experiments to study the energy coupling, strike physics and the reproducibility of these target configurations have been initiated. Radiation measurements of the off-axis pinch radiation as well as on-axis flux measurements taken with absolutely calibrated x-ray diode arrays will be presented. *Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin company, for the US-DOE under contract DE-AC04- 94AL85000.

Chandler, G. A.; Fehl, D. L.; Derzon, M. S.; Nash, T. J.; Olson, R. E.; Torres, J.; Deeney, C.

1997-11-01

207

An Interpretation of the Caterpillar Structures in Single-Wire Z Pinch Experiments*  

NASA Astrophysics Data System (ADS)

A series of experiments have been performed on single-wire Z pinches (1-2 kA, 20 kV, pulselength 500 ns; Al, Ag, W, or Cu wire of diameter 7.5 - 50 ?m, length 2.5 cm). Excimer laser absorption photographs show expansion of metallic plasmas on a time scale of order 100 ns. The edge of this plasma plume begins to develop structures resembling a caterpillar only after the current pulse reaches its peak value. With the use of a simple model, it is found that the growth of these caterpillar structures is consistent with the Rayleigh-Taylor (RT) instability of the decelerating plasma plume front at the later stage of the current pulse. For these slow current-rise, single-wire experiments, the RT growth rate is relatively mild, with amplitude gain typically on the order of three e-folds during the 500 ns current pulse. From this model, which is relatively insensitive to the detail dynamics, we estimate that the initial perturbation at the onset of the RT instability is on the order of, but larger than, the initial wire diameter.\\$Research supported by DOE through a Sandia National Laboratories subcontract to the University of Michigan.

Lau, Y. Y.; Johnston, M. D.; Gilgenbach, R. M.; Strickler, T. S.; Jones, M. C.; Mehlhorn, T. A.; Cuneo, M. E.

2003-10-01

208

Z-pinch Simulations Using a Fast and Efficient Filamentary Conductor Model*  

NASA Astrophysics Data System (ADS)

We present a fast, memory efficient method to calculate the current distributions in solid wires in wire z-pinch arrays. Building upon previous work, we reformulate inductance equations to significantly reduce the number of variables from N_wxNb to N_w+N_b-1, where Nw is the number of wires and Nb is the number of return conductor elements, or backposts. Test cases of Nw and Nb in the hundreds show reduction of computing time by as much as five orders of magnitude. Extension of this inductive model to include resistive effects is indicated. Recently, we implemented a current driven version of the equations so that a known current pulse could be imposed on the system. By coupling an equation of motion to the current-driven model, we simulate conditions on Sandia's Z-machine to analyze the effects of symmetry perturbations on pinch rise time. [11pt]^*This work is funded by the DoE through a Sandia National Laboratory subcontract to the University of Michigan.

Strickler, T. S.; Gilgenbach, R. M.; Johnston, M. D.; Lau, Y. Y.; Cuneo, M. E.; Mehlhorn, T. A.

2003-10-01

209

Effect of driver impedance on dense plasma focus Z-pinch neutron yield  

NASA Astrophysics Data System (ADS)

The Z-pinch phase of a dense plasma focus (DPF) heats the plasma by rapid compression and accelerates ions across its intense electric fields, producing neutrons through both thermonuclear and beam-target fusion. Driver characteristics have empirically been shown to affect performance, as measured by neutron yield per unit of stored energy. We are exploring the effect of driver characteristics on DPF performance using particle-in-cell (PIC) simulations of a kJ scale DPF. In this work, our PIC simulations are fluid for the run-down phase and transition to fully kinetic for the pinch phase, capturing kinetic instabilities, anomalous resistivity, and beam formation during the pinch. The anode-cathode boundary is driven by a circuit model of the capacitive driver, including system inductance, the load of the railgap switches, the guard resistors, and the coaxial transmission line parameters. It is known that the driver impedance plays an important role in the neutron yield: first, it sets the peak current achieved at pinch time; and second, it affects how much current continues to flow through the pinch when the pinch inductance and resistance suddenly increase. Here we show from fully kinetic simulations how total neutron yield depends on the impedance of the driver and the distributed parameters of the transmission circuit. Direct comparisons between the experiment and simulations enhance our understanding of these plasmas and provide predictive design capability for neutron source applications.

Sears, Jason; Link, Anthony; Schmidt, Andrea; Welch, Dale

2014-12-01

210

Characteristics and scaling of tungsten-wire-array z -pinch implosion dynamics at 20 MA.  

PubMed

We present observations for 20-MA wire-array z pinches of an extended wire ablation period of 57%+/-3% of the stagnation time of the array and non-thin-shell implosion trajectories. These experiments were performed with 20-mm-diam wire arrays used for the double- z -pinch inertial confinement fusion experiments [M. E. Cuneo, Phys. Rev. Lett. 88, 215004 (2002)] on the Z accelerator [R. B. Spielman, Phys. Plasmas 5, 2105 (1998)]. This array has the smallest wire-wire gaps typically used at 20 MA (209 microm ). The extended ablation period for this array indicates that two-dimensional (r-z) thin-shell implosion models that implicitly assume wire ablation and wire-to-wire merger into a shell on a rapid time scale compared to wire acceleration are fundamentally incorrect or incomplete for high-wire-number, massive (>2 mg/cm) , single, tungsten wire arrays. In contrast to earlier work where the wire array accelerated from its initial position at approximately 80% of the stagnation time, our results show that very late acceleration is not a universal aspect of wire array implosions. We also varied the ablation period between 46%+/-2% and 71%+/-3% of the stagnation time, for the first time, by scaling the array diameter between 40 mm (at a wire-wire gap of 524 mum ) and 12 mm (at a wire-wire gap of 209 microm ), at a constant stagnation time of 100+/-6 ns . The deviation of the wire-array trajectory from that of a thin shell scales inversely with the ablation rate per unit mass: f(m) proportional[dm(ablate)/dt]/m(array). The convergence ratio of the effective position of the current at peak x-ray power is approximately 3.6+/-0.6:1 , much less than the > or = 10:1 typically inferred from x-ray pinhole camera measurements of the brightest emitting regions on axis, at peak x-ray power. The trailing mass at the array edge early in the implosion appears to produce wings on the pinch mass profile at stagnation that reduces the rate of compression of the pinch. The observation of precursor pinch formation, trailing mass, and trailing current indicates that all the mass and current do not assemble simultaneously on axis. Precursor and trailing implosions appear to impact the efficiency of the conversion of current (driver energy) to x rays. An instability with the character of an m = 0 sausage grows rapidly on axis at stagnation, during the rise time of pinch power. Just after peak power, a mild m = 1 kink instability of the pinch occurs which is correlated with the higher compression ratio of the pinch after peak power and the decrease of the power pulse. Understanding these three-dimensional, discrete-wire implosion characteristics is critical in order to efficiently scale wire arrays to higher currents and powers for fusion applications. PMID:15903793

Cuneo, M E; Waisman, E M; Lebedev, S V; Chittenden, J P; Stygar, W A; Chandler, G A; Vesey, R A; Yu, E P; Nash, T J; Bliss, D E; Sarkisov, G S; Wagoner, T C; Bennett, G R; Sinars, D B; Porter, J L; Simpson, W W; Ruggles, L E; Wenger, D F; Garasi, C J; Oliver, B V; Aragon, R A; Fowler, W E; Hettrick, M C; Idzorek, G C; Johnson, D; Keller, K; Lazier, S E; McGurn, J S; Mehlhorn, T A; Moore, T; Nielsen, D S; Pyle, J; Speas, S; Struve, K W; Torres, J A

2005-04-01

211

Characteristics and scaling of tungsten-wire-array z-pinch implosion dynamics at 20 MA  

SciTech Connect

We present observations for 20-MA wire-array z pinches of an extended wire ablation period of 57%{+-}3% of the stagnation time of the array and non-thin-shell implosion trajectories. These experiments were performed with 20-mm-diam wire arrays used for the double-z-pinch inertial confinement fusion experiments [M. E. Cuneo et al., Phys. Rev. Lett. 88, 215004 (2002)] on the Z accelerator [R. B. Spielman et al., Phys. Plasmas 5, 2105 (1998)]. This array has the smallest wire-wire gaps typically used at 20 MA (209 {mu}m). The extended ablation period for this array indicates that two-dimensional (r-z) thin-shell implosion models that implicitly assume wire ablation and wire-to-wire merger into a shell on a rapid time scale compared to wire acceleration are fundamentally incorrect or incomplete for high-wire-number, massive (>2 mg/cm), single, tungsten wire arrays. In contrast to earlier work where the wire array accelerated from its initial position at {approx}80% of the stagnation time, our results show that very late acceleration is not a universal aspect of wire array implosions. We also varied the ablation period between 46%{+-}2% and 71%{+-}3% of the stagnation time, for the first time, by scaling the array diameter between 40 mm (at a wire-wire gap of 524 {mu}m) and 12 mm (at a wire-wire gap of 209 {mu}m), at a constant stagnation time of 100{+-}6 ns. The deviation of the wire-array trajectory from that of a thin shell scales inversely with the ablation rate per unit mass: f{sub m}{proportional_to}[dm{sub ablate}/dt]/m{sub array}. The convergence ratio of the effective position of the current at peak x-ray power is {approx}3.6{+-}0.6:1, much less than the {>=}10:1 typically inferred from x-ray pinhole camera measurements of the brightest emitting regions on axis, at peak x-ray power. The trailing mass at the array edge early in the implosion appears to produce wings on the pinch mass profile at stagnation that reduces the rate of compression of the pinch. The observation of precursor pinch formation, trailing mass, and trailing current indicates that all the mass and current do not assemble simultaneously on axis. Precursor and trailing implosions appear to impact the efficiency of the conversion of current (driver energy) to x rays. An instability with the character of an m=0 sausage grows rapidly on axis at stagnation, during the rise time of pinch power. Just after peak power, a mild m=1 kink instability of the pinch occurs which is correlated with the higher compression ratio of the pinch after peak power and the decrease of the power pulse. Understanding these three-dimensional, discrete-wire implosion characteristics is critical in order to efficiently scale wire arrays to higher currents and powers for fusion applications.

Cuneo, M.E.; Waisman, E.M.; Stygar, W.A.; Chandler, G.A.; Vesey, R.A.; Yu, E.P.; Nash, T.J.; Bliss, D.E.; Bennett, G.R.; Sinars, D.B.; Porter, J.L.; Simpson, W.W.; Ruggles, L.E.; Wenger, D.F.; Garasi, C.J.; Aragon, R.A.; Fowler, W.E.; Johnson, D.; Keller, K.; McGurn, J.S. [Pulsed Power Sciences Center, Sandia National Laboratories, Albuquerque, New Mexico 87195-1193 (United States)] [and others

2005-04-01

212

Shock waves in a Z-pinch and the formation of high energy density plasma  

NASA Astrophysics Data System (ADS)

A Z-pinch liner, imploding onto a target plasma, evolves in a step-wise manner, producing a stable, magneto-inertial, high-energy-density plasma compression. The typical configuration is a cylindrical, high-atomic-number liner imploding onto a low-atomic-number target. The parameters for a terawatt-class machine (e.g., Zebra at the University of Nevada, Reno, Nevada Terawatt Facility) have been simulated. The 2-1/2 D MHD code, MACH2, was used to study this configuration. The requirements are for an initial radius of a few mm for stable implosion; the material densities properly distributed, so that the target is effectively heated initially by shock heating and finally by adiabatic compression; and the liner's thickness adjusted to promote radial current transport and subsequent current amplification in the target. Since the shock velocity is smaller in the liner, than in the target, a stable-shock forms at the interface, allowing the central load to accelerate magnetically and inertially, producing a magneto-inertial implosion and high-energy density plasma. Comparing the implosion dynamics of a low-Z target with those of a high-Z target demonstrates the role of shock waves in terms of compression and heating. In the case of a high-Z target, the shock wave does not play a significant heating role. The shock waves carry current and transport the magnetic field, producing a high density on-axis, at relatively low temperature. Whereas, in the case of a low-Z target, the fast moving shock wave preheats the target during the initial implosion phase, and the later adiabatic compression further heats the target to very high energy density. As a result, the compression ratio required for heating the low-Z plasma to very high energy densities is greatly reduced.

Rahman, H. U.; Wessel, F. J.; Ney, P.; Presura, R.; Ellahi, Rahmat; Shukla, P. K.

2012-12-01

213

Measuring of spatio-temporal characteristics Z-pinch from deuterated polyethylene  

NASA Astrophysics Data System (ADS)

On the S-300 installation at currents up to 2 MA with rise time 100 ns, the investigation of the formation process of high-temperature plasma in fast Z-pinch was carried out. The central part of the loads was made from agar-agar and represented a deuterated polyethylene cylinder with small density 50 and 75 mg/sm3 and 1-2 mm diameter. On the ICT images, obtained in optical and soft X-ray range of a spectrum with 3-5 ns exposition, it is visible that on the axis of the polyethylene cylinder at the current`s rise time a cord is formed and it is separated into bright formations. They were observed on a background of a luminous area which occupied the initial neck volume. On time-integrated pinhole pictures obtained in SXR range (E > 1-4 keV), hot points with minimal size of 50 microns were registered. From the chronograms results, obtained by means of the optical high-speed-streak camera mount along the neck axis with time resolution < 1 ns, it follows that luminous formations arise sequentially during the different time moments (in 10-30 ns). Occurrence of luminous formations was accompanied by X-ray radiation occurrence with energy E > 1 keV with short duration of 2-4 ns. Simultaneously with X-ray radiation neutrons with the maximal yield of 4.5×109 were registered. The average energy measured in 4 directions under angles with an axis of: 0? (above the anode), 90?, 180? (under the cathode) and 270?, were accordingly: 2.4±0.2, 2.5±0.1, 2.5±0.1, 2.5±0.1 MeV.

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

2009-08-01

214

Time- and space-resolved X-ray absorption spectroscopy of aluminum irradiated by a subpicosecond high-power laser  

NASA Astrophysics Data System (ADS)

The ionization and recombination dynamics of transient aluminum plasmas was measured using point projection K-shell absorption spectroscopy. An aluminum plasma was produced with a subpicosecond beam of the 100-TW laser at the LULI facility and probed at different times with a picosecond X-ray backlighter created with a synchronized subpicosecond laser beam. Fourier-Domain-Interferometry (FDI) was used to measure the electron temperature at the peak of the heating laser pulse. Absorption X-ray spectra at early times are characteristic of a dense and rather homogeneous plasma, with limited longitudinal gradients as shown by hydrodynamic simulations. The shift of the Al K-edge was measured in the cold dense plasma located at the edge of the heated plasma. From the 1s 2p absorption spectra, the average ionization was measured as a function of time and was also modeled with a collisional-radiative atomic physics code coupled with hydrodynamic simulations.

Tzortzakis, S.; Audebert, P.; Renaudin, P.; Bastiani-Ceccotti, S.; Geindre, J. P.; Chenais-Popovics, C.; Nagels, V.; Gary, S.; Shepherd, R.; Girard, F.; Matsushima, I.; Peyrusse, O.; Gauthier, J.-C.

2006-05-01

215

Plasma flow control in the ablation and implosion phases in nested cylindrical and star wire array Z-pinches  

NASA Astrophysics Data System (ADS)

Wire array Z-pinches are the most powerful laboratory x-ray sources, and the optimization of the x-ray radiation output requires the understanding of diverse phenomena. During the wire array implosion in such arrays, the jxB forces ablate plasma from the wires to the center, before the whole array mass implodes. We studied the ablation and implosion dynamics in nested cylindrical and star wire array Z-pinches. The two implosion modes of nested arrays were simulated by Al star wire arrays with "gates". Arrays with regular-length gate wires imploded in the "nontransparent regime". Arrays with long, higher-Z gate wires imploded in the "transparent" regime. A two-frame end-on UV laser probing diagnostics was developed for the Zebra generator. Modified nested cylindrical arrays, called closely spaced arrays, were designed to implode without a precursor. Low-wire number arrays imploded accordingly. Precursor plasma was observed in higher wire-number arrays, despite outward jxB forces on the inner wires. The Al K-shell yield was highest for low wire-number nested arrays, which also imploded earlier. The presence of precursor in star wire arrays was determined by the direction of the jxB forces. Star wire array pairs were designed such that precursor and non-precursor arrays would have minimal differences. The presence of precursor decreased the x-ray yield parameters by 3-15%. Plasma flow control was achieved in these loads by varying the array configuration. Radiative properties of multicomponent Z-pinches and laser produced plasmas were studied. When high-Z element (W, Au) was mixed with Al plasma in a wire array, a decrease of the electron temperature was observed. The cooling effect was not present in laser-produced Al-Au plasmas, which may be explained by different heating mechanisms.

Papp, Daniel

216

Radiation Environments Generated by Plasma Z-Pinch Stagnation on Central Targets  

NASA Astrophysics Data System (ADS)

Calculations and experiments have been performed over the past two decades at Sandia National Laboratory, the Kurchatov Institute and Los Alamos National laboratory which explore the possibility of creating an intense radiation field in centrally located targets using an optically thick Z-pinch plasma driver. Pulsed power capabilities, particularly on the Sandia PBFA-Z machine, have evolved to the point where central temperatures of interest for applications experiments are now possible. The development and successful application of multi-dimensional computational radiation magnetohydrodynamic models, combined with advances in experimental and diagnostic capabilities, have contributed equally to our understanding of the physics of these complex systems. In these experiments, a cylindrical high -Z plasma driver implodes and stagnates on a centrally located target. It is arranged for the driver to become optically thick at maximum convergence in order to inhibit the radiative cooling of the target. The impact of the plasma driver on the target creates a radiation field inside the central target. Dubbed the 'flying radiation case' (FRC) at Los Alamos and the 'dynamic hohlraum' (DH) at Sandia, this configuration produces a radiation field that can be used to drive basic physics and ICF experiments. Three stages in the operation of a FRC can be identified. The first stage consists of the formation and implosion of the high-Z plasma driver. During this stage magnetic instabilities act on the outer, unstable surface of the plasma, and radiation may preheat the central target. The second stage consists of driver-target impact, re-assembly of the plasma on central target, and shock formation in the target. The third stage consists of the subsequent compression of the target and the evolution of the radiation environment. Issues affecting these stages of operation are reviewed. We review the historical development of the FRC concept, and summarize the results of recent pulsed power experiments and computations. These efforts lay the groundwork for several applications experiments, which will also be discussed. Alternate target concepts, which are being designed at Los Alamos and Sandia, and which offer the promise of reaching even higher temperatures on existing machines will be reviewed. Finally, we consider scaling to new pulsed power regimes and the implications for future applications experiments.

Brownell, John H.

1997-11-01

217

X-ray absorption spectroscopy for wire-array Z-pinches at the non-radiative stage  

NASA Astrophysics Data System (ADS)

Absorption spectroscopy was applied to wire-array Z-pinches on the 1 MA pulsed-power Zebra generator at the Nevada Terawatt Facility (NTF). The 50 TW Leopard laser was coupled with the Zebra generator for X-ray backlighting of wire arrays at the ablation stage. Broadband X-ray emission from a laser-produced Sm plasma was used to backlight Al star wire arrays in the range of 7-9 Å. Two time-integrated X-ray conical spectrometers recorded reference and absorption spectra. The spectrometers were shielded from the bright Z-pinch X-ray burst by collimators. The comparison of plasma-transmitted spectra with reference spectra indicates absorption lines in the range of 8.1-8.4 Å. Analysis of Al K-shell absorption spectra with detailed atomic kinetics models shows a distribution of electron temperature in the range of 10-30 eV that was fitted with an effective two-temperature model. Temperature and density distributions in wire-array plasma were simulated with a three-dimension magneto-hydrodynamic code. Post-processing of this code's output yields synthetic transmission spectrum which is in general agreement with the data.

Ivanov, V. V.; Hakel, P.; Mancini, R. C.; Chittenden, J. P.; Anderson, A.; Shevelko, A. P.; Wiewior, P.; Durmaz, T.; Altemara, S. D.; Papp, D.; Astanovitskiy, A. L.; Nalajala, V.; Chalyy, O.; Dmitriev, O.

2011-12-01

218

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

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

219

2D R-Z MHD simulations for sphinx experiments numerical study of single wire array Z-pinches with multi-microsecond current prepulse  

Microsoft Academic Search

The Sphinx machine based on microsecond LTD technology was used to implode single wire arrays. These z-pinch experiments were performed on Sphinx driver using a multi-microsecond current prepulse. This prepulse dramatically changes the ablation phase leading to an improvement of the axial homogeneity of both the implosion and the final radiating column. As a consequence, the number of parameters and

J. Grunenwald; H. Calamy; F. Lassalle; F. Zucchini; A. Loyen; P. Maury; A. Georges; A. Morell; J. P. Bedoch

2008-01-01

220

Development of M-shell x-ray spectroscopy and spectropolarimetry of z-pinch tungsten plasmas  

NASA Astrophysics Data System (ADS)

The development of spectroscopic modeling of M-shell tungsten z-pinch plasma is presented. The spectral region from 3.5 to 6.5 Å includes three distinct groups of transitions, and the best candidates for M-shell diagnostics are identified. Theoretical modeling is benchmarked with LLNL electron beam ion trap data produced at different energies of the electron beam and recorded by crystal spectrometers and a broadband microcalorimeter. A new high temperature plasma diagnostic tool, x-ray spectropolarimetry, is proposed to study polarization of W line emission and is illustrated using the results of x-pinch polarization-sensitive experiments. The x-ray line polarization of the prominent M-shell tungsten lines is calculated, and polarization markers are identified. The advantage of using x-pinch W wire experiments for the development of M-shell diagnostics is shown.

Shlyaptseva, A.; Fedin, D.; Hamasha, S.; Harris, C.; Kantsyrev, V.; Neill, P.; Ouart, N.; Safronova, U. I.; Beiersdorfer, P.; Boyce, K.; Brown, G. V.; Kelley, R.; Kilbourne, C. A.; Porter, F. S.

2004-10-01

221

A dual-channel, focusing x-ray spectrograph with uniform dispersion for Z pinch plasmas measurement  

SciTech Connect

A dual-channel, focusing x-ray spectrograph with uniform dispersion (i.e., the linear dispersion of this spectrograph is a constant) is described for measuring the x-ray spectra emission from the hot, dense Al Z pinch plasmas. The spectrograph uses double uniform-dispersed crystals (e.g., a Quartz 1010 crystal and a Mica 002 crystal) as dispersion elements and a double-film box as detector to achieve the simultaneous recording of the time integrated spectrum covering a wide spectral range of {approx}5-9 A. Since this spectrograph disperse the x-rays on the detector plane with uniform spacing for every wavelength, it needs not the calibration of the wavelength with spatial coordinate, thereby own the advantages of easiness and veracity for spectra identification. The design of this spectrograph and the example of experiment on the ''Yang'' accelerator are presented.

Yang Qingguo; Li Zeren; Chen Guanhua; Ye Yan; Huang Xianbin; Cai Hongchun; Li Jing [Institute of Fluid Physics, CAEP, Mianyang, Sichuan 621900 (China); Xiao Shali [Key Laboratory of Optic-electronic Technology and System, Ministry of Education, Chongqing University, Chongqing 400044 (China)

2012-01-15

222

Status On Multi-microsecond Prepulse Technique On Sphinx Machine Going From Nested To Single Wire Array For 800 ns Implosion Time Z-pinch  

Microsoft Academic Search

The Sphinx machine[1] is a 6 MA, 1 muS driver based on the LTD technology, used for Z-pinch experiments. Important improvements of Sphinx radiation output were recently obtained using a multi-microsecond current prepulse[2]. Total power per unit of length is multiplied by a factor of 6 and FWHM divided by a factor of 2.5. Early breakdown of the wires during

P. Maury; H. Calamy; J. Grunenwald; F. Lassalle; F. Zucchini; A. Loyen; A. Georges; A. Morell; J. P. Bedoch

2009-01-01

223

Results of radius scaling experiments and analysis of neon K-shell radiation data from an inductively driven Z-pinch  

Microsoft Academic Search

The K-shell radiated energy (yield) from neon Z-pinch implosions with annular, gas-puff nozzle radii of 1, 1.75, and 2.5 cm was measured for implosion times from 50 to 300 ns while systematically keeping the implosion kinetic energy nearly constant. The implosions were driven by the Hawk inductive-storage generator at the 0.65-MA level. Initial neutral-neon density distributions from the nozzles were

R. J. Commisso; J. P. Apruzese; D. C. Black; J. R. Boller; B. Moosman; D. Mosher; S. J. Stephanakis; B. V. Weber; F. C. Young

1998-01-01

224

Multicolor, time-gated, soft x-ray pinhole imaging of wire array and gas puff Z pinches on the Z and Saturn pulsed power generators  

SciTech Connect

A multicolor, time-gated, soft x-ray pinhole imaging instrument is fielded as part of the core diagnostic set on the 25 MA Z machine [M. E. Savage et al., in Proceedings of the Pulsed Power Plasma Sciences Conference (IEEE, New York, 2007), p. 979] for studying intense wire array and gas puff Z-pinch soft x-ray sources. Pinhole images are reflected from a planar multilayer mirror, passing 277 eV photons with <10 eV bandwidth. An adjacent pinhole camera uses filtration alone to view 1-10 keV photons simultaneously. Overlaying these data provides composite images that contain both spectral as well as spatial information, allowing for the study of radiation production in dense Z-pinch plasmas. Cu wire arrays at 20 MA on Z show the implosion of a colder cloud of material onto a hot dense core where K-shell photons are excited. A 528 eV imaging configuration has been developed on the 8 MA Saturn generator [R. B. Spielman et al., and A. I. P. Conf, Proc. 195, 3 (1989)] for imaging a bright Li-like Ar L-shell line. Ar gas puff Z pinches show an intense K-shell emission from a zippering stagnation front with L-shell emission dominating as the plasma cools.

Jones, B.; Coverdale, C. A.; Nielsen, D. S.; Jones, M. C.; Deeney, C. [Sandia National Laboratories, Albuquerque, New Mexico 8718 (United States); Serrano, J. D.; Nielsen-Weber, L. B.; Meyer, C. J. [Ktech Corporation, Albuquerque, New Mexico 87123 (United States); Apruzese, J. P.; Clark, R. W. [Naval Research Laboratory, Washington, DC 20375 (United States); Coleman, P. L. [Alameda Applied Sciences Corp., San Leandro, California 94577 (United States)

2008-10-15

225

Proposed design and mass production of wire arrays and targets for a Z-pinch IFE power plant  

NASA Astrophysics Data System (ADS)

This paper summarizes the results of a detailed study reported in Ref. [1]. A concept for a 1000MW(e) Z-Pinch IFE power plant has ten reactor chambers. A Load, consisting of a wire array surrounding a cryogenic dynamic hohlraum target with a 3-GJ yield, must be produced, inserted into a Replaceable Transmission Lines (RTL), transported to one of the chambers, and shot every second. The conceptual design of the load facilitates automatic mass manufacturing and insertion at 1 Hz at minimum cost. A sequence of operations necessary to (1) fabricate each wire array on a holding and insertion tool, (2)manufacture, evacuate, fill with DT, freeze, layer, and assemble each target with helium gas and liquid hydrogen, (3) insert a wire array and a target under vacuum into an RTL, and (4) remove their debris, is described. Detailed cost estimates derived for the complete load production and solid debris removal cycle in a commercial-scale facility are summarized.

Gallix, R.; Rickman, W. S.; Alexander, N. B.

2006-06-01

226

Numerical investigation on the implosion dynamics of wire-array Z-pinches in (r, {theta}) geometry  

SciTech Connect

The implosion dynamics of wire-array Z-pinches are investigated numerically in 2D (r, {theta}) geometry by using a resistive MHD code. It is assumed that the wires have expanded to plasmas with diameter d{sub 0}, which is used as the initial condition for the consequent implosion process. In fact, the explosion process of individual wires is not included. By changing d{sub 0}, the effects of the wire expansion degree on the implosion dynamics are analyzed. When d{sub 0} is larger, the current density is more concentrated at the outer side of the wires and the fraction of current flow around the wire plasmas is nearly in proportion to d{sub 0}. As a result, the ablation rate of wires is increased and the implosion phase starts earlier. This conclusion agrees with the simulation works of other authors [Chittenden et al., Phys. Plasmas 11(3), 1118 (2004)]. When the array radius and initial wire plasma diameter are fixed, the increase of wire number leads to the azimuthal merge of wires during implosion. When the wires number exceed a critical value, which is related to d{sub 0}, wire plasmas can merge to a continuous shell with an azimuthal perturbation in density, which depends on the initial wires number.

Huang Jun; Ding Ning; Ning Cheng; Sun Shunkai; Zhang Yang; Xiao Delong; Xue Chuang [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)

2012-06-15

227

Radiation symmetry studies in double-Z-pinch hohlraums on Z using 4.7-mm capsules*  

NASA Astrophysics Data System (ADS)

Via x-ray backlit capsule shell distortion measurements, the time-averaged polar radiation uniformity in a 70 eV high-yield-scale double-z-pinch-driven hohlraum (cylindrical) on Sandia National Laboratories Z accelerator has recently been measured to the 3.0 +/- 1.4% level on the best shots [Bennett et al., Phys. Plasmas, in press]. This 3.0% symmetry would scale to 0.9% at 220 eV HY (high yield) conditions on a dual power-feed HY accelerator, close to that required for ignition, due to increased hohlraum wall albedo. These studies were performed in non-optimized hohlraums that were dominated by a P2 Legendre mode, controlled by hohlraum length [Vesey et al., Phys. Plasmas 10, 1854 (2003)], using 2.13-mm-diam plastic capsules. Experiments in Sept 2003 will use Ge-doped thin shell capsules of 4.7-mm diameter in order to improve the accuracy of the symmetry measurement, while replicating the case-to-capsule ratio of the HY design. Both P2 and P4 will be varied in these experiments, and this paper will focus on the most symmetric implosions that result.

Bennett, G. R.; Cuneo, M. E.; Vesey, R. A.; Porter, J. L.; Adams, R. G.; Aragon, R. A.; Rambo, P. K.; Ruggles, L. E.; Simpson, W. W.; Smith, I. C.; Wunsch, S. E.; Afeyan, B. B.

2003-10-01

228

Numerical and experimental investigations on the interaction of light wire-array Z-pinches with embedded heavy foam converters  

SciTech Connect

The interaction of a light tungsten wire-array Z-pinch with an embedded heavy foam converter, whose mass ratio is typically less than 0.16, is numerically analyzed and experimentally investigated on the 1.3 MA “QiangGuang I” facility. Computational results show that this implosion process can be divided into three stages: acceleration of the tungsten wire-array plasma, collision, and stagnation. The tungsten plasma is accelerated to a high speed by the J?×?B force and interacts weakly with the foam plasma in the first stage. Strong energy conversions take place in the second collision stage. When the high speed tungsten plasma impacts on the foam converter, the plasma is thermalized and a radial radiation peak is produced. Meanwhile, a shock wave is generated due to the collision. After the shock rebounds from the axis and meets the W/Foam boundary, the plasma stagnates and the second radial radiation peak appears. The collision and stagnation processes were observed and the two-peak radial radiation pulse was produced in experiments. Increasing the wire-array radius from 4?mm to 6?mm, the kinetic energy of the tungsten plasma is increased, causing a stronger thermalization and generating a higher first radiation peak. Experimental results also showed a higher ratio of the first peak to the second peak in the case of larger wire-array radius. If we add a thin CH film cover onto the surface of the embedded foam converter, the first radiation peak will be hardly changed, because the acceleration of the tungsten plasma is not evidently affected by the film cover. However, the second radiation peak decreases remarkably due to the large load mass and the corresponding weak compression.

Xiao, Delong; Ding, Ning; Sun, Shunkai [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)] [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Ye, Fan; Ning, Jiamin; Hu, Qingyuan; Chen, Faxin; Qin, Yi; Xu, Rongkun; Li, Zhenghong [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)] [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

2014-04-15

229

Symmetric inertial confinement fusion capsule implosions in a high-yield-scale double-Z-pinch-driven hohlraum on Z  

NASA Astrophysics Data System (ADS)

Detailed radiation-hydrodynamics calculations indicate that the dual-63-MA Z-pinch high-yield (HY) 220-eV inertial confinement fusion concept [Phys. Plasmas 6, 2129 (1999)] may release 400 MJ of fusion yield, if pulse shaping, capsule preheat, and x-radiation drive uniformity can be acceptably controlled. Radiation symmetry is under detailed investigation in an advanced, 70-eV HY-scale scoping hohlraum [Phys. Rev. Lett. 88, 215004 (2002)] driven by the single 20-MA power feed of Sandia National Laboratories' Z accelerator. The time-averaged polar radiation asymmetry, /I, is inferred from direct distortion measurements of an imploding capsule's limb-darkened ("backlit") shell, via 6.7 keV point projection x-ray imaging. Thus far, /I has been measured at the 3.0±1.4 (%) level, on the best shots, in hohlraums (cylindrical) with length/radius ratios L/R of 1.61 and 1.69, either side of a L/R=1.66 predicted optimum for a zeroed P2 Legendre mode. Simulations suggest that when scaled to 220 eV with zeroed odd Legendre modes, relevant to the best fraction of shots on a dual power-feed HY accelerator, the increased hohlraum wall albedo would reduce the field asymmetry to the 0.9% level; thus approaching the uniformity requirements of high-yield ignition. Future studies at L/R=1.66 will include refinements in experimental methods and image analysis techniques (denoising), and the measured symmetry is anticipated to improve further.

Bennett, G. R.; Vesey, R. A.; Cuneo, M. E.; Porter, J. L.; Adams, R. G.; Aragon, R. A.; Rambo, P. K.; Rovang, D. C.; Ruggles, L. E.; Simpson, W. W.; Smith, I. C.; Speas, C. S.; Struve, K. W.; Wenger, D. F.; Landen, O. L.

2003-09-01

230

Z-Pinch Generated X-Rays in Static-Wall Hohlraum Geometry Demonstrate Potential for Indirect-Drive ICF Studies  

SciTech Connect

Hohlraums of full ignition scale (6-mm diameter by 7-mm length) have been heated by x-rays from a z-pinch magnet on Z to a variety of temperatures and pulse shapes which can be used to simulate the early phases of the National Ignition Facility (NIF) temperature drive. The pulse shape is varied by changing the on-axis target of the z pinch in a static-wall-hohlraum geometry. A 2-{micro}m-thick walled Cu cylindrical target of 8-mm diameter filled with 10 mg/cm{sup 3} CH, for example, produces foot-pulse conditions of {approx}85 eV for a duration of {approx}10 ns, while a solid cylindrical target of 5-mm diameter and 14-mg/cm{sup 3} CH generates first-step-pulse conditions of {approx}122 eV for a duration of a few ns. Alternatively, reducing the hohlraum size (to 4-mm diameter by 4-mm length) with the latter target has increased the peak temperature to {approx}150 eV, which is characteristic of a second-step-pulse temperature. In general, the temperature T of these x-ray driven hohlraums is in agreement with the Planckian relation T{approx}(P/A){sup 1/4}. P is the measured x-ray input power and A is the surface area of the hohlraum. Fully-integrated 2-D radiation-hydrodynamic simulations of the z pinch and subsequent hohlraum heating show plasma densities within the useful volume of the hohlraums to be on the order of air or less.

BOWERS,RICHARD; CHANDLER,GORDON A.; HEBRON,DAVID E.; LEEPER,RAMON J.; MATUSLKA,WALTER; MOCK,RAYMOND CECIL; NASH,THOMAS J.; OLSON,CRAIG L.; PETERSON,BOB; PETERSON,DARRELL; RUGGLES,LAURENCE E.; SANFORD,THOMAS W. L.; SIMPSON,WALTER W.; STRUVE,KENNETH W.; VESEY,ROGER A.

1999-11-01

231

Planar Wire-Array Z-Pinch Implosion Dynamics and X-Ray Scaling at Multiple-MA Drive Currents for a Compact Multisource Hohlraum Configuration  

SciTech Connect

An indirect drive configuration is proposed wherein multiple compact Z-pinch x-ray sources surround a secondary hohlraum. Planar compact wire arrays allow reduced primary hohlraum surface area compared to cylindrical loads. Implosions of planar arrays are studied at up to 15 TW x-ray power on Saturn with radiated yields exceeding the calculated kinetic energy, suggesting other heating paths. X-ray power and yield scaling studied from 1-6 MA motivates viewfactor modeling of four 6-MA planar arrays producing 90 eV radiation temperature in a secondary hohlraum.

Jones, B.; Ampleford, D. J.; Vesey, R. A.; Cuneo, M. E.; Coverdale, C. A.; Waisman, E. M.; Jones, M. C.; Fowler, W. E.; Stygar, W. A. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Serrano, J. D. [Ktech Corp., Albuquerque, New Mexico 87123 (United States); Vigil, M. P. [LMATA Government Services LLC, Albuquerque, New Mexico 87109 (United States); Esaulov, A. A.; Kantsyrev, V. L.; Safronova, A. S.; Williamson, K. M. [University of Nevada, Reno, Nevada 89557 (United States); Chuvatin, A. S. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, 91128 Palaiseau (France); Rudakov, L. I. [Icarus Research, Bethesda, Maryland 20824-0780 (United States)

2010-03-26

232

Searching for efficient X-ray radiators for wire array Z-pinch plasmas using mid-atomic-number single planar wire arrays on Zebra at UNR  

NASA Astrophysics Data System (ADS)

We continue to search for more efficient X-ray radiators from wire array Z-pinch plasmas. The results of recent experiments with single planar wire array (SPWA) loads made from mid-atomic-number material wires such as Alumel, Cu, Mo, and Ag are presented and compared. In particular, two new efficient X-ray radiators, Alumel (95% Ni, 2% Al, and 2% Si) and Ag, are introduced, and their radiative properties are discussed in detail. The experiments were performed on the 1 MA Zebra generator at UNR. The X-ray yields from such mid-atomic-number SPWAs exceed twice those from low-atomic-number SPWAs, such as Al, and increase with the atomic number to reach more than 27-29 kJ for Ag. To consider the main contributions to the total radiation, we divided the time interval of the Z-pinch dynamic where wire ablation and implosion, stagnation, and plasma expansion occur in corresponding phases and studied the radiative and implosion characteristics within them. Theoretical tools such as non-LTE kinetics and wire ablation dynamic models were applied in the data analysis. These results and the models developed have much broader applications, not only for SPWAs on Zebra, but for other HED plasmas with mid-atomic-number ions.

Safronova, A. S.; Esaulov, A. A.; Kantsyrev, V. L.; Ouart, N. D.; Shlyaptseva, V.; Weller, M. E.; Keim, S. F.; Williamson, K. M.; Shrestha, I.; Osborne, G. C.

2011-12-01

233

Predictions of non-LTE spectra from large scale 3D magneto-hydrodynamic modelling of wire array Z-pinches  

NASA Astrophysics Data System (ADS)

The last few years have seen considerable advances in the application of high performance computing techniques to 3D simulations of wire array Z-pinches. Whilst the intense soft X-ray radiation output is the principle application of wire arrays, the ability to encompass spectrally detailed models of this emission within such 3D calculations was thought to be computationally prohibitive. We have developed a non-LTE atomic and radiation physics model with detailed configuration accounting and n-l splitting which is sufficiently streamlined to run in-line with large scale 3D simulations. In order to handle the volume of data generated by the spectral treatment of the billions of numerical cells, a novel data structure derived from a self-balancing binary search tree was developed, enabling the use of non-LTE DCA calculations within large scale 3D simulations for the first time. A brief description of the model is provided and the application of the simulations to understanding the X-ray generation processes within wire array Z-pinches on the Z generator at Sandia National Laboratory is reported. The contribution of the ion temperature and the motion of the unstable plasma at stagnation to the Doppler widths of the lines is described in detail.

Niasse, Nicolas; Chittenden, Jeremy

2012-10-01

234

Equilibrium and Stability Properties for Long Stability Period and High-Field Regimes in the ZaP Flow Z-Pinch  

NASA Astrophysics Data System (ADS)

The ZaP Flow Z-Pinch experiment investigates the effect of sheared axial flows on the gross stability of a Z-pinch. The cathode is replaced with a larger version to increase heating through increased adiabatic compression and to increase flexibility of gas injection through a greater number of gas valves. Two operational regimes are identified with the electrode configuration: long stability period; high peak magnetic field. The long stability regime results in a well-centered pinch with little magnetic mode activity for an extended period of time which appears to be limited by the current pulse. The high-field regime results in a ramp-up of magnetic field by a factor of two. Loss of stability is typically correlated with the magnetic field peak. Radial density profile is calculated using a four-chord HeNe interferometer, magnetic field and mode activity are measured with an azimuthal array of probes and total temperature is estimated from these values. Equilibrium and stability properties are calculated and reported.

Knecht, S. D.; Shumlak, U.; Golingo, R. P.; Nelson, B. A.

2009-11-01

235

ALUMINUM  

E-print Network

This fact sheet answers the most frequently asked health questions (FAQs) about aluminum. For more information, call the ATSDR Information Center at 1-800-232-4636. This fact sheet is one in a series of summaries about hazardous substances and their health effects. It is important you understand this information because this substance may harm you. The effects of exposure to any hazardous substance depend on the dose, the duration, how you are exposed, personal traits and habits, and whether other chemicals are present. HIGHLIGHTS: Everyone is exposed to low levels of aluminum from food, air, water, and soil. Exposure to high levels of aluminum may result in respiratory and neurological problems. Aluminum (in compounds combined with other elements) has been found in at least 596 of the 1,699 National Priority List (NPL) sites identified by the Environmental Protection Agency (EPA). What is aluminum? Aluminum is the most abundant metal in the earth’s crust. It is always found combined with other elements such as oxygen, silicon, and fluorine. Aluminum as the metal is obtained from

unknown authors

236

Initial magnetic field compression studies using gas-puff Z-pinches and thin liners on COBRA This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-print Network

field compression ratio implies efficient and homogenous field compression./083006 Abstract This magnetic compression of cylindrical liners filled with DT gas has promise as an efficient wayInitial magnetic field compression studies using gas-puff Z-pinches and thin liners on COBRA

Kroupp, Eyal

237

Studies of x-ray and XUV radiation from wire-array z-pinches on COBRA using an x-ray streak camera  

NASA Astrophysics Data System (ADS)

Time- and space- resolved short-wavelength radiation from wire-array z-pinches has been studied using a low-magnification Kentech x-ray streak camera in experiments on the 1 MA COBRA pulsed power generator at Cornell University. In the x-ray spectral band, a standard photochode and imaging slit were used to record one-dimensional images in the axial direction. Axial and radial images of wire arrays were recorded in XUV radiaion using an open pinhole and a specially made transparent mesh-type photocathode. The development of the precursor plasma and hot spots in the stagnated plasma have been observed. The images were compared with results obtained with an optical streak camera and 4-frame gated microchannel plate imager.

Gourdain, P.-A.; Pikuz, S. A.; Shelkovenko, T. A.; Knapp, P. F.; Hammer, D. A.; Simar, D. B.

2008-11-01

238

COBRA-STAR, a five frame point-projection x-ray imaging system for 1 MA scale wire-array Z pinches  

NASA Astrophysics Data System (ADS)

A new imaging system for 1MA scale wire-array Z-pinch experiments that produces up to five high-resolution x-ray images per experimental pulse has been developed. Calibrated areal density measurements of the Z-pinch plasma can be obtained from each pulse. The system substitutes five molybdenum (Mo) X pinches for the normal copper return-current conductors to provide point sources of x-rays for point-projection radiography. Each backlighting X pinch consists of four Mo wires, the x-ray burst timing of which was controlled by varying the wire diameter (mass) from 10.2to30?m in the five X pinches. Typical images have a 16×8mm2 field of view at the wire array and a magnification of about 6.5:1 on the x-ray-sensitive film. Titanium (Ti) filters in front of the films transmit continuum radiation in the spectral range of 3-5keV. Inclusion on the Ti of a step wedge having known thickness increments of the same material as the wires enables the calibrated areal density measurements to be made of the exploding wire plasmas. Here, we used tungsten (W) step wedges with step thicknesses ranging from 0.015to1.1?m to obtain accurate (±10%) areal density measurements of W plasmas from the spatial profile of film exposure. When imaging arrays that produce intense radiation pulses, a plastic monofilament "quencher" is placed on axis to avoid film saturation. Images have subnanosecond temporal resolution and about 7?m spatial resolution.

Douglass, J. D.; Hammer, D. A.

2008-03-01

239

Analysis of Plasma Formation in an Experiment with Pulsed Megagauss Field on 1.0-mm Diameter Aluminum Rods  

Microsoft Academic Search

Summary form only given. The physics of the interaction between large magnetic field and conducting media is important to wire-array z-pinches, high current fuses, magnetically insulated transmission lines, ultrahigh magnetic field generators, magnetized target fusion, and astrophysics. In an experiment on the 1 MA UNR Zebra Marx generator, megagauss magnetic field was pulsed on the surface of 1.0-mm-diameter aluminum rods.

T. J. Awe; B. S. Bauer; R. E. Siemon; S. Fuelling; V. Makhin; T. Goodrich; V. V. Ivanov; B. Le Galloudec; A. Oxner; R. Presura

2007-01-01

240

Study of the radiation spectra of fast Z-pinches formed during the implosion of wire arrays in the Angara-5-1 facility  

NASA Astrophysics Data System (ADS)

Results are presented from measurements of the radiation spectra of the Z-pinch tungsten plasma produced during the implosion of cylindrical wire arrays with a linear mass of 200-400 ?g/cm and an initial diameter of 12-20 mm at a current of ˜3 MA in the experiments performed at the Angara-5-1 facility. The radiation spectra in the photon energy range of 50-900 eV were recorded on a UF-4 X-ray film by using a spectrograph with a transmission grating. The radiation spectrum in the photon energy range of 1-3 keV was recorded using a crystalline panoramic spectrograph. A curtain shutter was used to protect the transmission grating from fast microparticles produced due to the erosion of high-voltage electrodes. The total radiation yield was measured with a thermocouple calorimeter. It is shown that most of the tungsten plasma radiation energy is emitted in the photon energy range of 80-300 eV. Measurements of the spectral intensity of pinch radiation with a spatial resolution along the pinch radius showed that the effective transverse diameter of the pinch did not exceed 2 mm, which agrees with independent current measurements of the pinch size. The results of measurements of the spectral intensity of pinch radiation were compared with calculations per-formed under the assumption of a stationary homogeneous plasma.

Bolkhovitinov, E. A.; Volkov, G. S.; Vichev, I. Yu.; Grabovski, E. V.; Gritsyk, A. N.; Zaitsev, V. I.; Novikov, V. G.; Oleinik, G. M.; Rupasov, A. A.; Svetlov, E. V.; Shikanov, A. S.; Fedulov, M. V.

2012-10-01

241

Specific features of the structure of the Z-pinch emitting region formed during the implosion of a foam-wire load at the ANGARA-5-1 facility  

NASA Astrophysics Data System (ADS)

Results are presented from experimental studies of the structure of the compressed plasma of a Z-pinch produced during the implosion of a foam-wire load at the current of up to 3 MA. The foam-wire load consisted of two nested cylindrical cascades, one of which was a solid or hollow cylinder made of low-density agar-agar foam, while the other was a wire array. The wall thickness of a hollow foam cylinder was 100-200 ?m. The images of the pinch and its spectrum obtained with the help of multiframe X-ray cameras and a grazing incidence spectrograph with a spatial resolution were analyzed. Data on the spatial structure of the emitting regions and the soft X-ray (SXR) spectrum of the Z-pinch in the final stage of compression of a foam-wire load were obtained. The implosion modes characterized by the formation of hot regions during implosion of such loads were revealed. The characteristic scale lengths of the hot regions were determined. It is shown that the energy distribution of SXR photons in the energy range from 80 eV to 1 keV forms the spatial structure of Z-pinch images recorded during the implosion of foam-wire loads. It is revealed that the spectral density of SXR emission in the photon energy range of 300-600 eV from hot Z-pinch regions exceeds the spectral density of radiation from the neighboring Z-pinch regions by more than one order of magnitude. Groups of lines related to the absorption and emission of radiation by atoms and multicharged ions of carbon and oxygen in the outer foam cascade of a foam-wire load were recorded for the first time by analyzing the spatial distribution of the SXR spectra of multicharged ions of the Z-pinch. The groups of absorption lines of ions (C III, O III, O IV, and O VI) corresponding to absorption of SXR photons in the Z-pinch of a tungsten wire array, which served as the inner cascade of a foam-wire load, were identified. The plasma electron temperature measured from the charge composition of carbon and oxygen ions in the outer agar-agar foam cascade was 10-40 eV. During the implosion of foam-wire loads at currents of up to 3 MA, SXR pulses ( h? > 100 eV) with a duration of 10 ns and peak power of 3 TW were detected. It is shown that the temporal profile of single-peak and double-peak SXR pulses can be controlled by varying the parameters of the outer and inner cascades of the foam-wire load.

Mitrofanov, K. N.; Grabovski, E. V.; Gritsuk, A. N.; Laukhin, Ya. N.; Aleksandrov, V. V.; Oleinik, G. M.; Medovshchikov, S. F.; Shevel'ko, A. P.

2013-01-01

242

Specific features of the structure of the Z-pinch emitting region formed during the implosion of a foam-wire load at the ANGARA-5-1 facility  

SciTech Connect

Results are presented from experimental studies of the structure of the compressed plasma of a Z-pinch produced during the implosion of a foam-wire load at the current of up to 3 MA. The foam-wire load consisted of two nested cylindrical cascades, one of which was a solid or hollow cylinder made of low-density agar-agar foam, while the other was a wire array. The wall thickness of a hollow foam cylinder was 100-200 {mu}m. The images of the pinch and its spectrum obtained with the help of multiframe X-ray cameras and a grazing incidence spectrograph with a spatial resolution were analyzed. Data on the spatial structure of the emitting regions and the soft X-ray (SXR) spectrum of the Z-pinch in the final stage of compression of a foam-wire load were obtained. The implosion modes characterized by the formation of hot regions during implosion of such loads were revealed. The characteristic scale lengths of the hot regions were determined. It is shown that the energy distribution of SXR photons in the energy range from 80 eV to 1 keV forms the spatial structure of Z-pinch images recorded during the implosion of foam-wire loads. It is revealed that the spectral density of SXR emission in the photon energy range of 300-600 eV from hot Z-pinch regions exceeds the spectral density of radiation from the neighboring Z-pinch regions by more than one order of magnitude. Groups of lines related to the absorption and emission of radiation by atoms and multicharged ions of carbon and oxygen in the outer foam cascade of a foam-wire load were recorded for the first time by analyzing the spatial distribution of the SXR spectra of multicharged ions of the Z-pinch. The groups of absorption lines of ions (C III, O III, O IV, and O VI) corresponding to absorption of SXR photons in the Z-pinch of a tungsten wire array, which served as the inner cascade of a foam-wire load, were identified. The plasma electron temperature measured from the charge composition of carbon and oxygen ions in the outer agar-agar foam cascade was 10-40 eV. During the implosion of foam-wire loads at currents of up to 3 MA, SXR pulses (h{nu} > 100 eV) with a duration of 10 ns and peak power of 3 TW were detected. It is shown that the temporal profile of single-peak and double-peak SXR pulses can be controlled by varying the parameters of the outer and inner cascades of the foam-wire load.

Mitrofanov, K. N., E-mail: mitrofan@triniti.ru; Grabovski, E. V.; Gritsuk, A. N.; Laukhin, Ya. N.; Aleksandrov, V. V.; Oleinik, G. M.; Medovshchikov, S. F. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)] [Troitsk Institute for Innovation and Fusion Research (Russian Federation); Shevel'ko, A. P. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)] [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

2013-01-15

243

Recyclable transmission line (RTL) and linear transformer driver (LTD) development for Z-pinch inertial fusion energy (Z-IFE) and high yield.  

SciTech Connect

Z-Pinch Inertial Fusion Energy (Z-IFE) complements and extends the single-shot z-pinch fusion program on Z to a repetitive, high-yield, power plant scenario that can be used for the production of electricity, transmutation of nuclear waste, and hydrogen production, all with no CO{sub 2} production and no long-lived radioactive nuclear waste. The Z-IFE concept uses a Linear Transformer Driver (LTD) accelerator, and a Recyclable Transmission Line (RTL) to connect the LTD driver to a high-yield fusion target inside a thick-liquid-wall power plant chamber. Results of RTL and LTD research are reported here, that include: (1) The key physics issues for RTLs involve the power flow at the high linear current densities that occur near the target (up to 5 MA/cm). These issues include surface heating, melting, ablation, plasma formation, electron flow, magnetic insulation, conductivity changes, magnetic field diffusion changes, possible ion flow, and RTL mass motion. These issues are studied theoretically, computationally (with the ALEGRA and LSP codes), and will work at 5 MA/cm or higher, with anode-cathode gaps as small as 2 mm. (2) An RTL misalignment sensitivity study has been performed using a 3D circuit model. Results show very small load current variations for significant RTL misalignments. (3) The key structural issues for RTLs involve optimizing the RTL strength (varying shape, ribs, etc.) while minimizing the RTL mass. Optimization studies show RTL mass reductions by factors of three or more. (4) Fabrication and pressure testing of Z-PoP (Proof-of-Principle) size RTLs are successfully reported here. (5) Modeling of the effect of initial RTL imperfections on the buckling pressure has been performed. Results show that the curved RTL offers a much greater buckling pressure as well as less sensitivity to imperfections than three other RTL designs. (6) Repetitive operation of a 0.5 MA, 100 kV, 100 ns, LTD cavity with gas purging between shots and automated operation is demonstrated at the SNL Z-IFE LTD laboratory with rep-rates up to 10.3 seconds between shots (this is essentially at the goal of 10 seconds for Z-IFE). (7) A single LTD switch at Tomsk was fired repetitively every 12 seconds for 36,000 shots with no failures. (8) Five 1.0 MA, 100 kV, 100 ns, LTD cavities have been combined into a voltage adder configuration with a test load to successfully study the system operation. (9) The combination of multiple LTD coaxial lines into a tri-plate transmission line is examined. The 3D Quicksilver code is used to study the electron flow losses produced near the magnetic nulls that occur where coax LTD lines are added together. (10) Circuit model codes are used to model the complete power flow circuit with an inductive isolator cavity. (11) LTD architectures are presented for drivers for Z-IFE and high yield. A 60 MA LTD driver and a 90 MA LTD driver are proposed. Present results from all of these power flow studies validate the whole LTD/RTL concept for single-shot ICF high yield, and for repetitive-shot IFE.

Sharpe, Robin Arthur; Kingsep, Alexander S. (Kurchatov Institute, Moscow, Russia); Smith, David Lewis; Olson, Craig Lee; Ottinger, Paul F. (Naval Research Laboratory, Washington, DC); Schumer, Joseph Wade (Naval Research Laboratory, Washington, DC); Welch, Dale Robert (Voss Scientific, Albuquerque, NM); Kim, Alexander (High Currents Institute, Tomsk, Russia); Kulcinski, Gerald L. (University of Wisconsin, Madison, WI); Kammer, Daniel C. (University of Wisconsin, Madison, WI); Rose, David Vincent (Voss Scientific, Albuquerque, NM); Nedoseev, Sergei L. (Kurchatov Institute, Moscow, Russia); Pointon, Timothy David; Smirnov, Valentin P. (Kurchatov Institute, Moscow, Russia); Turgeon, Matthew C.; Kalinin, Yuri G. (Kurchatov Institute, Moscow, Russia); Bruner, Nichelle "Nicki" (Voss Scientific, Albuquerque, NM); Barkey, Mark E. (University of Alabama, Tuscaloosa, AL); Guthrie, Michael (University of Wisconsin, Madison, WI); Thoma, Carsten (Voss Scientific, Albuquerque, NM); Genoni, Tom C. (Voss Scientific, Albuquerque, NM); Langston, William L.; Fowler, William E.; Mazarakis, Michael Gerrassimos

2007-01-01

244

Status On Multi-microsecond Prepulse Technique On Sphinx Machine Going From Nested To Single Wire Array For 800 ns Implosion Time Z-pinch  

SciTech Connect

The Sphinx machine{sup [1]} is a 6 MA, 1 {mu}S driver based on the LTD technology, used for Z-pinch experiments. Important improvements of Sphinx radiation output were recently obtained using a multi-microsecond current prepulse{sup [2]}. Total power per unit of length is multiplied by a factor of 6 and FWHM divided by a factor of 2.5. Early breakdown of the wires during the prepulse phase dramatically changes the ablation phase leading to an improvement of axial homogeneity of both the implosion and the final radiating column. As a consequence, the cathode bubble observed on classical shots is definitively removed. The implosion is then centered and zippering effect is reduced, leading to simultaneous x-ray emission of the whole length. A great reproducibility is obtained. Nested arrays were used before to mitigate the Rayleigh-Taylor instabilities during the implosion phase. Further experiments with pre-pulse technique are described here were inner array was removed. The goal of these experiments was to see if long prepulse could give stable enough implosion with single array and at the same time increase the {eta} parameter by reducing the mass of the load. Experimental results of single wire array loads of typical dimension 5 cm in height with implosion time between 700 and 900 ns and diameter varying between 80 and 140 mm are given. Parameters of the loads were varying in term of radius and number of wires. Comparisons with nested wire array loads are done and trends are proposed. Characteristics of both the implosion and the final radiating column are shown. 2D MHD numerical simulations of single wire array become easier as there is no interaction between outer and inner array anymore. A systematic study was done using injection mass model to benchmark simulation with experiments.

Maury, P.; Calamy, H.; Grunenwald, J.; Lassalle, F.; Zucchini, F.; Loyen, A.; Georges, A.; Morell, A.; Bedoch, J. P. [Centre d'Etudes de Gramat, BP 80200 46500 Gramat (France)

2009-01-21

245

Status On Multi-microsecond Prepulse Technique On Sphinx Machine Going From Nested To Single Wire Array For 800 ns Implosion Time Z-pinch  

NASA Astrophysics Data System (ADS)

The Sphinx machine[1] is a 6 MA, 1 ?S driver based on the LTD technology, used for Z-pinch experiments. Important improvements of Sphinx radiation output were recently obtained using a multi-microsecond current prepulse[2]. Total power per unit of length is multiplied by a factor of 6 and FWHM divided by a factor of 2.5. Early breakdown of the wires during the prepulse phase dramatically changes the ablation phase leading to an improvement of axial homogeneity of both the implosion and the final radiating column. As a consequence, the cathode bubble observed on classical shots is definitively removed. The implosion is then centered and zippering effect is reduced, leading to simultaneous x-ray emission of the whole length. A great reproducibility is obtained. Nested arrays were used before to mitigate the Rayleigh-Taylor instabilities during the implosion phase. Further experiments with pre-pulse technique are described here were inner array was removed. The goal of these experiments was to see if long prepulse could give stable enough implosion with single array and at the same time increase the ? parameter by reducing the mass of the load. Experimental results of single wire array loads of typical dimension 5 cm in height with implosion time between 700 and 900 ns and diameter varying between 80 and 140 mm are given. Parameters of the loads were varying in term of radius and number of wires. Comparisons with nested wire array loads are done and trends are proposed. Characteristics of both the implosion and the final radiating column are shown. 2D MHD numerical simulations of single wire array become easier as there is no interaction between outer and inner array anymore. A systematic study was done using injection mass model to benchmark simulation with experiments.

Maury, P.; Calamy, H.; Grunenwald, J.; Lassalle, F.; Zucchini, F.; Loyen, A.; Georges, A.; Morell, A.; Bedoch, J. P.

2009-01-01

246

High power density targets  

NASA Astrophysics Data System (ADS)

In the context of new generation rare isotope beam facilities based on high-power heavy-ion accelerators and in-flight separation of the reaction products, the design of the rare isotope production targets is a major challenge. In order to provide high-purity beams for science, high resolution is required in the rare isotope separation. This demands a small beam spot on the production target which, together with the short range of heavy ions in matter, leads to very high power densities inside the target material. This paper gives an overview of the challenges associated with this high power density, discusses radiation damage issues in targets exposed to heavy ion beams, and presents recent developments to meet some of these challenges through different projects: FAIR, RIBF and FRIB which is the most challenging. Extensive use of Finite Element Analysis (FEA) has been made at all facilities to specify critical target parameters and R&D work at FRIB successfully retired two major risks related to high-power density and heavy-ion induced radiation damage.

Pellemoine, Frederique

2013-12-01

247

High Power Cryogenic Targets  

SciTech Connect

The development of high power cryogenic targets for use in parity violating electron scattering has been a crucial ingredient in the success of those experiments. As we chase the precision frontier, the demands and requirements for these targets have grown accordingly. We discuss the state of the art, and describe recent developments and strategies in the design of the next generation of these targets.

Gregory Smith

2011-08-01

248

High-power red VCSEL arrays  

NASA Astrophysics Data System (ADS)

High-power red laser sources are used in many applications such as cosmetics, cancer photodynamic therapy, and DNA sequencing in the medical field, laser-based RGB projection display, and bar-code scanning to name a few. Verticalcavity surface-emitting lasers (VCSELs) can be used as high-power laser sources, as efficient single devices can be configured into high-power two-dimensional arrays and scaled into modules of arrays. VCSELs emit in a circular, uniform beam which can greatly reduce the complexity and cost of optics. Other advantages include a narrow and stable emission spectrum, low speckle of the far-field emission, and good reliability. However, developing efficient red VCSEL sources presents some challenges because of the reduced quantum-well carrier confinement and the increased Aluminum content (to avoid absorption) which increases thermal impedance, and also decreases the DBR index contrast resulting in increased penetration length and cavity losses. We have recently developed VCSEL devices lasing in the visible 6xx nm wavelength band, and reaching 30% power conversion efficiency. We fabricated high-power 2D arrays by removing the GaAs substrate entirely and soldered the chips on high thermal conductivity submounts. Such arrays have demonstrated several Watts of output power at room temperature, in continuous-wave (CW) operation. Several tens of Watts are obtained in QCW operation. Results and challenges of these high-power visible VCSEL arrays will be discussed.

Seurin, Jean-Francois; Khalfin, Viktor; Xu, Guoyang; Miglo, Alexander; Li, Daizong; Zhou, Delai; Sundaresh, Mukta; Zou, Wei-Xiong; Lu, Chien-Yao; Wynn, James D.; Ghosh, Chuni

2013-03-01

249

Influence of insulating coating on aluminum wire explosions  

SciTech Connect

Single wire explosions are widely used in understanding the early stages of z-pinch experiments. This paper presents a serial of experiments conducted on the pulse power generator with ?1?kA peak current and ?10?ns rising time in Xi'an Jiao Tong University. Polyimide coated aluminum wires and uncoated ones were tested under three different voltages to analyze the effect of insulating coating. Experimental results showed that insulating coating can increase the energy deposition 10%?30% in aluminum wires by delaying the voltage collapse and raising the maximum load resistance. The substantial energy deposition resulted in about 20% faster expansion rates for coated wires. Experimental evidence that plasma channel shunts the current from the wire core was observed by streak camera and schlieren graphs. This paper also briefly discussed the influence of nonuniform coating on the morphology of wire expansion.

Li, Yang; Wu, Jian, E-mail: jxjawj@gmail.com [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049 (China); State Key Laboratory of Intense Pulse Radiation of Simulation and Effect, Northwest Institute of Nuclear Technology, Xi'an 710024 (China); Sheng, Liang; Zhao, Jizhen; Zhang, Mei; Yuan, Yuan; Peng, Bodong [State Key Laboratory of Intense Pulse Radiation of Simulation and Effect, Northwest Institute of Nuclear Technology, Xi'an 710024 (China); Li, Xingwen [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049 (China)

2014-10-15

250

High power microwave generator  

DOEpatents

A device (10) for producing high-powered and coherent microwaves is described. The device comprises an evacuated, cylindrical, and hollow real cathode (20) that is driven to inwardly field emit relativistic electrons. The electrons pass through an internally disposed cylindrical and substantially electron-transparent cylindrical anode (24), proceed toward a cylindrical electron collector electrode (26), and form a cylindrical virtual cathode (32). Microwaves are produced by spatial and temporal oscillations of the cylindrical virtual cathode (32), and by electrons that reflex back and forth between the cylindrical virtual cathode (32) and the cylindrical real cathode (20).

Minich, Roger W. (Patterson, CA)

1988-01-01

251

High power coaxial ubitron  

NASA Astrophysics Data System (ADS)

In the ubitron, also known as the free electron laser, high power coherent radiation is generated from the interaction of an undulating electron beam with an electromagnetic signal and a static periodic magnetic wiggler field. These devices have experimentally produced high power spanning the microwave to x-ray regimes. Potential applications range from microwave radar to the study of solid state material properties. In this dissertation, the efficient production of high power microwaves (HPM) is investigated for a ubitron employing a coaxial circuit and wiggler. Designs for the particular applications of an advanced high gradient linear accelerator driver and a directed energy source are presented. The coaxial ubitron is inherently suited for the production of HPM. It utilizes an annular electron beam to drive the low loss, RF breakdown resistant TE01 mode of a large coaxial circuit. The device's large cross-sectional area greatly reduces RF wall heat loading and the current density loading at the cathode required to produce the moderate energy (500 keV) but high current (1-10 kA) annular electron beam. Focusing and wiggling of the beam is achieved using coaxial annular periodic permanent magnet (PPM) stacks without a solenoidal guide magnetic field. This wiggler configuration is compact, efficient and can propagate the multi-kiloampere electron beams required for many HPM applications. The coaxial PPM ubitron in a traveling wave amplifier, cavity oscillator and klystron configuration is investigated using linear theory and simulation codes. A condition for the dc electron beam stability in the coaxial wiggler is derived and verified using the 2-1/2 dimensional particle-in-cell code, MAGIC. New linear theories for the cavity start-oscillation current and gain in a klystron are derived. A self-consistent nonlinear theory for the ubitron-TWT and a new nonlinear theory for the ubitron oscillator are presented. These form the basis for simulation codes which, along with MAGIC, are used to design a representative 200 MW, 40% efficient, X-band amplifier for linear accelerators and a 1 GW, 21% efficient, S-band oscillator for directed energy. The technique of axial mode profiling in the ubitron cavity oscillator is also proposed and shown to increase the simulated interaction efficiency to 46%. These devices are realizable and their experimental implementation, including electron beam formation and spurious mode suppression techniques, is discussed.

Balkcum, Adam J.

252

High Power Density Motors  

NASA Technical Reports Server (NTRS)

With the growing concerns of global warming, the need for pollution-free vehicles is ever increasing. Pollution-free flight is one of NASA's goals for the 21" Century. , One method of approaching that goal is hydrogen-fueled aircraft that use fuel cells or turbo- generators to develop electric power that can drive electric motors that turn the aircraft's propulsive fans or propellers. Hydrogen fuel would likely be carried as a liquid, stored in tanks at its boiling point of 20.5 K (-422.5 F). Conventional electric motors, however, are far too heavy (for a given horsepower) to use on aircraft. Fortunately the liquid hydrogen fuel can provide essentially free refrigeration that can be used to cool the windings of motors before the hydrogen is used for fuel. Either High Temperature Superconductors (HTS) or high purity metals such as copper or aluminum may be used in the motor windings. Superconductors have essentially zero electrical resistance to steady current. The electrical resistance of high purity aluminum or copper near liquid hydrogen temperature can be l/lOO* or less of the room temperature resistance. These conductors could provide higher motor efficiency than normal room-temperature motors achieve. But much more importantly, these conductors can carry ten to a hundred times more current than copper conductors do in normal motors operating at room temperature. This is a consequence of the low electrical resistance and of good heat transfer coefficients in boiling LH2. Thus the conductors can produce higher magnetic field strengths and consequently higher motor torque and power. Designs, analysis and actual cryogenic motor tests show that such cryogenic motors could produce three or more times as much power per unit weight as turbine engines can, whereas conventional motors produce only 1/5 as much power per weight as turbine engines. This summer work has been done with Litz wire to maximize the current density. The current is limited by the amount of heat it generates. By increasing the heat transfer out of the wire, the wires can carry a larger current and therefore produce more force. This was done by increasing the surface area of the wire to allow more coolant to flow over it. Litz wire was used because it can carry high frequency current. It also can be deformed into configurations that would increase the surface area. The best configuration was determined by heat transfer and force plots that were generated using Maxwell 2D. Future work will be done by testing and measuring the thrust force produced by the wires in a magnetic field.

Kascak, Daniel J.

2004-01-01

253

VUV absorption spectroscopy measurements of the role of fast neutral atoms in high-power gap breakdown  

SciTech Connect

The maximum power achieved in a wide variety of high-power devices, including electron and ion diodes, z pinches, and microwave generators, is presently limited by anode-cathode gap breakdown. A frequently-discussed hypothesis for this effect is ionization of fast neutral atoms injected throughout the anode-cathode gap during the power pulse. The authors describe a newly-developed diagnostic tool that provides the first direct test of this hypothesis. Time-resolved vacuum-ultraviolet absorption spectroscopy is used to directly probe fast neutral atoms with 1 mm spatial resolution in the 10 mm anode-cathode gap of the SABRE 5 MV, 1 TW applied-B ion diode. Absorption spectra collected during Ar RF glow discharges and with CO{sub 2} gas fills confirm the reliability of the diagnostic technique. Throughout the 50--100 ns ion diode pulses no measurable neutral absorption is seen, setting upper limits of 0.12--1.5 x 10{sup 14} cm{sup {minus}3} for ground state fast neutral atom densities of H, C, N, O, F. The absence of molecular absorption bands also sets upper limits of 0.16--1.2 x 10{sup 15} cm{sup {minus}3} for common simple molecules. These limits are low enough to rule out ionization throughout the gap as a breakdown mechanism. This technique can now be applied to quantify the role of neutral atoms in other high-power devices.

FILUK,A.B.; BAILEY,JAMES E.; CUNEO,MICHAEL E.; LAKE,PATRICK WAYNE; NASH,THOMAS J.; NOACK,DONALD D.; MARON,Y.

2000-03-20

254

K-shell emission x-ray imaging of z-pinch plasmas with a pinhole and a logarithmic spiral crystal  

SciTech Connect

An in-chamber, mini x-ray imaging instrument employs a pinhole and a logarithmic spiral crystal has been developed for obtaining K-shell line images of the imploding aluminum wire array on the ''Yang'' accelerator. The logarithmic spiral crystal acts as a monochromator and a non-dispersive mirror that reflects the pinhole image to a x-ray film detector with a very narrow photon energy bandwidth (<1 eV, mainly determined by the width of rocking curve of the crystal). Two imaging configurations with the use of Quartz (1010) crystal and Mica (002) crystal are designed, respectively, to image the Al Ly{sub {alpha}2} line (1727.7 eV) emission and Al He{sub {alpha}} intercombination line (1588.3 eV) emission. The primary experimental data corresponding to these two configurations are presented and discussed.

Yang Qingguo; Li Zeren; Peng Qixian; Yang Libing; Chen Guanhua; Ye Yan; Huang Xianbin; Cai Hongchun; Li Jing [Institute of Fluid Physics, CAEP, Mianyang, Sichuan 621900 (China); Xiao Shali [Key Laboratory of Optic-electronic Technology and System, Ministry of Education, Chongqing University, Chongqing 400044 (China)

2011-09-15

255

Microtargetry for High Power Lasers  

NASA Astrophysics Data System (ADS)

Microtargetry for high power lasers (HPLs) offers considerable challenges and opportunities at the cutting edge of the application of microtechnology production techniques. In this chaptermicrotarget production issues are discussed particularly in the context of the mass production of such components which has become one of the major challenges in delivering targets for High Power Laser (HPL) systems and will become essential in the near future as lasers move to application based systems. The challenges of microtarget placement are also discussed.

Tolley, Martin; Spindloe, Chris

256

High power ferrite microwave switch  

NASA Technical Reports Server (NTRS)

A high power ferrite microwave switch was developed along with associated electronic driver circuits for operation in a spaceborne high power microwave transmitter in geostationary orbit. Three units were built and tested in a space environment to demonstrate conformance to the required performance characteristics. Each unit consisted of an input magic-tee hybrid, two non-reciprocal latching ferrite phase shifters, an out short-slot 3 db quadrature coupler, a dual driver electronic circuit, and input logic interface circuitry. The basic mode of operation of the high power ferrite microwave switch is identical to that of a four-port, differential phase shift, switchable circulator. By appropriately designing the phase shifters and electronic driver circuits to operate in the flux-transfer magnetization mode, power and temperature insensitive operation was achieved. A list of the realized characteristics of the developed units is given.

Bardash, I.; Roschak, N. K.

1975-01-01

257

High power gas laser amplifier  

DOEpatents

A high power output CO.sub.2 gas laser amplifier having a number of sections, each comprising a plurality of annular pumping chambers spaced around the circumference of a vacuum chamber containing a cold cathode, gridded electron gun. The electron beam from the electron gun ionizes the gas lasing medium in the sections. An input laser beam is split into a plurality of annular beams, each passing through the sections comprising one pumping chamber.

Leland, Wallace T. (Los Alamos, NM); Stratton, Thomas F. (Los Alamos, NM)

1981-01-01

258

Anode arc motion in high power arcjets  

NASA Technical Reports Server (NTRS)

The long-term operational lifetime of most medium to high power arcjets is currently limited by the rapid deterioration of the arcjet electrodes. To a large extent, the rate of this deterioration is related to the motion of the arc discharge on the electrode surfaces. This paper details a series of experiments aimed at studying the temporal behavior of dc arcs on a water-cooled radially-segmented 30 kW class arcjet anode. The experimental anode used for these tests was made of copper, and was divided into four equivalent radial segments which were electrically isolated with aluminum oxide gaskets. The current carried by each segment was measured independently using four calibrated resistive shunts, and was analyzed by digital computer. The tests were limited to nitrogen propellant over a current range of 100-250 A dc. Results show that for the range of total currents considered here, the current distribution in the segmented arcjet anode is generally asymmetric, exhibiting random fluctuations over a wide range of frequencies.

Harris, W. J.; O'Hair, E. A.; Hatfield, L. L.; Kristiansen, M.; Mankins, J. S.

1992-01-01

259

Microfabricated wire arrays for Z-pinch.  

SciTech Connect

Microfabrication methods have been applied to the fabrication of wire arrays suitable for use in Z. Self-curling GaAs/AlGaAs supports were fabricated as an initial route to make small wire arrays (4mm diameter). A strain relief structure that could be integrated with the wire was designed to allow displacements of the anode/cathode connections in Z. Electroplated gold wire arrays with integrated anode/cathode bus connections were found to be sufficiently robust to allow direct handling. Platinum and copper plating processes were also investigated. A process to fabricate wire arrays on any substrate with wire thickness up to 35 microns was developed. Methods to handle and mount these arrays were developed. Fabrication of wire arrays of 20mm diameter was demonstrated, and the path to 40mm array fabrication is clear. With some final investment to show array mounting into Z hardware, the entire process to produce a microfabricated wire array will have been demonstrated.

Spahn, Olga Blum; Rowen, Adam M.; Cich, Michael Joseph; Peake, Gregory Merwin; Arrington, Christian L.; Nash, Thomas J.; Klem, John Frederick; Romero, Dustin Heinz

2008-10-01

260

Estimating Z-Pinch computing resources.  

SciTech Connect

The Z facility at Sandia National Laboratories produces high energy density environments. Computer simulations of the experiments provide key insights and help make the most efficient use of the facility. This document estimates the computer resources needed in order to support the experimental program. The resource estimate is what we would like to have in about five years and assumes that we will have a robust, scalable simulation capability as well as enough physicists to run the simulations.

Brunner, Thomas A.

2007-04-01

261

Compact, Planar and High-Power Spatial Power Combiner by Active Integrated Antenna Technique at 5.8 GHz  

Microsoft Academic Search

Compact planar active integrated antenna arrays with a high power amplifier were developed with effective heat sink mechanism. Adding a heat extension function by an aluminum plate attached to the back side of the circuit substrate with the high power devices, a space of the air flow duct integrated in the array was created by a creased circuit substrate. Alternatively,

Shigeo KAWASAKI

2007-01-01

262

High Power Laser Calibrations NIST Measurement Services  

E-print Network

High Power Laser Calibrations at NIST NIST Measurement Services: NIST Special Publication 250 250-77 NIST MEASUREMENT SERVICES: High Power Laser Calibrations at NIST Xiaoyu Li Joshua Hadler ........................................................ 2 3.1.1 NIST Primary Standard for High Power Laser Measurements .................. 3 3

263

High power Josephson effect sources  

NASA Astrophysics Data System (ADS)

Progress is reported toward the development of high power linear array Josephson effect sources for the submillimeter wave. A series biased array, fabricated at IBM, was successfully tested and demonstrated fully coherent operation with a power of over 1 microns W into 50 omega near 300 GHz. A single chip source detector was designed, fabricated (at Stony Brook) and tested. On-chip source-mixing between two small array sources operating near 300 GHz was accomplished with the IF, near 10 GHz, being coupled out of the cryostat for direct linewidth measurement. The measured linewidth agreed with theory. This chip also demonstrated a new array design in which groups of multiple, closely spaced junctions were placed at wavelength intervals. This permitted much higher density and consequently higher power per unit area from the arrays. This new design was incorporated into a 500 junction source, also fabricated at IBM, which delivered nearly 5O microns W to a load of over 50 omega near 400 GHz. The PARTS process used by IBM for this fabrication has now been set up at Stony Brook permitting on-site fabrication o even higher power sources.

Lukens, James

1994-09-01

264

High-power RF compressor  

SciTech Connect

We discuss here the possibility of rapidly compressing resonant RF fields in a coaxial cavity with a moving, magnetically confined plasma ring. The possibility of accelerating a plasma ring and various acceleration configurations was discussed earlier. Since the ring velocity can be high, compression to high energy density and high power can be achieved before significant resistive loss or vaporization of the cavity walls occurs. An example is given of compressing 10/sup 5/ J of lambda = 15 cm stored energy to 2 x 10/sup 6/ J of lambda = 1.0 cm RF energy with the energy released in 3 nsec for a maximum power of 6 x 10/sup 14/ W. A proof of principle plasma ring accelerator experiment could provide a significant test by compressing 125 joules of 14 cm RF to 1.25 kJ of 1.4 cm radiation, released in 5 nsec for a very respectable peak power of 2.5 x 10/sup 11/ W.

Hartman, C.W.; Hammer, J.H.; Meeker, D.

1984-03-30

265

High-Power Rf Load  

DOEpatents

A compact high-power RF load comprises a series of very low Q resonators, or chokes [16], in a circular waveguide [10]. The sequence of chokes absorb the RF power gradually in a short distance while keeping the bandwidth relatively wide. A polarizer [12] at the input end of the load is provided to convert incoming TE.sub.10 mode signals to circularly polarized TE.sub.11 mode signals. Because the load operates in the circularly polarized mode, the energy is uniformly and efficiently absorbed and the load is more compact than a rectangular load. Using these techniques, a load having a bandwidth of 500 MHz can be produced with an average power dissipation level of 1.5 kW at X-band, and a peak power dissipation of 100 MW. The load can be made from common lossy materials, such as stainless steel, and is less than 15 cm in length. These techniques can also produce loads for use as an alternative to ordinary waveguide loads in small and medium RF accelerators, in radar systems, and in other microwave applications. The design is easily scalable to other RF frequencies and adaptable to the use of other lossy materials.

Tantawi, Sami G. (San Mateo, CA); Vlieks, Arnold E. (Livermore, CA)

1998-09-01

266

Thermal transients during processing of materials by very high power ultrasonic additive manufacturing  

Microsoft Academic Search

Dynamic recrystallisation at interfaces has been suggested as the bonding mechanism in the joining of metallic tapes, during very high power ultrasonic additive manufacturing. To understand the reasons for such occurrence of dynamic recrystallization, thermal transients from the interface regions were recorded during processing of aluminum alloy (3003 and 6061 series) and 11000 copper tapes under similar conditions. Measurements in

M. R. Sriraman; Matt Gonser; Hiromichi T. Fujii; S. S. Babu; Matt Bloss

2011-01-01

267

Photoconductive switching for high power microwave generation  

SciTech Connect

Photoconductive switching is a technology that is being increasingly applied to generation of high power microwaves. Two primary semiconductors used for these devices are silicon and gallium arsenide. Diamond is a promising future candidate material. This paper discusses the important material parameters and switching modes, critical issues for microwave generation, and future directions for this high power, photoconductive switching technology.

Pocha, M.D.; Hofer, W.W.

1990-10-01

268

High Power UV LED Industrial Curing Systems  

Microsoft Academic Search

UV curing is a green technology that is largely underutilized because UV radiation sources like Hg Lamps are unreliable and difficult to use. High Power UV LEDs are now efficient enough to replace Hg Lamps, and offer significantly improved performance relative to Hg Lamps. In this study, a modular, scalable high power UV LED curing system was designed and tested,

Karlicek; F. Robert; Robert Sargent

2012-01-01

269

High power laser perforating tools and systems  

DOEpatents

ystems devices and methods for the transmission of 1 kW or more of laser energy deep into the earth and for the suppression of associated nonlinear phenomena. Systems, devices and methods for the laser perforation of a borehole in the earth. These systems can deliver high power laser energy down a deep borehole, while maintaining the high power to perforate such boreholes.

Zediker, Mark S; Rinzler, Charles C; Faircloth, Brian O; Koblick, Yeshaya; Moxley, Joel F

2014-04-22

270

Very High Power THz Radiation Sources.  

PubMed

We report the production of high power (20watts average, ? 1 Megawatt peak) broadbandTHz light based on coherent emission fromrelativistic electrons. Such sources areideal for imaging, for high power damagestudies and for studies of non-linearphenomena in this spectral range. Wedescribe the source, presenting theoreticalcalculations and their experimentalverification. For clarity we compare thissource with one based on ultrafast lasertechniques. PMID:23345851

Carr, G L; Martin, M C; McKinney, W R; Jordan, K; Neil, G R; Williams, G P

2003-06-01

271

NASA GRC High Power Electromagnetic Thruster Program  

NASA Technical Reports Server (NTRS)

High-power electromagnetic thrusters have been proposed as primary in-space propulsion options for several bold new interplanetary and deep-space missions. As the lead center for electric propulsion, the NASA Glenn Research Center designs, develops, and tests high-power electromagnetic technologies to meet these demanding mission requirements. Two high-power thruster concepts currently under investigation by Glenn are the magnetoplasmadynamic (MPD) thruster and the Pulsed Inductive Thruster (PIT). This paper describes the MPD thruster and the test facility.

LaPointe, Michael R.; Pensil, Eric J.

2004-01-01

272

Characterization of High-Power Lasers  

E-print Network

This paper discusses methods for characterization of high power lasers. Specifically, these methods have been developed for the High Energy Laser Joint Technology Office and used for independent, government-sponsored testing ...

Edwards, Brian E.

273

Aluminum Hydroxide  

MedlinePLUS

Aluminum hydroxide is used for the relief of heartburn, sour stomach, and peptic ulcer pain and to ... Aluminum hydroxide comes as a capsule, a tablet, and an oral liquid and suspension. The dose and ...

274

High-power solid-state amplifiers  

Microsoft Academic Search

High-power amplifiers are needed, particularly in the area of sound reinforcement for public address and auditorium usage. Paralleling a number of amplifiers to obtain the required power level has never been a wholly satisfactory solution. This paper presents the design philosophies and goals achieved in two high-power solid-state amplifiers, rated at 150 and 330 watts, respectively. In addition, there is

L. Garner

1967-01-01

275

Thermal design and test of a high power spacecraft transponder platform  

NASA Technical Reports Server (NTRS)

The high power transponder subsystem on board the Communications Technology Satellite (CTS) requires some unique thermal control techniques to maintain the required temperature limits throughout all mission phases. The transponder subsystem includes redundant 20-W output travelling wave tubes and a single 200-W output TWT with highly concentrated thermal dissipations of 70 W and 143 W, respectively. A thermal control system which maintains all components within the required temperature ranges has been designed and verified in thermal balance testing. Included in the design are second surface quartz mirrors on an aluminum honeycomb platform, high thermal conductivity aluminum doubler plates, commandable thermal control heaters and a Variable Conductance Heat Pipe System (VCHPS).

Stipandic, E. A.; Gray, A. M.; Gedeon, L.

1975-01-01

276

High Power Co-Axial Coupler  

SciTech Connect

A very high power Coax RF Coupler (MW-Level) is very desirable for a number of accelerator and commercial applications. For example, the development of such a coupler operating at 1.5 GHz may permit the construction of a higher-luminosity version of the Electron-Ion Collider (EIC) being planned at JLab. Muons, Inc. is currently funded by a DOE STTR grant to develop a 1.5-GHz high-power doublewindowcoax coupler with JLab (about 150 kW). Excellent progress has been made on this R&D project, so we propose an extension of this development to build a very high power coax coupler (MW level peak power and a max duty factor of about 4%). The dimensions of the current coax coupler will be scaled up to provide higher power capability.

Neubauer, M. [Muons, Inc.; Dudas, A. [Muons, Inc.; Rimmer, Robert A. [JLAB; Guo, Jiquan [JLAB; Williams, R. Scott [JLAB

2013-12-01

277

High Power Lasers... Another approach to  

E-print Network

1 High Power Lasers... Another approach to Fusion Energy John Sethian Plasma Physics Division Naval Program to develop the science and technologies for Laser Fusion Energy: The NRL Nike Program and the High simulations show high gains (>150) needed for energy · Lasers appear to be able to meet physics & engineering

278

Automated System Tests High-Power MOSFET's  

NASA Technical Reports Server (NTRS)

Computer-controlled system tests metal-oxide/semiconductor field-effect transistors (MOSFET's) at high voltages and currents. Measures seven parameters characterizing performance of MOSFET, with view toward obtaining early indication MOSFET defective. Use of test system prior to installation of power MOSFET in high-power circuit saves time and money.

Huston, Steven W.; Wendt, Isabel O.

1994-01-01

279

CHALLENGES FACING HIGH POWER PROTON ACCELERATORS  

SciTech Connect

This presentation will provide an overview of the challenges of high power proton accelerators such as SNS, J-PARC, etc., and what we have learned from recent experiences. Beam loss mechanisms and methods to mitigate beam loss will also be discussed.

Plum, Michael A [ORNL

2013-01-01

280

Aluminum Boats  

NSDL National Science Digital Library

Test the buoyancy of an aluminum foil boat and an aluminum foil ball. Why does the same material in different shapes sink or float? This activity explores the fact that the amount of water pushed aside by an object equals the force of water pushing upward on the object.

Center, Reuben H.

1999-01-01

281

High Power Disk Loaded Guide Load  

SciTech Connect

A method to design a matching section from a smooth guide to a disk-loaded guide, using a variation of broadband matching, [1, 2] is described. Using this method, we show how to design high power loads. The load consists of a disk-loaded coaxial guide operating in the TE{sub 01}-mode. We use this mode because it has no electric field terminating on a conductor, has no axial currents, and has no current at the cylinder-disk interface. A high power load design that has -35 dB reflection and a 200 MHz, -20 dB bandwidth, is presented. It is expected that it will carry the 600 MW output peak power of the pulse compression network. We use coaxial geometry and stainless steel material to increase the attenuation per cell.

Farkas, Z.D.; /SLAC

2006-02-22

282

Halo formation in high-power klystrons  

SciTech Connect

Beam losses and radio-frequency (rf) pulse shortening are important issues in the development of high-power microwave (HPM) sources such as high-power klystrons and relativistic magnetrons. In this paper, the authors explore the formation and characteristics of halos around intense relativistic electron beams in a Periodic Permanent Magnet focusing klystron as well as in a uniform solenoidal focusing klystron. A self-consistent electrostatic model is used to investigate intense relativistic electron beam transport as an rf field induced mismatch between the electron beam and the focusing field develops. To model the effect of such mismatch in the PPM klystron experiment, they initialize the beam with an envelope mismatch. For zero canonical angular momentum and an initial mismatch of 100 percent, for example, the preliminary results show halo particles with a maximum radius extending up to several core radii at the rf output section. Transient effects and the influence of finite canonical angular momentum are being studied.

Pakter, R.; Chen, C.

1999-07-01

283

Space applications of high power microwaves  

Microsoft Academic Search

A variety of methods have been suggested for transferring energy from Earth-to-space, space-to-Earth, and space-to-space using high power microwave beams. All use power beaming. Microwave beams have been studied for propelling spacecraft for launch to orbit, orbit raising, launch from orbit into interplanetary and interstellar space and deployment of large space structures. The microwave thermal rocket, called the ‘microwave thermal

James Benford

2007-01-01

284

Highly power-efficient quantum cascade lasers  

Microsoft Academic Search

Quantum cascade lasers are promising mid-infrared semiconductor light sources for molecular detection in applications such as environmental sensing or medical diagnostics. For such applications, researchers have been striving to improve device performance. Recently, improvements in wall plug efficiency have been pursued with a view to realizing compact, portable, power-efficient and high-power quantum cascade laser systems. However, advances have largely been

Peter Q. Liu; Anthony J. Hoffman; Matthew D. Escarra; Kale J. Franz; Jacob B. Khurgin; Yamac Dikmelik; Xiaojun Wang; Jen-Yu Fan; Claire F. Gmachl

2010-01-01

285

Silicon carbide high-power devices  

Microsoft Academic Search

In recent years, silicon carbide has received increased attention because of its potential for high-power devices. The unique material properties of SiC, high electric breakdown field, high saturated electron drift velocity, and high thermal conductivity are what give this material its tremendous potential in the power device arena. 4H-SiC Schottky barrier diodes (1400 V) with forward current densities over 700

Charles E. Weitzel; John W. Palmour; Karen Moore; Kevin J. Nordquist; Scott Allen; Christine Thero; Mohit Bhatnagar

1996-01-01

286

High Power Picosecond Laser Pulse Recirculation  

SciTech Connect

We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering based light sources. We demonstrate up to 36x average power enhancement of frequency doubled sub-millijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.

Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P

2010-04-12

287

High-power, solid-state amplifier  

Microsoft Academic Search

Recent advancements in bipolar and divider\\/combiner amplifier technologies allow solid state amplifiers to be configured in such a way that they may operate at high power levels over the L-, S-, and C-bands. Attention is presently given to the module and divider\\/combiner design features required for the achievement of 200-kW peak power at L-band, 70 kW at S-band, and 30

H. Hom; R. McMaster; B. Sanders

1984-01-01

288

Space Applications of High-Power Microwaves  

Microsoft Academic Search

Schemes have been suggested for transferring energy from Earth-to-space, space-to-Earth, and space-to-space using high-power microwave (HPM) beams. All use power beaming. Microwave beams have been studied for propelling spacecraft for launch to orbit, orbit raising, launch from orbit into interplanetary and interstellar space, and deployment of large space structures. The microwave thermal rocket, called the ldquomicrowave thermal thruster,rdquo is a

James Benford

2008-01-01

289

High Power UV LED Industrial Curing Systems  

SciTech Connect

UV curing is a green technology that is largely underutilized because UV radiation sources like Hg Lamps are unreliable and difficult to use. High Power UV LEDs are now efficient enough to replace Hg Lamps, and offer significantly improved performance relative to Hg Lamps. In this study, a modular, scalable high power UV LED curing system was designed and tested, performing well in industrial coating evaluations. In order to achieve mechanical form factors similar to commercial Hg Lamp systems, a new patent pending design was employed enabling high irradiance at long working distances. While high power UV LEDs are currently only available at longer UVA wavelengths, rapid progress on UVC LEDs and the development of new formulations designed specifically for use with UV LED sources will converge to drive more rapid adoption of UV curing technology. An assessment of the environmental impact of replacing Hg Lamp systems with UV LED systems was performed. Since UV curing is used in only a small portion of the industrial printing, painting and coating markets, the ease of use of UV LED systems should increase the use of UV curing technology. Even a small penetration of the significant number of industrial applications still using oven curing and drying will lead to significant reductions in energy consumption and reductions in the emission of green house gases and solvent emissions.

Karlicek, Robert, F., Jr; Sargent, Robert

2012-05-14

290

High Power MPD Thruster Performance Measurements  

NASA Technical Reports Server (NTRS)

High power magnetoplasmadynamic (MPD) thrusters are being developed as cost effective propulsion systems for cargo transport to lunar and Mars bases, crewed missions to Mars and the outer planets, and robotic deep space exploration missions. Electromagnetic MPD thrusters have demonstrated, at the laboratory level, the ability to process megawatts of electrical power while providing significantly higher thrust densities than electrostatic electric propulsion systems. The ability to generate higher thrust densities permits a reduction in the number of thrusters required to perform a given mission, and alleviates the system complexity associated with multiple thruster arrays. The specific impulse of an MPD thruster can be optimized to meet given mission requirements, from a few thousand seconds with heavier gas propellants up to 10,000 seconds with hydrogen propellant. In support of programs envisioned by the NASA Office of Exploration Systems, Glenn Research Center is developing and testing quasi-steady MW-class MPD thrusters as a prelude to steady state high power thruster tests. This paper provides an overview of the GRC high power pulsed thruster test facility, and presents preliminary performance data for a quasi-steady baseline MPD thruster geometry.

LaPointe, Michael R.; Strzempkowski, Eugene; Pencil, Eric

2004-01-01

291

High power impulse magnetron sputtering discharge  

SciTech Connect

The high power impulse magnetron sputtering (HiPIMS) discharge is a recent addition to plasma based sputtering technology. In HiPIMS, high power is applied to the magnetron target in unipolar pulses at low duty cycle and low repetition frequency while keeping the average power about 2 orders of magnitude lower than the peak power. This results in a high plasma density, and high ionization fraction of the sputtered vapor, which allows better control of the film growth by controlling the energy and direction of the deposition species. This is a significant advantage over conventional dc magnetron sputtering where the sputtered vapor consists mainly of neutral species. The HiPIMS discharge is now an established ionized physical vapor deposition technique, which is easily scalable and has been successfully introduced into various industrial applications. The authors give an overview of the development of the HiPIMS discharge, and the underlying mechanisms that dictate the discharge properties. First, an introduction to the magnetron sputtering discharge and its various configurations and modifications is given. Then the development and properties of the high power pulsed power supply are discussed, followed by an overview of the measured plasma parameters in the HiPIMS discharge, the electron energy and density, the ion energy, ion flux and plasma composition, and a discussion on the deposition rate. Finally, some of the models that have been developed to gain understanding of the discharge processes are reviewed, including the phenomenological material pathway model, and the ionization region model.

Gudmundsson, J. T.; Brenning, N.; Lundin, D.; Helmersson, U. [University of Michigan--Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240 (China) and Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Division of Space and Plasma Physics, School of Electrical Engineering, Royal Institute of Technology, SE-100 44, Stockholm (Sweden); Plasma and Coatings Division, IFM-Materials Physics, Linkoeping University, SE-581 83, Linkoeping (Sweden)

2012-05-15

292

Aluminum Analysis.  

ERIC Educational Resources Information Center

Presents three problems based on the price of aluminum designed to encourage students to be cooperative and to use an investigative approach to learning. Students collect and synthesize information, analyze results, and draw conclusions. (AIM)

Sumrall, William J.

1998-01-01

293

High power 2 µm femtosecond fiber laser.  

PubMed

A high power polarization maintaining femtosecond Tm-doped fiber laser system is demonstrated. A chirped fiber Bragg grating with normal dispersion was used to compensate the anomalous dispersion from the regular fiber in the 2 µm seed oscillator to generate mode locked pulses with a pulse repetition rate of 30.84 MHz. After chirped pulse amplification, an amplified power of 78 W was obtained. The pulse was compressed by a chirped volume Bragg grating based pulse compressor. A pulse duration of 760 fs and an average power of 36 W were obtained after compressor. PMID:24104012

Wan, Peng; Yang, Lih-Mei; Liu, Jian

2013-09-01

294

Towards high-power random fiber laser  

NASA Astrophysics Data System (ADS)

Study on random laser is an interesting topic in physics. In this paper we pay much attention to the high power random laser achievement in optical fiber. Two kinds of optical gains are used for light amplification. One is Raman gain and the other is Yb-doped fiber gain. The random signal is provided by distributed feedback came from Rayleigh scattering and amplified by those gain. We obtain the highest random laser output power results and different laser emitting characters are also reported.

Zhang, Hanwei; Zhou, Pu; Lv, Haibin; Xiao, Hu; Wang, Xiaolin; Xu, Xiaojun

2014-11-01

295

High power, high frequency, vacuum flange  

DOEpatents

An improved waveguide flange is disclosed for high power operation that helps prevent arcs from being initiated at the junctions between waveguide sections. The flanges at the end of the waveguide sections have counter bores surrounding the waveguide tubes. When the sections are bolted together the counter bores form a groove that holds a fully annealed copper gasket. Each counterbore has a beveled step that is specially configured to insure the gasket forms a metal-to-metal vacuum seal without gaps or sharp edges. The resultant inner surface of the waveguide is smooth across the junctions between waveguide sections, and arcing is prevented.

Felker, B.; McDaniel, M.R.

1993-03-23

296

CLIC RF High Power Production Testing Program  

SciTech Connect

The CLIC Power Extraction and Transfer Structure (PETS) is a passive microwave device in which bunches of the drive beam interact with the impedance of the periodically loaded waveguide and generate RF power for the main linac accelerating structure. The demands on the high power production ({approx} 150 MW) and the needs to transport the 100 A drive beam for about 1 km without losses, makes the PETS design rather unique and the operation very challenging. In the coming year, an intense PETS testing program will be implemented. The target is to demonstrate the full performance of the PETS operation. The testing program overview and test results available to date are presented.

Syratchev, I.; Riddone, G.; /CERN; Tantawi, S.G.; /SLAC

2011-11-02

297

MI high power operation and future plans  

SciTech Connect

Fermilab's Main Injector on acceleration cycles to 120 GeV has been running a mixed mode operation delivering beam to both the antiproton source for pbar production and to the NuMI[1] target for neutrino production since 2005. On January 2008 the slip stacking process used to increase the beam to the pbar target was expanded to include the beam to the NuMI target increasing both the beam intensity and power. The current high power MI operation will be described along with the near future plans.

Kourbanis, Ioanis; /Fermilab

2008-09-01

298

Interest in high power microwave research  

SciTech Connect

A general discussion of the goals the DOD has for High Power Microwave (HPM) research will be presented, as well as some of the current research on HPM being conducted at the Air Force Phillips Laboratory. This will include a brief introduction to HPM, comparisons to other technologies (such as Nuclear EMP, and Lasers), current state-of-the-art in HPM devices, and current estimate of technology needed. Broad objectives and the focus for the Army, Navy, Air Force, BMDO, and DNA programs will also be discussed. A snapshot of the current level of funding for each of the services/agencies will be presented. A brief look at the Joint Directors of Laboratories HPM organization among the services/agencies also will be presented. In addition, HPM interest by other countries will be briefly discussed. The current experimental and theoretical research being conducted at the Phillips Lab into advanced high power sources will be reviewed, including: the annular beam amplifier (ABA); the gyrotron-backward-wave oscillator (Gyro-BWO); the radial acceletron (RA); the multi-wave cerenkov generator (MWCG); and the split-cavity oscillator (SCO).

Agee, F.J. [Air Force Phillips Lab., Kirtland, NM (United States). Electromagnetics Sources Division; Chesser, N. [Directed Technologies Inc., Arlington, VA (United States)

1994-12-31

299

Powersail High Power Propulsion System Design Study  

NASA Astrophysics Data System (ADS)

A desire by the United States Air Force to exploit the space environment has led to a need for increased on-orbit electrical power availability. To enable this, the Air Force Research Laboratory Space Vehicles Directorate (AFRL/ VS) is developing Powersail: a two-phased program to demonstrate high power (100 kW to 1 MW) capability in space using a deployable, flexible solar array connected to the host spacecraft using a slack umbilical. The first phase will be a proof-of-concept demonstration at 50 kW, followed by the second phase, an operational system at full power. In support of this program, the AFRL propulsion Directorate's Spacecraft Propulsion Branch (AFRL/PRS ) at Edwards AFB has commissioned a design study of the Powersail High Power Propulsion System. The purpose of this study, the results of which are summarized in this paper, is to perform mission and design trades to identify potential full-power applications (both near-Earth and interplanetary) and the corresponding propulsion system requirements and design. The design study shall farther identify a suitable low power demonstration flight that maximizes risk reduction for the fully operational system. This propulsion system is expected to be threefold: (1) primary propulsion for moving the entire vehicle, (2) a propulsion unit that maintains the solar array position relative to the host spacecraft, and (3) control propulsion for maintaining proper orientation for the flexible solar array.

Gulczinski, Frank S., III

2000-11-01

300

Aluminum as anode for energy storage and conversion: a review  

NASA Astrophysics Data System (ADS)

Aluminum has long attracted attention as a potential battery anode because of its high theoretical voltage and specific energy. The protective oxide layer on the aluminum surface is however detrimental to the battery performance, contributing to failure to achieve the reversible potential and causing the delayed activation of the anode. By developing aluminum alloys as anodes and solution additives to electrolytes, a variety of aluminum batteries have been extensively investigated for various applications. From molten salt and other non-aqueous electrolytes, aluminum can be electrodeposited and therefore be suitable for developing rechargable batteries. Considerable efforts have been made to develop secondary aluminum batteries of high power density. In the present paper, these research activities are reviewed, including aqueous electrolyte primary batteries, aluminum-air batteries and molten salt secondary batteries.

Li, Qingfeng; Bjerrum, Niels J.

301

Laser Welding of Aluminum and Aluminum Alloys  

E-print Network

.. ) Laser Welding of Aluminum and Aluminum Alloys Welds made with sharp bevel-groove weld aluminum and by aluminum alloy 5456 have been studied. The results indicate that initial absorption varies of the most dramatic illustrations of the differences in beam characteristics occurs when welding aluminum

Eagar, Thomas W.

302

Robust cladding light stripper for high-power fiber lasers using soft metals.  

PubMed

In this paper we present a novel method to reliably strip the unwanted cladding light in high-power fiber lasers. Soft metals are utilized to fabricate a high-power cladding light stripper (CLS). The capability of indium (In), aluminum (Al), tin (Sn), and gold (Au) in extracting unwanted cladding light is examined. The experiments show that these metals have the right features for stripping the unwanted light out of the cladding. We also find that the metal-cladding contact area is of great importance because it determines the attenuation and the thermal load on the CLS. These metals are examined in different forms to optimize the contact area to have the highest possible attenuation and avoid localized heating. The results show that sheets of indium are very effective in stripping unwanted cladding light. PMID:24787586

Babazadeh, Amin; Nasirabad, Reza Rezaei; Norouzey, Ahmad; Hejaz, Kamran; Poozesh, Reza; Heidariazar, Amir; Golshan, Ali Hamedani; Roohforouz, Ali; Jafari, S Naser Tabatabaei; Lafouti, Majid

2014-04-20

303

High-Power Options for LANSCE  

SciTech Connect

The LANSCE linear accelerator at Los Alamos National Laboratory has a long history of successful beam operations at 800 kW. We have recently studied options for restoration of high-power operations including approaches for increasing the performance to multi-MW levels. In this paper we will discuss the results of this study including the present limitations of the existing accelerating structures at LANSCE, and the high-voltage and RF systems that drive them. Several options will be discussed and a preferred option will be presented that will enable the first in a new generation of scientific facilities for the materials community. The emphasis of this new facility is 'Matter-Radiation Interactions in Extremes' (MaRIE) which will be used to discover and design the advanced materials needed to meet 21st century national security and energy security challenges.

Garnett, Robert W. [Los Alamos National Laboratory

2011-01-01

304

Photoconductive semiconductor switches for high power radiation  

SciTech Connect

In this paper we present the results of experiments on Si and GaAs Photoconductive Semiconductor Switches (PCSS). Our goal is to improve their performance for high power electromagnetic pulse generation. For Si, we show ways to alter carrier lifetime achieve higher repetition rates, improvements in switch lifetimes to over 10{sup 7} pulses at high field, and methods that reduce or eliminate thermal runaway and heating. For GaAs, the effects of focused trigger radiation was studied and a further reduction (by a factor of 100) in the required light energy was observed. The gain in these switches is now about 100,000 electrons generated per absorbed or trigger photon. It was further demonstrated that light can be piped through fiber optics to trigger multiple current filaments in GaAs. These results show the ability to control the location of the current filaments.

Loubriel, G.M.; Zutavern, F.J.; Denison, G.J.; Helgeson, W.D.; McLaughlin, D.L.; O`Malley, M.W. [Sandia National Labs., Albuquerque, NM (United States); Demarest, J.A. [Kaman Sciences Corp., Albuquerque, NM (United States)

1992-09-01

305

Photoconductive semiconductor switches for high power radiation  

SciTech Connect

In this paper we present the results of experiments on Si and GaAs Photoconductive Semiconductor Switches (PCSS). Our goal is to improve their performance for high power electromagnetic pulse generation. For Si, we show ways to alter carrier lifetime achieve higher repetition rates, improvements in switch lifetimes to over 10{sup 7} pulses at high field, and methods that reduce or eliminate thermal runaway and heating. For GaAs, the effects of focused trigger radiation was studied and a further reduction (by a factor of 100) in the required light energy was observed. The gain in these switches is now about 100,000 electrons generated per absorbed or trigger photon. It was further demonstrated that light can be piped through fiber optics to trigger multiple current filaments in GaAs. These results show the ability to control the location of the current filaments.

Loubriel, G.M.; Zutavern, F.J.; Denison, G.J.; Helgeson, W.D.; McLaughlin, D.L.; O'Malley, M.W. (Sandia National Labs., Albuquerque, NM (United States)); Demarest, J.A. (Kaman Sciences Corp., Albuquerque, NM (United States))

1992-01-01

306

Feedthrough terminal for high-power cell  

DOEpatents

A feedthrough terminal for a high power electrochemical storage cell providing low resistance coupling to the conductive elements therein while isolating the terminal electrode from the highly corrosive environment within the cell is disclosed. A large diameter, cylindrical copper electrode is enclosed in a stainless steel tube with a BN powder feedthrough seal maintained around the stainless steel tube by means of facing insulative bushings and an outer sleeve. One end of the copper conductor is silver-brazed directly to a flat, butterfly bus bar within the cell, with the adjacent end of the surrounding outer feedthrough sleeve welded to the bus bar. A threaded seal is fixedly positioned on a distal portion of the stainless steel tube immediately adjacent the distal insulative bushing so as to compress the feedthrough seal in tight fitting relation around the stainless steel tube in providing a rugged, leak-proof electrical feedthrough terminal for the power cell.

Kaun, T.D.

1982-05-28

307

Interaction of a High-Power Laser Beam with Metal Sheets  

SciTech Connect

Experiments with a high-power laser beam directed onto thin aluminum sheets, with a large spot size, demonstrate that airflow produces a strong enhancement of the interaction. The enhancement is explained in terms of aerodynamic effects. As laser heating softens the material, the airflow-induced pressure difference between front and rear faces causes the metal to bulge into the beam. The resulting shear stresses rupture the material and remove it at temperatures well below the melting point. The material heating is shown to conform to an elementary model. We present an analytic model of elastic bulging. Scaling with respect to spot size, wind speed, and material parameters is determined.

Boley, C D; Cutter, K P; Fochs, S N; Pax, P H; Rotter, M D; Rubenchik, A M; Yamamoto, R M

2009-06-24

308

Microtechnology for compact, efficient high-power lasers  

Microsoft Academic Search

High power lasers are valuable tools for cutting and welding in industrial materials processing. Along with high power, an ideal laser would have a relatively short wavelength to provide a small spot size and would be both safe and convenient to op- erate. At present, however, no laser simultaneously meets all of these requirements. Commonly-used CO2 lasers offer high power

Carol Livermore; Tyrone Hill; Benjamin Wilhite; Luis Velasquez-Garcia; Alan Epstein; Klavs Jensen

2007-01-01

309

Measuring temperature profiles in high-power optical fiber components  

E-print Network

Measuring temperature profiles in high-power optical fiber components Vladimir Goloborodko, Shay in temperature distribution caused by coupling a high-power laser beam into an optical fiber and by splicing two a significant role in high-power lasers.2 Moreover fiber imperfections such as optical defects at the fiber end

Horowitz, Moshe

310

Welcome to the Laboratory for High Power Electronic Systems  

E-print Network

for High Power Electronic Systems (HPE) focusses on high power converter systems including operation are adressed in the following main areas: New medium voltage DC and AC converter concepts (E.g. MultiWelcome to the Laboratory for High Power Electronic Systems Welcome to the web site

311

Prospects for using high-power x rays as a volumetric heat source  

NASA Astrophysics Data System (ADS)

Third-generation, high-intensity, x-ray synchrotron radiation sources are capable of producing high heat-flux x- ray beams. In many applications finding ways to handle these powers is viewed as a burden. However, there are some technological applications where the deep penetration length of the x-rays may find beneficial uses as a volumetric heat source. In this paper we discuss the prospects for using high power x-rays for volumetric heating and report some recent experimental results. The particular applications we focus on are welding and surface heat treatment. The radiation source is an undulator at the Advanced Photon Source. Results of preliminary tests on aluminum, aluminum metal matrix composites, and steel will be presented.

Rosenberg, Richard A.; Farrell, William; Ma, Qing; Mancini, Derrick C.; Khounsary, Ali M.; Sheng, I. C. A.; Crozier, E. D.; Soerensen, Georg J.; Gordon, Robert A.; Jiang, De-Tong

1997-12-01

312

Aluminum Cans  

NSDL National Science Digital Library

In this data analysis activity students investigate data in connection with recyclable materials and develop plans to help the environment. Students collect data about aluminum can usage and graph that data in a line plot. The lesson includes student worksheet and extension suggestions.

2008-01-01

313

Aluminum Pannier  

USGS Multimedia Gallery

This aluminum pannier was made for the storage of meat, vegetables and other food products. The pannier could be buried in the ground or placed in water in order to keep the contents cool. It was designed by Dr. J. D. Love and made for him in 1945. For transportation, this pannier, along with two re...

2009-07-22

314

High power, high beam quality regenerative amplifier  

DOEpatents

A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

Hackel, Lloyd A. (Livermore, CA); Dane, Clifford B. (Livermore, CA)

1993-01-01

315

High-power microwave development in Russia  

NASA Astrophysics Data System (ADS)

This is a survey of Russian research and development in high-power microwave (HPM) sources. It emphasizes those sources of nanoseconds pulse duration time which have potential weapon as well as radar applications. It does not cover the whole range of Russian HPM research and development but concentrates on those aspects which may lead to military applications. Russian investigators have achieved many world firsts in HPM generation; for example, a multiwave Cerenkov generator with a peak output power of 15 gigawatts. Their successes are based on their impressive capability in pulsed power technology which has yielded high-current generators of terawatt peak power. They have transformed the energy of these currents into microwave radiation using tubes of both conventional and novel designs exploiting relativistic electron beams. Recently, the development of high-current mini-accelerators has moved relativistic electron-beam (REB) HPM generation out of the laboratory and enabled the development of deployable military systems with peak powers in the gigawatt range. As a result, they now see development of a REB-based radar systems as one of the most promising directions in radar systems. Details of such a system are described and the implications for HPM weapons are considered.

Gauthier, Sylvain

1995-03-01

316

Improved Collectors for High Power Gyrotrons  

SciTech Connect

High power gyrotrons are used for electron cyclotron heating, current drive and parasitic mode suppression in tokamaks for fusion energy research. These devices are crucial for successful operation of many research programs around the world, including the ITER program currently being constructed in France. Recent gyrotron failures resulted from cyclic fatigue of the copper material used to fabricated the collectors. The techniques used to collect the spent beam power is common in many gyrotrons produced around the world. There is serious concern that these tubes may also be at risk from cyclic fatigue. This program addresses the cause of the collector failure. The Phase I program successfully demonstrated feasibility of a mode of operation that eliminates the cyclic operation that caused the failure. It also demonstrated that new material can provide increased lifetime under cyclic operation that could increase the lifetime by more than on order of magnitude. The Phase II program will complete that research and develop a collector that eliminates the fatigue failures. Such a design would find application around the world.

R. Lawrence Ives, Amarjit Singh, Michael Read, Philipp Borchard, Jeff Neilson

2009-05-20

317

High-power Broadband Organic THz Generator  

PubMed Central

The high-power broadband terahertz (THz) generator is an essential tool for a wide range of THz applications. Here, we present a novel highly efficient electro-optic quinolinium single crystal for THz wave generation. For obtaining intense and broadband THz waves by optical-to-THz frequency conversion, a quinolinium crystal was developed to fulfill all the requirements, which are in general extremely difficult to maintain simultaneously in a single medium, such as a large macroscopic electro-optic response and excellent crystal characteristics including a large crystal size with desired facets, good environmental stability, high optical quality, wide transparency range, and controllable crystal thickness. Compared to the benchmark inorganic and organic crystals, the new quinolinium crystal possesses excellent crystal properties and THz generation characteristics with broader THz spectral coverage and higher THz conversion efficiency at the technologically important pump wavelength of 800?nm. Therefore, the quinolinium crystal offers great potential for efficient and gap-free broadband THz wave generation. PMID:24220234

Jeong, Jae-Hyeok; Kang, Bong-Joo; Kim, Ji-Soo; Jazbinsek, Mojca; Lee, Seung-Heon; Lee, Seung-Chul; Baek, In-Hyung; Yun, Hoseop; Kim, Jongtaek; Lee, Yoon Sup; Lee, Jae-Hyeok; Kim, Jae-Ho; Rotermund, Fabian; Kwon, O-Pil

2013-01-01

318

Considerations for very-high-power accelerators  

NASA Astrophysics Data System (ADS)

A Heavy Ion Fusion powerplant driver, if built today, would become the highest average-power accelerator ever built, probably by at least an order of magnitude. However, if some of the projects being planned now are constructed, there will be several plants of comparable or greater average power. We will look at ways in which large science projects are supported and at what steps must be taken for a project to obtain international support. We will also note how large science construction projects are being organized as costs and visibility increase. The physics aspects of large, high-power accelerators will be noted with the particular vantage of the advisory committee for the 170 MW proton linac being designed by the Los Alamos team for the Accelerator Production of Tritium (APT). Although a cw proton linac is very different from a driver with its pulsed beams of heavy ions, designers of both facilities need to be extraordinarily careful to protect against beam loss. Also, both facilities are required to have very high availability. Utilities have made reliability and availability extremely important requirements, while the APT requires high reliability to achieve its production goals.

Herrmannsfeldt, W. B.

319

High power electrically pumped VECSELs and arrays  

NASA Astrophysics Data System (ADS)

VECSELs are characterized by an outstanding brightness of 100kW/mm²/sr and a small spectral width. Electrical pumping and the potential to combine many emitters in arrays allow for highly integrated and easy to manufacture laser sources which can be scaled towards high power. This almost ideal value proposition is affected by the penalty in efficiency which reduces the output power from VCSELs towards multimode VECSELs and finally single mode VECSELs. The root causes for this lower efficiency are optical losses in the extended cavity, a mismatch of pump and mode profile and losses related to the oxide aperture which is used for current confinement. The reduction of losses requires a careful design of spatial doping distributions in the epitaxially grown layers as these losses have to be balanced against the requirement of low electrical resistance across the many hetero-interfaces in the DBR mirrors. The mismatch of pump and mode profile and the aperture related losses are addressed by an improved current injection enabled by a tailored electrical contact. In this paper optimized structures will be presented which enable a significant increase of efficiency and output power towards more than 150mW in a single mode and more than 300mW in multimode operation. The optical concept of the extended cavity can use a plane mirror in the simplest case thus facilitating the power scaling in arrays with many individual VECSEL apertures combined on a single chip.

Moench, Holger; Andreadaki, Anastasia; Gronenborn, Stephan; Kolb, Johanna S.; Loosen, Peter; Miller, Michael; Schwarz, Thomas; van der Lee, Alexander; Weichmann, Ulrich

2014-03-01

320

High power, high beam quality regenerative amplifier  

DOEpatents

A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

Hackel, L.A.; Dane, C.B.

1993-08-24

321

High power THz sources for nonlinear imaging  

NASA Astrophysics Data System (ADS)

Many biological and chemical compounds have unique absorption features in the THz (0.1 - 10 THz) region, making the use of THz waves attractive for imaging in defense, security, biomedical imaging, and monitoring of industrial processes. Unlike optical radiation, THz frequencies can pass through many substances such as paper, clothing, ceramic, etc. with little attenuation. The use of currently available THz systems is limited by lack of highpower, sources as well as sensitive detectors and detector arrays operating at room temperature. Here we present a novel, high power THz source based on intracavity downconverison of optical pulses. The source delivers 6 ps pulses at 1.5 THz, with an average power of >300 ?W and peak powers >450 mW. We propose an imaging method based on frequency upconverison that is ideally suited to use the narrow bandwidth and high peak powers produced by the source. By upconverting the THz image to the infrared, commercially available detectors can be used for real time imaging.

Tekavec, Patrick F.; Kozlov, Vladimir G.

2014-02-01

322

High power linear pulsed beam annealer  

DOEpatents

A high power pulsed electron beam is produced in a system comprised of an electron gun having a heated cathode, control grid, focus ring, and a curved drift tube. The drift tube is maintained at a high positive voltage with respect to the cathode to accelerate electrons passing through the focus ring and to thereby eliminate space charge. A coil surrounding the curved drift tube provides a magnetic field which maintains the electron beam focused about the axis of the tube and imparts motion on electrons in a spiral path for shallow penetration of the electrons into a target. The curvature of the tube is selected so there is no line of sight between the cathode and a target holder positioned within a second drift tube spaced coaxially from the curved tube. The second tube and the target holder are maintained at a reference voltage that decelerates the electrons. A second coil surrounding the second drift tube maintains the electron beam focused about the axis of the second drift tube and compresses the electron beam to the area of the target. The target holder can be adjusted to position the target where the cross section of the beam matches the area of the target.

Strathman, Michael D. (Concord, CA); Sadana, Devendra K. (Berkeley, CA); True, Richard B. (Sunnyvale, CA)

1983-01-01

323

High power THz sources for nonlinear imaging  

SciTech Connect

Many biological and chemical compounds have unique absorption features in the THz (0.1 - 10 THz) region, making the use of THz waves attractive for imaging in defense, security, biomedical imaging, and monitoring of industrial processes. Unlike optical radiation, THz frequencies can pass through many substances such as paper, clothing, ceramic, etc. with little attenuation. The use of currently available THz systems is limited by lack of highpower, sources as well as sensitive detectors and detector arrays operating at room temperature. Here we present a novel, high power THz source based on intracavity downconverison of optical pulses. The source delivers 6 ps pulses at 1.5 THz, with an average power of >300 ?W and peak powers >450 mW. We propose an imaging method based on frequency upconverison that is ideally suited to use the narrow bandwidth and high peak powers produced by the source. By upconverting the THz image to the infrared, commercially available detectors can be used for real time imaging.

Tekavec, Patrick F.; Kozlov, Vladimir G. [Microtech Instruments, 858 West Park Street, Eugene, OR 97401 (United States)

2014-02-18

324

High power diode laser remelting of metals  

NASA Astrophysics Data System (ADS)

This article is focused on the laser surface remelting of the steel samples with predefined overlapping of the laser spots. The goal of our experimental work was to evaluate microstructure and hardness both in overlapped zone and single pass ones for three kinds of ferrous metals with different content of carbon, cast iron, non-alloy structural steel and tool steel. High power fibre coupled diode laser Laserline LDF 3600-100 was used with robotic guided processing head equipped by the laser beam homogenizer that creates rectangular beam shape with uniform intensity distribution. Each sample was treated with identical process parameters - laser power, beam diameter, focus position, speed of motion and 40% spot overlap. Dimensions and structures of the remelted zone, zone of the partial melting, heat affected zone and base material were detected and measured by means of laser scanning and optical microscopes. Hardness progress in the vertical axis of the overlapped zone from remelted surface layer to base material was measured and compared with the hardness of the single spots. The most hardness growth was found for cast iron, the least for structural steel. Experiment results will be used to processing parameters optimization for each tested material separately.

Chmelickova, H.; Tomastik, J.; Ctvrtlik, R.; Supik, J.; Nemecek, S.; Misek, M.

2014-04-01

325

Ablation dynamics in coiled wire-array Z-pinches  

SciTech Connect

Experiments to study the ablation dynamics of coiled wire arrays were performed on the MAGPIE generator (1 MA, 240 ns) at Imperial College, and on the COBRA generator at Cornell University's Laboratory of Plasma Studies (1 MA, 100 ns). The MAGPIE generator was used to drive coiled wires in an inverse array configuration to study the distribution of ablated plasma. Using interferometry to study the plasma distribution during the ablation phase, absolute quantitative measurements of electron line density demonstrated very high density contrasts between coiled ablation streams and inter-stream regions many millimetres from the wire. The measured density contrasts for a coiled array were many times greater than that observed for a conventional array with straight wires, indicating that a much greater axial modulation of the ablated plasma may be responsible for the unique implosion dynamics of coiled arrays. Experiments on the COBRA generator were used to study the complex redirection of plasma around a coiled wire that gives rise to the ablation structure exhibited by coiled arrays. Observations of this complex 3D plasma structure were used to validate the current model of coiled array ablation dynamics [Hall et al., Phys. Rev. Lett. 100, 065003 (2008)], demonstrating irrefutably that plasma flow from the wires behaves as predicted. Coiled wires were observed to ablate and implode in the same manner on both machines, indicating that current rise time should not be an issue for the scaling of coiled arrays to larger machines with fast current rise times.

Hall, G. N.; Lebedev, S. V.; Suzuki-Vidal, F.; Swadling, G.; Chittenden, J. P.; Bland, S. N.; Harvey-Thompson, A. [Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom); Knapp, P. F.; Blesener, I. C.; McBride, R. D.; Chalenski, D. A.; Blesener, K. S.; Greenly, J. B.; Pikuz, S. A.; Shelkovenko, T. A.; Hammer, D. A.; Kusse, B. R. [Laboratory of Plasma Studies, Cornell University, 439 Rhodes Hall, Ithaca, New York 14853 (United States)

2013-02-15

326

Calculation of Tungsten Emission Spectra for Megaamper Z-Pinches  

Microsoft Academic Search

Summary form only given. The calculations of tungsten emission spectra were carried out in a wide range of temperature and density (50 < T < 250 eV, 0.01 < p < 0.1 g\\/cm3). The codes THERMOS & BELINE were used for computation of nonLTE spectra of plane and cylindrical tungsten layers. At most important cases the calculations were verified as

I. Y. Vichev; V. G. Novikov; A. D. Solomyannaya

2007-01-01

327

Status of Z-Pinch Research Fusion Power Associates  

E-print Network

Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. Refurbished Demolition Completed Installation Completed Sept `06 Aug `07 Tank Modifications Completed Jan `07 Sept `07

328

Breakdown phenomena in high power klystrons  

NASA Astrophysics Data System (ADS)

In the course of developing new high peak power klystrons at SLAC, high electric fields in several regions of these devices have become an important source of vacuum breakdown phenomena. In addition, a renewed interest in breakdown phenomena for nanosecond pulse, multi-megavolt per centimeter fields has been sparked by recent R and D work in the area of gigawatt RF sources. The most important regions of electrical breakdown are in the output cavity gap area, the RF ceramic windows, and the gun ceramic insulator. The details of the observed breakdown in these regions, experiments performed to understand the phenomena and solutions found to alleviate the problems will be discussed. Recently experiments have been performed on a new prototype R and D klystron. Peak electric fields across the output cavity gaps of this klystron exceed 2 MV/cm. The effect of peak field duration (i.e., pulse width) on the onset of breakdown have been measured. The pulse widths varied from tens of nanoseconds to microseconds. Results from these experiments will be presented. The failure of ceramic RF windows due to multipactor and puncturing was an important problem to overcome in order that our high power klystrons would have a useful life expectancy. Consequently many studies and tests were made to understand and alleviate window breakdown phenomena. Some of the results in this area, especially the effects of surface coatings, window materials and processing techniques and their effects on breakdown will be discussed. Another important source of klystron failure in the recent past at SLAC has been the puncturing of the high voltage ceramic insulator in the gun region. A way of alleviating this problem has been found although the actual cause of the puncturing is not yet clear. The practical solution to this breakdown process will be described and a possible mechanism for the puncturing will be presented.

Vlieks, A. E.; Allen, M. A.; Callin, R. S.; Fowkes, W. R.; Hoyt, E. W.; Lebacqz, J. V.; Lee, T. G.

1988-03-01

329

Facet engineering of high power single emitters  

NASA Astrophysics Data System (ADS)

The ever increasing demand for high-power, high-reliability operation of single emitters at 9xx nm wavelengths requires the development of laser diodes with improved facet regions immune to both catastrophic and wear-out failure modes. In our study, we have evaluated several laser facet definition technologies in application to 90 micron aperture single emitters in asymmetric design (In)GaAs/AlGaAs based material emitting at 915, 925 and 980nm. A common epitaxy and emitter design makes for a straightforward comparison of the facet technologies investigated. Our study corroborates a clear trend of increasing difficulty in obtaining reliable laser operation from 980nm down to 915nm. At 980nm, one can employ dielectric facet passivation with a pre-clean cycle delivering a device lifetime in excess of 3,000 hours at increasing current steps. At 925nm, quantum-well intermixing can be used to define non-absorbing mirrors giving good device reliability, albeit with a large efficiency penalty. Vacuum cleaved emitters have delivered excellent reliability at 915nm, and can be expected to perform just as well at 925 and 980nm. Epitaxial regrowth of laser facets is under development and has yet to demonstrate an appreciable reliability improvement. Only a weak correlation between start-of-life catastrophic optical mirror damage (COMD) levels and reliability was established. The optimized facet design has delivered maximum powers in excess of 19 MW/sq.cm (rollover limited) and product-grade 980nm single emitters with a slope efficiency of >1 W/A and a peak efficiency of >60%. The devices have accumulated over 1,500 hours of CW operation at 11W. A fiber-coupled device emits 10W ex-fiber with 47% efficiency.

Yanson, Dan; Levi, Moshe; Shamay, Moshe; Tesler, Renana; Rappaport, Noam; Don, Yaroslav; Karni, Yoram; Schnitzer, Itzhak; Sicron, Noam; Shusterman, Sergey

2011-03-01

330

Innovations in high power fiber laser applications  

NASA Astrophysics Data System (ADS)

Diffraction-limited high power lasers represent a new generation of lasers for materials processing, characteristic traits of which are: smaller, cost-effective and processing "on the fly". Of utmost importance is the high beam quality of fiber lasers which enables us to reduce the size of the focusing head incl. scanning mirrors. The excellent beam quality of the fiber laser offers a lot of new applications. In the field of remote cutting and welding the beam quality is the key parameter. By reducing the size of the focusing head including the scanning mirrors we can reach scanning frequencies up to 1.5 kHz and in special configurations up to 4 kHz. By using these frequencies very thin and deep welding seams can be generated experienced so far with electron beam welding only. The excellent beam quality of the fiber laser offers a high potential for developing new applications from deep penetration welding to high speed cutting. Highly dynamic cutting systems with maximum speeds up to 300 m/min and accelerations up to 4 g reduce the cutting time for cutting complex 2D parts. However, due to the inertia of such systems the effective cutting speed is reduced in real applications. This is especially true if complex shapes or contours are cut. With the introduction of scanner-based remote cutting systems in the kilowatt range, the effective cutting speed on the contour can be dramatically increased. The presentation explains remote cutting of metal foils and sheets using high brightness single mode fiber lasers. The presentation will also show the effect of optical feedback during cutting and welding with the fiber laser, how those feedbacks could be reduced and how they have to be used to optimize the cutting or welding process.

Beyer, Eckhard; Mahrle, Achim; Lütke, Matthias; Standfuss, Jens; Brückner, Frank

2012-02-01

331

High Power Amplifier and Power Supply  

NASA Technical Reports Server (NTRS)

A document discusses the creation of a high-voltage power supply (HVPS) that is able to contain voltages up to -20 kV, keep electrical field strengths to below 200 V/mil (approximately equal to 7.87 kV/mm), and can provide a 200-nanosecond rise/fall time focus modulator swinging between cathode potential of 16.3 kV and -19.3 kV. This HVPS can protect the 95-GHz, pulsed extended interaction klystron (EIK) from arcs/discharges from all sources, including those from within the EIK fs vacuum envelope. This innovation has a multi-winding pulse transformer design, which uses new winding techniques to provide the same delays and rise/fall times (less than 10 nanoseconds) at different potential levels ranging from -20 kV to -16 kV. Another feature involves a high-voltage printed-wiring board that was corona-free at -20 kV DC with a 3- kV AC swing. The corona-free multilayer high-voltage board is used to simulate fields of less than 200 V/mil (approximately equal to 7.87 kV/mm) at 20 kV DC. Drive techniques for the modulator FETs (field-effect transistors) (four to 10 in a series) were created to change states (3,000-V swing) without abrupt steps, while still maintaining required delays and transition times. The packing scheme includes a potting mold to house a ten-stage modulator in the space that, in the past, only housed a four-stage modulator. Problems keeping heat down were solved using aluminum oxide substrate in the high-voltage section to limit temperature rise to less than 10 while withstanding -20 kV DC voltage and remaining corona-free.

Duong, Johnny; Stride, Scot; Harvey, Wayne; Haque, Inam; Packard, Newton; Ng, Quintin; Ispirian, Julie Y.; Waian, Christopher; Janes, Drew

2008-01-01

332

High-power semiconductor separate-confinement double heterostructure lasers  

SciTech Connect

The review is devoted to high-power semiconductor lasers. Historical reference is presented, physical and technological foundations are considered, and the concept of high-power semiconductor lasers is formulated. Fundamental and technological reasons limiting the optical power of a semiconductor laser are determined. The results of investigations of cw and pulsed high-power semiconductor lasers are presented. Main attention is paid to inspection of the results of experimental studies of single high-power semiconductor lasers. The review is mainly based on the data obtained in the laboratory of semiconductor luminescence and injection emitters at the A.F. Ioffe Physicotechnical Institute. (review)

Tarasov, I S [A.F. Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg (Russian Federation)

2010-10-15

333

High Power Flex-Propellant Arcjet Performance  

NASA Technical Reports Server (NTRS)

A MW-class electrothermal arcjet based on a water-cooled, wall-stabilized, constricted arc discharge configuration was subjected to extensive performance testing using hydrogen and simulated ammonia propellants with the deliberate aim of advancing technology readiness level for potential space propulsion applications. The breadboard design incorporates alternating conductor/insulator wafers to form a discharge barrel enclosure with a 2.5-cm internal bore diameter and an overall length of approximately 1 meter. Swirling propellant flow is introduced into the barrel, and a DC arc discharge mode is established between a backplate tungsten cathode button and a downstream ringanode/ spin-coil assembly. The arc-heated propellant then enters a short mixing plenum and is accelerated through a converging-diverging graphite nozzle. This innovative design configuration differs substantially from conventional arcjet thrusters, in which the throat functions as constrictor and the expansion nozzle serves as the anode, and permits the attainment of an equilibrium sonic throat (EST) condition. During the test program, applied electrical input power was varied between 0.5-1 MW with hydrogen and simulated ammonia flow rates in the range of 4-12 g/s and 15-35 g/s, respectively. The ranges of investigated specific input energy therefore fell between 50-250 MJ/kg for hydrogen and 10-60 MJ/kg for ammonia. In both cases, observed arc efficiencies were between 40-60 percent as determined via a simple heat balance method based on electrical input power and coolant water calorimeter measurements. These experimental results were found to be in excellent agreement with theoretical chemical equilibrium predictions, thereby validating the EST assumption and enabling the utilization of standard TDK nozzle expansion analyses to reliably infer baseline thruster performance characteristics. Inferred specific impulse performance accounting for recombination kinetics during the expansion process implied nearly frozen flow in the nozzle and yielded performance ranges of 800-1100 sec for hydrogen and 400-600 sec for ammonia. Inferred thrust-to-power ratios were in the range of 30-10 lbf/MWe for hydrogen and 60-20 lbf/MWe for ammonia. Successful completion of this test series represents a fundamental milestone in the progression of high power arcjet technology, and it is hoped that the results may serve as a reliable touchstone for the future development of MW-class regeneratively-cooled flex-propellant plasma rockets.

Litchford, Ron J.

2011-01-01

334

High power infrared QCLs: advances and applications  

NASA Astrophysics Data System (ADS)

QCLs are becoming the most important sources of laser radiation in the midwave infrared (MWIR) and longwave infrared (LWIR) regions because of their size, weight, power and reliability advantages over other laser sources in the same spectral regions. The availability of multiwatt RT operation QCLs from 3.5 ?m to >16 ?m with wall plug efficiency of 10% or higher is hastening the replacement of traditional sources such as OPOs and OPSELs in many applications. QCLs can replace CO2 lasers in many low power applications. Of the two leading groups in improvements in QCL performance, Pranalytica is the commercial organization that has been supplying the highest performance QCLs to various customers for over four year. Using a new QCL design concept, the non-resonant extraction [1], we have achieved CW/RT power of >4.7 W and WPE of >17% in the 4.4 ?m - 5.0 ?m region. In the LWIR region, we have recently demonstrated QCLs with CW/RT power exceeding 1 W with WPE of nearly 10 % in the 7.0 ?m-10.0 ?m region. In general, the high power CW/RT operation requires use of TECs to maintain QCLs at appropriate operating temperatures. However, TECs consume additional electrical power, which is not desirable for handheld, battery-operated applications, where system power conversion efficiency is more important than just the QCL chip level power conversion efficiency. In high duty cycle pulsed (quasi-CW) mode, the QCLs can be operated without TECs and have produced nearly the same average power as that available in CW mode with TECs. Multiwatt average powers are obtained even in ambient T>70°C, with true efficiency of electrical power-to-optical power conversion being above 10%. Because of the availability of QCLs with multiwatt power outputs and wavelength range covering a spectral region from ~3.5 ?m to >16 ?m, the QCLs have found instantaneous acceptance for insertion into multitude of defense and homeland security applications, including laser sources for infrared countermeasures for protecting aircraft from MANPADS, testing of infrared countermeasures, MWIR and LWIR lasers for identify-friend-or-foe (IFF) personnel beacons, infrared target illuminators and designators and tunable QCL applications including in-situ and standoff detection of chemical warfare agents (CWAs) and explosives. The last of these applications addresses a very important and timely need for detection of improvised explosive devices (IEDs) in combat environments like Iraq and Afghanistan.

Patel, C. Kumar N.

2012-01-01

335

(Data in thousand metric tons of metal unless otherwise noted) Domestic Production and Use: In 2013, 5 companies operated 10 primary aluminum smelters; 3 smelters were  

E-print Network

,020 Price, ingot, average U.S. market (spot), cents per pound 79.4 104.4 116.1 101.0 94.7 Stocks: Aluminum 11 bankruptcy protection, citing high power prices, low aluminum prices, high debt levels, and legacy 2014. The expansion project had been delayed from 2012 owing to declining aluminum prices

336

Fusion cutting of aluminum, magnesium, and titanium alloys using high-power fiber laser  

NASA Astrophysics Data System (ADS)

The effects of cutting speed and assist gas pressure on laser cutting of 1-mm thick Al 1050, AZ31, and Ti6Al4V lightweight alloys are experimentally investigated. Fiber laser cutting of these materials is not broadly investigated and the acquisition of a new level of knowledge is of fundamental importance for applications like sheet metal trimming in automotive industry. The main process outputs are in depth compared with results reported in literature and obtained by cutting with CO2 and Nd?YAG lasers. The good cut quality, the high productivity, and the easy delivery of the beam obtained at the same time, corroborate the advantage of using fiber lasers for thin sheets lightweight alloys cutting.

Scintilla, Leonardo Daniele; Tricarico, Luigi

2013-07-01

337

Microfabricated TWTs as high power, wideband sources of THz radiation  

Microsoft Academic Search

Envisioned applications of THz radiation, such as advanced communications, remote sensing and biomedical imaging, require innovations in high power, compact and efficient sources. For example, specific absorption rates (SARs) in biological tissue are large above 100 GHz, and hence more power is needed to enable imaging. Microfabricated vacuum electron devices (µVEDs) represent a promising solution to obtaining high power (

J. H. Booske; W.-J. Lee; S. Gallagher; D. van der Weide; S. Limbach; K. Jain; C. L. Kory

338

Design of Power Supply for Driving High Power Piezoelectric Actuators  

E-print Network

Design of Power Supply for Driving High Power Piezoelectric Actuators Rongyuan Li, Michael and power density, they are applied more and more in aircrafts and industry. These actuators are normally focus on the power supply and its control architecture for driving high power piezoelectric actuators

Paderborn, Universität

339

Development of High Power Lasers for Materials Interactions  

Microsoft Academic Search

The Lawrence Livermore National Laboratory (LLNL) has a long history of developing high power lasers for use in basic science and applications. The Laser Science and Technology Program (LS&T) at LLNL supports advanced lasers and optics development both for the National Ignition Facility (NIF) as well as for high power lasers and optics technology for a broader range of government,

Hackel

2003-01-01

340

Innovative ceramic slab lasers for high power laser applications  

Microsoft Academic Search

Diode Pumped Solid State Lasers (DPSSL) are gaining increasing interest for high power industrial application, given the continuous improvement in high power diode laser technology reliability and affordability. These sources open new windows in the parameter space for traditional applications such as cutting , welding, marking and engraving for high reflectance metallic materials. Other interesting applications for this kind of

Antonio Lapucci; Marco Ciofini

2005-01-01

341

Recent application of silicon carbide to high power microwave  

Microsoft Academic Search

Silicon carbide is emerging semiconductor material which is now proven to be especially well suited for high power, high frequency applications. Recent results verify the superiority of silicon carbide over both silicon or gallium arsenide for fabrication of high power transistors from DC through X-band. A silicon carbide UHF television module has demonstrated good signal fidelity at the 2000 W

A. W. Morse; P. M. Esker; S. Sriram; J. J. Hawkins; L. S. Chen; J. A. Ostop; T. J. Smith; C. D. Davis; R. R. Barron; R. C. Clarke; R. R. Siergiej; C. D. Brandt

1997-01-01

342

Water Cooling of High Power Light Emitting Diode Henrik Srensen  

E-print Network

becomes comparable in magnitude with e.g. a nuclear reactions [1]. The high rate of heat generatedWater Cooling of High Power Light Emitting Diode Henrik Sørensen Department of Energy Technology light. High power LEDs has problems with low efficiency, and together with a high current this leads

Berning, Torsten

343

Numerical calculation of high power microwave propagation trace in atmosphere  

Microsoft Academic Search

When high power microwave is propagating in atmosphere, the effect of atmospheric refraction will take place and the extent of it mainly depends on the variation gradient of refractive index and the initial quadrant elevation according to path. Based on the lower atmosphere section data, this paper divides the propagation trace of high power microwave when the atmosphere is not

Hou De-tins; Hu Tao; Jiang Chang-yi; Zhou Dong-fang; Wang Gong-lin

2003-01-01

344

A high power high frequency laser diodes driver  

Microsoft Academic Search

Summary form only given. A new high power laser diode driver has been developed and tested. The possibilities for driving high power laser diode bars and stacks at high frequencies has been shown. The driver is with 0.5% noise and ripple at DC, and can be modulated with 15 ns rise\\/fall times at 100 A, with maximum frequency for square

P. Yankov; D. Todorov

2004-01-01

345

Aluminum extraction from aluminum industrial wastes  

NASA Astrophysics Data System (ADS)

Aluminum dross tailings, an industrial waste from the Egyptian Aluminum Company (Egyptalum), was used to produce two types of alums: aluminum sulfate alum (Al2(SO4)3·12H2O) and ammonium aluminum alum {(NH4)2SO4AL2 (SO4)3·24H2O}. This was carried out in two processes. The first involves leaching the impurities using diluted H2SO4 with different solid/liquid ratios at different temperatures to dissolve the impurities present in the starting material in the form of aluminum sulfates. The second process is the extraction of aluminum (as aluminum sulfate) from the purified aluminum dross tailings thus produced. This was carried out in an autoclave. The effects of temperature, time of reaction, and acid concentration on pressure leaching and extraction processes were studied in order to specify the optimum conditions to be applied in the bench scale production as well as the kinetics of leaching process.

Amer, A. M.

2010-05-01

346

Helium irradiated high-power P i N diode with low ON-state voltage drop  

NASA Astrophysics Data System (ADS)

The application of a 300 nm thick platinum silicide (PtSi) layer at the place of the anode contact layer of a soft recovery 2.5 kV/100 A high-power P-i-N diode brought a reduction of the forward voltage drop at several tens percent (for the rating current of 100 A) compared to that of the conventional aluminum and Ti-Ni-Ag layers. This enabled us to greatly improve the trade-off curve between the ON-state and turn-OFF losses of the diode subjected to helium irradiation into the anode and anode junction region. The application of PtSi layers thus opens a new way for the improvement of power devices.

Vobecký, J.; Hazdra, P.; Záhlava, V.

2003-01-01

347

The Jefferson Lab High Power THz User Facility  

SciTech Connect

We describe here, a high power (100 Watt average, 10 MW peak) broadband THz facility based on emission from sub-picosecond bunches of relativistic electrons and the beam transport system that delivers this beam in to a user laboratory.

John Klopf; Amelia Greer; Joseph Gubeli; George Neil; Michelle D. Shinn; Timothy Siggins; David W. Waldman; Gwyn Williams; Alan Todd; Vincent Christina; Oleg Chubar

2007-04-27

348

Bipolar rechargeable lithium battery for high power applications  

NASA Technical Reports Server (NTRS)

Viewgraphs of a discussion on bipolar rechargeable lithium battery for high power applications are presented. Topics covered include cell chemistry, electrolytes, reaction mechanisms, cycling behavior, cycle life, and cell assembly.

Hossain, Sohrab; Kozlowski, G.; Goebel, F.

1993-01-01

349

Innovative fuel designs for high power density pressurized water reactor  

E-print Network

One of the ways to lower the cost of nuclear energy is to increase the power density of the reactor core. Features of fuel design that enhance the potential for high power density are derived based on characteristics of ...

Feng, Dandong, Ph. D. Massachusetts Institute of Technology

2006-01-01

350

Design of annular fuel for high power density BWRs  

E-print Network

Enabling high power density in the core of Boiling Water Reactors (BWRs) is economically profitable for existing or new reactors. In this work, we examine the potential for increasing the power density in BWR plants by ...

Morra, Paolo

2005-01-01

351

Plasma potential mapping of high power impulse magnetron sputtering discharges  

E-print Network

magnetron sputtering with pulsed power technology. 1-3 Inis especially true in pulsed power systems, where L·di/dtPulsed emissive probe techniques have been used to determine the plasma potential distribution of high power

Rauch, Albert

2013-01-01

352

Generation of high power tunable multicycle teraherz pulses  

E-print Network

We demonstrate generation of high-power, multicycle, and frequency-tunable terahertz pulses with microjoule energies by tilting the intensity front of a quasi-sinusoidal intensity-modulated optical waveform. The spatiotemporally ...

Chen, Zhao

353

Custom Beam Shaping for High-Power Fiber Laser Welding.  

E-print Network

?? With the ever increasing power and performance of solid-state lasers, autogenous laser welding is becoming more practical for thick-section welding applications. High-power, high-beam-quality fiber… (more)

Victor, Brian M.

2009-01-01

354

Arc-Free High-Power dc Switch  

NASA Technical Reports Server (NTRS)

Hybrid switch allows high-power direct current to be turned on and off without arcing or erosion. Switch consists of bank of transistors in parallel with mechanical contacts. Transistor bank makes and breaks switched circuit; contacts carry current only during steady-state "on" condition. Designed for Space Shuttle orbiter, hybrid switch can be used also in high-power control circuits in aircraft, electric autos, industrial furnaces, and solar-cell arrays.

Miller, W. N.; Gray, O. E.

1982-01-01

355

High power laser workover and completion tools and systems  

DOEpatents

Workover and completion systems, devices and methods for utilizing 10 kW or more laser energy transmitted deep into the earth with the suppression of associated nonlinear phenomena. Systems and devices for the laser workover and completion of a borehole in the earth. These systems and devices can deliver high power laser energy down a deep borehole, while maintaining the high power to perform laser workover and completion operations in such boreholes deep within the earth.

Zediker, Mark S; Rinzler, Charles C; Faircloth, Brian O; Koblick, Yeshaya; Moxley, Joel F

2014-10-28

356

Apparatus for advancing a wellbore using high power laser energy  

DOEpatents

Delivering high power laser energy to form a borehole deep into the earth using laser energy. Down hole laser tools, laser systems and laser delivery techniques for advancement, workover and completion activities. A laser bottom hole assembly (LBHA) for the delivery of high power laser energy to the surfaces of a borehole, which assembly may have laser optics, a fluid path for debris removal and a mechanical means to remove earth.

Zediker, Mark S.; Land, Mark S.; Rinzler, Charles C.; Faircloth, Brian O.; Koblick, Yeshaya; Moxley, Joel F.

2014-09-02

357

High-Power, High-Temperature Superconductor Technology Development  

NASA Technical Reports Server (NTRS)

Since the first discovery of high-temperature superconductors (HTS) 10 years ago, the most promising areas for their applications in microwave systems have been as passive components for communication systems. Soon after the discovery, experiments showed that passive microwave circuits made from HTS material exceeded the performance of conventional devices for low-power applications and could be 10 times as small or smaller. However, for superconducting microwave components, high-power microwave applications have remained elusive until now. In 1996, DuPont and Com Dev Ltd. developed high-power superconducting materials and components for communication applications under a NASA Lewis Research Center cooperative agreement, NCC3-344 "High Power High Temperature Superconductor (HTS) Technology Development." The agreement was cost shared between the Defense Advanced Research Projects Agency's (DARPA) Technology Reinvestment Program Office and the two industrial partners. It has the following objectives: 1) Material development and characterization for high-power HTS applications; 2) Development and validation of generic high-power microwave components; 3) Development of a proof-of-concept model for a high-power six-channel HTS output multiplexer.

Bhasin, Kul B.

2005-01-01

358

An innovative demonstration of high power density in a compact MDH (magnetohydrodynamic) generator  

NASA Astrophysics Data System (ADS)

The present program was conducted by the University of Tennessee Space Institute (UTSI). It was by its nature a high risk experimental program to demonstrate the feasibility of high power density operation in a laboratory scale combustion driven MHD generator. Maximization of specific energy was not a consideration for the present program, but the results have implications in this regard by virtue of high energy fuel used. The power density is the ratio of the electrical energy output to the internal volume of the generator channel. The MHD process is a volumetric process and the power density is therefore a direct measure of the compactness of the system. Specific energy, is the ratio of the electrical energy output to consumable energy used for its production. The two parameters are conceptually interrelated. To achieve high power density and implied commensurate low system volume and weight, it was necessary to use an energetic fuel. The high energy fuel of choice was a mixture of powdered aluminum and carbon seeded with potassium carbonate and burned with gaseous oxygen. The solid fuel was burned in a hybrid combustion scheme wherein the fuel was cast within a cylindrical combustor in analogy with a solid propellant rocket motor. Experimental data is limited to gross channel output current and voltage, magnetic field strength, fuel and oxidizer flow rates, flow train external temperatures and combustor pressure. Similarly, while instantaneous oxidizer flow rates were measured, only average fuel consumption based on pre and post test component weights and dimensions was possible.

Schmidt, H. J.; Lineberry, J. T.; Chapman, J. N.

1990-06-01

359

14 CFR 101.25 - Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets.  

Code of Federal Regulations, 2014 CFR

...TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES MOORED BALLOONS, KITES, AMATEUR ROCKETS AND UNMANNED FREE BALLOONS Amateur Rockets § 101.25 Operating limitations for Class 2-High Power Rockets and Class...

2014-01-01

360

14 CFR 101.25 - Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets.  

Code of Federal Regulations, 2012 CFR

...TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES MOORED BALLOONS, KITES, AMATEUR ROCKETS AND UNMANNED FREE BALLOONS Amateur Rockets § 101.25 Operating limitations for Class 2-High Power Rockets and Class...

2012-01-01

361

14 CFR 101.25 - Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets.  

Code of Federal Regulations, 2013 CFR

...TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES MOORED BALLOONS, KITES, AMATEUR ROCKETS AND UNMANNED FREE BALLOONS Amateur Rockets § 101.25 Operating limitations for Class 2-High Power Rockets and Class...

2013-01-01

362

High-power slim-hole drilling system  

SciTech Connect

The objective of this project is to implement new high-power slim-hole motors and bits into field gas well drilling applications. Development of improved motors and bits is critical because rotating time constitutes the major cost of drilling gas wells. Conventional motors drill most formations 2 to 3 times faster than rotary continuous coring systems due to greater power transfer to the drill bit. New high-power motors and large-cutter TSP bits being developed by Maurer Engineering, Inc. (MEI) drill 2 to 3 times faster than conventional motors. These slim-hole high-power motors and bits, which are ready for field testing on this DOE project, should reduce drilling costs by 20 to 40 percent in many areas. The objective of Phase I is to design, manufacture and laboratory test improved high-power slim-hole motors and large-cutter TSP bits. This work will be done in preparation for Phase II field tests. The objective of Phase II will be to field test the high-power motors and bits in Amoco`s Catoosa shallow-test well near Tulsa, OK, and in deep gas wells. The goal will be to drill 2 to 3 times faster than conventional motors and to reduce the drilling costs by 20 to 40 percent over the intervals drilled.

Cohen, J.H.

1995-07-01

363

High-power lead-acid batteries for different applications  

NASA Astrophysics Data System (ADS)

High-power lead-acid batteries have been used for a rather long time in various applications, especially for uninterruptible power supplies (UPSs) and starting of automobiles. Future automotive service requires, in addition to cold-cranking performance, the combination of high-power capability, a very good charge-acceptance, and an excellent cycle-life. Such applications include stop-start, regenerative braking, and soft, mild and full hybrid vehicles. For UPS, there has been a clear tendency to shorter discharge times and higher discharge rates. During the past decades, the specific power of lead-acid batteries has been raised steadily and there is still, room for further improvement. This paper gives an overview of the progress made in the development of high-power lead-acid batteries and focuses on stationary and automotive applications.

Wagner, Rainer

364

Output spectrum of high-power CW fiber amplifier  

NASA Astrophysics Data System (ADS)

A generation spectrum of a high-power Yb-doped fiber amplifier (YDFA) becomes broader with increasing power in the master oscillator power amplifier (MOPA) configuration, which degenerating the coherence of the laser. In this work, a spectral model had been proposed for the high-power YDFA in Continuous Wave (CW) region. A fiber amplifier was built at the 600W level and experiments were conducted for its output spectral characteristics based on this model. Through this model, the output spectrum of high-power YDFA in CW region could be calculated. Though the theoretical spectra were in little different from the measured ones, the predictions of the theory were still in excellent quantitative agreement with the experimental results.

Liu, Wei; Xiao, Hu; Wang, Xiaolin; Zhou, Pu

2013-09-01

365

Klamath Falls: High-Power Acoustic Well Stimulation Technology  

SciTech Connect

Acoustic well stimulation (AWS) technology uses high-power sonic waves from specific frequency spectra in an attempt to stimulate production in a damaged or low-production wellbore. AWS technology is one of the most promising technologies in the oil and gas industry, but it has proven difficult for the industry to develop an effective downhole prototype. This collaboration between Klamath Falls Inc. and the Rocky Mountain Oilfield Testing Center (RMOTC) included a series of tests using high-power ultrasonic tools to stimulate oil and gas production. Phase I testing was designed and implemented to verify tool functionality, power requirements, and capacity of high-power AWS tools. The purpose of Phase II testing was to validate the production response of wells with marginal production rates to AWS stimulation and to capture and identify any changes in the downhole environment after tool deployment. This final report presents methodology and results.

Black, Brian

2006-07-24

366

Thrust stand for high-power electric propulsion devices  

NASA Technical Reports Server (NTRS)

This paper describes a new high-power thrust stand developed for use with high-power (up to 250 kW) magnetoplasmadynamic (MPD) thrusters, which is installed in a high-vacuum MPD facility at Lewis Research Center. The design of the stand is based on inverted pendulum configuration, with the result of large displacements and high resolution. Calibration results showed that thrust measurements were linear and repeatable to within a fraction of 1 percent. The thrust stand was used for testing water-cooled MPD thrusters at power levels up to 125 kW. The thruster, however, is quite well suited for testing other types of electric propulsion devices.

Haag, T. W.

1991-01-01

367

Nanosecond high-power dense microplasma switch for visible light  

NASA Astrophysics Data System (ADS)

Spark discharges in high-pressure gas are known to emit a broadband spectrum during the first 10 s of nanoseconds. We present calibrated spectra of high-pressure discharges in xenon and show that the resulting plasma is optically thick. Laser transmission data show that such a body is opaque to visible light, as expected from Kirchoff's law of thermal radiation. Nanosecond framing images of the spark absorbing high-power laser light are presented. The sparks are ideal candidates for nanosecond, high-power laser switches.

Bataller, A.; Koulakis, J.; Pree, S.; Putterman, S.

2014-12-01

368

The High Power Electric Propulsion (HiPEP) Ion Thruster  

NASA Technical Reports Server (NTRS)

Practical implementation of the proposed Jupiter Icy Moon Orbiter (JIMO) mission, which would require a total delta V of approximately 38 km/s, will require the development of a high power, high specific impulse propulsion system. Initial analyses show that high power gridded ion thrusters could satisfy JIMO mission requirements. A NASA GRC-led team is developing a large area, high specific impulse, nominally 25 kW ion thruster to satisfy both the performance and the lifetime requirements for this proposed mission. The design philosophy and development status as well as a thruster performance assessment are presented.

Foster, John E.; Haag, Tom; Patterson, Michael; Williams, George J., Jr.; Sovey, James S.; Carpenter, Christian; Kamhawi, Hani; Malone, Shane; Elliot, Fred

2004-01-01

369

Aluminum and Young Artists.  

ERIC Educational Resources Information Center

The author suggests a variety of ways in which aluminum and aluminum foil can be used in elementary and junior high art classes: relief drawing and rubbing; printing; repousse; sculpture; mobiles; foil sculpture; and three dimensional design. Sources of aluminum supplies are suggested. (SJL)

Anderson, Thomas

1980-01-01

370

Aluminum reference electrode  

DOEpatents

A stable reference electrode is described for use in monitoring and controlling the process of electrolytic reduction of a metal. In the case of Hall cell reduction of aluminum, the reference electrode comprises a pool of molten aluminum and a solution of molten cryolite, Na[sub 3]AlF[sub 6], wherein the electrical connection to the molten aluminum does not contact the highly corrosive molten salt solution. This is accomplished by altering the density of either the aluminum (decreasing the density) or the electrolyte (increasing the density) so that the aluminum floats on top of the molten salt solution. 1 fig.

Sadoway, D.R.

1988-08-16

371

2nd High-Power Targetry Workshop MATERIAL IRRADIATION STUDIES  

E-print Network

- customized carbon-carbon composites - Super-alloys (gum metal, albemet, super-invar, etc.) While calculations affects bonding) · 3D Carbon-Carbon Composite · Toyota "Gum Metal" · Graphite (IG-43) · Al High-Power Targetry Workshop GUM Metal 90% cold-worked

McDonald, Kirk

372

Resonance tracking and vibration stablilization for high power ultrasonic transducers.  

PubMed

Resonant frequency shift and electrical impedance variation are common phenomena in the application of high power ultrasonic transducers, e.g. in focused ultrasound surgery and in cutting. They result in low power efficiency and unstable vibration amplitude. To solve this problem, a driving and measurement system has been developed to track the resonance of high power transducers and to stabilise their vibration velocity. This has the ability to monitor the operating and performance parameters of the ultrasonic transducers in real time. The configuration of the system, with its control algorithm implemented in LabVIEW (National Instruments, Newbury, UK), ensures flexibility to suit different transducers and load conditions. In addition, with different programs, it can be utilised as a high power impedance analyser or an instantaneous electrical power measurement system for frequencies in the MHz range. The effectiveness of this system has been demonstrated in detailed studies. With it, high transducer performance at high power can be achieved and monitored in real time. PMID:23928264

Kuang, Y; Jin, Y; Cochran, S; Huang, Z

2014-01-01

373

Processing of concretes with a high power CO 2 laser  

Microsoft Academic Search

Laser material processing, being a non-contact process, minimizes many of the complexities involved in the decontamination and decommissioning of nuclear facilities. A high power laser beam incident on a concrete surface can produce spalling, glazing or vaporization, depending upon the laser power density and scan speed. This paper presents effect of various laser processing parameters on the efficiency of material

B. Tirumala Rao; Harish Kumar; A. K. Nath

2005-01-01

374

MATERIAL IRRADIATION DAMAGE STUDIES FOR HIGH POWER ACCELERATORS*  

E-print Network

MATERIAL IRRADIATION DAMAGE STUDIES FOR HIGH POWER ACCELERATORS* N. Simos# , H. Kirk, L. Trung, H under severe shock and high irradiation exposure. The limitations of solid materials to function as high performance targets and in particular the effects of irradiation on key material properties are assessed

McDonald, Kirk

375

Alternative designs for high power single mode active optical fibres  

Microsoft Academic Search

In this paper, we propose, through different theoretical examples of composite fibre designs, some alternative ways to push up the limits of active optical fibres. Highly ytterbium-doped large cores are required for high power delivery and low non linear limitations. Such cores usually support several guided modes. We demonstrate in this paper that by surrounding the core with a tailored

P. Roy; M. Devautour; S. Fevrier; L. Lavoute; K. Schuster; J. Kobelke; S. Grimm

2009-01-01

376

Polymer Separators for High Power, High Efficiency Microbial Fuel Cells  

E-print Network

) was dissolved in 23 g H2O at 90 °C to prepare ~8 wt% transparent viscous polymer solution. To this solution 1 Polymer Separators for High Power, High Efficiency Microbial Fuel Cells Guang Chen, Bin), tetra-n- butylammonium chloride, Nafion solution (Nafion 117 solution, 5 wt % in a mixture of lower

377

High power linear pulsed beam annealer. [Patent application  

Microsoft Academic Search

A high power pulsed electron beam system for annealing semiconductors is comprised of an electron gun having a heated cathode, control grid and focus ring for confining the pulsed beam of electrons to a predetermined area, and a curved drift tube. The drift tube and an annular Faraday shield between the focus ring and the drift tube are maintained at

M. D. Strathman; D. K. Sadana; R. B. True

1980-01-01

378

Super-X Divertor High Power Density Devices  

Microsoft Academic Search

The Super-X divertor (SXD), a new magnetic geometry that isolates the divertor from the main plasma, can solve the severe heat exhaust problem of fusion reactors as well as next-generation high power density devices. Using axisymmetric PF coils with currents comparable to standard divertor configurations, the SXD places divertor plates at the largest possible radius inside TF coils. This increases

Prashant Valanju

2008-01-01

379

Using a Balun Transformer Combiner for High Power Microwave Experiments  

SciTech Connect

A novel coaxial power combiner design has been duplicated that has distinct advantages over other combiner geometries that can handle high power. This design is being applied to combine four 3 kW power supplies to obtain a 10 kW, 5 MHz system for an ICRF antenna on HSX. In the past, Wilkinson type combiners have had limited application to high power systems because of the lack of non-inductive, high power, 100 Omega balance loads. With this new design, standard 50 Omega dummy loads can be used instead for the balance load. The cost is considerably lower than lumped element combiner designs which are dominated by capacitor costs. At such a relatively low frequency, a 3-dB quarter-wave coupled-line coupler becomes impractically long, and a conventional branch-line hybrid requires 35 Omega-line, which is commercially unavailable. The balun combiner uses less transmission line than a ring hybrid and has good bandwidth characteristics even away from its best line impedance. Theoretical calculations and modeling were performed for line impedances from 65 Omega to 75 Omega. Measurements from a low-power test device show excellent agreement with theory, and construction of the high power system is underway.

Kaufman, Michael C [ORNL; Pesavento, Philip V [ORNL

2011-01-01

380

Characteristics of high power VECSELs with silicon carbide heatspreaders  

Microsoft Academic Search

In this paper, we demonstrate that highly advantageous thermal management properties of the SiC heatspreader are wholly compatible with direct diode pumping. We investigate the transverse and longitudinal mode behaviour of the high-power vertical external-cavity surface-emitting semiconductor laser with the intra-cavity heatspreader.

J. E. Hastie; J.-M. Hopkins; S. Calvez; C. W. Jeon; D. Burns; M. D. Dawson; R. Abram; E. Riis; A. I. Ferguson

2003-01-01

381

High-power, high-intensity laser propagation and interactions  

SciTech Connect

This paper presents overviews of a number of processes and applications associated with high-power, high-intensity lasers, and their interactions. These processes and applications include: free electron lasers, backward Raman amplification, atmospheric propagation of laser pulses, laser driven acceleration, atmospheric lasing, and remote detection of radioactivity. The interrelated physical mechanisms in the various processes are discussed.

Sprangle, Phillip [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Electrical and Computer Engineering and Physics, University of Maryland, College Park, Maryland 20740 (United States); Hafizi, Bahman [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States)

2014-05-15

382

High Powered Cluster Heads for Extending Sensor Network Lifetime  

E-print Network

Ah in comparison to normal sensors of 700 mAh. Comparing our approach with an equivalent LEACH system whereHigh Powered Cluster Heads for Extending Sensor Network Lifetime Malka N. Halgamuge, Student Member for a sensor network is important for most if not all applications. We propose a method to extend network

Halgamuge, Malka N.

383

Load characteristics of high power sandwich piezoelectric ultrasonic transducers  

Microsoft Academic Search

Based on the equivalent circuit theory, the load characteristics of high power piezoelectric ultrasonic sandwich transducers are studied. Two types of loads are studied. One is liquid load as in ultrasonic cleaning, and the other is solid load as in ultrasonic drilling and machining. The effect of load and structure of the transducer on the resonance frequency of the transducer

Lin Shuyu

2005-01-01

384

High power fiber lasers the revitalisation of laser technology  

Microsoft Academic Search

Summary form only given. A comprehensive range of CW and pulsed fibre lasers and amplifiers delivering from 1 to 30 W average power is reported. The novel technological platform exploiting the advantages of silica fibre lasers along with high power laser diode pumping results in developing a new generation of laser sources suitable for multiple applications. The main features of

V. P. Gapontsev; I. E. Samartsev; V. Fomin; N. S. Platonov; S. V. Chemikov; J. R. Taylor

1997-01-01

385

Iterative Learning Control Applications to High Power Microwave Tubes  

E-print Network

1 Iterative Learning Control Applications to High Power Microwave Tubes V. S. Soualian, G.T. Park, USA. Abstract In this paper, we present a ``smart'' high­peak power microwave tube, by implementing tube in order to build a ``smart tube'' HPM source. By smart tube we mean an HPM source capable

386

Iterative Learning Control Applications to High Power Microwave Tubes  

E-print Network

1 Iterative Learning Control Applications to High Power Microwave Tubes V. S. Soualian, G.T. Park, USA. Abstract In this paper, we present a ``smart'' high­peak power microwave tube, by implementing is then to implement the control algorithms on a physical tube in order to build a ``smart tube'' HPM source. By smart

387

Iterative Learning Control Applications to High Power Microwave Tubes  

E-print Network

1 Iterative Learning Control Applications to High Power Microwave Tubes V. S. Soualian, G.T. Park, USA. Abstract In this paper, we present a "smart" high-peak power microwave tube, by implementing is then to implement the control algorithms on a physical tube in order to build a "smart tube" HPM source. By smart

388

Hermetic metallization of aluminum nitride for RF windows  

Microsoft Academic Search

Aluminum nitride (AlN) is a leading candidate for replacing BeO or high-purity alumina as RF window material for high power, multi-megawatt (20 MW-100 MW) microwaves both at cryogenic temperatures, i.e., 2 K and room temperature (300 K) because of its high thermal conductivity (200 W\\/m°K), high dielectric strength (>15 kV\\/mm), low dielectric loss (tangent 6=0.0005), and good mechanical strength (400-450

E. Savrun; V. Nguyen

2004-01-01

389

An innovative demonstration of high power density in a compact MHD (magnetohydrodynamic) generator  

SciTech Connect

The present program was conducted by the University of Tennessee Space Institute (UTSI). It was by its nature a high risk experimental program to demonstrate the feasibility of high power density operation in a laboratory scale combustion driven MHD generator. Maximization of specific energy was not a consideration for the present program, but the results have implications in this regard by virtue of high energy fuel used. The power density is the ratio of the electrical energy output to the internal volume of the generator channel. The MHD process is a volumetric process and the power density is therefore a direct measure of the compactness of the system. Specific energy, is the ratio of the electrical energy output to consumable energy used for its production. The two parameters are conceptually interrelated. To achieve high power density and implied commensurate low system volume and weight, it was necessary to use an energetic fuel. The high energy fuel of choice was a mixture of powdered aluminum and carbon seeded with potassium carbonate and burned with gaseous oxygen. The solid fuel was burned in a hybrid combustion scheme wherein the fuel was cast within a cylindrical combustor in analogy with a solid propellant rocket motor. Experimental data is limited to gross channel output current and voltage, magnetic field strength, fuel and oxidizer flow rates, flow train external temperatures and combustor pressure. Similarly, while instantaneous oxidizer flow rates were measured, only average fuel consumption based on pre and post test component weights and dimensions was possible. 4 refs., 60 figs., 9 tabs.

Schmidt, H.J.; Lineberry, J.T.; Chapman, J.N.

1990-06-01

390

Faraday isolator based on TSAG crystal for high power lasers.  

PubMed

A Faraday isolator based on a new magneto-optical medium, TSAG (terbium scandium aluminum garnet) crystal, has been constructed and investigated experimentally. The device provides an isolation ratio of more than 30 dB at 500 W laser power. It is shown that this medium can be used in Faraday isolators for kilowatt-level laser powers. PMID:25321791

Mironov, E A; Palashov, O V

2014-09-22

391

The desire to achieve both high power density and high power conversion efficiency leads to several required features of a first wall and blanket concept. Achieving high  

E-print Network

, resulting in low structural distortion and thermal stresses. 5. The lithium flow rate is approximatelyThe desire to achieve both high power density and high power conversion efficiency leads to several properties (high thermal conductivity, low thermal expansion, etc.). Achieving high power conversion

California at Los Angeles, University of

392

Designing high power targets with computational fluid dynamics (CFD)  

SciTech Connect

High power liquid hydrogen (LH2) targets, up to 850 W, have been widely used at Jefferson Lab for the 6 GeV physics program. The typical luminosity loss of a 20 cm long LH2 target was 20% for a beam current of 100 ?A rastered on a square of side 2 mm on the target. The 35 cm long, 2500 W LH2 target for the Qweak experiment had a luminosity loss of 0.8% at 180 ?A beam rastered on a square of side 4 mm at the target. The Qweak target was the highest power liquid hydrogen target in the world and with the lowest noise figure. The Qweak target was the first one designed with CFD at Jefferson Lab. A CFD facility is being established at Jefferson Lab to design, build and test a new generation of low noise high power targets.

Covrig, S. D. [Thomas Jefferson National Laboratory, Newport News, VA 23606 (United States)

2013-11-07

393

TE_01 High Power Disk Loaded Guide Load  

SciTech Connect

A method to design a matching section from a smooth guide to a disk-loaded guide, using a variation of broadband matching, [1, 2] is described. Using this method, we show how to design high power loads, attenuators and filters. The load consists of a disk-loaded coaxial guide operating in the TE{sub 01}-mode. We use this mode because it has no electric field terminating on a conductor, has no axial currents, and has no current at the cylinder-disk interface. A high power load design that has -35 dB reflection and a 200 MHz, -20 dB bandwidth, is presented. It is expected that it will carry the 600 MW output peak power of the pulse compression network. We use coaxial geometry and stainless steel material to increase the attenuation per cell.

Farkas, Z.D.; /SLAC

2005-06-01

394

SPALLATION NEUTRON SOURCE HIGH-POWER PROTECTION MODULE TEST STAND  

SciTech Connect

The Spallation Neutron Source (SNS) High-Power Protection Module (HPM) provides interlocks and fast shutdown for the radio frequency (RF) system to protect the accelerating structures and high power RF (HPRF) Distribution System. The HPM has required some functional upgrades since the start of beam operations and an upgrade to the HPM test stand was required to support these added features. The HPM test stand currently verifies functionality, RF channel calibration, and measurement of the speed of shutdown to ensure the specifications are met. The upgraded test stand was implemented in a Field Programmable Gate Array (FPGA) to allow for future growth and flexibility. Work is currently progressing on automation of the test stand to better perform the required module calibration schedule.

Lee, Sung-Woo [ORNL] [ORNL; Ball, Jeffrey Allen [ORNL] [ORNL; Crofford, Mark T [ORNL] [ORNL; Davidson Jr, Taylor L [ORNL] [ORNL; Jones, Stacey L [ORNL] [ORNL; Hardek, Thomas W [ORNL] [ORNL

2010-01-01

395

Photoconductive switching for HPM (high power microwave) generation  

SciTech Connect

Photoconductive switching has been explored at LLNL and demonstrated to be a viable technology for high power microwave (HPM) generation. This technology enables the development of compact, portable, and efficient HPM sources. At LLNL we have successfully switched 35 KV in <200 ps using laser triggered, 1 {times} 5 {times} 20 mm GaAs switches. Based on these results we are developing an HPM generator with applications for HPM weapons and high power, wideband radar. The paper will discuss the physics limits and tradeoffs in the application of this technology. Among the topics discussed will be switching efficiency, candidate switch materials, laser requirements, applicable laser technologies, generator configurations, and cooling requirements and techniques. In addition to presenting theoretical and practical considerations, the paper will discuss on-going work at LLNL and elsewhere. 11 refs., 2 figs., 1 tab.

Pocha, M.D.; Hofer, W.W.

1990-01-01

396

Technology requirements for high-power Lithium Lorentz Force accelerators  

NASA Astrophysics Data System (ADS)

Lithium Lorentz Force Accelerators (LFA's) are capable of processing very high power levels and are therefore applicable to a wide range of challenging missions. An analysis of a reusable orbit transfer vehicle with a solar or nuclear electric power source was performed to assess the applicability of high-power LFA's to this mission and to define engine performance and lifetime goals to help guide the technology development program. For this class of missions, the emphasis must be on achieving high efficiency at an Isp of 4000-5000 s at power levels of 200-250 kWe. The engines must demonstrate very reliable operation for a service life of about 3000 hours. These goals appear to be achievable with engine technologies currently under development.

Polk, James; Frisbee, Robert; Krauthamer, Stan; Tikhonov, Viktor; Semenikhin, Sergei; Kim, Vladimir

1997-01-01

397

High power repetitive TEA CO2 pulsed laser  

NASA Astrophysics Data System (ADS)

A high power repetitive spark-pin UV-preionized TEA CO2 laser system is presented. The discharge for generating laser pulses is controlled by a rotary spark switch and a high voltage pulsed trigger. Uniform glow discharge between two symmetrical Chang-electrodes is realized by using an auto-inversion circuit. A couple of high power axial-flow fans with the maximum wind speed of 80 m/s are used for gas exchange between the electrodes. At a repetitive operation, the maximum average output laser power of 10.4 kW 10.6 ?m laser is obtained at 300 Hz, with an electro-optical conversion efficiency of 15.6%. At single pulsed operation, more pumping energy and higher gases pressures can be injected, and the maximum output laser energy of 53 J is achieved.

Yang, Guilong; Li, Dianjun; Xie, Jijiang; Zhang, Laiming; Chen, Fei; Guo, Jin; Guo, Lihong

2012-07-01

398

Innovative ceramic slab lasers for high power laser applications  

NASA Astrophysics Data System (ADS)

Diode Pumped Solid State Lasers (DPSSL) are gaining increasing interest for high power industrial application, given the continuous improvement in high power diode laser technology reliability and affordability. These sources open new windows in the parameter space for traditional applications such as cutting , welding, marking and engraving for high reflectance metallic materials. Other interesting applications for this kind of sources include high speed thermal printing, precision drilling, selective soldering and thin film etching. In this paper we examine the most important DPSS laser source types for industrial applications and we describe in details the performances of some slab laser configurations investigated at our facilities. The different architectures' advantages and draw-backs are briefly compared in terms of performances, system complexity and ease of scalability to the multi-kW level.

Lapucci, Antonio; Ciofini, Marco

2005-09-01

399

A Lemon Cell Battery for High-Power Applications  

NASA Astrophysics Data System (ADS)

This article discusses the development of a lemon cell battery for high-power applications. The target application is the power source of a dc electric motor for a model car constructed by first-year engineering students as part of their introductory course design project and competition. The battery is composed of a series of lemon juice cells made from UV vis cuvets that use a magnesium anode and copper cathode. Dilution of the lemon juice to reduce the rate of corrosion of the magnesium anode and the addition of table salt to reduce the internal resistance of the cell are examined. Although our specific interest is the use of this lemon cell battery to run an electric dc motor, high-power applications such as radios, portable cassette or CD players, and other battery-powered toys are equally appropriate for demonstration and laboratory purposes using this battery.

Muske, Kenneth R.; Nigh, Christopher W.; Weinstein, Randy D.

2007-04-01

400

Test Results From a High Power Linear Alternator Test Rig  

NASA Technical Reports Server (NTRS)

Stirling cycle power conversion is an enabling technology that provides high thermodynamic efficiency but also presents unique challenges with regard to electrical power generation, management, and distribution. The High Power Linear Alternator Test Rig (HPLATR) located at the NASA Glenn Research Center (GRC) in Cleveland, Ohio is a demonstration test bed that simulates electrical power generation from a Stirling engine driven alternator. It implements the high power electronics necessary to provide a well regulated DC user load bus. These power electronics use a novel design solution that includes active rectification and power factor control, active ripple suppression, along with a unique building block approach that permits the use of high voltage or high current alternator designs. This report describes the HPLATR, the test program, and the operational results.

Birchenough, Arthur G.; Hervol, David S.; Gardner, Brent G.

2010-01-01

401

Test Results from a High Power Linear Alternator Test Rig  

NASA Technical Reports Server (NTRS)

Stirling cycle power conversion is an enabling technology that provides high thermodynamic efficiency but also presents unique challenges with regard to electrical power generation, management, and distribution. The High Power Linear Alternator Test Rig (HPLATR) located at the NASA Glenn Research Center (GRC) in Cleveland, OH is a demonstration test bed that simulates electrical power generation from a Stirling engine driven alternator. It implements the high power electronics necessary to provide a well regulated DC user load bus. These power electronics use a novel design solution that includes active rectification and power factor control, active ripple suppression, along with a unique building block approach that permits the use of high voltage or high current alternator designs. This presentation describes the HPLATR, the test program, and the operational results.

Birchenough, Arthur G.; Hervol, David S.; Gardner, Brent G.

2010-01-01

402

Liquid crystals under high-power, nanosecond laser irradiation  

NASA Astrophysics Data System (ADS)

High-damage threshold liquid crystal optical elements are used for high-power laser applications as mirrors, waveplates and optical power limiters. Several nonlinear optical effects under high-power, nanosecond laser irradiation of liquid crystals will be outlined: (1) athermal helical pitch dilation and unwinding of cholesteric mirrors by the field of a light wave (in free space and in a laser resonator); (2) dependence of nonlinear refraction of liquid crystal on the laser beam diameter in presence of two-photon absorption; (3) cumulative effects in nonlinear absorption and refraction at low repetition rate (5-10 Hz); (4) feedback-free kaleidoscope of patterns in dye-doped liquid crystals (hexagons/stripes).

Lukishova, Svetlana G.

2013-03-01

403

High power microwave components for space communications satellite  

NASA Technical Reports Server (NTRS)

Analyzed, developed, and tested were high power microwave components for communications satellites systems. Included were waveguide and flange configurations with venting, a harmonic filter, forward and reverse power monitors, electrical fault sensors, and a diplexer for two channel simultaneous transmission. The assembly of 8.36 GHz components was bench tested, and then operated for 60 hours at 3.5 kW CW in a high vacuum. The diplexer was omitted from this test pending a modification of its end irises. An RF leakage test showed only that care is required at flange junctions; all other components were RF tight. Designs were extrapolated for 12 GHz and 2.64 GHz high power satellite systems.

Jankowski, H.; Geia, A.

1972-01-01

404

High-power laser diodes, laser diode modules, and their applications  

Microsoft Academic Search

High power laser diodes and especially high power laser diode modules made enormous progress in the last few years. Different aspects of high power laser diodes are treated starting from general description of high power laser diodes and their mounting techniques, characterizing the electro- optical behavior of single laser bars and finally presenting beamshaping optics for the collimation of large

Franz X. Daiminger; Friedhelm Dorsch; D. Lorenzen

1998-01-01

405

High-power microwave bandwidth broadening by air breakdown  

NASA Astrophysics Data System (ADS)

Wideband, high-power microwave pulses are expected to have important applications in ultra-wideband radar. The wide bandwidth should generate increased information for target characterization and identification. The high power should result in increased target detection range for conventional targets and targets with reduced signatures. A way to generate wideband, high-power microwave pulses with relatively conventional technology is to tail erode high-power pulses by passage through a low pressure air cell. In this process, the tails of short (3 to 10 ns), high amplitude (greater than 1 MV/m) pulses are removed. This erosion shortens the pulses and generates transmitted pulses with broadened bandwidths. The pressure must be matched to several incident pulse characteristics to create enough electron density to cause strong tail erosion. The important pulse characteristics are amplitude, frequency, pulse length, and pulse shape. We have shown experimentally that tail erosion from air breakdown broadens the 3 dB bandwidths of 2.8608 GHz incident pulses in a rectangular waveguide at 3.5 torr. The incident pulse amplitude varied from 0.67 to 1.16 MV/m. The pulse bandwidth increased from 0.147 GHz by 0.34 to 1.4 pct. relative. The incident bandwidth was 5.12 pct. relative to the incident carrier frequency. This experimental broadening was simulated with a 2D, electromagnetic, electron fluid computer code for avalanche ionization. The simulation predicted bandwidth broadening by 0.029 to 0.13 GHz or 1.0 to 4.4 pct. relative for a peak initial electron density of 10 electrons/cu cm. Although the measured and calculated transmitted electric field envelopes were in close agreement, the calculated bandwidths exceeded those measured by 13 to 47 pct. Because the detectors were not fast enough to resolve individual cycles we presently conclude that the simulation gives better estimates of reality than do the measurements.

Mayhall, D. J.; Yee, J. H.; Alvarez, R. A.

1991-12-01

406

Two-Stage Uninterruptible Power Supply With High Power Factor  

Microsoft Academic Search

An uninterruptible power supply (UPS) with high power factor and two conversion stages is suggested. The double-conversion configuration has three stages, but normally, only two stages are operating at the same time. The first stage of the proposed scheme integrates the power-factor-correction stage and the battery charger of the double-conversion configuration, obtaining a two-stage UPS. The second stage is based

Nimrod Vazquez; JesÚs Villegas-Saucillo; Claudia Hernandez; Elias Rodriguez; Jaime Arau

2008-01-01

407

THz radiation using high power, microfabricated, wideband TWTs  

Microsoft Academic Search

Microfabricated, miniature, folded waveguide traveling wave tube (FWG-TWT) devices are potential compact sources of wideband (~20% instantaneous bandwidth), high power (0.01-1 W) THz radiation. We present theoretical analyses and numerical simulations indicating that a 560 GHz, 56 mW, 1% (intrinsic) efficiency oscillator is realistically achievable, and amplifiers with gains between 10 and 30 dB are feasible with circuit lengths of

C. L. Kory; J. H. Booske; W.-J. Lee; S. Gallagher; D. W. van der Weide; S. Limbach; S. Bhattacharjee

2002-01-01

408

Method and apparatus for improved high power impulse magnetron sputtering  

DOEpatents

A high power impulse magnetron sputtering apparatus and method using a vacuum chamber with a magnetron target and a substrate positioned in the vacuum chamber. A field coil being positioned between the magnetron target and substrate, and a pulsed power supply and/or a coil bias power supply connected to the field coil. The pulsed power supply connected to the field coil, and the pulsed power supply outputting power pulse widths of greater that 100 .mu.s.

Anders, Andre

2013-11-05

409

High-power COIL and YAG laser welding  

Microsoft Academic Search

We have constructed a laser welding system, which enabled high-power laser welding by combining three laser beams of 1 mm wavelength. Its wavelength enables optical silica fibers transmission and the flexible system. The heart of this system consists of a 4 kW and a 6 kW Nd:YAG lasers and a 10 kW Chemical Oxygen-Iodine Laser (COIL). The average power of

Fumio Wani; Tokuhiro Nakabayashi; Akiyoshi Hayakawa; Sachio Suzuki; Kozu Yasuda

2002-01-01

410

High-power COIL and Nd:YAG laser welding  

Microsoft Academic Search

We have constructed a laser welding system, which enabled high-power laser welding by combining three laser beams of 1 µm wavelength. Its wavelength enables optical silica fibers transmission and the flexible system. The heart of this system consists of a 4 kW and a 6 kW Nd:YAG lasers and a 10 kW class Chemical Oxygen-Iodine Laser (COIL) beams of 6

Fumio Wani; T. Nakabayashi; A. Hayakawa; S. Suzuki; K. Yasuda

2003-01-01

411

Laser welding with high power lasers combining system  

Microsoft Academic Search

We have developed the high power laser beam combining system with the 10kW class chemical oxygen-iodine laser (COIL) of wavelength 1.315µm and the 6kW class Nd:YAG laser of wavelength 1.064µm. The characteristic of the beam propagation, the combining beam quality and the optics were evaluated. The combining beam providing power was up to over 16kW. The combining beam was used

Mikio Muro; Tokuhiro Nakabayashi; Yoshiaki Hayakawa; Fumio Wani; Kozo Yasuda; Fumisato Mifune; Kouichi Yoshida

2000-01-01

412

Development of adaptive resonator techniques for high-power lasers  

SciTech Connect

The design of an adaptive wavefront control system for a high-power Nd:Glass laser will be presented. Features of this system include: an unstable resonator in confocal configuration, a multi-module slab amplifier, and real-time intracavity adaptive phase control using deformable mirrors and high-speed wavefront sensors. Experimental results demonstrate the adaptive correction of an aberrated passive resonator (no gain).

An, J; Brase, J; Carrano, C; Dane, C B; Flath, L; Fochs, S; Hurd, R; Kartz, M; Sawvel, R

1999-07-12

413

High-power 4H-SiC JBS rectifiers  

Microsoft Academic Search

This paper reports the detailed design, fabrication, and characterization of two sets of high-power 4H-silicon carbide (4H-SiC) junction barrier Schottky (JBS) diodes - one with a 1500-V, 4-A capability and another with 1410-V, 20-A capability. Two-dimensional (2-D) device simulations show that a grid spacing of 4 ?m results in the most optimum trade-off between the on-state and off-state characteristics for

Ranbir Singh; D. Craig Capell; Allen R. Hefner; Jason Lai; John W. Palmour

2002-01-01

414

High power all solid state laser system near 280 nm  

Microsoft Academic Search

We present a stable high power all solid state laser system emitting 1-W of continuous wave laser radiation at a wavelength of 559 nm or 275 mW near 280 nm. The system consists of a commercial 2-W fiber laser with a line width of less than 200 kHz at 1118 nm and two home-built subsequent second harmonic generation external ring cavities using LBO and BBO

A. Friedenauer; F. Markert; H. Schmitz; L. Petersen; S. Kahra; M. Herrmann; Th. Udem; T. W. Hänsch; T. Schätz

2006-01-01

415

High power resonant Switched-Capacitor step-down converter  

Microsoft Academic Search

This paper treats a new type of high power switched-capacitor-DC-DC-converter (SCDDC), which is characterized by resonant switching transitions. This drastically reduces switching losses and opens up the possibility to employ thyristors instead of turn-off power semiconductors. At the same time a larger energy can be transferred per switching cycle and\\/or the application of the SCDDCs can be extended into the

Oliver Keiser; Peter K. Steimer; Johann W. Kolar

2008-01-01

416

A Brief Technology Survey of High-Power Microwave Sources  

SciTech Connect

This report provides a brief summary of the characteristics of contemporary high-power microwave sources. The focus is on their physical and operational characteristics and regions of application rather than their theory of operation. Magnetrons, linear beam tubes, split-cavity oscillators, virtual cathode oscillators, gyrotrons, free-electron lasers, and orbitron microwave masers are described. Power supply requirements and engineering issues of the application of HPM devices are addressed.

BACON,LARRY D.; RINEHART,LARRY F.

2001-04-01

417

Optical fiber instrumentation of a high power generator and turbine  

NASA Astrophysics Data System (ADS)

The instrumentation of a high power generator and its complementary systems including the turbine bearings is presented and discussed. The generator consists of a 175MW hydroelectric generator installed in the Salto Osório power plant in the southern region of Brazil. Results show good agreement with the already existing instrumentation and demonstrate the technology potential for a full optical fiber sensing system to monitor these large machines.

da Silva, Erlon Vagner; Dreyer, Uilian José; de Morais Sousa, Kleiton; Babinski, Valderi Junot; Somenzi, Jonas; Mezzadri, Felipe; de Lourenço Junior, Ivo; Martelli, Cicero; Cardozo da Silva, Jean Carlos

2013-05-01

418

High-power continuous-wave quantum cascade lasers  

Microsoft Academic Search

High-power continuous-wave (CW) laser action is reported for a GaInAs-AlInAs quantum cascade structure operating in the mid-infrared (?≃5 ?m). Gain optimization and reduced heating effects have been achieved by employing a modulation-doped funnel injector with a three-well vertical-transition active region and by adopting InP as the waveguide cladding material to improve thermal dissipation and lateral conductance. A CW optical power

J. Faist; A. Tredicucci; F. Capasso; C. Sirtori; D. L. Sivco; J. N. Baillargeon; A. L. Hutchinson; A. Y. Cho

1998-01-01

419

High power impulse magnetron sputtering using a rotating cylindrical magnetron  

SciTech Connect

Both the industrially favorable deposition technique, high power impulse magnetron sputtering (HIPIMS), and the industrially popular rotating cylindrical magnetron have been successfully combined. A stable operation without arcing, leaks, or other complications for the rotatable magnetron was attained, with current densities around 11 A cm{sup -2}. For Ti and Al, a much higher degree in ionization in the plasma region was observed for the HIPIMS mode compared to the direct current mode.

Leroy, W. P.; Mahieu, S.; Depla, D.; Ehiasarian, A. P. [Department of Solid State Sciences, Ghent University, Krijgslaan 281/S1, 9000 Ghent (Belgium); Nanotechnology Center for PVD Research, Sheffield Hallam University, S1 1WB Sheffield (United Kingdom)

2010-01-15

420

High power pulsed magnetron sputtered CrN x films  

Microsoft Academic Search

Microstructure and macroscopic properties of droplet free CrN films deposited by the recently developed high power pulsed magnetron sputtering (HIPIMS) technique are presented. Magnetron glow discharges with peak power densities reaching 3000 W cm?2 were used to sputter Cr targets in both inert and reactive gas atmospheres. The flux arriving at the substrates consisted of neutrals and ions (approx. 70\\/30)

A. P Ehiasarian; W.-D Münz; L Hultman; U Helmersson; I Petrov

2003-01-01

421

Tape high power neutron producing target for NCT V. Kononova  

E-print Network

therapy. Typical power of available proton beam is within 5 kW, the one of the accelerators under construction ­ 25 kW. Innovative lithium target using energy accumulation for more high power proton beams threshold 7 Li(p,n)7 Be reaction at proton beam with energies 1.915 MeV or 2.5 MeV. Stationary 25 kW neutron

Taskaev, Sergey Yur'evich

422

Further development of high-power pump laser diodes  

Microsoft Academic Search

AlGaAs\\/InGaAs based high power pump laser diodes with wavelength of around 980 nm are key products within erbium doped fiber amplifiers (EDFA) for today's long haul and metro-communication networks, whereas InGaAsP\\/InP based laser diodes with 14xx nm emission wavelength are relevant for advanced, but not yet widely-used Raman amplifiers. Due to the changing industrial environment cost reduction becomes a crucial

Berthold Schmidt; Norbert Lichtenstein; Boris Sverdlov; Nicolai Matuschek; Stefan Mohrdiek; Tomas Pliska; Juergen Mueller; Susanne Pawlik; Sebastian Arlt; Hans-Ulrich Pfeiffer; Arnaud Fily; Christoph Harder

2003-01-01

423

High Power Ka-Band Solid State Amplifier  

Microsoft Academic Search

A Ka-band, high-power, solid-state amplifier has been developed as a direct replacement unit for a TWT in an EHF satellite communications earth terminal. The two-stage amplifier uses silicon double-drift IMPATT diodes and waveguide cavity power-combining techniques to provide 6.2 W of RF output power at an operating frequency of 36.815 GHz. The l-dB injection-locking bandwidth is 270 MHz at the

E. W. Holmes; Y. C. Ngan

1983-01-01

424

Aspects of aluminum toxicity  

SciTech Connect

Aluminum is the most abundant metal in the earth's crust. The widespread occurrence of aluminum, both in the environment and in foodstuffs, makes it virtually impossible for man to avoid exposure to this metal ion. Attention was first drawn to the potential role of aluminum as a toxic metal over 50 years ago, but was dismissed as a toxic agent as recently as 15 years ago. The accumulation of aluminum, in some patients with chronic renal failure, is associated with the development of toxic phenomena; dialysis encephalopathy, osteomalacic dialysis osteodystrophy, and an anemia. Aluminum accumulation also occurs in patients who are not on dialysis, predominantly infants and children with immature or impaired renal function. Aluminum has also been implicated as a toxic agent in the etiology of Alzheimer's disease, Guamiam amyotrophic lateral sclerosis, and parkinsonism-dementia. 119 references.

Hewitt, C.D.; Savory, J.; Wills, M.R. (Univ. of Virginia Health Sciences Center, Charlottesville (USA))

1990-06-01

425

Department of Defense high power laser program guidance  

NASA Astrophysics Data System (ADS)

The DoD investment of nominally $200 million per year is focused on four high power laser (HPL) concepts: Space-Based Laser (SBL), a Ballistic Missile Defense Organization effort that addresses boost-phase intercept for Theater Missile Defense and National Missile Defense; Airborne Laser (ABL), an Air Force effort that addresses boost-phase intercept for Theater Missile Defense; Ground-Based Laser (GBL), an Air Force effort addressing space control; and Anti-Ship Missile Defense (ASMD), a Navy effort addressing ship-based defense. Each organization is also supporting technology development with the goal of achieving less expensive, brighter, and lighter high power laser systems. These activities represent the building blocks of the DoD program to exploit the compelling characteristics of the high power laser. Even though DoD's HPL program are focused and moderately strong, additional emphasis in a few technical areas could help reduce risk in these programs. In addition, a number of options are available for continuing to use the High-Energy Laser System Test Facility (HELSTF) at White Sands Missile Range. This report provides a brief overview and guidance for the five efforts which comprise the DoD HPL program (SBL, ABL, GBL, ASMD, HELSTF).

Muller, Clifford H.

1994-06-01

426

Freeform beam shaping for high-power multimode lasers  

NASA Astrophysics Data System (ADS)

Widening of using high power multimode lasers in industrial laser material processing is accompanied by special requirements to irradiance profiles in such technologies like metal or plastics welding, cladding, hardening, brazing, annealing, laser pumping and amplification in MOPA lasers. Typical irradiance distribution of high power multimode lasers: free space solid state, fiber-coupled solid state and diodes lasers, fiber lasers, is similar to Gaussian. Laser technologies can be essentially improved when irradiance distribution on a workpiece is uniform (flattop) or inverse-Gauss; when building high-power pulsed lasers it is possible to enhance efficiency of pumping and amplification by applying super-Gauss irradiance distribution with controlled convexity. Therefore, "freeform" beam shaping of multimode laser beams is an important task. A proved solution is refractive field mapping beam shaper like Shaper capable to control resulting irradiance profile - with the same unit it is possible to get various beam profiles and choose optimum one for a particular application. Operational principle of these devices implies transformation of laser irradiance distribution by conserving beam consistency, high transmittance, providing collimated low divergent output beam. Using additional optics makes it possible to create resulting laser spots of necessary size and round, elliptical or linear shape. Operation out of focal plane and, hence, in field of lower wavefront curvature, allows extending depth of field. The refractive beam shapers are implemented as telescopes and collimating systems, which can be connected directly to fiber-coupled lasers or fiber lasers, thus combining functions of beam collimation and irradiance transformation.

Laskin, Alexander; Laskin, Vadim

2014-03-01

427

Completely monolithic linearly polarized high-power fiber laser oscillator  

NASA Astrophysics Data System (ADS)

We have demonstrated a linearly polarized cw all-in-fiber oscillator providing 1 kW of output power and a polarization extinction ratio (PER) of up to 21.7 dB. The design of the laser oscillator is simple and consists of an Ytterbium-doped polarization maintaining large mode area (PLMA) fiber and suitable fiber Bragg gratings (FBG) in matching PLMA fibers. The oscillator has nearly diffraction-limited beam quality (M² < 1.2). Pump power is delivered via a high power 6+1:1 pump coupler. The slope efficiency of the laser is 75 %. The electro/optical efficiency of the complete laser system is ~30 % and hence in the range of Rofin's cw non-polarized fiber lasers. Choosing an adequate bending diameter for the Yb-doped PLMA fiber, one polarization mode as well as higher order modes are sufficiently supressed1. Resulting in a compact and robust linearly polarized high power single mode laser without external polarizing components. Linearly polarized lasers are well established for one dimensional cutting or welding applications. Using beam shaping optics radially polarized laser light can be generated to be independent from the angle of incident to the processing surface. Furthermore, high power linearly polarized laser light is fundamental for nonlinear frequency conversion of nonlinear materials.

Belke, Steffen; Becker, Frank; Neumann, Benjamin; Ruppik, Stefan; Hefter, Ulrich

2014-03-01

428

Active high-power RF switch and pulse compression system  

DOEpatents

A high-power RF switching device employs a semiconductor wafer positioned in the third port of a three-port RF device. A controllable source of directed energy, such as a suitable laser or electron beam, is aimed at the semiconductor material. When the source is turned on, the energy incident on the wafer induces an electron-hole plasma layer on the wafer, changing the wafer's dielectric constant, turning the third port into a termination for incident RF signals, and. causing all incident RF signals to be reflected from the surface of the wafer. The propagation constant of RF signals through port 3, therefore, can be changed by controlling the beam. By making the RF coupling to the third port as small as necessary, one can reduce the peak electric field on the unexcited silicon surface for any level of input power from port 1, thereby reducing risk of damaging the wafer by RF with high peak power. The switch is useful to the construction of an improved pulse compression system to boost the peak power of microwave tubes driving linear accelerators. In this application, the high-power RF switch is placed at the coupling iris between the charging waveguide and the resonant storage line of a pulse compression system. This optically controlled high power RF pulse compression system can handle hundreds of Megawatts of power at X-band.

Tantawi, Sami G. (San Mateo, CA); Ruth, Ronald D. (Woodside, CA); Zolotorev, Max (Mountain View, CA)

1998-01-01

429

High-power ultra-broadband frequency comb from ultraviolet to infrared by high-power fiber amplifiers.  

PubMed

A high-power ultra-broadband frequency comb covering the spectral range from ultraviolet to infrared was generated directly by nonlinear frequency conversion of a multi-stage high-power fiber comb amplifier. The 1030-nm infrared spectral fraction of a broadband Ti:sapphire femtosecond frequency comb was power-scaled up to 100 W average power by using a large-mode-area fiber chirped-pulse amplifier. We obtained a frequency-doubled green comb at 515 nm and frequency-quadrupled ultraviolet pulses at 258 nm with the average power of 12.8 and 1.62 W under the input infrared power of 42.2 W, respectively. The carrier envelope phase stabilization was accomplished with an ultra-narrow line-width of 1.86 mHz and a quite low accumulated phase jitter of 0.41 rad, corresponding to a timing jitter of 143 as. PMID:22714317

Yang, Kangwen; Li, Wenxue; Yan, Ming; Shen, Xuling; Zhao, Jian; Zeng, Heping

2012-06-01

430

Transmission of High-Power Electron Beams Through Small Apertures  

SciTech Connect

Tests were performed to pass a 100 MeV, 430 kWatt c.w. electron beam from the energy-recovery linac at the Jefferson Laboratory's FEL facility through a set of small apertures in a 127 mm long aluminum block. Beam transmission losses of 3 p.p.m. through a 2 mm diameter aperture were maintained during a 7 hour continuous run.

Tschalaer, Christoph [MIT Bates Linear Accelerator; Alarcon, Ricardo O.; Balascuta, S.; Benson, Stephen V. [JLAB; Bertozzi, William; Boyce, James R. [College of William and Mary; Cowan, Ray Franklin [MIT; Douglas, David R. [JLAB; Evtushenko, Pavel [JLAB; Fisher, Peter H.; Ihloff, Ernest E. [MIT Bates Linear Accelerator; Kalantarians, Narbe [Unversity of Texas; Kelleher, Aidan Michael [MIT Bates Linear Accelerator; Legg, Robert A. [JLAB; Milner, Richard; Neil, George R. [JLAB; Ou, Longwu [MIT; Schmookler, Barak Abraham [MIT; Tennant, Christopher D. [JLAB; Williams, Gwyn P. [JLAB; Zhang, Shukui [JLAB

2013-11-01

431

Performances of a Compact, High-Power WB Source with Circular Polarization  

NASA Astrophysics Data System (ADS)

This paper presents the design and the performances of an embedded high-power microwave (HPM) wideband source, developed and built at the French-German Research Institute of Saint-Louis. The system was intended for dual use, homeland security, and military applications. It is powered by a 400 kV compact Marx generator with specificities in coaxial design and low energy. The slow monopolar signal from the Marx is sharpened using a pulse-forming stage, made of a switching module pressurized with nitrogen, followed by a monopulse-to-monocycle converter. The duration and rise times of this signal could be adjusted by varying the pressure and space between electrodes. Repetitive operations were performed up to 100 Hz during 10 s without a gas flow. Two kinds of antennas can be connected to the source. The first one is a TEM horn, with an optional dielectric lens, that radiates a vertically polarized UWB short pulse. The second one is a nine-turn helix, working in Kraus monopolar axial mode and radiating a circularly polarized wideband signal along the main axis. A dedicated conical reflector increases its directivity and bandwidth. The whole source is designed to be embedded inside an aluminum trailer, powered by batteries and remote controlled through an optical fiber.

Delmote, P.; Pinguet, S.; Bieth, F.

432

Radiation effects at a high power accelerator and applications to advanced energy sources  

SciTech Connect

Many materials are exposed to atom-displacing radiation at high-power accelerators such as the Los Alamos Meson Physics Facility (LAMPF). Beam current densities in the 800-MeV proton beam vary from 12.5 mA cm{sup {minus}2} (8 {times} 10{sup 16} p/cm{sup 2}s) on graphite targets to 20-{mu}A cm{sup {minus}2} (1.3 {times} 10{sup 14} p/cm{sup 2}s) on metal-alloy windows. High-level radiation damage results from these particle fluxes. As a consequence of secondary-particle generation in targets and windows and low-level beam losses that lead to particle interactions with structural material, various components are exposed to low-level proton fluxes, gamma radiation, and neutron fluxes of 10{sup 6}--10{sup 10} n/cm{sup 2}s. These include vacuum seals and vacuum chambers of stainless steel and aluminum alloys, solid-state devices for control, diagnostic, and data acquisition electronics, closed-loop cooling-water systems, and insulators. Properties of these materials are degraded by the radiation exposure. Studies of LAMPF and other accelerators, however, have produced solutions to materials problems, allowing the machines to operate for acceptable times without failure. Nevertheless, additional improvements are being investigated in order to further improve operational reliability and safety. 25 refs., 3 figs., 3 tabs.

Sommer, W.F.; Garner, F.A.; Brown, R.D.; Wechsler, M.S. (Los Alamos National Lab., NM (USA); Battelle Pacific Northwest Lab., Richland, WA (USA); Los Alamos National Lab., NM (USA); Iowa State Univ. of Science and Technology, Ames, IA (USA))

1989-01-01

433

High-power and high-brightness laser diode structures using Al-free active region  

NASA Astrophysics Data System (ADS)

High bit-rate, WDM, networks are reliant on Er or Er/Yb doped fiber amplifiers. Reliable, high power laser diodes at 980nm and 1480nm are key devices for pumping these amplifiers. We have developed several 980 nm laser diode structures at 980 nm, using an Aluminum free active region and standard AR/HR coatings on the facets. Our laser show low optical losses, low threshold current density and a high external differential efficiency. We demonstrate a mini-bar of small angle index guided tapered laser diodes (emissive width of 3 mm) with an optical output power of 20W at 33A under CW operation (25°C). The far field of the slow axis has a Gaussian single lobed shape, with a FWHM of 3.5° at maximum power, which is two times less than obtained with multimode broad area lasers. With such a device, we expect to couple 10W into a 100?m diameter fiber. We also demonstrate a large aperature gain-guided tapered laser with an output power of 2.4W and a calculated M21/c2 = 3, the M21/c2 factor being calculated with the method based on measurements of the fields profiles widths at 1/c2.

Auzanneau, Sophie-Charlotte; Krakowski, Michel M.; Berlie, Francois; Calligaro, Michel; Robert, Yannick; Parillaud, Olivier; Lecomte, Michel; Boulant, B.; Fillardet, Thierry

2003-07-01

434

Anodizing Aluminum with Frills.  

ERIC Educational Resources Information Center

"Anodizing Aluminum" (previously reported in this journal) describes a vivid/relevant laboratory experience for general chemistry students explaining the anodizing of aluminum in sulfuric acid and constrasting it to electroplating. Additions to this procedure and the experiment in which they are used are discussed. Reactions involved are also…

Doeltz, Anne E.; And Others

1983-01-01

435

Aluminum composite driveshafts  

SciTech Connect

This article examines the development and performance of a metal matrix composite lightweight driveshaft tube of 6061 aluminum alloy with an even dispersion of 20[percent] aluminum oxide particles. The topics of the article include evolution of the lightweight design, raw material production, tubing fabrication, driveshaft performance, and modulus testing.

Not Available

1994-02-01

436

Correlating Aluminum Burning Times  

Microsoft Academic Search

Characteristics of aluminum combustion are summarized in an overview of the subject, focusing on the burning time of individual particles. Combustion data from over ten different sources with almost 400 datum points have been cataloged and correlated. Available models have also been used to evaluate combustion trends with key environmental parameters. The fundamental concepts that control aluminum combustion are discussed,

M. W. Beckstead

2005-01-01

437

Beamshaping for high-power lasers using freeform refractive optics  

NASA Astrophysics Data System (ADS)

High power laser beamshapers based on lens arrays are widely used to generate square, rectangular or hexagonal flat-top far-field beam profiles. These devices can provide high efficiency and excellent brightness preservation, but offer a limited range of far-field profiles and can suffer from diffraction-related artefacts when used with spatially-coherent beams. Diffractive optical elements (DOE) offer a far wider range of far-field profiles, and better speckle behavior, but bring performance trade-offs in terms of brightness, efficiency, scattered power and residual zeroth-order power. Freeform refractive optics offer additional choices in the design of high power laser beamshapers. Freeform lens arrays offer a wider range of beam profile options than that available from catalogue lens array parts. Freeform field mapping beamshapers can generate a wide range of application-specific beam profiles with high efficiency and, where required, minimal reduction in brightness. More complex quasi-random freeform surfaces can act as a pseudorandom refractive intensity mapping element (PRIME), providing a level of beamshaper design flexibility closer to that of DOEs, but without the related high-order scatter and zeroth order leakage. We describe the design and implementation of these different types of refractive beam shaper in fused silica, using PowerPhotonic's direct-write freeform fabrication process. This is ideal for use in high-power laser systems, where high damage threshold and low loss are essential. We compare and contrast the performance, benefits and limitations of these types of beamshaper, and describe how to select the ideal beamshaper type based on source coherence properties and application beam profile requirements.

McBride, Roy; Trela, Natalia; Currie, Matthew O.; Walker, Duncan; Baker, Howard J.

2014-02-01

438

Numerical characterization of micro heat exchangers using experimentally tested porous aluminum layers  

Microsoft Academic Search

A microporous heat exchanger device is being developed for cooling high-power electronics. The device uses a mechanically compressed aluminum porous layer to improve the heat transfer at the coolant\\/solid interface and to provide more uniform cooling of the electronics. The hydraulic characteristics (porosity, permeability, and Forchheimer coefficient) of nine distinct compressed layers are obtained experimentally. These layers have porosity from

D. C. Price; R. M. Weber

1996-01-01

439

Fabrication of pump combiners for high-power fiber lasers  

NASA Astrophysics Data System (ADS)

A custom fabrication procedure for pump combiners matched to a wide variety of double-clad fibers used in high power fiber lasers has been developed. Both combiners with and without feedthrough can be fabricated with an improved repeatability thanks to a specific mechanical setup that simplifies placing the fibers in their proper location within the input bundle before the tapering and fusion processes. Extensive characterization results on 7-to-1 and on (6+1)-to-1 combiners are confirming the validity of the proposed approach.

Braglia, Andrea; Olivero, Massimo; Neri, Alessandra; Perrone, Guido

2011-02-01

440

Optical power splitter for splitting high power light  

DOEpatents

An optical power splitter for the distribution of high-power light energy has a plurality of prisms arranged about a central axis to form a central channel. The input faces of the prisms are in a common plane which is substantially perpendicular to the central axis. A beam of light which is substantially coaxial to the central axis is incident on the prisms and at least partially strikes a surface area of each prism input face. The incident beam also partially passes through the central channel. 5 figs.

English, R.E. Jr.; Christensen, J.J.

1995-04-18

441

COMPARATIVE STUDIES OF PROTON ACCELERATORS FOR HIGH POWER APPLICATIONS.  

SciTech Connect

There are many applications requiring high power proton accelerators of various kinds. However, each type of proton accelerator can only provide beam with certain characteristics, hence the match of accelerators and their applications need careful evaluation. In this talk, the beam parameters and performance limitations of linac, cyclotron, synchrotron, and FFAG accelerators are studied and their relative merits for application in neutron, muon, neutrino, and ADS will be assessed in terms of beam energy, intensity, bunch length, repetition rate, and beam power requirements. A possible match between the applications and the accelerator of choice is presented in a matrix form. The accelerator physics and technology issues and challenges involved will also be discussed.

WENG, W.T.

2006-05-29

442

High power RF solid state power amplifier system  

NASA Technical Reports Server (NTRS)

A high power, high frequency, solid state power amplifier system includes a plurality of input multiple port splitters for receiving a high-frequency input and for dividing the input into a plurality of outputs and a plurality of solid state amplifier units. Each amplifier unit includes a plurality of amplifiers, and each amplifier is individually connected to one of the outputs of multiport splitters and produces a corresponding amplified output. A plurality of multiport combiners combine the amplified outputs of the amplifiers of each of the amplifier units to a combined output. Automatic level control protection circuitry protects the amplifiers and maintains a substantial constant amplifier power output.

Sims, III, William Herbert (Inventor); Chavers, Donald Gregory (Inventor); Richeson, James J. (Inventor)

2011-01-01

443

A high-power compact regenerative amplifier FEL  

SciTech Connect

The Regenerative Amplifier FEL (RAFEL) is a new FEL approach aimed at achieving the highest optical po