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1

Dynamics of a high-power aluminum-wire array Z-pinch implosion  

SciTech Connect

Annular Al-wire Z-pinch implosions on the Saturn accelerator [D. D. Bloomquist {ital et al.}, {ital Proceedings, 6th Pulsed Power Conference} (Institute of Electrical and Electronics Engineers, New York, 1987), p. 310] that have high azimuthal symmetry exhibit both a strong first and weaker second x-ray burst that correlate with strong and weaker radial compressions, respectively. Measurements suggest that the observed magnetic Rayleigh{endash}Taylor (RT) instability prior to the first compression seeds an m=0 instability observed later. Analyses of axially averaged spectral data imply that, during the first compression, the plasma is composed of a hot core surrounded by a cooler plasma halo. Two-dimensional (2-D) radiation magnetohydrodynamic computer simulations show that a RT instability grows to the classic bubble and spike structure during the course of the implosion. The main radiation pulse begins when the bubble reaches the axis and ends when the spike finishes stagnating on axis and the first compression ends. These simulations agree qualitatively with the measured characteristics of the first x-ray pulse and the overall energetics, and they provide a 2-D view into the plasma hydrodynamics of the implosion.

Sanford, T.W.; Nash, T.J.; Mock, R.C.; Spielman, R.B.; Struve, K.W. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States); Hammer, J.H.; De Groot, J.S. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Whitney, K.G.; Apruzese, J.P. [Naval Research Laboratory, Radiation Hydrodynamics Branch, Washington, D.C. 20375 (United States)] [Naval Research Laboratory, Radiation Hydrodynamics Branch, Washington, D.C. 20375 (United States)

1997-06-01

2

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

3

Structure of stagnated plasma in aluminum wire array Z pinches  

NASA Astrophysics Data System (ADS)

Experiments with aluminum wire array Z pinches have been carried out on the mega-ampere generator for plasma implosion experiments (MAGPIE) at Imperial College London [I. H. Mitchell et al., Rev. Sci. Instrum. 67, 1533 (1996)]. It has been shown that in these arrays, there are two intense sources of radiation during stagnation; Al XII line emission from a precursor-sized object, and both continuum and Al XIII radiation from bright spots of either significantly higher temperature or density randomly distributed around this object so as to produce a hollow emission profile. Spatially resolved spectra produced by spherically bent crystals were recorded, both time-integrated and time-resolved, and were used to show that these two sources of radiation peak at the same time.

Hall, G. N.; Pikuz, S. A.; Shelkovenko, T. A.; Bland, S. N.; Lebedev, S. V.; Ampleford, D. J.; Palmer, J. B. A.; Bott, S. C.; Rapley, J.; Chittenden, J. P.; Apruzese, J. P.

2006-08-01

4

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

5

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

6

Use of the Pegasus Z pinch machine to study inertial instabilities in aluminum: a preliminary report  

SciTech Connect

We have designed a target to probe the use of the Pegasus Z-Pinch machine to image inertial instabilities that develop on cylindrical- convergent material interfaces. The Z-pinch is tailored so that the target, soft Al 1100-O, remains solid; instabilities and inertial effects are seeded by wire inclusions of different densities. We present here the first images and preliminary results from this experiment.

Chandler, E.; Egan, P.; Winer, K.; Stokes, J.; Fulton, R.D.; King, N.S.P.; Morgan, D.V.; Obst, A.W.; Oro, D.W.

1997-06-13

7

On Perspectives of Creation of High-Power Neutron Source at Deuterium Plasma Compression in Z-? Pinch Geometry  

NASA Astrophysics Data System (ADS)

Calculation results of thermonuclear neutrons yield at compression of cylindrical column of deuterium plasma with longitudinal magnetic field, compressed by external tungsten plasma liner (Z-? pinch geometry) are presented. Numerical simulations are presented for conditions of PBFA-Z facility in complete one-dimensional magneto-hydro-dynamical setup with radiation transfer in diffuse approximation. Scaling dependencies of neutron yield from the value of initial longitudinal magnetic field and mass density of deuterium gas are obtained.

Selemir, V. D.; Ivanovsky, A. V.; Orlov, A. P.; Yermolovich, V. F.; Dolgoleva, G. V.; Demidov, V. A.; Karelin, V. I.; Repin, P. B.

2002-12-01

8

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

9

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

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

10

Characterization of axially directed x rays generated from a target within a high-power z-pinch (abstract)  

NASA Astrophysics Data System (ADS)

X-ray powers on the order of 10 TW over an area of 4.5 mm2 are produced in the axial direction from the compression of a low-density foam target centered within a z-pinch on the Z generator.1 The x rays from this source are used for high-energy-density physics experiments, including the heating of hohlraums for inertial confinements fusion studies.2 In this article, detailed characteristics of this radiation source measured using an upgraded axial-radiation-diagnostic suite3 together with other on- and off-axis diagnostics are summarized and discussed in terms of Eulerian and Lagrangian radiation-magnetohydrodynamic code simulations. The source, characterized here, employs a nested array of 10-mm-long tungsten wires, at radii of 20 and 10 mm, having a total masses of 2 and 1 mg, and wire numbers of 240 and 120, respectively. The target is a 14 mg/cc CH2 foam cylinder of 5 mm diameter. The codes take into account the development of the Rayleigh-Taylor instability in the r-z plane, and provide integrated calculations of the implosion together with the x-ray generation. The radiation exiting the imploding target through the 4.5 mm2 aperture is measured primarily by the axial diagnostic suite that now includes diagnostics at an angle of ~30° to the z axis. The near on-axis diagnostics include: (1) a seven-element filtered silicon-diode array,4 (2) a five-element filtered x-ray diffraction (XRD) array,5 (3) a six-element filtered PCD array,6 (4) a three-element bolometer,7 (5) time-resolved and time-integrating crystal spectrometers, and (6) two fast-framing x-ray pinhole cameras having 11 frames each. The filtered silicon diodes, XRDs, and PCDs are sensitive to 1-200, 140-2300, and 1000-4000 eV x rays, respectively. They (1) establish the magnitude of the prepluse generated during the run in of the imploding wire arrays, (2) measure the Planckian nature of the dominant thermal, and (3) nonthermal component of the emission. The bolometers and XRDs mounted on the near-normal and 30° LOS (line-of-sight) measure the total power and check the Lambertian nature of the emission. Additionally, a suite of filtered fast-framing x-ray pinhole cameras and silicon-diode arrays behind a transmission grating, mounted on LOSs nearly normal to the z axis, quantify the plasma plume exiting the aperture. The hard bremsstrahlung generated is estimated with both on- and off-axis shielded scintillator photomultiplier diagnostics.

Sanford, T. W. L.; Bailey, J. E.; Chandler, G. A.; Cuneo, M. E.; Fehl, D. L.; Hebron, D. E.; Leeper, R. J.; Lemke, R. W.; Mock, R. C.; Olson, R. E.; Nash, T. J.; Porter, J. L.; Ruggles, L. E.; Ruiz, C. L.; Simpson, W. W.; Struve, K. W.; Stygar, W. A.; Bowers, R. L.; Chrien, R. E.; Idzorek, G. C.; Matuska, W.; Peterson, D. L.; Watt, R. G.

2001-01-01

11

Dense Z-pinch plasmas  

SciTech Connect

Early researchers recogniZed the desirable features of the linear Z-pinch configuration as a magnetic fusion scheme. In particular, a Z-pinch reactor might not require auxiliary heating or external field coils, and could constitute an uncomplicated, high plasma ..beta.. geometry. The simple Z pinch, however, exhibited gross MHD instabilities that disrupted the plasma, and the linear Z pinch was abandoned in favor of more stable configurations. Recent advances in pulsed-power technology and an appreciation of the dynamic behavior of an ohmically heated Z pinch have led to a reexamination of the Z pinch as a workable fusion concept.

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

1985-07-12

12

Fusion with Z-pinches  

SciTech Connect

In the past thirty-six months, great progress has been made in x-ray production using high-current z-pinches. Today, the x-ray energy and power output of the Z accelerator (formerly PBFA-II) is the largest available in the laboratory. These z-pinch x-ray sources have the potential to drive high-yield ICF reactions at affordable cost if several challenging technical problems can be overcome. In this paper, the recent technical progress with Z-pinches will be described, and a technical strategy for achieving high-yield ICF with z-pinches will be presented.

Cook, D.

1998-06-01

13

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

14

Physics of fast Z pinches.  

National Technical Information Service (NTIS)

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 therm...

D. D. Ryutov M. S. Derzon M. K. Matzen

1998-01-01

15

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

16

Z-pinch like Experimental Arrangements  

SciTech Connect

The Plasma Physics Group at Pontificia Universidad Catolica de Chile (PUCC) has been investigating z-pinch like plasmas for the last twenty years. Here we present experimental observations on a variety of z-pinch like plasmas, using a range of very small to medium size pulse power drivers. The experiments include low and high current capillary discharge, plasma focus pinch, hollow gas embedded z-pinch, x-pinch and wire-array pinch. Different diagnostics are used to characterize the plasma dynamics and radiation properties of the different z-pinch plasma, as well as the emission of plasma jets and ion beams.

Favre, M.; Aliaga-Rossel, R.; Pernas, A.; Avaria, G.; Bhuyan, H.; Caballero, S.; Chuaqui, H.; Mitchell, I.; Molina, F.; Suzuki, F.; Veloso, F.; Wyndham, E. [Departamento de Fisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile)

2006-12-04

17

Intense neutron pulse generation in dense Z-pinch  

SciTech Connect

The problem of intense neutron pulse generation with fast dense Z-pinches (ZP) is analyzed for a modified approach. The analysis pertains to the interaction of a High Power Deuterium Beam (HPDB) with hot ({ital T}{sub {ital e}}{congruent}1 keV) deuterium target formed by a ZP. The considerable decrease of the Coulomb ion-electron scattering cross-sections gives a corresponding increase of the deuterium range and neutron yield in the hot target.

Bystritskii, V.M.; Glusko, Y.A.; Mesyats, G.A. (Institute of Electrophysics,Sverdlovsk (USSR)); Ratakhin, N.A. (Institute of High Current Electronics, Tomsk (USSR))

1989-12-01

18

The physics of fast Z pinches  

Microsoft Academic Search

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. At present Z pinches are the most intense laboratory x-ray sources (1.8 MJ in 5 ns from a

D. D. Ryutov; M. S. Derzon; M. K. Matzen

2000-01-01

19

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

20

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. At present 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 quasiequilibrium 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. Nonmagnetohydrodynamic 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. (c) 2000 The American Physical Society.

Ryutov, D. D. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Derzon, M. S. [Sandia National Laboratories, Albuquerque, New Mexico, 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico, 87185 (United States); Matzen, M. K. [Sandia National Laboratories, Albuquerque, New Mexico, 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico, 87185 (United States)

2000-01-01

21

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

22

Plasma formation in metallic wire Z pinches  

SciTech Connect

Plasma formation in metallic wire Z pinches is modeled using a two-dimensional resistive magnetohydrodynamics code. Modified Thomas-Fermi equations of state and dense plasma transport coefficients allow the phase transitions from solid to plasma to be approximated. Results indicate the persistence of a two-component structure with a cold, dense core embedded within a much hotter, low density, m=0 unstable corona. Extensive benchmark testing against data from a number of single-wire experiments is presented. Artificial laser schlieren and x-ray back-lighting images generated from the code data are compared directly to experimental results. The results were found to be insensitive to inaccuracies in the equations of state and transport coefficients. Simulations of individual wires in a wire array show different behavior to that observed experimentally due to the absence of three-dimensional effects. Simulations with similar conditions to wires in an array show a general trend in the plasma structure at start of implosion from discrete wires with large m=0 perturbation amplitudes to partially merged wires with smaller perturbation amplitudes as the number of wires is increased. Results for a wire number scan with aluminum wire arrays on the SATURN generator suggest that the observed sharp transition to high x-ray power at around 40 wires corresponds to a sharp decrease in m=0 perturbation amplitude and hence a sharp decrease in the seed perturbation for the Rayleigh-Taylor instability. (c) 2000 The American Physical Society.

Chittenden, J. P. [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom)] [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom); Lebedev, S. V. [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom)] [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom); Ruiz-Camacho, J. [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom)] [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom); Beg, F. N. [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom)] [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom); Bland, S. N. [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom)] [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom); Jennings, C. A. [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom)] [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom); Bell, A. R. [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom)] [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom); Haines, M. G. [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom)] [Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom); Pikuz, S. A. [P. N. Lebedev Physical Institute, Moscow 121433, Russia (Russian Federation)] [P. N. Lebedev Physical Institute, Moscow 121433, Russia (Russian Federation); Shelkovenko, T. A. [P. N. Lebedev Physical Institute, Moscow 121433, Russia (Russian Federation)] [P. N. Lebedev Physical Institute, Moscow 121433, Russia (Russian Federation)

2000-04-01

23

Inertial Confinement Fusion in a Z-? Pinch  

NASA Astrophysics Data System (ADS)

The implosion of a dense ? pinch plasma driven by an annular Z-pinch is considered. A cryogenic fiber is coaxially located within an annular gas jet Z-pinch. The imploding Z-pinch traps an applied axial magnetic field and conserves flux. The axial magnetic field increases due to compression of the outer pinch and attains values in excess of tens of megagauss with field risetimes of order, dB/dt = 10MG/ns, with an order of magnitude shorter rise time than the Z-pinch current. An azimuthal ?-current is induced on the fiber surface with a similar rise time; which could not otherwise be achieved in a simple fiber Z-pinch due to the large inductance initially presented by the small diameter axial plasma. The implosion transfers Z-pinch kinetic energy to the magnetic field and then to the ?-pinch. The final plasma pressure of the ?- pinch exceeds the magnetic pressure so that the ?-pinch then expands-the only confinement is inertial. To reach break-even and beyond, with reasonable Z-pinch currents, we increase the radiative losses by seeding the discharge with high Z impurities. Seeding a cryogenic Hydrogen-like fiber with high Z-impurities would substantially reduce the preheat in the ?-pinch, over a non-seeded discharge, and increase the final density by radiative collapse. Thus n? ~ 1014 cm-3 -s could be reached with a confinement time of 0.01 ns and density of 1025 cm-3 predicted in this paper.

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

1994-03-01

24

Use of Z-pinch sources for high-pressure shock wave studies  

SciTech Connect

In this paper, we will discuss the use of z-pinch sources for shock wave studies at multi-Mbar pressures. Experimental plans to use the technique for absolute shock Hugoniot measurements are discussed. Recent developments have demonstrated the use of pulsed power techniques for producing intense radiation sources (Z pinches) for driving planar shock waves in samples with spatial dimensions significantly larger than possible with other radiation sources. Initial indications are that using Z pinch sources for producing Planckian radiation sources in secondary hohlraums can be used to drive shock waves in samples with diameters to a few millimeters and thickness approaching one millimeter in thickness. These dimensions provides the opportunity to measure both shock velocity and the particle velocity behind the shock front with accuracy comparable to that obtained with gun launchers. In addition, the peak hohlraum temperatures of nearly 150 eV that are now possible with Z pinch sources result in shock wave pressures approaching 45 Mbar in high impedance materials such as tungsten and 10-15 Mbar in low impedance materials such as aluminum and plastics. In this paper, we discuss the use of Z pinch sources for making accurate absolute EOS measurements in the megabar pressure range.

Konrad, C.H.; Asay, J.R.; Hall, C.A. [and others

1998-01-01

25

Modeling of Z-pinch-driven hohlraums  

NASA Astrophysics Data System (ADS)

We extend earlier modeling of z-pinch driven hohlraum experiments and continue to evaluate the potential for ICF in a double-ended z-pinch driven hohlraum configuration(J.H. Hammer, et al., Phys. Plas. 6, 2129 (1999).). Initial experiments on hohlraum energetics in a single-ended geometry are in good agreement with detailed radiation hydrodynamics calculations. Modeling of foam ball experiments gives ablation rates and symmetry in good agreement with observations near the peak of the radiation pulse, but less early-time ablation than observed. We will explore sources of the early foam ball ablation, e.g. more low-level "foot" radiation than included in the initial modeling or plasma flow from the pinch region. Energy coupling from the pinch hohlraum to the secondary hohlraum through a spoke array is a critical feature of the concept and will also be discussed.

Hammer, James; Rambo, Peter; Zimmerman, George; Cuneo, Michael; Asay, James; Hall, Clint; Hanson, David; Porter, John, Jr.; Slutz, Steve; Vesey, Roger

1999-11-01

26

Evaluation of a Z-pinch-driven ICF Concept  

Microsoft Academic Search

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

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

1998-01-01

27

Enhanced Staged Z-Pinch Stability  

NASA Astrophysics Data System (ADS)

A Staged Z-Pinch(H. U. Rahman, F. J. Wessel, N. Rostoker, Phys. Rev. Lett 74), p. 714(1995). consisting of a high-Z shell imploding onto a low-Z coaxial-target was investigated for enhanced stability of the implosion of the coaxial-target. This stability results from the high magnetic shear developed from an external axial-magnetic field and the azimuthal-magnetic field diffusing through the high-Z shell. The load configuration consists of a 4-cm diameter Krypton-gas shell impoding onto a coaxial 3-cm Deuterium gas column, with a 0-0.5 Tesla external axial-magnetic field. This Staged Z-Pinch is being tested on the UCI ZOT Pinch Facility with 50 kJ bank energy, 1.4 MA current, 1.1-?sec risetime and various diagnostics. Recent experimental findings will be reported.

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

1998-11-01

28

Fusion Propulsion Z-Pinch Engine Concept  

NASA Technical Reports Server (NTRS)

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 spaceflight 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 assembly1. 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(exp -6 sec). 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 Decade Module 2 (DM2), approx.500 KJ pulsed-power is coming to the RSA Aerophysics Lab managed by UAHuntsville in January, 2012. 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.

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

2011-01-01

29

Stagnation of a Gas Puff Z Pinch  

NASA Astrophysics Data System (ADS)

Two dimensional MHD computer simulations of the stagnation of a gas puff Z pinch were carried out using an adaptation of the M3D code [1]. The implosion of the Z pinch is driven by a magnetic piston. The piston front is Rayleigh Taylor unstable. Ahead of the magnetic piston is a shock wave, which is stable. The laminar, stable shock reaches the geometric axis and reflects. The high density core plasma expands until it collides with the incoming magnetic piston at the stagnation radius. Thereafter the plasma column contracts, and turbulent motion is transferred to the plasma column, causing it to break up. The kinetic energy in the plasma column decays on the time scale in which the plasma expands to the stagnation radius. Stagnation occurs for ?<=1, where ? is the ratio of plasma pressure in the column to magnetic pressure outside the column. A simple radiation model is introduced, and the dependence of stagnation radius on radiation and ? is determined. Recent measurements [2] are consistent with these results. [4pt] [1] W. Park, E.V. Belova, G.Y. Fu, X. Tang, H.R. Strauss, L.E. Sugiyama, Phys. Plasmas 6, 1796 (1999). [0pt] [2] E. Kroupp, D. Osin, A. Starobinets, V. Fisher, V. Bernshtam, Y. Maron, I. Uschmann, E. F"orster, A. Fisher, and C. Deeney, Phys. Rev. Lett. 98, 115001 (2007).

Strauss, Henry

2011-11-01

30

Modeling Z-pinch implosions in two dimensions  

Microsoft Academic Search

Summary form only given. Ideally, simulations of Z-pinch implosions should provide useful information about important physics processes underlying observed experimental results and provide design capabilities for future experiments. With this goal we have developed a methodology for simulating hollow Z-pinches in two dimensions and applied it to experiments conducted on the Pegasus I and Pegasus II capacitor banks, the Procyon

D. Peterson; R. Bowers; J. Brownell; C. Lund; W. Matuska; K. McLenithan; H. Oona; T. Scannapieco; C. Deeney; M. Derzon; R. B. Spielman; T. Nash; G. Chandler; R. Mock; T. W. L. Sanford; M. K. Matzen

1997-01-01

31

Recent results on the dense Z-pinch  

SciTech Connect

A detailed description of the ongoing high density Z-pinch experiments at Los Alamos is given. A review of past dense experiments is included. A model for a dense Z pinch as a high-Q, low yield, reactor system is presented.

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

1982-01-01

32

Z-pinch plasma neutron sources  

NASA Astrophysics Data System (ADS)

A deuterium gas-puff load imploded by a multi-MA current driver from a large initial diameter could be a powerful source of fusion neutrons, a plasma neutron source (PNS). Unlike the beam-target neutrons produced in Z-pinch plasmas in the 1950s and deuterium-fiber experiments in the 1980s, the neutrons generated in deuterium gas-puffs with current levels achieved in recent experiments on the Z facility at Sandia National Laboratories could contain a substantial fraction of thermonuclear origin. For recent deuterium gas-puff shots on Z, our analytic estimates and one- and two-dimensional simulations predict thermal neutron yields ~3×1013, in fair agreement with the yields recently measured on Z [C. A. Coverdale et al., Phys. Plasmas (to be published)]. It is demonstrated that the hypothesis of a beam-target origin of the observed fusion neutrons implies a very high Z-pinch-driver-to-fast-ions energy transfer efficiency, 5 to 10%, which would make a multi-MA deuterium Z-pinch the most efficient light-ion accelerator. No matter what mechanism is eventually determined to be responsible for generating fusion neutrons in deuterium gas-puff shots on Z, the deuterium neutron yield is shown to scale as Yn~Im4, where Im is the peak current of the pinch. Theoretical estimates and numerical modeling of deuterium gas-puff implosions demonstrate that the yields of thermonuclear fusion neutrons that can be produced on ZR and the next-generation machines are sufficiently high to make PNS the most powerful, cost- and energy-efficient laboratory sources of 2.5-14 MeV fusion neutrons, just like plasma radiation sources are the most powerful sources of soft and keV x rays. In particular, the predicted deuterium-tritium thermal neutron-producing capability of PNS driven by the next-generation ZR and ZX accelerators is ~5×1016 and ~1018, respectively.

Velikovich, A. L.; Clark, R. W.; Davis, J.; Chong, Y. K.; Deeney, C.; Coverdale, C. A.; Ruiz, C. L.; Cooper, G. W.; Nelson, A. J.; Franklin, J.; Rudakov, L. I.

2007-02-01

33

Breakeven Fusion in Staged Z Pinch  

NASA Astrophysics Data System (ADS)

We are studying the prospect for breakeven thermonuclear fusion considering a Mega joule (MJ) class, 100 ns, impulse generator using a modified version of MACH2, a 2-1/2 D, radiation-code. The load is a cylindrical, xenon plasma shell that implodes radially onto a co-axial, deuterium-tritium plasma target. Optimized plasma density and pinch radius lead to a fusion-energy output that is many times the stored capacitor bank energy. In this ``Staged Z-pinch'' shock fronts form that preheat the DT plasma to several hundred eV, before adiabatic compression. During compression, the Xe liner becomes Rayleigh-Taylor (RT) unstable while the DT target remains stable. Proper selection of the initial pinch radius and plasma density is crucial for optimum implosion efficiency.

Rahman, Hafiz; Ney, Paul; Rostoker, Norman; Wessel, Frank

2008-03-01

34

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

35

Implosion dynamics of a radiative composite Z-pinch  

SciTech Connect

2D simulation of a composite Z-pinch was performed by the complete radiative magnetohydrodynamic code ZETA including detailed calculation of EOS, spectral properties of materials and radiation transport in non-LTE multicharged ions plasma.

Benattar, R.; Ney, P.; Nikitin, A.; Zakharov, S. V.; Otochin, A. A.; Starostin, A. N.; Stepanov, A. E.; Roerich, V. K.; Nikiforov, A. F.; Novikov, V. G.; Solomyannaya, A. D.; Gasilov, V. A.; Krukovskii, A. Yu. [LPMI, Ecole Polytechnique (France); Troitsk Institute for Innovation and Thermonuclear Investigation (TRINITI) (Russian Federation); Keldysh Institute for Applied Mathematics (Russian Federation); Institute for Mathematical Modeling (Russian Federation)

1997-05-05

36

Implosion dynamics of a radiative composite Z-pinch  

Microsoft Academic Search

2D simulation of a composite Z-pinch was performed by the complete radiative magnetohydrodynamic code ZETA including detailed calculation of EOS, spectral properties of materials and radiation transport in non-LTE multicharged ions plasma.

R. Benattar; P. Ney; A. Nikitin; S. V. Zakharov; A. A. Otochin; A. N. Starostin; A. E. Stepanov; V. K. Roerich; A. F. Nikiforov; V. G. Novikov; A. D. Solomyannaya; V. A. Gasilov; A. Yu. Krukovskii

1997-01-01

37

Implosion dynamics of a radiative composite Z-pinch  

NASA Astrophysics Data System (ADS)

2D simulation of a composite Z-pinch was performed by the complete radiative magnetohydrodynamic code ZETA including detailed calculation of EOS, spectral properties of materials and radiation transport in non-LTE multicharged ions plasma.

Benattar, R.; Ney, P.; Nikitin, A.; Zakharov, S. V.; Otochin, A. A.; Starostin, A. N.; Stepanov, A. E.; Roerich, V. K.; Nikiforov, A. F.; Novikov, V. G.; Solomyannaya, A. D.; Gasilov, V. A.; Krukovskii, A. Yu.

1997-05-01

38

Z-Pinch Drivers for Shock Physics Research  

Microsoft Academic Search

The recent development of Z pinch drivers for producing intense radiation envkomn~ enables study of physical and mechanical properties of condensed materials in regimes previously inaccessible in the Mm-am-y. With Z pinch radiation sources, it is possible fo subject mm-sized sampies to pianar compressions of a fe w Mbar. Tie-resolved velocity interferometry was used to perform the first shock loading

J. Asay; M. Bernard; B. Clark; K. Fleming; C. Hall; K. Holland; D. McDaniel; R. Spielman; W. Stygar; W. Trott

1998-01-01

39

Self-Organized Structures In Z-Pinch Devices  

NASA Astrophysics Data System (ADS)

In several z-pinch devices there has been observation of regular structures, which appear systematically when repeating the experiments. The fact that very identifiable, recurrent, geometrical structures appear in z-pinches, which are relatively long lived, has motivated the analysis of the experimental data from the point of view of self-organization: there is an input of energy in the form of Joule heating, and densely magnetized plasma is formed, stabilized by several MHD effects and the expulsion of entropy.

Ortiz-Tapia, Arturo

2006-12-01

40

Implosion dynamics of a radiative composite Z-pinch  

Microsoft Academic Search

Two-dimensional simulation of a composite Z-pinch was performed by the complete radiative magnetohydrodynamic (MHD) code ZETA including detailed calculation of equations of state, spectral properties of materials, and radiation transport in non-local thermodynamic equilibrium multicharged ions plasma. The initial geometry, the substance components, and the electric current through the Z-pinch were similar to the joint experiment set up JEX-94 at

R. Benattar; P. Ney; A. Nikitin; S. V. Zakharov; A. A. Otochin; A. N. Starostin; A. E. Stepanov; V. K. Roerich; A. F. Nikiforov; V. G. Novikov; A. D. Solomyannaya; V. A. Gasilov; A. Yu. Krukovskii

1998-01-01

41

Faraday Rotation Measurements on Z-Pinches Final Report  

SciTech Connect

The Campus Executive Program sponsored this research at Cornell University. The research was directed toward the implementation of laser-based diagnostics for wire-array Z-pinches. Under this contract we were able to carry out all the necessary preparations to setup the laser diagnostics to complement our x-ray backlighting measurements of the early phase of exploding wire z-pinch plasma formation.

Greenley, J.B.

1998-10-01

42

Common understandings of phenomena in z-pinches  

NASA Astrophysics Data System (ADS)

Common problems which are observed in gas-puff z-pinch experiments are discussed. The crowbar of plasma current is observed in z-pinches which automatically occurs due to short circuiting near the power feed. The emissivity of x-ray increases with z of the operating gas. The higher the z of the gas, the larger the input energy during the contraction.

Takasugi, Keiichi; Suzuki, Hideaki; Moriyama, Kinya; Miyamoto, Tetsu

1994-06-01

43

The high density Z-pinch  

SciTech Connect

During the past few years techniques have been developed for producing pinches in solid deuterium. The conditions which exist in these plasmas are quiet different from those produced earlier. The pinch is formed from a fiber of solid deuterium rather than from a low density gas, and the current is driven by a low impedance, high voltage pulse generator. Because of the high initial density, it is not necessary to compress the pinch to reach thermonuclear conditions, and the confinement time required for energy production is much shorter than for a gas. The experimental results, which have been verified by experiments performed at higher current were quite surprising and encouraging. The pinch appeared to be stable for a time much longer than the Alfven radial transit time. In this paper, however, I argue that the pinch is not strictly stable, but it does not appear to disassemble in a catastrophic fashion. It appears that there may be a distinction between stability and confinement in the high density pinch. In the discussion below I will present the status of the high density Z-pinch experiments at laboratories around the world, and I will describe some of the calculational and experimental results. I will confine my remarks to recent work on the high density pinch. 17 refs. 10 figs.

McCall, G.H.

1988-01-01

44

Observations on a compressional z-pinch  

NASA Astrophysics Data System (ADS)

Observataions on a compressional Z-pinch, in which the heating is due to a cylindrical shock, are presented. The pinch is formed in hydrogen or argon in a 20 mm diameter quartz tube and is driven by a pulse forming line delivering a current pulse of 100-150 kA reversing after 260 ns. In previously reported work it was shown that the pinch was maintained after current reversal. No instabilities were seen. For hydrogen pinches soft X-ray observations have been analysed to give radial profiles of the electron temperature and density, and from these, using pressure equilibrium, the current distribution and total current in the pinch is determined. The results show that the current in the pinch does not reverse. This confirms that there is a crowbar of the current through a wall plasma when the pinch is formed and that this is responsible for the long term equilibrium. The stability is compared with theoretical models. The observations of argon pinches show that these also exhibit long term equilibrium and gross stability. An applicatation of the argon pinch to obtain and X-ray laser at 69.8 nm is discussed.

Bayley, J. M.; Baldock, P.; Dangor, A. E.

1989-12-01

45

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

46

An ICF system based on Z-pinch radiation produced by an explosive magnetic generator  

NASA Astrophysics Data System (ADS)

It is known that a thermonuclear target can be ignited by an implosion accomplished with X-radiation generated by means of laser radiation conversion or by a Z pinch formed by a high-power current pulse. For these purposes laser facility NIF has been constructed in the USA, 'Megajoule' is being constructed in France and there is a project of laser facility UFL in Russia. The project of stationary facility X has been developed in SNL USA to produce a Z pinch capable of generating an x-ray pulse with parameters close to the ignition threshold. There is a great chance, however, that the already tested technologies, including disc explosive magnetic generators (DEMG), systems of current peaking based on electrically exploded foil opening switches and high-voltage switching devices, allow the intriguing problem of the ignition feasibility to be solved and the quickest and cheapest way to accomplish this to be provided. To explore this possibility, the paper will sequentially analyse the ignition conditions. The required parameters of Z pinch X-radiation and the size of the DEMG-based facility to obtain these parameters will be evaluated. Capabilities of the new current sources based on the DEMG and of the devices shaping a current pulse will be presented and compared with those required for the ignition.

Garanin, S. G.; Ivanovsky, A. V.; Mkhitariyan, L. S.

2011-10-01

47

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

48

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

49

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

50

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

51

Adaptive Wavelet Techniques in Z-Pinch Research  

NASA Astrophysics Data System (ADS)

We examine denoising, pattern detection and information compression capabilities of special classes of wavelet families adapted to various 1D and 2D signals that arise in Z-Pinch research. In particular, we analyze X-ray bolometry data where the challenge is to extract accurate power vs time information (which requires differentiation) from noisy energy data. We will also treat X-ray images of symmetric ICF capsule implosions from double Z-Pinch hohlraum drives. Here we wish to denoise the data and identify the contributions from certain low order Legendre polynomials which indicate the degree of asymmetry found in these implosions [M. E. Cuneo et al., PRL 88, 215004-1, 2002]. A combined wavelet-Legendre, cartesian tensor product wavelet and polar coordinate decompositions will be presented together with a comparison of wavelet vs curvelet techniques. Extensions to other X-ray data from Z-Pinch implosions such as pinhole imagery or their simulation, will be given.

Afeyan, Bedros; Won, Kirk; Struve, Kenneth; Deeny, Christopher; Cuneo, Michael; Bennett, Guy; Vessey, Roger; Porter, John

2002-11-01

52

Seeded perturbations in wire array Z-Pinches.  

SciTech Connect

Controlled seeding of perturbations is employed to study the evolution of wire array z-pinch implosion instabilities which strongly impact x-ray production when the 3D plasma stagnates on axis. Wires modulated in radius exhibit locally enhanced magnetic field and imploding bubble formation at discontinuities in wire radius due to the perturbed current path. Wires coated with localized spectroscopic dopants are used to track turbulent material flow. Experiments and MHD modeling offer insight into the behavior of z-pinch instabilities.

Robinson, Allen Conrad; Fedin, Dmitry (University of Nevada, Reno); Kantsyrev, Victor Leonidovich (University of Nevada, Reno); Wunsch, Scott Edward; Oliver, Bryan Velten (Mission Research); Lebedev, Sergey V. (Imperial College); Coverdale, Christine Anne; Ouart, Nicholas D. (University of Nevada, Reno); LePell, Paul David (Ktech Corporation); Safronova, Alla S. (University of Nevada, Reno); Shrestha, I. (University of Nevada, Reno); McKenney, John Lee; Ampleford, David J. (Imperial College); Rapley, J. (Imperial College); Bott, S. C. (Imperial College); Palmer, J. B. A. (Imperial College); Sotnikov, Vladimir Isaakovich (University of Nevada, Reno); Bland, Simon Nicholas (Imperial College); Ivanov, Vladimir V. (University of Nevada, Reno); Chittenden, Jeremy Paul (Imperial College); Jones, B.; Garasi, Christopher Joseph; Hall, Gareth Neville (Imperial College); Yilmaz, M. Faith (University of Nevada, Reno); Mehlhorn, Thomas Alan; Deeney, Christopher; Pokala, S. (University of Nevada, Reno); Nalajala, V. (University of Nevada, Reno)

2005-07-01

53

Polycrystalline diamond based detector for Z-pinch plasma diagnosis  

SciTech Connect

A detector setup based on polycrystalline chemical-vapor-deposition diamond film is developed with great characteristics: low dark current (lower than 60 pA within 3 V/{mu}m), fast pulsed response time (rise time: 2-3 ns), flat spectral response (3-5 keV), easy acquisition, low cost, and relative large sensitive area. The characterizing data on Qiangguang-I accelerator show that this detector can satisfy the practical requirements in Z-pinch plasma diagnosis very well, which offers a promising prototype for the x-ray detection in Z-pinch diagnosis.

Liu Linyue; Zhao Jizhen; Chen Liang [Northwest Institute of Nuclear Technology, P.O. Box 69-9, Xi'an 710024 (China); Ouyang Xiaoping [Northwest Institute of Nuclear Technology, P.O. Box 69-9, Xi'an 710024 (China); School of Nuclear Science and Technology, Xi'an Jiaotong University, Xi'an 710049 (China); Wang Lan [Northwest Institute of Nuclear Technology, P.O. Box 69-9, Xi'an 710024 (China); Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

2010-08-15

54

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

55

Electron temperature diagnostics of aluminium plasma in a z-pinch experiment at the “QiangGuang-1" facility  

NASA Astrophysics Data System (ADS)

Two curved crystal spectrometers are set up on the “QiangGuang-1" generator to measure the z-pinch plasma spectra emitted from planar aluminum wire array loads. Kodak Biomax-MS film and an IRD AXUVHS5# array are employed to record time-integrated and time-resolved free-bound radiation, respectively. The photon energy recorded by each detector is ascertained by using the L-shell lines of molybdenum plasma. Based on the exponential relation between the continuum power and photon energies, the aluminum plasma electron temperatures are measured. For the time-integrated diagnosis, several “bright spots" indicate electron temperatures between (450 eV ~ 520 eV) ± 35%. And for the time-resolved ones, the result shows that the electron temperature reaches about 800 eV ± 30% at peak power. The system satisfies the demand of z-pinch plasma electron temperature diagnosis on a ~ 1 MA facility.

Li, Mo; Wu, Jian; Wang, Liang-Ping; Wu, Gang; Han, Juan-Juan; Guo, Ning; Qiu, Meng-Tong

2012-12-01

56

Physics of Fast Z Pinches;Review of Modern Physics.  

National Technical Information Service (NTIS)

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 therm...

D. D. Ryutov Derzon M. Matzen

1999-01-01

57

MHD simulation studies of z-pinch shear flow stabilization  

NASA Astrophysics Data System (ADS)

The development of the m=0 instability in a z-pinch in the presence of sheared plasma flows is investigated with the aid of a two-dimensional magnetohydrodynamic (MHD) simulation code (MHRDR). The linear growth rates are compared to the results obtained by solving the ideal MHD linearized equations [1] and to the results obtained using a 3D hybrid simulation code [2]. The instability development is followed into the nonlinear regime where its growth and saturation are examined. [1] V.I. Sotnikov, I. Paraschiv, V. Makhin, B.S. Bauer, J.-N. Leboeuf, and J.M. Dawson, "Linear analysis of sheared flow stabilization of global magnetohydrodynamic instabilities based on the Hall fluid mode", Phys. Plasmas 9, 913 (2002). [2] V.I. Sotnikov, V. Makhin, B.S. Bauer, P. Hellinger, P. Travnicek, V. Fiala, J.-N. Leboeuf, "Hybrid Simulations of Current-Carrying Instabilities in Z-pinch Plasmas with Sheared Axial Flow", AIP Conference Proceedings, Volume 651, Dense Z-Pinches: 5th International Conference on Dense Z-Pinches, edited by J. Davis et al., page 396, June 2002.

Paraschiv, I.; Bauer, B. S.; Sotnikov, V. I.; Makhin, V.; Siemon, R. E.

2003-10-01

58

The high density z-pinch II experiment  

SciTech Connect

The HDZP II is an experiment with the objective of taking a z-pinch plasma, created from a small diameter solid deuterium fiber, up to the Pease-Braginskii current limit while maintaining Bennett equilibrium (constant radius) throughout the current pulse. This paper discusses this experiment.

Hammel, J.

1989-01-01

59

Z-pinch experiments on Saturn at 30 TW  

SciTech Connect

We have recently completed the first gas-puff Z-pinch experiments on Saturn (32 TW, 1.4 MJ, 1.9 MV, 40-ns FWHM, and 0.11 {Omega}). These experiments used the most powerful driver to date for fast Z-pinch experiments. Saturn, a 36 module accelerator, uses a double post-hole vacuum convolute to deliver the total machine current to the load. The 10-nH Saturn Z-pinch diode is capable of delivering a peak current of 10.5 MA. We diagnosed the current using segmented Rogowski coils at the insulator, resistive shunts in the vacuum transmission lines, and B-dot loops and piezoelectric pressure gauges near the load. On most shots electrical losses in the vacuum convolute were minimal with nearly complete current delivery to the Z-pinch load. We have conducted experiments with deuterium, neon, argon, krypton, and xenon gas puffs. A maximum total radiation yield of 505{plus minus}25 kJ was obtained with xenon. The peak keV x-ray yields were 100{plus minus}5 kJ for neon L-shell radiation, 30{plus minus}4 kJ for krypton l-shell radiation, and 39{plus minus}4 kJ for argon K-shell radiation.

Spielman, R.B.; Dukart, R.J.; Hanson, D.L.; Hammel, B.A.; Hsing, W.W.; Matzen, M.K.; Porter, J.L. (Sandia National Laboratories, Albuquerque, NM (USA))

1989-12-01

60

Z-pinch experiments on Saturn at 30 TW  

SciTech Connect

We have recently completed the first gas-puff z-pinch on Saturn (32 TW, 1.4 MJ, 1.9 MV, 40-ns FWHM, and 0.11 ..cap omega..). These experiments used the most powerful driver to date for fast z-pinch experiments. Saturn, a 36 module accelerator, uses a double post-hole vacuum convolute to deliver the total machine current to the load. The 10-nH Saturn z-pinch diode is capable of delivering a peak current of 10.5 MA. We diagnosed the current using segmented Rogowski coils at the insulator, resistive shunts in the vacuum transmission lines, and B-dot loops and piezoelectric pressure gauges near the load. On most shots electrical losses in the vacuum convolute were minimal with nearly complete current delivery to the z-pinch load. We have conducted experiments with deuterium, neon, argon, krypton, and xenon gas puffs. A maximum total radiation yield of 505 /+-/ 25 kJ was obtained with xenon. The peak keV x-ray yields were 100 /+-/ 5 kJ for neon K-shell radiation, 30 /+-/ 4 kJ for krypton L-shell radiation, and 39 /+-/ 4 kJ for argon K-shell radiation. 12 refs., 15 figs., 2 tabs.

Spielman, R.B.; Dukart, R.J.; Hanson, D.L.; Hammel, B.A.; Hsing, W.W.; Matzen, M.K.; Porter, J.L.

1989-01-01

61

The prospects for high yield ICF with a Z -pinch driven dynamic hohlraum  

Microsoft Academic Search

Recent success with the Sandia Z machine has renewed interest in utilizing fast Z -pinches for ICF. One promising concept places the ICF capsule internal to the imploding Z -pinch. At machine parameters relevant to achieving high yield, the imploding Z -pinch mass has sufficient opacity to trap radiation giving rise to a `dynamic hohlraum'. Our concept utilizes a 12

J. S. Lash; G. A. Chandler; G. Cooper; M. Derzon; M. R. Douglas; D. Hebron; R. Leeper; M. K. Matzen; T. A. Mehlhorn; T. Nash; R. Olson; C. Ruiz; T. Sanford; S. A. Slutz; D. L. Peterson; R. Chrien

2000-01-01

62

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

63

Status of Pulsed Power/Beams/Z-pinch Researches in Japan  

NASA Astrophysics Data System (ADS)

Fruitful progresses have been achieved in pulsed power technology and its applications in Japan in materials science, environmental, medical, biological, etc. At Nagaoka Univ. of Tech., main efforts are devoted in materials science such as the preparation of thin films or ultrafine nanosized powders (UNP) by high-density ablation plasma produced by pulsed ion beam evaporation. Alternatively, UNPs were produced by rapid cooling of the plasma produced by pulsed wire discharge (PWD) as well. The ablation plasma is also very effective to build-in metals (e.g., tungsten, aluminum, copper) in via holes of LSIs. Flue-gas treatment of NOx is studied by pulsed, relativistic electron beam. At Tokyo Inst. of Tech., studies are carried out on pulse discharge using powders, soft X-ray by capillary discharge, and development of pulse power sources for industrial applications. At Kumamoto Univ., studies are concerned on NOx removal by pulsed power, gas-puff z-pinch, and opening switches. Converting the pulsed power to z-pinches, charged particles beams, or plasma foci have also been carried out in many universities. Systematic studies are carried out under good collaboration among many universities, national laboratories and companies.

Yatsui, Kiyoshi

2002-12-01

64

Polarity Contact and Risetime Effects on Wire Array Z-Pinches  

NASA Astrophysics Data System (ADS)

The Cornell COBRA pulser is a 1MA, negative polarity machine. COBRA can operate with 100 to 200 ns current risetimes. 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 change the electric field at the wires, thereby producing positive polarity with respect to ground at the load. Data presented are the culmination of experiments studying the combined effects of contact, polarity and risetime on wire array z-pinches. Data were collected on 16-wire Aluminum z-pinch arrays in both negative and positive polarity, with solder and non-solder contacts, and with slow and fast risetimes (100ns and 200ns). Five shots were collected for each case. The initiation, ablation, implosion and stagnation phases were compared for the various cases.

Chalenski, David; Kusse, Bruce

2009-11-01

65

Relative Timing of Coronal Plasma Formation for Individual Wires in a Wire Array Z-Pinch  

NASA Astrophysics Data System (ADS)

We are investigating the initial stages of plasma formation around individual wires in low-wire-number wire-array z-pinches using the 1 MA COBRA pulsed power generator. The experiments are designed to examine the time-dependence of the current distribution among individual wires and pairs of wires in wire-array z-pinches using 5-10 aluminum or tungsten wires. To accomplish this we inductively isolate the wires, or pairs of wires, from each other using segmented load hardware. Each segment is able to hold one or two wires and is connected to machine ground through its own return current post. Experimental goals include determining the timing of the initiation of coronal plasma around each wire and determination of parameters that affect this timing. In addition, we will compare the early time rate of rise of the total currents from the segmented anode experiments to that from conventional arrays in order to make estimates of the temporal spread in coronal plasma formation when the anode is not segmented. *This research was supported by the Stewardship Sciences Academic Alliances program of the National Nuclear Security Administration under DOE Cooperative agreement DE-FC03-02NA00057 and by Sandia National Laboratories contract AO258.

Knapp, Patrick; Chalenski, D. A.; Douglass, J. D.; Greenly, J. B.; McBride, R. D.; Pikuz, S.; Shelkovenko, T.; Hammer, D. A.; Kusse, B. R.

2007-11-01

66

Instabilities in Z-pinch and liner systems  

SciTech Connect

Recent results concerning plasma instabilities and their influence on Z-pinches and liners dynamics are considered in the report. Three-dimensional two-fluid instabilities (TFI) can be responsible for the high value of anomalous electric resistance of plasma column. Two-dimensional two-fluid MHD simulation, taking into account such anomalous resistance, was performed to evaluate a threshold of sausage instability stabilization. This threshold is expressed in the terms of Z-pinch mass per unit length. Competition of the TFI's and usual Rayleigh-Taylor instability (RTI) for thin plasma liner is also discussed. The effect of an extremely fast redeployment of current from liner to a central load which had been discovered previously by the ANGARA-5 team is examined from the viewpoint of liner instabilities.

Sasorov, P. V.; Esaulov, A. A. [Institute for Theoretical and Experimental Physics, Moscow, 117259 (Russian Federation); Nedoseev, S. L. [TRINITI, Troitsk, Moscow region, 142092 (Russian Federation)

1997-05-05

67

Optimization of Capsule Symmetry in Z-Pinch Driven Hohlraums  

NASA Astrophysics Data System (ADS)

The uniformity of the radiation flux incident on the capsule is a critical issue for indirect drive fusion using the z-pinch driven hohlraum high-yield concept(J.H. Hammer et al., Phys. Plas. 6), 2129 (1999).. Experiments on the Z accelerator at Sandia have demonstrated the ability to diagnose the uniformity of the flux striking a foam ball (surrogate capsule)(P.A. Amendt et al., Phys. Plas. 4), 1862 (1997); S.G. Glendinning et al. Rev. Sci. Instrum. 70, 536 (1999).. These single-sided drive experiments have been modeled using radiosity and radiation-hydrodynamics codes, yielding agreement with the measured ablation rate vs. angle on the foam ball. Flux uniformity at the 1-2% level needed for high-convergence capsule implosions requires a 2-sided drive (top and bottom z-pinch) configuration. Constrained optimization methods have identified hohlraum geometries with improved symmetry.

Vesey, R. A.; Cuneo, M.; Hanson, D.; Porter, J.; Mehlhorn, T.; Ruggles, L.; Simpson, W.; Vargas, M.; Hammer, J.; Landen, O.

1999-11-01

68

Pitfalls in Radiation Modeling of Z-Pinch Plasmas  

NASA Astrophysics Data System (ADS)

Over the last three decades there has been a quantum jump in the production of x-rays from pulsed power driven Z-pinch plasmas. Total radiative yields have gone from a few kilojoules to almost two megajoules. This increase occurred as a result of higher current drivers coupled with improvements in our understanding of the issues most relevant to good load design. Critical analyses of experimental data have led to a better understanding of the load dynamics, which includes all phases of load evolution extending from the cold start to the final collapsed phase and the emission of the x-ray pulse. A Z pinch is a deceptively simple device that has a very complex plasma dynamics. It can be a platform for demonstrating a variety of textbook plasma instabilities. However, its primary application in the present context is as an intense source of x-ray radiation. Therefore it is attractive both as a direct source of x-rays and for creating hohlraum conditions for plasma fusion experiments. After a few historical comments are offered on how radiation has been treated in modeling Z pinches, some of the methodologies and models that are employed in this endeavor are discussed. These include both nonLTE and LTE ionization dynamic models and escape probability radiation transport and LTE radiation diffusion models. To illustrate their use, comparisons are made between experimental data from a stainless steel wire array pinch implosion and 1-D MHD calculations that employ these models. The consequences that stem from the compromises and trade-offs that result from the different approximations used in these models are addressed. We will explore the role that radiation plays in the dynamic evolution of a Z-pinch and demonstrate the need for as near a self-consistent radiation-hydrodynamics treatment as possible.

Davis, J.; Giuliani, J. L.; Apruzese, J. P.; Clark, R. W.; Thornhill, J. W.; Whitney, K. G.; Velikovich, A.; Chong, Y. K.; Coverdale, C. A.; Deeney, C.; Lepell, P. D.

2002-12-01

69

Fabrication and characterization of Z-pinch foam targets  

Microsoft Academic Search

This article describes the fabrication and characterization of targets produced for Z-pinch physics experiments. Low density foams with densities as low as 1 mg\\/cc were made. Targets fabricated include 1 cmÃ1 cm solid cylinders of SiOâ aerogels at various densities, 1 cmÃ1 cm solid cylinders of 10 mg\\/cc agar, and 10 mg\\/cc agar annuli with 10 mm o.d., 9 mm

A. J. Antolak; A. Demiris; M. S. Derzon; L. W. Hrubesh; H. Louis; W. F. McNamara; D. H. Morse; J. F. Poco

1997-01-01

70

Two-dimensional integrated Z-pinch ICF design simulations  

Microsoft Academic Search

Summary form only given, as follows. The dynamic hohlraum ICF concept for a Z-pinch driver utilizes the imploding wire array collision with a “target” to produce a radiation history suitable for driving an embedded inertial confinement fusion (ICF) capsule. This “target” may consist of various shaped layers of low-density foams or solid-density materials. The use of detailed radiation magneto-hydrodynamic (RMHD)

J. S. Lash

1999-01-01

71

Z-pinch implosion driven X-ray laser research  

Microsoft Academic Search

In experiments performed during the past two years on Proto II (a 10-TW pulsed-power accelerator), annular plasmas were imploded onto thin-walled annular X-ray laser targets in order to create a radiation pump source for X-ray laser physics studies. This Z-pinch must be axially uniform and must efficiently produce the pump radiation without destroying the laser medium on the cylindrical axis

M. K. Matzen; R. J. Dukart; B. A. Hammel; D. L. Hanson; W. W. Hsing

1986-01-01

72

Adaptive Wavelet Techniques in Z-Pinch Research  

Microsoft Academic Search

We examine denoising, pattern detection and information compression capabilities of special classes of wavelet families adapted to various 1D and 2D signals that arise in Z-Pinch research. In particular, we analyze X-ray bolometry data where the challenge is to extract accurate power vs time information (which requires differentiation) from noisy energy data. We will also treat X-ray images of symmetric

Bedros Afeyan; Kirk Won; Kenneth Struve; Christopher Deeny; Michael Cuneo; Guy Bennett; Roger Vessey; John Porter

2002-01-01

73

Dynamics of conical wire array Z-pinch implosions  

NASA Astrophysics Data System (ADS)

A modification of the wire array Z pinch, the conical wire array, has applications to the understanding of wire array implosions and potentially to pulse shaping relevant to inertial confinement fusion. Results are presented from imploding conical wire array experiments performed on university scale 1 MA generators-the MAGPIE generator (1 MA, 240 ns) at Imperial College London [I. H. Mitchell et al., Rev. Sci Instrum. 67, 1533 (1996)] and the Nevada Terawatt Facility's Zebra generator (1 MA, 100 ns) at the University of Nevada, Reno [B. Bauer et al., in Dense Z-Pinches, edited by N. Pereira, J. Davis, and P. Pulsifer (AIP, New York, 1997), Vol. 409, p. 153]. This paper will discuss the implosion dynamics of conical wire arrays. Data indicate that mass ablation from the wires in this complex system can be reproduced with a rocket model with fixed ablation velocity. Modulations in the ablated plasma are present, the wavelength of which is invariant to a threefold variation in magnetic field strength. The axial variation in the array leads to a zippered precursor column formation. An initial implosion of a magnetic bubble near the cathode is followed by the implosion zippering upwards. Spectroscopic data demonstrating a variation of plasma parameters (e.g., electron temperature) along the Z-pinch axis is discussed, and experimental data are compared to magnetohydrodynamic simulations.

Ampleford, D. J.; Lebedev, S. V.; Bland, S. N.; Bott, S. C.; Chittenden, J. P.; Jennings, C. A.; Kantsyrev, V. L.; Safronova, A. S.; Ivanov, V. V.; Fedin, D. A.; Laca, P. J.; Yilmaz, M. F.; Nalajala, V.; Shrestha, I.; Williamson, K.; Osborne, G.; Haboub, A.; Ciardi, A.

2007-10-01

74

Measurement of radiation symmetry in Z-pinch-driven hohlraums  

NASA Astrophysics Data System (ADS)

The Z-pinch-driven hohlraum (ZPDH) [J. H. Hammer et al., Phys. Plasmas 6, 2129 (1999)] is a promising approach to high yield inertial confinement fusion currently being characterized in experiments on the Sandia Z accelerator [M. E. Cuneo et al., Phys. Plasmas 8, 2257 (2001)]. Simulations show that capsule radiation symmetry, a critical issue in ZPDH design, is governed primarily by hohlraum geometry, dual-pinch power balance, and pinch timing. In initial symmetry studies on Z without the benefit of a laser backlighter, highly-asymmetric pole-hot and equator-hot single Z-pinch hohlraum geometries were diagnosed using solid low density foam burnthrough spheres. These experiments demonstrated effective geometric control and prediction of polar flux symmetry at the level where details of the Z-pinch implosion and other higher order effects are not critical. Radiation flux symmetry achieved in Z double-pinch hohlraum configurations exceeds the measurement sensitivity of this self-backlit foam ball symmetry diagnostic. To diagnose radiation symmetry at the 2%-5% level attainable with present ZPDH designs, high-energy x rays produced by the recently-completed Z-Beamlet laser backlighter are being used for point-projection imaging of thin-wall implosion and symmetry capsules.

Hanson, D. L.; Vesey, R. A.; Cuneo, M. E.; Porter, J. L.; Chandler, G. A.; Ruggles, L. E.; Simpson, W. W.; Torres, J.; McGurn, J.; Hebron, D.; Dropinski, S. C.; Hammer, J. H.; Bennett, G. R.; Seaman, H.; Gilliland, T. L.; Schroen, D. G.

2002-05-01

75

Z-Pinch Driven Hohlraum Energetics and Load Development  

NASA Astrophysics Data System (ADS)

The Z-pinch driven hohlraum ICF concept [1] is being studied on the Z accelerator, and appears to scale to conditions required for high-yield. The Z-pinch radiation source resides in a primary hohlraum. Radiation is transported into a high-yield scale secondary (3400 mm^3) through a Be-spoke electrode. We have developed a 0-D energetics model for the coupled hohlraums to infer the pinch power (120-150 TW) and transparency (60-65%) of the spokes from the measured primary (125±7 eV) and secondary (101±5 eV) temperatures. These experiments give the highest power coupled to the secondary (30±6 TW) for Z-pinch systems. We are developing experiments to study the scaling of radiation-driven gap closure in the transmission line feed and to improve P1 with double-sided illumination. [1] J.H. Hammer et al., Phys. Plas. 6, 2129(1999).

Cuneo, M. E.; Vesey Porter, R. A., Jr.; Hammer, J. H.; Ruggles, L. E.; Simpson, W. W.; Hall, C. A.; Asay, J. R.; Hanson, D. L.; Nash, T. J.; Chandler, G. A.; Spielman, R. B.; Seamen, J. F.; Gilliland, T. L.

1999-11-01

76

Architecture of petawatt-class z-pinch accelerators.  

SciTech Connect

We have developed an accelerator architecture that can serve as the basis of the design of petawatt-class z-pinch drivers. The architecture has been applied to the design of two z-pinch accelerators, each of which can be contained within a 104-m-diameter cylindrical tank. One accelerator is driven by slow ({approx}1 {micro}s) Marx generators, which are a mature technology but which necessitate significant pulse compression to achieve the short pulses (<<1{micro}s) required to drive z pinches. The other is powered by linear transformer drivers (LTDs), which are less mature but produce much shorter pulses than conventional Marxes. Consequently, an LTD-driven accelerator promises to be (at a given pinch current and implosion time) more efficient and reliable. The Marx-driven accelerator produces a peak electrical power of 500 TW and includes the following components: (i) 300 Marx generators that comprise a total of 1:8 x 10{sup 4} capacitors, store 98 MJ, and erect to 5 MV; (ii) 600 water-dielectric triplate intermediate-store transmission lines, which also serve as pulse-forming lines; (iii) 600 5-MV laser-triggered gas switches; (iv) three monolithic radial-transmission-line impedance transformers, with triplate geometries and exponential impedance profiles; (v) a 6-level 5.5-m-diameter 15-MV vacuum insulator stack; (vi) six magnetically insulated vacuum transmission lines (MITLs); and (vii) a triple-post-hole vacuum convolute that adds the output currents of the six MITLs, and delivers the combined current to a z-pinch load. The accelerator delivers an effective peak current of 52 MA to a 10-mm-length z pinch that implodes in 95 ns, and 57 MA to a pinch that implodes in 120 ns. The LTD-driven accelerator includes monolithic radial transformers and a MITL system similar to those described above, but does not include intermediate-store transmission lines, multimegavolt gas switches, or a laser trigger system. Instead, this accelerator is driven by 210 LTD modules that include a total of 1 x 10{sup 6} capacitors and 5 x 10{sup 5} 200-kV electrically triggered gas switches. The LTD accelerator stores 182 MJ and produces a peak electrical power of 1000 TW. The accelerator delivers an effective peak current of 68 MA to a pinch that implodes in 95 ns, and 75 MA to a pinch that implodes in 120 ns. Conceptually straightforward upgrades to these designs would deliver even higher pinch currents and faster implosions.

Stygar, William A.; Mazarakis, Michael Gerrassimos; Cuneo, Michael Edward; Leeper, Ramon Joe; Ives, H. C. (EG& G, Albuquerque, NM); Headley, D. I.; Wagoner, Tim C. (Ktech Corporation, Albuquerque, NM); Porter, John Larry, Jr.

2006-02-01

77

Advances in compact wire-array Z-pinch X-ray sources and Z-pinch diagnostics  

Microsoft Academic Search

Summary form only given. The Z facility at Sandia National Laboratories is a 100-ns, 20-MA pulsed power driver for plasma radiation sources. Experiments with tungsten wire-array Z pinches on the Z facility can produce >200 TW and 1.8 MJ of soft X rays in the 100-10,000 eV range. The best performance from tungsten wire arrays on the Z facility was

D. B. Sinars

2006-01-01

78

End-On Laser Interferometry of Wire Array Z-Pinch Implosions on the MAGPIE Generator  

NASA Astrophysics Data System (ADS)

End-On interferometric measurements of the electron density distribution of wire array z-pinches has revealed striking differences in the behavior of ablation plasmas. A change in wire material from aluminum to tungsten results in a change from a highly collisional structure dominated by shock formations to a much less collisional regime. Analysis of the results will be presented and comparisons made to both simulations produced using the GORGON MHD code, and calculations of the expected mean-free-path of the plasma. Experiments were carried out on the MAGPIE generator (1.4 MA peak, 240ns rise) at Imperial College, London. A two-color Mach-Zender imaging interferometer was used to collect the data. This uses the 2^nd and 3rd harmonics (532nm and 355nm) of a pulsed Nd:YAG laser with a pulse duration of ˜500ps.

Swadling, G.; Lebedev, S. V.; Patankar, S.; Harvey-Thompson, A.; Suzuki-Vidal, F.; Hall, G. N.; Bland, S. N.; Burdiak, G.; Chittenden, J. P.; de Grouchy, P.; Skidmore, J.; Pickworth, L.; Suttle, L.; Bennett, M.; Smith, R. A.

2012-10-01

79

Radiation-Hydromagnetic Models of a Z-Pinch Implosion with an Axial Magnetic Field  

Microsoft Academic Search

Experimental results on a 1MA pulser suggest that axial magnetic fields can stabilize z-pinch implosions and enhance the compression ratio(S. Sorokin and S. Chaikovsky, Dense Z-Pinches, AIP Conf. Proc. 299, p.83 (1993).). The present theoretical work calculates the effects of an axial magnetic field on the plasma and field profiles in an imploding z-pinch. The initial mass configuration is an

R. W. Clark; J. L. Giuliani; R. Terry; J. Davis; A. L. Velikovich

1997-01-01

80

Wire-array z pinches as intense x-ray sources for inertial confinement fusion  

Microsoft Academic Search

Progress in pulsed power technologies has enabled the use of z pinches for inertial confinement fusion (ICF). Z pinches can provide x-ray powers of 200 TW and x-ray energies approaching 2 MJ. Computational capabilities have advanced to the point that 2-D radiation magneto-hydrodynamics computer codes can be used as detailed design tools. Several ICF configurations have been proposed. The z-pinch

R. B. Spielman; C. Deeney; M. R. Douglas; G. A. Chandler; M. E. Cuneo; T. J. Nash; J. L. Porter; L. E. Ruggles; T. W. L. Sanford; W. A. Stygar; K. W. Struve; M. K. Matzen; D. H. McDaniel; D. L. Peterson; J. H. Hammer

2000-01-01

81

Radiation Symmetry Control for ICF Capsule Implosions in Double Z-Pinch Hohlraums on Z  

Microsoft Academic Search

The double z-pinch hohlraum high-yield concept [Phys. Plasmas 6, 2129 (1999)] utilizes two 60-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 at Sandia National Laboratories have developed an advanced single-sided power feed, double z-pinch load to study radiation symmetry and pinch power balance

Roger A. Vesey

2002-01-01

82

Performance Study of the Ablative Z-pinch Pulsed Plasma Thruster  

Microsoft Academic Search

The ablative Z-pinch PPT utilizes the Z-pinch effect to produce an axially streaming plasma. When the current is fully pinched in this device, a large axial pressure gradient exists and thus plasma accelerates in the axial direction due to the gasdynamic force. In the present paper, a model of the electrical discharge in the Ablative Z-pinch Pulsed Plasma Thruster is

Michael Keidar; Iain D. Boyd; Neal Lepsetz; Thomas E. Markusic; Kurt A. Polzin; Edgar Y. Choueiri

2001-01-01

83

The Prospects for High-Yield ICF with a Z-Pinch Driven Dynamic Hohlraum  

SciTech Connect

Recent success with the Sandia Z machine has renewed interest in utilizing fast z-pinenes for ICF. One promising concept places the ICF capsule internal to the imploding z-pinch. At machine parameters relevant to achieving high yield, the imploding z-pinch mass has sufficient opacity to trap radiation giving rise to a dynamic hohlraum. The concept utilizes a 12 MJ, 54 MA z-pinch driver producing a capsule drive temperature exceeding 300 eV to realize a 550 MJ thermonuclear yield. They present the current high-yield design and its development that supports high-yield ICF with a z-pinch driven dynamic hohlraum.

CHANDLER, GORDON A.; CHRIEN, R.; COOPER, GARY WAYNE; DERZON, MARK S.; DOUGLAS, MELISSA R.; HEBRON, DAVID E.; LASH, JOEL S.; LEEPER, RAMON J.; MATZEN, M. KEITH; MEHLHORN, THOMAS A.; NASH, THOMAS J.; OLSON, RICHARD E.; PETERSON, D.L.; RUIZ, CARLOS L.; SANFORD, THOMAS W. L.; SLUTZ, STEPHEN A.

1999-09-07

84

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

85

Electron Beams in Wire Array Z-pinches  

NASA Astrophysics Data System (ADS)

The intensity and the radial profile of electron beams from wire-array z-pinches have been measured on the MAGPIE generator (1MA, 240ns) at Imperial College, London. A Faraday-cup was used to measure the electron beam current from both aluminium and copper wire-arrays with spatial and temporal resolution. Time integrated hard x-ray spectroscopy using spherically-bent crystals produced axially resolved images of the copper K? line, a signature of the presence of electron beams. This research was sponsored by Sandia National Laboratories Albuquerque, the SSAA program of NNSA under DOE Cooperative Agreement DE-FC03-02NA00057.

Bland, Simon; Hall, Gareth; Lebedev, Sergey; Bott, Simon; Palmer, James; Suzuki, Francisco; Chittenden, Jeremy

2006-10-01

86

Nonlinear Rayleigh-Taylor instabilities in fast z-pinches  

SciTech Connect

A simplified analytic model is presented to describe the implosion of a plasma column by an azimuthal magnetic field of sufficient magnitude to drive a strong shock wave into the plasma. This model is employed together with buoyancy-drag-based models of nonlinear single-mode and turbulent multimode Rayleigh-Taylor (RT) growth to investigate the mixing process in such fast z-pinches. These models give predictions that characterize limitations the instability can impose on the implosion in terms of maximum convergence ratios (CR) attainable for an axially coherent pinch. Both the implosion and instability models are validated with results from high-resolution numerical simulations.

Miles, A R

2008-09-16

87

Nonlinear Rayleigh-Taylor instabilities in fast Z pinches  

SciTech Connect

A simplified analytic model is presented to describe the implosion of a plasma column by an azimuthal magnetic field of sufficient magnitude to drive a strong shock wave into the plasma. This model is employed together with buoyancy-drag-based models of nonlinear single-mode and turbulent multimode Rayleigh-Taylor growth to investigate the mixing process in such fast Z pinches. These models give predictions that characterize limitations the instability can impose on the implosion in terms of maximum convergence ratios attainable for an axially coherent pinch. Both the implosion and instability models are validated with results from high-resolution numerical simulations.

Miles, Aaron R. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2009-03-15

88

A time-resolved spectroscopic diagnostic based on fast scintillator and optical fiber array for z-pinch plasmas  

SciTech Connect

We report a specially designed type of temporal resolved x-ray spectroscopic diagnostic using a spherically bent quartz crystal for z-pinch plasmas. Registration of time-resolved spectra was accomplished by coupling fast plastic scintillator, an optical fiber array, an optical streak camera, and a charge coupled device as the recording medium of this diagnostic. The diagnostic has been tested in imploding wire array experiments on S-300 pulsed power facility. Time-resolved K-shell lines were successfully obtained for aluminum wire array implosion plasmas.

Ye Fan [Institute of Nuclear Physics and Chemistry, P.O. Box 919-212, Mianyang 621900 (China); Key Laboratory of Particle and Radiation Imaging, Tsinghua University, Beijing 100084 (China); Qin Yi; Jiang Shuqing; Xue Feibiao; Li Zhenghong; Yang Jianlun; Xu Rongkun [Institute of Nuclear Physics and Chemistry, P.O. Box 919-212, Mianyang 621900 (China); Anan'ev, S. S.; Dan'ko, S. A.; Kalinin, Yu. G. [RRC Kurchatov Institute, Moscow 123182 (Russian Federation)

2009-10-15

89

A time-resolved spectroscopic diagnostic based on fast scintillator and optical fiber array for z-pinch plasmas.  

PubMed

We report a specially designed type of temporal resolved x-ray spectroscopic diagnostic using a spherically bent quartz crystal for z-pinch plasmas. Registration of time-resolved spectra was accomplished by coupling fast plastic scintillator, an optical fiber array, an optical streak camera, and a charge coupled device as the recording medium of this diagnostic. The diagnostic has been tested in imploding wire array experiments on S-300 pulsed power facility. Time-resolved K-shell lines were successfully obtained for aluminum wire array implosion plasmas. PMID:19895094

Ye, Fan; Qin, Yi; Jiang, Shuqing; Xue, Feibiao; Li, Zhenghong; Yang, Jianlun; Xu, Rongkun; Anan'ev, S S; Dan'ko, S A; Kalinin, Yu G

2009-10-01

90

A time-resolved spectroscopic diagnostic based on fast scintillator and optical fiber array for z-pinch plasmas  

NASA Astrophysics Data System (ADS)

We report a specially designed type of temporal resolved x-ray spectroscopic diagnostic using a spherically bent quartz crystal for z-pinch plasmas. Registration of time-resolved spectra was accomplished by coupling fast plastic scintillator, an optical fiber array, an optical streak camera, and a charge coupled device as the recording medium of this diagnostic. The diagnostic has been tested in imploding wire array experiments on S-300 pulsed power facility. Time-resolved K-shell lines were successfully obtained for aluminum wire array implosion plasmas.

Ye, Fan; Qin, Yi; Jiang, Shuqing; Xue, Feibiao; Li, Zhenghong; Yang, Jianlun; Xu, Rongkun; Anan'ev, S. S.; Dan'ko, S. A.; Kalinin, Yu. G.

2009-10-01

91

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.

92

Self-organized structures in z-pinch devices  

NASA Astrophysics Data System (ADS)

In several z-pinch devices there has been observation of regular structures, which appear systematically when repeating the experiments. The fact that very identifiable, recurrent, geometrical structures appear in z-pinches, which are relatively long lived, has motivated the analysis of the experimental data in a way that would cast light over these structures. In order to study this problem, diagnostic methods such as Schlieren photography, Quadro camera diagnostics, X-ray diagnostics, interferometry measurements and streak camera were used. This work includes analysis of experimental results, and the determination of some of the parameters which probably give rise to self-organized structures and some regular structures. It was found that a major contributor, for self-organization to occur, was the dominance of electromagnetic energy over the kinetic energy in the wire corona. The induction of an azimuthal magnetic field contributed to the generation of azimuthal currents, which in turn induced an axial magnetic field. Both axial and azimuthal magnetic fields contributed to the formation of helical-like structures, at least until the pinch began to dissipate. An important stabilizing factor for the plasma channel could have been played by the solid remains of part of the fiber inside the channel. There is a positive strong correlation between the expulsion of entropy and the persistence in the existence of self-organized structures.

Ortíz-Tapia, Arturo

2002-11-01

93

Increasing Z-pinch vacuum hohlraum capsule coupling efficiency.  

SciTech Connect

Symmetric capsule implosions in the double-ended vacuum hohlraum (DEH) on Z have demonstrated convergence ratios of 14-21 for 2.15-mm plastic ablator capsules absorbing 5-7 kJ of x-rays, based on backlit images of the compressed ablator remaining at peak convergence [1]. Experiments with DD-filled 3.3-mm diameter capsules designed to absorb 14 kJ of x-rays have begun as an integrated test of drive temperature and symmetry, complementary to thin-shell symmetry diagnostic capsules. These capsule implosions are characterized by excellent control of symmetry (< 3% time-integrated), but low hohlraum efficiency (< 2%). Possible methods to increase the capsule absorbed energy in the DEH include mixed-component hohlraums, large diameter foam ablator capsules, transmissive shine shields between the z-pinch and capsule, higher spoke electrode x-ray transmission, a double-sided power feed, and smaller initial radius z-pinch wire arrays. Simulations will explore the potential for each of these modifications to increase the capsule coupling efficiency for near-term experiments on Z and ZR.

Callahan, Debbie (LLNL); Vesey, Roger Alan; Cochrane, Kyle Robert (KTech); Nikroo, A. (General Atomics); Bennett, Guy R.; Schroen, Diana Grace (Schafer); Ruggles, Laurence E.; Porter, John L.; Streit, Jon (Schafer); Mehlhorn, Thomas Alan; Cuneo, Michael Edward

2004-11-01

94

PIC Simulations of Dense Plasma Focus Z-pinch  

NASA Astrophysics Data System (ADS)

Dense Plasma Focus (DPF) Z-pinches are abundant sources of radiation, including neutrons, x-rays, and energetic electron and ion beams. Energetic protons and deuterons up to 10 MeV have been observed from cm-scale-length pinches, implying average acceleration gradients up to 1 GV/m. Gradients of this magnitude could potentially be exploited in the design of a compact accelerator. However, the physical mechanisms behind these immense electric fields are not well understood and thus DPF design cannot currently be optimized to maximize these gradients. At LLNL, we have assembled a DPF Z-pinch experiment and will be using a 4 MV ion probe beam to directly measure pinch-induced gradients. LSP, a fully relativistic electromagnetic Particle-In-Cell (PIC) code is used to perform time-dependent simulations of the pinch phase of the DPF and to gain insight into the origin and evolution of the large accelerating fields. LSP can be used in 2D or 3D geometries and can model the ions kinetically with fluid electrons (hybrid model) or model both species kinetically (fully kinetic model). We present results from both pressure and sheath width scans using LSP. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and supported by the Laboratory Directed Research and Development Program (11-ERD-063) at LLNL.

Schmidt, A.; Blackfield, D.; Tang, V.; Welch, D.; Rose, D.

2011-11-01

95

Time-Resolved 1-D X-ray Imaging Technique for Z-Pinch Plasma Diagnosis  

SciTech Connect

A sensitive time-resolved 1-D x-ray imaging system with linear energy response to 100eV-2keV x-rays is developed and applied in Z-Pinch experiments to investigate time dependent x-ray distribution with one-dimensional(1-D) spatial resolution of 0.1mm{approx}0.4mm and temporal resolution of 3ns. A slit in the system relays the 1-D image of the pinch plasma to a plastic scintillator foil with a thickness of 0.2mm which converts x-ray to visible and near-infrared light and has linear response to x-ray energy. With an optical fiber array consisting of 40 linearly arranged individual fibers behind the scintillator foil, it is capable of transmitting the 1-D image out from within the vacuum chamber. The optical fiber array is subsequently coupled to a streak camera via optical fiber bundle consisting of 40 individual 30-meter-long fibers to allow the investigation of time-resolved 1D x-ray distribution. To avoid viewing the plasma-generated visible light and covering aluminum foil on the scintillator, both the scintillator foil and the fiber array are tilted at an angle of 45 degrees from the line of sight. This diagnostic system has been successfully applied in gas-puff and tungsten wire-array Z-Pinch experiments carried out on Qiang-Guang-1, S-300, and Angara-5-1 facilities for time-resolved measurement of x-ray power distribution along the axis or radius of the imploding plasma. In these experiments, the current is in the range of 1-3MA and the x-ray radiation energy is in the order of 10-50kJ. Some experimental results will be presented in this paper.

Yang, J.L.; Li, Z.H.; Xu, R.K.; Li, L.B.; Ning, J.M.; Guo, C.; Song, F.J.; Xu, Z.P.; Xia, G.X. [Institute of Nuclear Physics and Chemistry, P.O.Box 919-212, Mianyang 621900 (China)

2006-01-05

96

Wire Array Z-pinches on Sphinx Machine: Experimental Results and Relevant Points of Microsecond Implosion Physics  

SciTech Connect

Centre d'Etudes de Gramat (France) has developed an efficient long implosion time (800 ns) Aluminum plasma radiation source (PRS). Based on the LTD technology, the SPHINX facility is developed as a 1-3MJ, 1{mu}s rise time, 4-10 MA current driver. In this paper, it was used in 1MJ, 4MA configuration to drive Aluminum nested wire arrays Z-pinches with K-shell yield up to 20 kJ and a FWHM of the x-ray pulse of about 50 ns. We present latest SPHINX experiments and some of the main physic issues of the microsecond regime. Experimental setup and results are described with the aim of giving trends that have been obtained. The main features of microsecond implosion of wire arrays can be analyzed thanks to same methods and theories as used for faster Z-pinches. The effect of load polarity was examined. The stability of the implosion , one of the critical point of microsecond wire arrays due to the load dimensions imposed by the time scale, is tackled. A simple scaling from 100 ns Z-pinch results to 800 ns ones gives good results and the use of nested arrays improves dramatically the implosion quality and the Kshell yield of the load. However, additional effects such as the impact of the return current can geometry on the implosion have to be taken into account on our loads. Axial inhomogeneity of the implosion the origin of which is not yet well understood occurs in some shots and impacts the radiation output. The shape of the radiative pulse is discussed and compared with the homogeneity of the implosion. Numerical 2D R-Z and R-{theta} simulations are used to highlight some experimental results and understand the plasma conditions during these microsecond wire arrays implosions.

Calamy, H.; Hamann, F.; Lassalle, F.; Bayol, F.; Mangeant, C.; Morell, A.; Huet, D.; Bedoch, J.P.; Chittenden, J.P.; Lebedev, S.V.; Jennings, C.A.; Bland, S.N. [Centre d'Etudes de Gramat, BP 80200, 46500 Gramat (France) and Blackett Laboratory, Imperial College, London, SW7 2BW (United Kingdom)

2006-01-05

97

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

98

Theory of Wire Number Scaling in Wire-Array Z Pinches.  

National Technical Information Service (NTIS)

Pulsed-power-driven z-pinches, produced by imploding cylindrical arrays of many wires, have generated very high x- ray radiation powers (> 200 TW) and energies (2 M J). Experiments have revealed a steady improvement in z-pinch performance with incr...

M. P. Desjarlais B. M. Marder

1998-01-01

99

The Past, Present and Future of Z-pinches  

NASA Astrophysics Data System (ADS)

The Z-pinch is enjoying a renaissance as the world's most powerful soft x-ray source, and there is a growing interest in both understanding the basic physics and its application to controlled fusion, particularly through indirect drive inertial confinement. It has the advantages of being efficient and having high energy and power density. The early history will be traced from 1790, when Martinus van Marum conducted exploding wire experiments in Holland, the Australian pinching of a copper tube lightning conductor, the seminal lecture at Harwell in 1956 by Kurchatov, and the classic contributions of Bennett, Pease and Braginskii. The most notable feature of the Z-pinch is its instability. The various regimes of stability analysis will be reviewed, including resistive and viscous effects, finite ion Larmor radius and the effect of sheared axial flow. Work in the last 10 years on single fibres, especially of cryogenic deuterium, gave neutrons but, alas, they were of the same origin, namely beam-plasma interactions, as reported by Kurchatov. The renaissance has come about through the implosion first of gas puffs but now, most importantly, of arrays of fine wires. Research at Sandia National Laboratory has shown that by using more and more, finer and finer wires, the x-ray radiation emitted at stagnation increased in power and decreased in pulse width. The understanding of these results has been advanced considerably by theory, simulation and smaller-scale, well diagnosed experiments. The dominant instability during the implosion is the magneto-Rayleigh-Taylor instability. The seeding of the mode seems to be associated with the MHD m = 0 instability that develops in an uncorrelated way on each individual wire as it evolves from a molten metal cylinder surrounded by a plasma corona. The global magnetic field leads both to the inward jetting of the plasma to the axis and to the development of a correlated global mode with seed amplitude proportional to the (number of wires)-1/2 in agreement with a heuristic model. The Rayleigh-Taylor instability can be mitigated by having a second inner array, and at least three modes of behaviour have been identified. It is with a tungsten nested array on the Z-accelerator at Sandia that a record 280TW of power or 1.8MJ of soft x-rays have been produced. In the future, generators and hopefully x-ray yield will be enhanced. There are several hohlraum designs based on Z-pinches for high yield inertial confinement fusion, and already some ideas for going towards inertial fusion energy. Other applications include radiation-hydrodynamics, equation of state and opacity studies. It appears to have an exciting future.

Haines, M. G.

1999-11-01

100

Fabrication and characterization of Z-pinch foam targets  

SciTech Connect

This article describes the fabrication and characterization of targets produced for Z-pinch physics experiments. Low density foams with densities as low as 1 mg/cc were made. Targets fabricated include 1 cm{times}1 cm solid cylinders of SiO{sub 2} aerogels at various densities, 1 cm{times}1 cm solid cylinders of 10 mg/cc agar, and 10 mg/cc agar annuli with 10 mm o.d., 9 mm i.d., and 1 cm length. Target geometry and density uniformity were characterized by ion microtomography (IMT) which can nondestructively measure three-dimensional density variations to 1{percent} with micron-scale resolution. The results of IMT measurements on several targets are reported and a discussion of factors affecting the quantitative microanalysis of these materials is presented.

Antolak, A.J. [Sandia National Laboratories, Livermore, California 94550 (United States)] [Sandia National Laboratories, Livermore, California 94550 (United States); Demiris, A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Derzon, M.S. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Hrubesh, L.W.; Louis, H. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); McNamara, W.F. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Morse, D.H. [Sandia National Laboratories, Livermore, California 94550 (United States)] [Sandia National Laboratories, Livermore, California 94550 (United States); Poco, J.F. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

1997-01-01

101

Spectroscopic diagnosis of foam z-pinch plasmas on SATURN  

SciTech Connect

Solid and annular silicon aerogel and agar foams were shot on the accelerator SATURN to study plasma initiation, acceleration, and stagnation. SATURN delivers 7 MA with a 50 nsec rise time to these foam loads. We fielded several spectroscopic diagnostics to measure plasma parameters throughout the z-pinch discharge. A spatially resolved single frame time-gated EUV spectrometer measured the extent of plasma ablation off the surface foam. A time integrated crystal spectrometer showed that characteristic K shell radiation of silicon in the aerogel and of S and Na impurities in the agar were all attenuated when the foam loads were coated with a conductive layer of gold. The time resolved pinhole camera showed that in general the quality of the pinch implosions was poor but improved with increasing efforts to improve current continuity such as prepulse and conductive coatings.

Nash, T.J.; Derzon, M.S.; Allshouse, G.; Deeney, C.; Jobe, D.; McGurn, J. [Sandia National Labs., Albuquerque, NM (United States); MacFarlane, J.J.; Wang, P. [Wisconsin Univ., Madison, WI (United States)

1996-06-01

102

Spectroscopic diagnosis of foam z-pinch plasmas on SATURN  

SciTech Connect

Solid and annular silicon aerogel and agar foams were imploded on the SATURN accelerator to study plasma initiation, acceleration, and stagnation. SATURN delivers 7 MA with a 50 ns rise time to these foam loads. We fielded several spectroscopic diagnostics to measure plasma parameters throughout the z-pinch discharge. A spatially resolved single frame time-gated extreme ultraviolet spectrometer measured the extent of plasma ablation off the surface of the foam. A time integrated crystal spectrometer showed that characteristic K shell radiation of silicon in the aerogel and of sulfur and sodium impurities in the agar were attenuated when the foam loads were coated with a conductive layer of gold. A time-resolved pinhole camera showed that in general the quality of the pinch implosions was poor but improved with increasing efforts to improve current continuity such as prepulse and conductive coatings. {copyright} {ital 1997 American Institute of Physics.}

Nash, T.J.; Derzon, M.S.; Allshouse, G.; Deeney, C.; Jobe, D.; Seaman, J.; Gilliland, T.; McGurn, J. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1193 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185-1193 (United States); MacFarlane, J.J.; Wang, P. [University of Wisconsin, Madison, Wisconsin (United States)] [University of Wisconsin, Madison, Wisconsin (United States)

1997-01-01

103

Jets from young stars and z-pinch machines  

NASA Astrophysics Data System (ADS)

Outflows and jets are intimately related to the formation of stars, and play a central role in redistributing mass, energy and angular momentum within the core, disk and parent cloud. The interplay between magnetic field and rotation is widely thought to be responsible for launching and collimating these outflows. Shear induced by differential rotation along initially poloidal field lines results in an azimuthal component of the magnetic field being generated; the magnetic pressure gradient then accelerates the plasma, and inflates bipolar magnetic cavities within the circumstellar matter. However, the resulting winding of the magnetic field can be potentially disrupted by magneto-hydrodynamic instabilities. To better understand the role of magnetic fields in shaping these ouflows, a series of experiments on pulsed-power z-pinch machines have been developed. In this talk I will present results related to the formation of jets in young stellar objects and in the laboratory, and draw a parallel between the two systems.

Ciardi, A.

2012-02-01

104

Conceptual Design of a Z-Pinch Fusion Propulsion System  

NASA Technical Reports Server (NTRS)

This slide presentation reviews a project that aims to develop a conceptual design for a Z-pinch thruster, that could be applied to develop advanced thruster designs which promise high thrust/high specific impulse propulsion. Overviews shows the concept of the design, which use annular nozzles with deuterium-tritium (D-T) fuel and a Lithium mixture as a cathode, Charts show the engine performance as a function of linear mass, nozzle performance (i.e., plasma segment trajectories), and mission analysis for possible Mars and Jupiter missions using this concept for propulsion. Slides show views of the concepts for the vehicle configuration, thrust coil configuration, the power management system, the structural analysis of the magnetic nozzle, the thermal management system, and the avionics suite,

Adams, Robert; Polsgrove, Tara; Fincher, Sharon; Fabinski, Leo; Maples, Charlotte; Miernik, Janie; Stratham, Geoffrey; Cassibry, Jason; Cortez, Ross; Turner, Matthew; Santarius, John; Percy, Thomas

2010-01-01

105

Dense Z-Pinch Research at the Nevada Terawatt Facility  

NASA Astrophysics Data System (ADS)

A high-repetition-rate, 2-terawatt z-pinch (HDZP-II from LANL: 2 MV, 1.2 MA, 100 ns, 200 kJ, 1.9 ohm) is being reassembled to investigate the early-time evolution of a current-driven wire, the plasma turbulence around and between wires, and the suppression or reduction of instabilities. Time-resolved x-ray imaging and backlighting, imaging spectroscopy, and laser diagnostics are under development. Calculations indicate x-ray polarization spectroscopy may help measure the electron distribution function and the magnetic field. Preliminary measurements of the heating and expansion of wires with current prepulses similar to those at SNL-Z will be presented (see theory by De Groot et. al., and simulations by Reisman et. al., this session).

Bauer, B. S.; Kantsyrev, V. L.; Le Galloudec, N.; Mancini, R. C.; Sarkisov, G. S.; Shlyaptseva, A. S.; Winterberg, F.; Farley, J. W.; de Groot, J. S.

1998-11-01

106

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

107

Spectroscopic study of z-pinch stagnation on Z.  

SciTech Connect

Fast z-pinches provide intense 1-10 keV photon energy radiation sources. Here, we analyze time-, space-, and spectrally-resolved {approx}2 keV K-shell emissions from Al (5% Mg) wire array implosions on Sandia's Z machine pulsed power driver. The stagnating plasma is modeled as three separate radial zones, and collisional-radiative modeling with radiation transport calculations are used to constrain the temperatures and densities in these regions, accounting for K-shell line opacity and Doppler effects. We discuss plasma conditions and dynamics at the onset of stagnation, and compare inferences from the atomic modeling to three-dimensional magneto-hydrodynamic simulations.

Maron, Yitzhak (Weizmann Institute of Science); Weingarten, L. (Weizmann Institute of Science); Starobinets, A. (Weizmann Institute of Science); Fisher, V. (Weizmann Institute of Science); Jennings, Christopher A.; Ampleford, David J.; Bailey, James E.; Yu, Edmund P.; Bernshtam, V. (Weizmann Institute of Science); Cuneo, Michael Edward; Rochau, Gregory Alan; Coverdale, Christine Anne; Jones, Brent Manley; Hansen, Stephanie B.

2010-11-01

108

Evolution of the gas-puff z-pinch column  

SciTech Connect

The gas-puff Z-pinch is nowadays used mainly as a source of X-ray radiation and neutrons. The evolution of a neon implosion of low energy discharge (4 kJ, 40 kV, 150 kA, 1.1 {micro}s) was studied using X-ray, schlieren, and high speed electrooptical visible gated quadro camera diagnostics. The geometry, an helical structure of pinched column, two steps of pinching, and X-ray emission have been studied. The hypothesis of an axial component of magnetic field generation, the helical shape of the magnetic and electric field lines, and the release of magnetic energy during the second pinching of the column are discussed.

Kubes, P; Kravarik, J. [Czech Technical Univ., Prague (Czech Republic). Faculty of Electrotechnical Engineering] [Czech Technical Univ., Prague (Czech Republic). Faculty of Electrotechnical Engineering; Kolacek, K.; Krejci, A. [Academy of Sciences CR, Prague (Czech Republic). Inst. of Plasma Physics] [Academy of Sciences CR, Prague (Czech Republic). Inst. of Plasma Physics; Paduch, M.; Tomaszewski, K. [Inst. of Plasma Physics and Laser Microfusion, Warsaw (Poland)] [Inst. of Plasma Physics and Laser Microfusion, Warsaw (Poland)

1998-08-01

109

Magnetohydrodynamic Simulation of Solid-Deuterium - Z-Pinch Experiments  

NASA Astrophysics Data System (ADS)

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 (at a time depending on current ramp and fiber thickness), 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, Peter Trogdon

110

Instability heating of solid-fiber Z pinches  

SciTech Connect

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 {mu}m. 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

111

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

112

Progress in symmetric ICF capsule implosions and wire-array z-pinch source physics for double z-pinch driven hohlraums.  

SciTech Connect

Over the last several years, rapid progress has been made evaluating the double-z-pinch indirect-drive, inertial confinement fusion (ICF) high-yield target concept (Hammer et al 1999 Phys. Plasmas 6 2129). We have demonstrated efficient coupling of radiation from two wire-array-driven primary hohlraums to a secondary hohlraum that is large enough to drive a high yield ICF capsule. The secondary hohlraum is irradiated from two sides by z-pinches to produce low odd-mode radiation asymmetry. This double-pinch source is driven from a single electrical power feed (Cuneo et al 2002 Phys. Rev. Lett. 88 215004) on the 20 MA Z accelerator. The double z-pinch has imploded ICF capsules with even-mode radiation symmetry of 3.1 {+-} 1.4% and to high capsule radial convergence ratios of 14-21 (Bennett et al 2002 Phys. Rev. Lett. 89 245002; Bennett et al 2003 Phys. Plasmas 10 3717; Vesey et al 2003 Phys. Plasmas 10 1854). Advances in wire-array physics at 20 MA are improving our understanding of z-pinch power scaling with increasing drive current. Techniques for shaping the z-pinch radiation pulse necessary for low adiabat capsule compression have also been demonstrated.

Bliss, David Emery; Vesey, Roger Alan; Rambo, Patrick K.; Lebedev, Sergey V. (Blackett Laboratory, Imperial College, London, UK); Hanson, David L.; Nash, Thomas J.; Yu, Edmund P.; Matzen, Maurice Keith; Afeyan, Bedros B. (Polymath Research, Inc., Pleasanton, CA); Smith, Ian Craig; Stygar, William A.; Porter, John Larry, Jr.; Cuneo, Michael Edward; Bennett, Guy R.; Campbell, Robert B.; Sinars, Daniel Brian; Chittenden, Jeremy Paul (Blackett Laboratory, Imperial College, London, UK); Waisman, Eduardo Mario; Mehlhorn, Thomas Alan

2005-07-01

113

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

114

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.

115

Study of soft X-ray emission from Z-pinches with a complex atomic composition  

SciTech Connect

Results are presented from experimental studies of Z-pinches produced by implosion of aluminum and tungsten cylindrical wire arrays in the Angara-5-1 facility. The electron temperature T{sub e} and density n{sub e} of the high-temperature pinch plasma have been determined by analyzing line emission from multicharged ions. For the same mass and radius of the array and the same number of wires in it, the intensity of line emission of H- and He-like Al ions from an imploded Al + W wire array containing even a small amount of tungsten (7 wt %) is one order of magnitude lower than that from an Al array. As the W content increases, the total soft X-ray (SXR) yield increases, while the duration of the SXR pulse decreases. For the 30% W content in the array, the power and duration of the SXR pulse are nearly the same as those recorded during the implosion of a W array with the same linear mass and radius and the same number of wires. Results are also presented from experiments with nested wire arrays in which the outer and inner shells were made of Al and W wires, respectively. It is found that, in this case, the effect of tungsten on the line emission of aluminum is much weaker than that in experiments with arrays in which tungsten and aluminum wires were placed in the same shell, even if the mass of the inner (tungsten) shell was larger than that of the outer (aluminum) one. At the same time, the inner W shell plays a significant role in the implosion dynamics of a nested wire array, reducing the duration of the SXR pulse and increasing the SXR power.

Volkov, G. S.; Zaitsev, V. I.; Grabovski, E. V.; Fedulov, M. V.; Aleksandrov, V. V.; Lakhtyushko, N. I. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)

2010-03-15

116

Study of soft X-ray emission from Z-pinches with a complex atomic composition  

NASA Astrophysics Data System (ADS)

Results are presented from experimental studies of Z-pinches produced by implosion of aluminum and tungsten cylindrical wire arrays in the Angara-5-1 facility. The electron temperature T e and density n e of the high-temperature pinch plasma have been determined by analyzing line emission from multicharged ions. For the same mass and radius of the array and the same number of wires in it, the intensity of line emission of H- and He-like Al ions from an imploded Al + W wire array containing even a small amount of tungsten (7 wt %) is one order of magnitude lower than that from an Al array. As the W content increases, the total soft X-ray (SXR) yield increases, while the duration of the SXR pulse decreases. For the 30% W content in the array, the power and duration of the SXR pulse are nearly the same as those recorded during the implosion of a W array with the same linear mass and radius and the same number of wires. Results are also presented from experiments with nested wire arrays in which the outer and inner shells were made of Al and W wires, respectively. It is found that, in this case, the effect of tungsten on the line emission of aluminum is much weaker than that in experiments with arrays in which tungsten and aluminum wires were placed in the same shell, even if the mass of the inner (tungsten) shell was larger than that of the outer (aluminum) one. At the same time, the inner W shell plays a significant role in the implosion dynamics of a nested wire array, reducing the duration of the SXR pulse and increasing the SXR power.

Volkov, G. S.; Zaitsev, V. I.; Grabovski, E. V.; Fedulov, M. V.; Aleksandrov, V. V.; Lakhtyushko, N. I.

2010-03-01

117

Current redistribution and generation of kinetic energy in the stagnated Z pinch.  

PubMed

The structure of magnetic fields was investigated in stagnated wire-array Z pinches using a Faraday rotation diagnostic at the wavelength of 266 nm. The distribution of current in the pinch and trailing material was reconstructed. A significant part of current can switch from the main pinch to the trailing plasma preheated by x-ray radiation of the pinch. Secondary implosions of trailing plasma generate kinetic energy and provide enhanced heating and radiation of plasma at stagnation. Hot spots in wire-array Z pinches also provide enhanced radiation of the Z pinch. A collapse of a single hot spot radiates 1%-3% of x-ray energy of the Z pinch with a total contribution of hot spots of 10%-30%. PMID:23944569

Ivanov, V V; Anderson, A A; Papp, D; Astanovitskiy, A L; Talbot, B R; Chittenden, J P; Niasse, N

2013-07-01

118

Current redistribution and generation of kinetic energy in the stagnated Z pinch  

NASA Astrophysics Data System (ADS)

The structure of magnetic fields was investigated in stagnated wire-array Z pinches using a Faraday rotation diagnostic at the wavelength of 266 nm. The distribution of current in the pinch and trailing material was reconstructed. A significant part of current can switch from the main pinch to the trailing plasma preheated by x-ray radiation of the pinch. Secondary implosions of trailing plasma generate kinetic energy and provide enhanced heating and radiation of plasma at stagnation. Hot spots in wire-array Z pinches also provide enhanced radiation of the Z pinch. A collapse of a single hot spot radiates 1%-3% of x-ray energy of the Z pinch with a total contribution of hot spots of 10%-30%.

Ivanov, V. V.; Anderson, A. A.; Papp, D.; Astanovitskiy, A. L.; Talbot, B. R.; Chittenden, J. P.; Niasse, N.

2013-07-01

119

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 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

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; R. J. Leeper; 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. Reyers; L. E. Ruggles; C. L. Ruiz; T. W. L. Sandford; 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

1998-01-01

120

X-Ray Imaging Measurements of Capsule Implosions Driven by a Z-Pinch Dynamic Hohlraum  

Microsoft Academic Search

The radiation and shock generated by impact of an annular tungsten Z-pinch plasma on a 10-mm diam 5-mg\\/cc CH2 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 ~135-eV radiation field imploded a 2.1-mm-diam CH capsule. The measured radiation temperature, shock radius, and capsule radius agreed well with

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

2002-01-01

121

Electromagnetic Wave Propagation Through the ZR Z-Pinch Accelerator  

SciTech Connect

A fully three-dimensional electromagnetic model of the major pulsed power components of the 26-MA ZR accelerator is presented. This large-scale simulation model tracks the evolution of electromagnetic waves through the intermediate storage capacitors, laser-triggered gas switches, pulse-forming lines, water switches, tri-plate transmission lines, and water convolute to the vacuum insulator stack. The plates at the insulator stack are coupled to a transmission line circuit model of the four-level magnetically-insulated transmission line section and post-hole convolutes. The vacuum section circuit model is terminated by either a short-circuit load or dynamic models of imploding z-pinch loads. The simulations results are compared with electrical measurements made throughout the ZR accelerator and good agreement is found, especially for times before and up to peak load power. This modeling effort represents new opportunities for modeling existing and future large-scale pulsed power systems used in a variety of high energy density physics and radiographic applications.

Rose, D. V.; Welch, D. R.; Madrid, E. A.; Miller, C. L.; Clark, R. E. [Voss Scientific, LLC, Albuquerque, New Mexico (United States); Stygar, W. A.; Struve, K. [Sandia National Laboratories, Albuquerque, New Mexico (United States); Corcoran, P. A.; Whitney, B. [L-3 Communications, San Leandro, California (United States)

2009-01-21

122

Electromagnetic wave propagation through the ZR Z-pinch accelerator.  

SciTech Connect

A fully three-dimensional electromagnetic model of the major pulsed power components of the 26-MA ZR accelerator is presented. This large-scale simulation model tracks the evolution of electromagnetic waves through the intermediate storage capacitors, laser-triggered gas switches, pulse-forming lines, water switches, tri-plate transmission lines, and water convolute to the vacuum insulator stack. The plates at the insulator stack are coupled to a transmission line circuit model of the four-level magnetically-insulated transmission line section and post-hole convolutes. The vacuum section circuit model is terminated by either a short-circuit load or dynamic models of imploding z-pinch loads. The simulations results are compared with electrical measurements made throughout the ZR accelerator and good agreement is found, especially for times before and up to peak load power. This modeling effort represents new opportunities for modeling existing and future large-scale pulsed power systems used in a variety of high energy density physics and radiographic applications.

Welch, Dale Robert (Voss Scientific, LLC, Albuquerque, NM); Clark, R. E. (Voss Scientific, LLC, Albuquerque, NM); Rose, David Vincent (Voss Scientific, LLC, Albuquerque, NM); Madrid, Elizabeth Ann (Voss Scientific, LLC, Albuquerque, NM); Corcoran, P. A. (L-3 Communications, San Leandro, CA); Struve, Kenneth William; Stygar, William A.; Miller, C. L. (Voss Scientific, LLC, Albuquerque, New Mexico); Whitney, B. (L-3 Communications, San Leandro, CA)

2008-08-01

123

Cylindrical Liner Z-pinch Experiments on the MAGPIE Generator  

NASA Astrophysics Data System (ADS)

Experimental data from gas-filled cylindrical liner z-pinch experiments is presented. The MAGPIE current (1.4 MA, 240 ns) is applied to a thin walled (80um) Al tube with a static gas-fill inside. The system is diagnosed axially using interferometry, optical streak photography and optical spectroscopy. We observe a series of cylindrically converging shock waves driven into the gas-fill from the inside liner surface. No bulk motion of the liner occurs. The timing of the shocks and their trajectories provide information on the shock launching mechanisms. This in turn allows a study of the response of the liner to the current pulse. Shock wave timing is compared to measurements of the liner resistance and optical images of the liner's outside surface. The system provides a useful, essentially 1D problem for testing MagLIF relevant MHD codes, particularly with regards to EOS, strength and resistivity models. This work may also be relevant to the study of shocks in astrophysical plasmas. The shocks launched into the gas radiatiate strongly; spatially resolved optical spectroscopy data and radial electron density profiles from interferometry images provide evidence for a radiative precursor ahead of the first shock. Instabilities are seen to develop in the downstream regions.

Burdiak, Guy; Lebedev, Sergey V.; Harvey-Thompson, Adam J.; Swadling, George F.; Suzuki-Vidal, Francisco; Skidmore, Jonathan; Suttle, Lee; Khoory, Essa; Pickworth, Louisa; de Grouchy, Philip; Hall, Gareth N.; Bland, Simon N.; Weinwurm, Marcus; Chittenden, Jeremy P.

2012-10-01

124

K-? emission spectroscopic analysis from a Cu Z-pinch  

NASA Astrophysics Data System (ADS)

Advances in diagnostic techniques at the Sandia Z-facility have facilitated the production of very detailed spectral data. In particular, data from the copper nested wire-array shot Z1975 provides a wealth of information about the implosion dynamics and ionization history of the pinch. Besides the dominant valence K- and L-shell lines in Z1975 spectra, K-? lines from various ionization stages were also observed. K-shell vacancies can be created from inner-shell excitation and ionization by hot electrons and from photo-ionization by high-energy photons; these vacancies are subsequently filled by Auger decay or resonance fluorescence. The latter process produces the K-? emission. For plasmas in collisional equilibrium, K-? emission usually occurs from highly charged ions due to the high electron temperatures required for appreciable excitation of the K-? transitions. Our simulation of Z1975 was carried out with the NRL 1-D DZAPP non-LTE radiation-hydrodynamics model, and the resulting K- and L-shell synthetic spectra are compared with measured radiation data. Our investigation will focus on K-? generation by both impacting electrons and photons. Synthetic K-? spectra will be generated either by self-consistently calculating the K-shell vacancy production in a full Z-pinch simulation, or by post-processing data from a simulation. The analysis of these K-? lines as well as K- and L-shell emission from valence electrons should provide quantitative information about the dynamics of the pinch plasma.

Dasgupta, A.; Clark, R. W.; Giuliani, J. L.; Ouart, N. D.; Jones, B.; Ampleford, D. J.; Hansen, S. B.

2013-06-01

125

Fully Kinetic Simulations of Dense Plasma Focus Z-Pinch  

NASA Astrophysics Data System (ADS)

Dense plasma focus (DPF) z pinch devices are sources of copious high energy electrons and ions, x-rays, and neutrons. The mechanisms through which these physically simple devices generate such high energy beams in a relatively short distance are not fully understood. We now have, for the first time, demonstrated a capability to model these plasmas fully kinetically, allowing us to simulate the pinch process at the particle scale. We present here the results of the initial kinetic simulations, which reproduce experimental neutron yields and high energy (MeV) beams for the first time. We present a comparison between fully kinetic, hybrid (kinetic ions/fluid electrons), and fluid simulations. Only fully kinetic simulations predict MeV-energy ions and experimental neutron yields. A frequency analysis of the electric field in the fully kinetic simulation shows plasma fluctuations near the lower hybrid frequency. This suggests the presence of lower hybrid drift instability, a possible contributor to anomalous resistivity in the plasma. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and supported by the Laboratory Directed Research and Development Program (11-ERD-063) at LLNL.

Schmidt, Andrea; Tang, Vincent; Welch, Dale

2012-10-01

126

Radiative collapse of a Bennett-relaxed z-pinch  

NASA Astrophysics Data System (ADS)

The global evolution of a z-pinch has been studied with the assumption of a relaxed state consisting of ions and electrons, each in a rigidly drifting isothermal Maxwellian distribution. This speculative approach has the pragmatic feature of possessing phenomenologically useful global parameters such as drift velocity and temperature that vary in accordance with global physical quantities such as energy and entropy. The plasma gains energy from a time-dependent electric field by means of Poynting's vector. Coulomb collisions between electrons and ions are calculated with a Fokker-Planck treatment analogous to that used by Dreicer to calculate runaways. For a variety of initial conditions and time-independent applied electric fields, the pinch evolution always culminates in a time-independent (attractor) state whose current is the Pease-Braginskii current and whose final radius is proportional to (line density to the 3/4 power)/(electric field to the 1/2 power). Before the final state is attained, the pinch may bounce toward and away from a highly collapsed state. For the case of a Bennett pinch, the classical limit of the resistivity is attained when the line density is much greater than 4(eta)m(sub e)/e(2)mu(sub 0); i.e., 3.55 x 10(14) m(-1).

Turner, Leaf

127

Radiative collapse of a Bennett-relaxed z-pinch  

SciTech Connect

The global evolution of a z-pinch has been studied with the assumption of a relaxed state consisting of ions and electrons, each in a rigidly drifting isothermal Maxwellian distribution. This speculative approach has the pragmatic feature of possessing phenomenologically useful global parameters such as drift velocity and temperature that vary in accordance with global physical quantities such as energy and entropy. The plasma gains energy from a time-dependent electric field by means of Poynting's vector. Coulomb collisions between electrons and ions is calculated with a Fokker-Planck treatment analogous to that used by Dreicer to calculate runaways. For a variety of initial conditions and time-independent applied electric fields, the pinch evolution always culminates in a time-independent (attractor) state whose current is the Pease-Braginskii current and whose final radius is proportional to (line density)/sup 3/4//(electric field)/sup 1/2/. Before the final state is attained, the pinch may bounce toward and away from a highly collapsed state. For the case of a Bennett pinch, the classical limit of the resistivity is attained when the line density is much greater than 4..pi..m/sub e//e/sup 2/..mu../sub o/; i.e., 3.55 /times/ 10/sup 14/ m/sup /minus/1/. 6 refs., 2 figs.

Turner, L.

1989-01-01

128

Radiative collapse of a Bennett-relaxed z-pinch  

SciTech Connect

The global evolution of a z-pinch has been studied with the assumption of a relaxed state consisting of ions and electrons, each in a rigidly drifting isothermal Maxwellian distribution. This speculative approach has the pragmatic feature of possessing phenomenologically useful global parameters such as drift velocity and temperature that vary in accordance with global physical quantities such as energy and entropy. The plasma gains energy from a time-dependent electric field by means of Poynting's vector. Coulomb collisions between electrons and ions is calculated with a Fokker-Planck treatment analogous to that used by Dreicer to calculate runaways. For a variety of initial conditions and time-dependent applied electric fields, the pinch evolution always culminates in a time-dependent (attractor) state whose current is the Pease-Braginskii current and whose final radius is proportional to (line density{sup 3/4})/(electric field){sup 1/2}. Before the final state is attained, the pinch may bounce toward and away from a highly collapsed state. For the case of a Bennett pinch, the classical limit of the resistivity is attained when the line density is much greater than 4{pi}{ital m}{sub {ital e}}/{ital e}{sup 2}{mu}{sub 0}; i.e., 3.55{times}10{sup 14} m{sup {minus}1}.

Turner, L. (Los Alamos National Laboratory, University of California, Los Alamos, NM (USA))

1989-12-01

129

Radiative collapse of a Bennett-relaxed z-pinch  

NASA Astrophysics Data System (ADS)

The global evolution of a z-pinch has been studied with the assumption of a relaxed state consisting of ions and electrons, each in a rigidly drifting isothermal Maxwellian distribution. This speculative approach has the pragmatic feature of possessing phenomenologically useful global parameters such as drift velocity and temperature that vary in accordance with global physical quantities such as energy and entropy. The plasma gains energy from a time-dependent electric field by means of Poynting's vector. Coulomb collisions between electrons and ions is calculated with a Fokker-Planck treatment analogous to that used by Dreicer to calculate runaways. For a variety of initial conditions and time-dependent applied electric fields, the pinch evolution always culminates in a time-dependent (attractor) state whose current is the Pease-Braginskii current and whose final radius is proportional to (line density3/4)/(electric field)1/2. Before the final state is attained, the pinch may bounce toward and away from a highly collapsed state. For the case of a Bennett pinch, the classical limit of the resistivity is attained when the line density is much greater than 4?me/e2?0; i.e., 3.55×1014 m-1.

Turner, Leaf

1989-12-01

130

Preliminary Results of a 10 kJ Z-Pinch  

SciTech Connect

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 {mu}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 switches triggered by a 100 kV, 13 ns trigger pulse. The discharge chamber is a cylindrical Pyrex glass tube externally surrounded by a SF{sub 6} isolation atmosphere with the electrodes at the ends. Two different chambers have been studied by discharging the capacitor bank energy in deuterium for optimizing the D-D nuclear fusion reactions: one of 100 mm long by 100 mm inner diameter and the other of the same length and 70 mm inner diameter. Several sequences of ultrahigh speed converter camera photography (5 ns) are presented showing the implosion of plasma columns for different deuterium pressure and currents. Preliminary measurements of integrated 2.45 MeV neutron emissions by a silver activated neutron counter are analyzed as a function of electrical and constructive parameters. A yield of 10{sup 7}-10{sup 8} D-D fusion reactions by shot is reported when the optimum conditions are reached conducting currents of 400-600 kA with a plasma column lifetime above 100 ns.

Cortazar, O. D.; Piriz, A. R.; Prieto, G. Rodriguez [Universidad de Castilla-La Mancha. E.T.S.I.I. Laboratorio de Plasmas y Descargas Electricas Campus de Ciudad Real-13071 Ciudad Real-Spain (Spain); Hoffmann, D. H. H.; Tahir, N. A. [G.S.I Darmstadt--Plasma Physics Division Planckstr 1-64291 Darmstadt--Germany (Germany)

2008-04-07

131

Preliminary Results of a 10 kJ Z-Pinch  

NASA Astrophysics Data System (ADS)

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 switches triggered by a 100 kV, 13 ns trigger pulse. The discharge chamber is a cylindrical Pyrex glass tube externally surrounded by a SF6 isolation atmosphere with the electrodes at the ends. Two different chambers have been studied by discharging the capacitor bank energy in deuterium for optimizing the D-D nuclear fusion reactions: one of 100 mm long by 100 mm inner diameter and the other of the same length and 70 mm inner diameter. Several sequences of ultrahigh speed converter camera photography (5 ns) are presented showing the implosion of plasma columns for different deuterium pressure and currents. Preliminary measurements of integrated 2.45 MeV neutron emissions by a silver activated neutron counter are analyzed as a function of electrical and constructive parameters. A yield of 107-108 D-D fusion reactions by shot is reported when the optimum conditions are reached conducting currents of 400-600 kA with a plasma column lifetime above 100 ns.

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

2008-04-01

132

Aluminum-doped lithium nickel cobalt oxide electrodes for high-power lithium-ion batteries  

Microsoft Academic Search

Non-doped and aluminum-doped LiNi0.8Co0.2O2 cathodes from three industrial developers coupled with graphite anodes were made into lithium-ion cells for high-power applications. The powder morphology of the active cathode materials was examined by a scanning electron microscope. The electrochemical performance of these cells was investigated by hybrid pulse power characterization (HPPC) testing, accelerated aging, and AC impedance measurement of symmetric cells.

C. H. Chen; J. Liu; M. E. Stoll; G. Henriksen; D. R. Vissers; K. Amine

2004-01-01

133

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

134

Fusion burn dynamics in Dense Z-Pinch (DZP)  

NASA Astrophysics Data System (ADS)

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. Magnetohydrodynamic 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 and for possible commercial power production are described. If f(sub B) approx. greater than 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 to 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 greater than 10(exp 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.

Krakowski, R. A.

1990-04-01

135

Driver Technology for Inertial Fusion Research 4.X-Ray Sources by Z-Pinch for Inertial Confinement Fusion  

Microsoft Academic Search

Inertial confinement nuclear fusion driven by X-ray from Z-pinch plasmas has been developed. Recently, extremely high X-ray power (290 TW) and energy (1.8 MJ) were produced in fast Z-pinch implosions on the Z accelerator (Sandia National Laboratories). Wire arrays are used to produce the initial plasma. The X-ray from Z-pinch plasmas produced by pulsed power has great potential as a

Hidenori Akiyama; Sunao Katsuki; Igor Lisitsyn

1999-01-01

136

Spatially-resolved spectra from a new uniform dispersion crystal spectrometer for characterization of Z-pinch plasmas  

NASA Astrophysics Data System (ADS)

Based on self-focusing and uniform dispersion principle, a novel mica uniform dispersion crystal spectrograph (UDCS) was developed, whose linear dispersion was designed to be constant. An aluminum wire-array imploding experiment was performed at “Yang” accelerator and K-shell emission spectra were measured to investigate Z-pinch aluminum plasma characteristics by using the UDCS. The linear dispersion deduced from obtained spectra with linear fitting was in good agreement with the theoretical value. By using the collisional-radiative equilibrium (CRE) model, the intensity ratios of Ly-?/He-? line and Ly-?/He-? were given as a function of electron temperature. The measured intensity ratios were compared to the computed ones and the electron temperatures were estimated to be 512 eV and 489 eV. The slope of the free-bound X-ray continuum provides a model-independent diagnostic of the core electron temperature which was around 1215 eV for this implosion. Analysis of Z-pinch radial temperature gradient shows that the temperature decreases sharply near the core and slowly to the shell regions. Benefiting from the UDCS providing high spectral resolution (?/??˜2500), the existence of first-order Langmuir dips were observed and reliably identified in Al Ly-? and Ly-? resonance line profiles. The relationship between the position from the line center of red Langmuir dips and electron density was studied. The electron densities deduced from these fine spectral features were 5.52×1021 cm-3 and 4.57×1021 cm-3 respectively, which compared well with those derived from measurements of the line shift. The ion temperature was determined from the Doppler broadening of Al He-? resonance, He-like intercombination and Li-like s, t (n=2) satellite lines.

Jian, Lu; Shali, Xiao; Qingguo, Yang; Lifeng, Liu; Yufen, Wu

2013-02-01

137

Development of the 50 TW laser for joint experiments with 1 MA z-pinches  

NASA Astrophysics Data System (ADS)

A 50 TW high-intensity laser (aka "Leopard" laser) was developed for experiments with the 1 MA z-pinch generator at the University of Nevada, Reno. The laser produces short pulses of 0.35 ps; energy is 15 J. Long pulses are 1 ns; energy is 30 J. The output beam diameter is 80 mm. The Leopard laser applies chirped pulse amplification technology. The laser is based on the 130 fs Ti:Sapphire oscillator, Öffner-type stretcher, Ti:Sapphire regenerative amplifier, mixed Nd:glass rod and disk amplifiers, and vacuum grating compressor. An adaptive optics system ameliorates focusing ability and augments the repetition rate. Two beam terminals are available for experiments: in the vacuum chamber of the z-pinch generator (aka "Zebra"), and a laser-only vacuum chamber (aka "Phoenix" chamber). The Leopard laser coupled to the Zebra z-pinch generator is a powerful diagnostic tool for dense z-pinch plasma. We outline the status, design, architecture and parameters of the Leopard laser, and its coupling to Zebra. We present the methods of laser-based z-pinch plasma diagnostics, which are under development at the University of Nevada, Reno.

Wiewior, P. P.; Ivanov, V. V.; Chalyy, O.

2010-08-01

138

Gas-puff Z-pinch driven by inductive energy storage pulsed power generator ASO-2  

NASA Astrophysics Data System (ADS)

An inductive energy storage pulsed power generator ASO-2 with two-staged opening switches was used as a power source of a gas-puff z-pinch and was compared with a fast bank with the same energy. A uniform discharge and a z-pinch implosion occurred at higher driving current than that of a fast bank. The intensity of soft x-rays driven by ASO-2 with only one-staged opening switch (copper wire fuses) was much increased in comparison with that driven by the fast bank. From the observation of hot spots by a pin-hole camera, the spatial positions of the hot spots did not move much shot to shot. These results are very important for applications of the gas-puff z-pinch in industry.

Imasaka, K.; Hasegawa, K.; Akiyama, H.; Maeda, S.

1994-06-01

139

Characteristics of the Z-pinch Implosion Plasmas on Low Current Generators  

SciTech Connect

The primary physical images of the low driven current (<7MA) Z-pinch experiments on the three facilities, including the Angara-5-1 and S-300 in Russia, and the Qiangguang-I in China, were analyzed and summarized. The wire-array Z-pinch implosion processes were simulated by using a zero-dimensional model and an one-dimensional radial-magneto-hydrodynamic code. It is found that in the different pulse power driver, even if there are the same peak currents, the process of the wire-array plasma implosion and the compression state can be quite different due to the different rising-time of the current. Moreover, it is also found that not total mass of the wire-array takes part in the implosion process in the Z-pinch experiment.

Ding Ning; Yang Zhenhua; Ning Cheng; Wu Jiming; Liu Quan; Fan Wenbin; Zhang Yang [Institute of Applied Physics and Computational Mathematics, P. O. Box 8009-11, Beijing 100088 (China)

2006-01-05

140

A Gas Embedded Z-pinch Driven by SPEED2 Generator  

SciTech Connect

A gas embedded Z-pinch has been implemented using the SPEED2 generator (4.1 {mu}F equivalent Marx generator capacity, 300 kV, 4 MA in short circuit, 187 kJ, 400 ns rise time, dI/dt{approx}1013 A/s). Initial conditions to produce a gas embedded z-pinch with enhanced stability by means resistive effects and by finite Larmor radius effects were obtained and electrodes were constructed in order to obtain a double column Z-pinch and a hollow discharge. Experiments were carried out in deuterium at mega amperes currents. Current derivative and voltage signals have been obtained. In addition interferograms have been obatined using a pulse Nd-YAG laser (8ns FWMH at 532nm). Preliminary results on neutron emission were also obtained.

Soto, Leopoldo; Moreno, Jose; Sylvester, Gustavo; Silva, Patricio; Zambra, Marcelo [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile); Pavez, Cristian [Universidad de Concepcion (Chile); Clausse, Alejandro [CNEA-CONICET-PLADEMA, Universidad del Centro, Tandil (Argentina)

2006-12-04

141

Insights and applications of two-dimensional simulations to Z-pinch experiments  

SciTech Connect

A two-dimensional (2D) Eulerian radiation-magnetohydrodynamic code has been used to successfully simulate hollow metallic {ital z}-pinch experiments fielded on several facilities with a wide variety of drive conditions, time scales, and loads. The 2D simulations of these experiments reproduce important quantities of interest including the radiation pulse energy, power, and pulse width. This match is obtained through the use of an initial condition: the amplitude of a random density perturbation imposed on the initial plasma shell. The perturbations seed the development of magnetically driven Rayleigh{endash}Taylor instabilities which greatly affect the dynamics of the implosion and the resulting production of radiation. Analysis of such simulations allows insights into the physical processes by which these calculations reproduce the experimental results. As examples, the insights gained from the simulations of Sandia {open_quotes}{ital Z}{close_quotes} accelerator [R. B. Spielman {ital et al.}, Phys. Plasmas {bold 5}, 2105 (1998)] experiments have allowed for the investigation of possible physical processes which produce high powers in {open_quotes}nested array{close_quotes} implosions and high temperatures within {open_quotes}dynamic hohlraum{close_quotes} loads. Building on these insights, the 2D code has been used in designing new experiments to optimize the desired physical conditions and in interpreting the experimental results obtained. These examples and others will be discussed as well as examples of simulation results where improvement is needed and what steps are being taken to make that improvement. {copyright} {ital 1999 American Institute of Physics.}

Peterson, D.L.; Bowers, R.L.; Matuska, W.; McLenithan, K.D. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Chandler, G.A.; Deeney, C.; Derzon, M.S.; Douglas, M.; Matzen, M.K.; Nash, T.J.; Spielman, R.B.; Struve, K.W.; Stygar, W.A. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Roderick, N.F. [University of New Mexico, Albuquerque, New Mexico 87131 (United States)] [University of New Mexico, Albuquerque, New Mexico 87131 (United States)

1999-05-01

142

Collective ion acceleration during the decay of a high-current Z-pinch  

SciTech Connect

A study is made of the Z-pinch plasma expansion after the current is switched off. Measurements were carried out in experiments on the implosion of tungsten wire arrays in the Angara-5-1 facility. It is found experimentally that, at a distance of 2 m from the pinch, the ion velocity in the expanding Z-pinch plasma is about (2.5-4.0) x 10{sup 7} cm/s, which substantially exceeds the thermal velocity of tungsten ions. A model describing the plasma expansion process is proposed that is based on the ambipolar acceleration mechanism. The results of numerical simulations are compared with the experimental data.

Zaitsev, V. I.; Volkov, G. S.; Kartashov, A. V.; Lakhtyushko, N. I. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)

2008-03-15

143

Collective ion acceleration during the decay of a high-current Z-pinch  

NASA Astrophysics Data System (ADS)

A study is made of the Z-pinch plasma expansion after the current is switched off. Measurements were carried out in experiments on the implosion of tungsten wire arrays in the Angara-5-1 facility. It is found experimentally that, at a distance of 2 m from the pinch, the ion velocity in the expanding Z-pinch plasma is about (2.5-4.0) × 107 cm/s, which substantially exceeds the thermal velocity of tungsten ions. A model describing the plasma expansion process is proposed that is based on the ambipolar acceleration mechanism. The results of numerical simulations are compared with the experimental data.

Zaitsev, V. I.; Volkov, G. S.; Kartashov, A. V.; Lakhtyushko, N. I.

2008-03-01

144

Enhancement of K-shell Radiation in Z-pinch Plasmas Due to Shock Heating  

NASA Astrophysics Data System (ADS)

The load in a Z-pinch can be tailored to enhance the effects of shock heating. The question is whether this approach can efficiently ionize the plasma through the L-shell and result in enhanced K-shell radiation. We investigate the ionization and radiation dynamics of a uniform plasma subjected to compression and heating at various rates, and relate the parameters to potential Z-pinch experiments. The numerical simulations are carried out with a time-dependent detailed configuration atomic model coupled to a 1-D non-LTE radiation transport algorithm.

Clark, R. W.; Apruzese, J. P.; Davis, J.

1999-11-01

145

Control of the Rayleigh-Taylor instability in a staged Z pinch  

SciTech Connect

Z-pinch experiments and computer simulations provide evidence for enhanced stability and current transfer in a staged Z pinch, consisting of an annular krypton shell imploding onto a deuterium gas fill. Visible-streak and Schlieren imaging provide evidence for a multilayer implosion where the outer plasma shell is Rayleigh-Taylor unstable and the inner plasma column is stable. Computer simulations indicate that the discharge current diffuses through the unstable, outer Kr shell. As the discharge current layer implodes onto the deuterium, current is transferred and a stable implosion results, producing a deuterium-compression ratio of 200.

Rahman, H.U.; Ney, P.; Rostoker, N.; Van Drie, A.; Wessel, F.J. [GTT International Inc., Riverside, California 92507 (United States); Mount San Jacinto College, Menifee, California (United States); Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)

2004-12-01

146

Nitrogen laser system for diagnosing z-pinch and x-pinch plasmas  

SciTech Connect

A nitrogen laser system built to probe dense z-pinch and x-pinch plasmas is described. This low-cost system consists of an atmospheric pressure oscillator and a low pressure amplifier. It generates a 1-cm-diam 3371 {Angstrom} laser beam with approximately 0.33 mJ in a {approx_lt}1 ns pulse, and with a coherence length of at least 5 cm. This laser has been used in several modes of operation, such as for simultaneous schlieren and interferometry imaging of dense z-pinch and x-pinch plasmas. Example results are presented. {copyright} {ital 1997 American Institute of Physics.}

Kalantar, D.H. [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States)] [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States); Hammer, D.A. [Laboratory of Plasma Studies and School of Electrical Engineering, Cornell University, Ithaca, New York 14853 (United States)] [Laboratory of Plasma Studies and School of Electrical Engineering, Cornell University, Ithaca, New York 14853 (United States); De Silva, A.W. [Institute for Plasma Research, University of Maryland, College Park, Maryland 20742-3511 (United States)] [Institute for Plasma Research, University of Maryland, College Park, Maryland 20742-3511 (United States)

1997-07-01

147

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

National Technical Information Service (NTIS)

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 dev...

G. A. Rochau M. S. Derzon G. A. Chandler S. E. Lazier

2000-01-01

148

Design, simulation, and application of quasi-spherical z-pinch implosions driven by tens of mega-amperes.  

SciTech Connect

A quasi-spherical z-pinch may directly compress foam or deuterium and tritium in three dimensions as opposed to a cylindrical z-pinch, which compresses an internal load in two dimensions only. Because of compression in three dimensions the quasi-spherical z-pinch is more efficient at doing pdV work on an internal fluid than a cylindrical pinch. Designs of quasi-spherical z-pinch loads for the 28 MA 100 ns driver ZR, results from zero-dimensional (0D) circuit models of quasi-spherical implosions, and results from 1D hydrodynamic simulations of quasi-spherical implosions heating internal fluids will be presented. Applications of the quasi-spherical z-pinch implosions include a high radiation temperature source for radiation driven experiments, a source of neutrons for treating radioactive waste, and a source of fusion energy for a power generator.

Struve, Kenneth William; Deeney, Christopher D.; Leeper, Ramon Joe; McDaniel, Dillon Heirman; Nash, Thomas J.; DeGroot, John Stacey; Sanford, Thomas W. L.

2004-08-01

149

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

Microsoft Academic Search

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

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

2000-01-01

150

Z-Pinch Generated X-Rays Demonstrate Indirect-Drive ICF Potential; Physical Review Letters.  

National Technical Information Service (NTIS)

Hohlraums (measuring 6-mm in diameter by 7-mm in height) have been heated by x-rays from a z-pinch. Over measured x-ray input powers P of 0.7 to 13 TW, the hohlraum radiation temperature T increases from ;55 to ;130 eV, and is in agreement with the Planck...

R. L. Bowers G. A. Chandler M. S. Derzon D. E. Hebron R. J. Leeper

1999-01-01

151

Application of 2-D simulations to hollow Z-pinch implosions  

Microsoft Academic Search

The application of simulations of z-pinch implosions should have at least two goals: first, to properly model the most important physical processes occurring in the pinch allowing for a better understanding of the experiments and second, provide a design capability for future experiments. Beginning with experiments fielded at Los Alamos on the Pegasus I and Pegasus II capacitor banks, we

D. L. Peterson; R. L. Bowers; J. H. Brownell; C. Lund; W. Matuska; K. McLenithan; H. Oona; C. Deeney; M. Derzon; R. B. Spielman; T. J. Nash; G. Chandler; R. C. Mock; T. W. L. Sanford; M. K. Matzen; N. F. Roderick

1997-01-01

152

Hotspot ignition using a Z-pinch precursor plasma in a magneto-inertial ICF scheme  

NASA Astrophysics Data System (ADS)

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

Chittenden, J. P.; Vincent, P.; Jennings, C. A.; Ciardi, A.

2006-01-01

153

O-d energetics scaling models for Z-pinch-driven hohlraums  

SciTech Connect

Wire array Z-pinches on the Z accelerator provide the most intense laboratory source of soft x-rays in the world. The unique combination of a highly-Planckian radiation source with high x-ray production efficiency (15% wall plug), large x-ray powers and energies ( >150 TW, {ge}1 MJ in 7 ns), large characteristic hohlraum volumes (0.5 to >10 cm{sup 3}), and long pulse-lengths (5 to 20 ns) may make Z-pinches a good match to the requirements for driving high-yield scale ICF capsules with adequate radiation symmetry and margin. The Z-pinch driven hohlraum approach of Hammer and Porter [Phys.Plasmas, 6, 2129(1999)] may provide a conservative and robust solution to the requirements for high yield, and is currently being studied on the Z accelerator. This paper describes a multiple region, 0-d hohlraum energetic model for Z-pinch driven hohlraums in four configurations. The authors observe consistency between the models and the measured x-ray powers and hohlraum wall temperatures to within {+-}20% in flux, for the four configurations.

CUNEO,MICHAEL E.; VESEY,ROGER A.; HAMMER,J.H.; PORTER,JOHN L.

2000-06-08

154

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

155

Wavelets, curvelets, and multiresolution analysis techniques in fast Z-pinch research  

Microsoft Academic Search

Z pinches produce an X ray rich plasma environment where backlighting imaging of imploding targets can be quite challenging to analyze. What is required is a detailed understanding of the implosion dynamics by studying snapshot images of its in flight deformations away from a spherical shell. We have used wavelets, curvelets and multiresolution analysis techniques to address some of these

Bedros Afeyan; Kirk Won; Jean-Luc Starck; Michael Cuneo

2003-01-01

156

Dust and debris transport modeling for experimental z-pinch driven inertial fusion systems  

NASA Astrophysics Data System (ADS)

A model using the TEXAS-NCV computer code is presented for the transport of dust and debris in a z-pinch driven explosive propagation of gas into vacuum. First, TEXAS-NC was improved, updated, and benchmarked against several experiments for quasi-one-dimensional shock propagation applications involving multi-component, multi-phase systems. Second, a vacuum transport model was developed and incorporated into TEXAS and benchmarked for adiabatic expansions and wall pressure histories at various dimensionless distances. This model eliminates the severe problem usually encountered with vacuum transport in Eulerian hydrodynamics codes, and gives TEXAS a rare set of capabilities that is not known to exist before. Third, TEXAS-NCV was used to model dust and debris transport in z-pinch driven experiments designed for application to the U.S. inertial fusion energy program. Results showed that if radioactive dust and debris is to be completely contained within the Z experiment chamber, explosive closures placed at the ends of the MITLs must complete the closure process in less than 1 ms. Substantially faster closure times will be required if the valves are to be placed closer to the center of the Z-pinch convolute or if magnetic effects during the z-pinch have already accelerated debris.

Utschig, Tristan Thomas

157

Target design for high fusion yield with the double Z-pinch-driven hohlraum  

SciTech Connect

A key demonstration on the path to inertial fusion energy is the achievement of high fusion yield (hundreds of MJ) and high target gain. Toward this goal, an indirect-drive high-yield inertial confinement fusion (ICF) target involving two Z-pinch x-ray sources heating a central secondary hohlraum is described by Hammer et al. [Phys. Plasmas 6, 2129 (1999)]. In subsequent research at Sandia National Laboratories, theoretical/computational models have been developed and an extensive series of validation experiments have been performed to study hohlraum energetics, capsule coupling, and capsule implosion symmetry for this system. These models have been used to design a high-yield Z-pinch-driven ICF target that incorporates the latest experience in capsule design, hohlraum symmetry control, and x-ray production by Z pinches. An x-ray energy output of 9 MJ per pinch, suitably pulse-shaped, is sufficient for this concept to drive 0.3-0.5 GJ capsules. For the first time, integrated two-dimensional (2D) hohlraum/capsule radiation-hydrodynamics simulations have demonstrated adequate hohlraum coupling, time-dependent radiation symmetry control, and the successful implosion, ignition, and burn of a high-yield capsule in the double Z-pinch hohlraum. An important new feature of this target design is mode-selective symmetry control: the use of burn-through shields offset from the capsule that selectively tune certain low-order asymmetry modes (P{sub 2},P{sub 4}) without significantly perturbing higher-order modes and without a significant energy penalty. This paper will describe the capsule and hohlraum design that have produced 0.4-0.5 GJ yields in 2D simulations, provide a preliminary estimate of the Z-pinch load and accelerator requirements necessary to drive the system, and suggest future directions for target design work.

Vesey, R. A.; Herrmann, M. C.; Lemke, R. W.; Desjarlais, M. P.; Cuneo, M. E.; Stygar, W. A.; Bennett, G. R.; Campbell, R. B.; Christenson, P. J.; Mehlhorn, T. A.; Porter, J. L.; Slutz, S. A. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185-1186 (United States)

2007-05-15

158

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

159

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

160

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

161

Application of 2-D Simulations to Z-Pinch Experiment Design and Analysis  

SciTech Connect

The successful 2-D simulations of z-pinch experiments (reproducing such features as the measured experimental current drive, radiation pulse shape, peak power and total radiated energy) can lead to a better understanding of the underlying physics in z-pinch implosions and to the opportunity to use such simulations in the analysis of experimental data and in the design of new experiments. Such use has been made with LANL simulations of experiments on the Sandia Saturn and Z accelerators. Applications have included ''vacuum'' and ''dynamic'' hohlraum experiments; variations in mass, radius and length; and ''nested'' array configurations. Notable examples include the explanation of the power/length results in reduced length pinches and the prediction of the current best power and pulsewidth nested array experiment. Examples of circumstances where the simulation results do not match the experiments will be given along with a discussion of opportunities for improved simulation results.

Peterson, D.L.; Bowers, R.L.; Matuska, W.; Chandler, G.A.; Deeney, C.; Derzon, M.S.; Matzen, M.K.; Mock, R.C.; Nash, T.J.; Sanford, T.W.L.; Spielman, R.B.; Struve, K.W.

1998-10-19

162

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

163

Progress in Z-pinch research driven by the mega-ampere device SPEED2  

SciTech Connect

Several pinch configurations have being studied at the Chilean Nuclear Energy Commission using the SPEED2 generator: plasma focus, gas embedded z-pinch and wire arrays. SPEED2 is a generator based on Marx technology (4.1 {mu}F equivalent Marx generator capacity, 300 kV, 4 MA in short circuit, 187 kJ, 400 ns rise time, dI/dt{approx}10{sup 13} A/s). Currently the device is being operated at 70kJ stored energy producing a peak current of 2.4 MA in short circuit. In this work results related to studies in gas embedded z-pinch in deuterium and studies in wire arrays are presented.

Pavez, Cristian; Soto, Leopoldo; Moreno, Jose [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile); Center for Research and Applications in Plasma Physics and Pulsed Power, P4 (Chile); Tarifeno, Ariel [Center for Research and Applications in Plasma Physics and Pulsed Power, P4 (Chile); Universidad de Concepcion (Chile); Sylvester, Gustavo [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile)

2008-04-07

164

Collective ion acceleration during the decay of a high-current Z-pinch  

SciTech Connect

A study is made of the Z-pinch plasma expansion after the current is switched off. Measurements were carried out in experiments on the implosion of tungsten wire arrays in the Angara-5-1 facility. It is found experimentally that, at a distance of 2 m from the pinch, the ion velocity in the expanding Z-pinch plasma is about (2.5-4.0) Multiplication-Sign 10{sup 7} cm/s, which substantially exceeds the thermal velocity of tungsten ions. A model describing the plasma expansion process is proposed that is based on the ambipolar acceleration mechanism. The results of numerical simulations are compared with the experimental data.

Zaitsev, V. I.; Volkov, G. S.; Kartashov, A. V.; Lakhtyushko, N. I. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)

2008-03-15

165

Interpretation of Spatially Resolved Z-pinch Spectra in the Presence of Photon Scattering.  

NASA Astrophysics Data System (ADS)

In collecting x-ray spectra of Z-pinches, the crystal and slit may be oriented to provide either axial or radial spatial resolution. However, intense spectral lines which originate from collisional excitation from the ground to excited levels in the dense inner core of a pinch may be absorbed and re-emitted (scattered) by a more tenuous outer halo. The weak radiation generated locally within the halo can be overwhelmed by the intensity of the scattered x-rays. Thus, the line intensities emitted from the direction of the halo may not be characteristic of its local conditions but in part reflect those of the denser inner core. We analyze what can be reasonably inferred using data and calculations from an Al:Si Z-pinch driven by the 4 MA Double EAGLE generator at Maxwell Physics International.

Apruzese, J. P.; Clark, R. W.; Davis, J.; Yadlowsky, E. J.; Carlson, E. P.; Niemel, J.; Barakat, F.; Hazelton, R. C.; Klepper, C. C.; Failor, B. H.; Levine, J. S.; Riordan, J. C.; Song, Y.; Whitton, B.

1999-11-01

166

A double post-hole vacuum convolute diode for z-pinch experiments on Saturn  

SciTech Connect

We have successfully tested a double post-hole vacuum convolute for driving z-pinch loads on Saturn (32 TW, 1.9 MV, 40 ns FWHM, and 0.11 ..cap omega..). We use the lower four insulators to feed four, conical self-magnetically insulated disk feeds (MITLs). The disk MITLs are convoluted using six anode posts (and cathode holes) to a single disk MITL (L /approximately/ 10 nH). A peak current of 12.5 MA was delivered to a low inductance short circuit load and 10.5 MA was delivered to a gas puff z-pinch load. Electron losses in the vacuum feed have been acceptable. 5 refs., 5 figs.

Spielman, R.B.; Corcoran, P.; Fockler, J.; Kishi, H.; Spence, P.W.

1989-01-01

167

Excitation of intense shock waves by soft X-radiation from a Z-pinch plasma  

SciTech Connect

The paper presents the measurements of the shock waves intensities, generated by soft X-radiation in Al and Pb targets. The soft X-radiation was induced by the dynamic compression and heating of the plasma in the cylindrical Z-pinch geometry in the ANGARA-5-1 installation. 1D computer simulation of shock wave generation were performed with realistic EOS and energy transfer models. {copyright} {ital 1996 American Institute of Physics.}

Fortov, V.E.; Dyabilin, K.; Lebedev, M.; Yu, V.O. [HEDRC RAS, 127412 Moscow (Russia); Grabovskij, E.; Smirnov, V. [TRINITI, 142092, Troizk (Russia); Goel, B. [Forschungszentrum Karlsruhe, INR, Postfach 3640, D-76021, Karlsruhe (Germany)

1996-05-01

168

Z-Pinch-Generated X Rays Demonstrate Potential for Indirect-Drive ICF Experiments  

Microsoft Academic Search

Hohlraums measuring 6 mm in diameter by 7 mm in height have been heated by x rays from a Z pinch. Over the measured x-ray input powers P of 0.7 to 13 TW, the hohlraum radiation temperature T increases from ~55 to ~130 eV, and is in agreement with the Planckian relation T~P1\\/4. The results suggest that indirect-drive inertial-confinement-fusion experiments

T. W. L. Sanford; R. E. Olson; R. L. Bowers; G. A. Chandler; M. S. Derzon; D. E. Hebron; R. J. Leeper; R. C. Mock; T. J. Nash; D. L. Peterson; L. E. Ruggles; W. W. Simpson; K. W. Struve; R. A. Vesey

1999-01-01

169

Current initiation in low-density foam z-pinch plasmas  

Microsoft Academic Search

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

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

1997-01-01

170

Insights and applications of two-dimensional simulations to Z-pinch experiments  

Microsoft Academic Search

A two-dimensional (2D) Eulerian radiation-magnetohydrodynamic code has been used to successfully simulate hollow metallic z-pinch experiments fielded on several facilities with a wide variety of drive conditions, time scales, and loads. The 2D simulations of these experiments reproduce important quantities of interest including the radiation pulse energy, power, and pulse width. This match is obtained through the use of an

D. L. Peterson; R. L. Bowers; W. Matuska; K. D. McLenithan; G. A. Chandler; C. Deeney; M. S. Derzon; M. Douglas; M. K. Matzen; T. J. Nash; R. B. Spielman; K. W. Struve; W. A. Stygar; N. F. Roderick

1999-01-01

171

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

172

Computational and experimental results of a wall-supported dense Z-pinch experiment  

Microsoft Academic Search

Summary form only given. In Magnetized Target Fusion (MTF) experiments, a preheated and magnetized target plasma is hydrodynamically compressed to fusion conditions by a magnetically driven liner. MTF requires initial target plasma conditions of order 10 18 cm-3, 100 eV, and 100 KGauss. A deuterium-fiber-initiated dense Z-pinch experiment to reach target plasma conditions has been designed, modelled, and built at

P. T. Sheehey; R. C. Kirkpatrick; I. R. Lindemuth; F. W. Wysocki; Y. C. F. Thio

1998-01-01

173

Identification of the governing parameters of self-organizing structures in z-pinch plasmas  

NASA Astrophysics Data System (ADS)

Using the S-300 device for wire plasma corona generation and streak, obscure and x-frame cameras for diagnostics, it was possible to determine the values of several parameters inside helical and toroidal structures formed in z-pinch. We concluded that the number of particles in the Debye sphere could be N D <1, which makes evident the non-ideal character of plasmas in the helical tube, allowing for long-range correlations and self-organization.

Ortiz-Tapia, Arturo; Kubeš, Pavel

2000-03-01

174

Time of Neutron Production on Z-Pinch and Plasma Focus Devices  

Microsoft Academic Search

In this paper we present the results obtained on the plasma focus PF-1000 in IPPLM Warsaw and on the z-pinch S-300 in RRC Kurchatov Institute in Moscow using a deuterium load. On the PF-1000 plasma-focus device with deuterium filling gas the energy of neutrons and time of their generation are determined by time-of-flight method from seven scintillation detectors positioned in

P. Kubes; J. Kravarik; D. Klir; M. Scholz; M. Paduch; K. Tomaszewski; I. Ivanova-Stanik; B. Bienkowska; L. Karpinski; M. Sadowski; H. Schmidt; Y. L. Bakshaev; P. I. Blinov; A. S. Chernenko; M. I. Ivanov; E. D. Kazakov; A. V. Korelsky; E. V. Kravchenko; V. D. Korolev; A. Y. Shashkov; G. I. Ustroev

2006-01-01

175

Target design for high fusion yield with the double Z-pinch-driven hohlraum.  

NASA Astrophysics Data System (ADS)

A key demonstration on the path to inertial fusion energy is the achievement of high fusion yield (hundreds of MJ) and high target gain. An indirect-drive high-yield inertial confinement fusion (ICF) target involving two z-pinch x-ray sources heating a central secondary hohlraum is described by Hammer, Tabak, Wilks, et al. [Phys. Plasmas 6, 2129 (1999)]. In subsequent research at Sandia National Laboratories, we have developed theoretical/computational models and performed an extensive series of validation experiments to study hohlraum energetics, capsule coupling, and capsule implosion symmetry. We are using these models to design a 0.5 GJ yield z-pinch-driven ICF target that incorporates the latest experience in capsule design, hohlraum symmetry control, and x-ray production by z-pinches. An x-ray energy output of 8-9 MJ per pinch, suitably pulse-shaped, is sufficient for this concept to drive 0.3-0.5 GJ capsules. Integrated 2D hohlraum/capsule LASNEX radiation-hydrodynamics simulations have demonstrated adequate hohlraum coupling, radiation symmetry control, and the successful implosion, ignition and burn of a 0.5 GJ ICF capsule. An important new feature of this target design is mode-selective symmetry control: the use of burnthrough shields offset from the capsule that selectively tune certain low-order asymmetry modes (P2, P4) without significantly perturbing higher-order modes. This talk will describe the capsule and hohlraum design that have produced 0.5 GJ yields in 2D simulations, as well as provide a preliminary design of the z-pinch load and accelerator requirements necessary to drive the system. In collaboration with M. C. Herrmann, R. W. Lemke, G. R. Bennett, R. B. Campbell, P. J. Christenson, M. E. Cuneo, M. P. Desjarlais, T. A. Mehlhorn, J. L. Porter, D. B. Sinars, S. A. Slutz, W. A. Stygar, E. P. Yu, and J. H. Hammer (LLNL).

Vesey, Roger

2006-10-01

176

Deuterium liner and multiparametric studies of the formation of an inverse Z-pinch  

Microsoft Academic Search

A method and results of measurements are presented of the ion energy distribution in a deuterium liner accelerated in the\\u000a inverse Z-pinch, in which the plasma is accelerated electrodynamically from the liner axis. Knowledge of the deuteron energy\\u000a distribution is of primary importance for the correct interpretation of the experimental results from the study of the dd-reaction in the range

Vit. M. Bystritskii; Vyach. M. Bystritsky; J. Wozniak; V. M. Grebenyuk; E. Gula; G. N. Dudkin; G. A. Mesyats; B. A. Nechaev; V. N. Padalko; S. S. Parzhitski; F. M. Pen’kov; N. A. Ratakhin; S. A. Sorokin; V. A. Stolupin

2002-01-01

177

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

Microsoft Academic Search

Fast Z-pinch implosions can efficiently convert 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 [R. B. Spielman {ital et al.}, in {ital Proceedings

M. Keith Matzen

1997-01-01

178

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

Microsoft Academic Search

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,

M. Keith Matzen

1996-01-01

179

Optical and X-ray observations of multi-wire z-pinch experiments  

Microsoft Academic Search

Summary form only given, as follows. An important question associated with z-pinch implosion experiments using fine wire arrays concerns the effect on the implosion of the plasma formed around and between the wires during the expansion phase. Heating and expansion occurs early on in the pulse, before the current is so high (>10 kA\\/wire) that the global magnetic fields are

Min Hu; Katherine Chandler; P. U. Duselis; D. B. Sinars; B. R. Kusse; D. A. Hammer; S. A. Pikuz; T. A. Shelkovenko

2001-01-01

180

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

181

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

Microsoft Academic Search

Fast Z-pinch implosions can efficiently convert 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 [R. B. Spielman &etal;, in Proceedings of the 2nd

M. Keith Matzen

1997-01-01

182

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

Microsoft Academic Search

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,

Matzen

1997-01-01

183

Wire initiation critical for radiation symmetry in z-pinch-driven dynamic hohlraums.  

PubMed

Axial symmetry in x-ray radiation of wire-array z pinches is important for the creation of dynamic hohlraums used to compress inertial-confinement-fusion capsules. We present the first evidence that this symmetry is directly correlated with the magnitude of the negative radial electric field along the wire surface. This field (in turn) is inferred to control the initial energy deposition into the wire cores, as well as any current shorting to the return conductor. PMID:17358953

Sanford, T W L; Jennings, C A; Rochau, G A; Rosenthal, S E; Sarkisov, G S; Sasorov, P V; Stygar, W A; Bennett, L F; Bliss, D E; Chittenden, J P; Cuneo, M E; Haines, M G; Leeper, R J; Mock, R C; Nash, T J; Peterson, D L

2007-02-01

184

Spectroscopic Studies of a Hollow-Cathode-Triggered Z-Pinch Discharge  

Microsoft Academic Search

Extreme ultraviolet (EUV) spectroscopy has been carried out on a xenon plasma generated using a hollow-cathode-triggered Z-pinch discharge. The temporal behavior of the electron temperature was estimated from the analysis of spectral data. The electron temperature measurements have been performed by the Boltzmann plot method using Xe I and Xe II lines. Furthermore, an analytical collisional-radiative model was used to

Stephan Wieneke; Stephan Bruckner; Wolfgang Viol

2007-01-01

185

Symmetric ICF Capsule Implosions in Double Z-Pinch Hohlraums on Z  

Microsoft Academic Search

Detailed calculations indicate that with a sufficiently uniform radiation drive, correct pulse shaping, and minimal capsule preheat, the dual-60-MA z-pinch high-yield (HY) ICF concept [Phys. Plasmas 6, 2129 (1999).] may release 400 MJ of fusion yield. Using an advanced, HY-scale scoping hohlraum [Phys. Rev. Lett. 88, 215004 (2002).] driven by the single 20-MA power-feed of Sandia National Laboratories Z accelerator,

Guy R. Bennett

2002-01-01

186

Wavelet Denoising of and X-Ray Power Extraction from Bolometry Data from fast Z Pinches  

Microsoft Academic Search

Bolometry data consists of X-ray energy vs time as released during a Z-pinch implosion. It is typically quite noisy and hence the extraction of power vs time is challenging (since it involves differentiating a noisy signal). Wavelet analysis can overcome these difficulties by nonlinear thresholding techniques. Both largest coefficient and level thresholding techniques are demonstrated on X-ray energy signals which

Bedros Afeyan; Michael Cuneo; Rick Spielman

2001-01-01

187

Gas-puff Z-pinch experiment on the LIMAY-I  

NASA Astrophysics Data System (ADS)

A gas-puff z-pinch plasma has been produced on the pulsed power generator LIMAY-I at IPP Nagoya University. The stored energy of the generator is 13 kJ, and it generates 600 kV-70 ns-3 ? power pulse. Ar or He gas is puffed from a hollow nozzle with 18 mm diameter, and a z-pinch plasma is produced by a discharge between 3 mm gap electrodes. The types of the discharge is classified into 4 patterns by the delay time from gas puffing. (I) At short delay time (<3 ms), the gas is not ejected and vacuum discharge occurs. This is usual ion beam mode. (II) at moderate delay time (3-4 ms), z-pinch plasma is produced. The plasma does not expand and it holds itself for much longer than the voltage pulse (~700 ns). As the external current has already been turned off, the plasma is thought to sustain itself. (III) At relatively longer delay (4-6 ms), the plasma diverges after pinch as usual. In this mode plasma current holds itself for a few ?s. The plasma operates as a self-crowbar switch. The ejected gas diffuse behind the electrode, and this causes crowbar discharge. (IV) At very long delay time (>~6 ms), most of the power is spent for the crowbar disharge, and the plasma does not collapse. The self-crowbar switch for the gas-puff z-pinch is demonstrated on the pulsed power generator in the region (III). As unexpectedly long lifetime plasma is found in the region (II).

Takasugi, K.; Miyamoto, T.; Akiyama, H.; Shimomura, N.; Sato, M.; Tazima, T.

1989-12-01

188

Heating of on-axis plasma heating for keV X-ray production with Z-pinches  

Microsoft Academic Search

We discuss a new opportunity of using Z-pinch plasma radiation sources for generating Ar K-shell radiation and harder keV quanta. Our approach to keV X-ray generation is based upon an analogy with laser fusion, where the imploding shell compressionally heats the low-density inner mass. The suggested design of a Z-pinch load consists then of one or two heavy outer shell(s)

Alexandre S. Chuvatin; Leonid I. Rudakov; Alexander L. Velikovich; Jack Davis; Vladimir I. Oreshkin

2005-01-01

189

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

Microsoft Academic Search

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

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

1998-01-01

190

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

Microsoft Academic Search

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

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

2003-01-01

191

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

Microsoft Academic Search

The double Z-pinch hohlraum high-yield concept [Hammer &etal;, 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 &etal;, Phys. Plasmas 5, 2105 (1998)] at Sandia National Laboratories have developed an advanced single-sided power feed, double

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

2003-01-01

192

Application of 2-D simulations to hollow z-pinch implosions  

SciTech Connect

The application of simulations of z-pinch implosions should have at least two goals: first, to properly model the most important physical processes occurring in the pinch allowing for a better understanding of the experiments and second, provide a design capability for future experiments. Beginning with experiments fielded at Los Alamos on the Pegasus 1 and Pegasus 2 capacitor banks, the authors have developed a methodology for simulating hollow z-pinches in two dimensions which has reproduced important features of the measured experimental current drive, spectrum, radiation pulse shape, peak power and total radiated energy. This methodology employs essentially one free parameter, the initial level of the random density perturbations imposed at the beginning of the 2-D simulation, but in general no adjustments to other parameters are required. Currently the authors are applying this capability to the analysis of recent Saturn and PBFA-Z experiments. The code results provide insight into the nature of the pinch plasma prior to arrival on-axis, during thermalization and development after peak pinch time. Among other things, the simulation results provide an explanation for the production of larger amounts of radiated energy than would be expected from a simple slug-model kinetic energy analysis and the appearance of multiple peaks in the radiation power. The 2-D modeling has also been applied to the analysis of Saturn dynamic hohlraum experiments and is being used in the design of this and other Z-Pinch applications on PBFA-Z.

Peterson, D.L.; Bowers, R.L.; Brownell, J.H. [and others

1997-12-01

193

Coronal plasma development in wire-array z-pinches made of twisted-pairs  

NASA Astrophysics Data System (ADS)

We have investigated coronal and core plasma development in wire array z-pinches in which single fine wires are replaced by twisted-pairs (``cable'') on the 1 MA, 100 ns rise time COBRA pulsed power generator. X-ray radiography, employed to investigate dense wire core expansion, showed periodic axial nonuniformity and evidence for shock waves developing where the individual wire plasmas collide. Laser shadowgraphy images indicated that the axial instability properties of the coronal plasma are substantially modified from ordinary wire arrays. Cable mass per unit length, material and the twist wavelength were varied in order to study their effects upon the instability wavelength. Implosion uniformity and bright-spot formation, as well as magnetic topology evolution, have also been investigated using self-emission imaging, x-ray diagnostics and small B-dot probes, respectively. Results from the cable-array z-pinches will be compared with results from ordinary wire-array z-pinches. This research was supported by the SSAA program of the National Nuclear Security Administration under DOE Cooperative agreement DE-FC03-02NA00057.

Hoyt, C. L.; Greenly, J. B.; Gourdain, P. A.; Knapp, P. F.; Pikuz, S. A.; Shelkovenko, T. A.; Hammer, D. A.; Kusse, B. R.

2009-11-01

194

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

195

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

196

Observations of the Influence of Protons on Argon Z-pinches  

NASA Astrophysics Data System (ADS)

Recent observations [Ref.1] showed that a low level of a H2S tracer could dramatically reduce the K-shell x-ray output of a double ``shell'' argon z-pinch. When the 5% (by partial pressure) H2S tracer was used in the outer gas plenum, the K-shell yield was reduced by about 30%. When the tracer was used in the inner gas plenum, the K-yield reduction was over 350%. Comparable tracers containing chlorine but not hydrogen have not had such an effect. Thus the data suggest that it is the presence of about 1 proton per 20 argon atoms, if concentrated near the pinch axis, that can strongly influence the pinch behavior. An understanding of the mechanism for this may enhance overall understanding of z-pinch dynamics. The data also suggest that extraneous sources of protons must be controlled to prevent inadvertent degradation in the z-pinch's implosion. We report here additional observations and analysis of this effect. The tests, conducted on the Double-EAGLE simulator at ˜3.5 MA peak current, utilized a large 12 cm diameter double-shell nozzle that was designed for use with the 300 ns rise-time pulse of the DECADE QUAD (DQ) pulsed power machine. * Work supported by the U. S. Defense Threat Reduction Agency. 1. P.L.Coleman, et.al., BEAMS 2004 Conference Proceedings, July 2004.

Coleman, Philip; Bixler, Alex; Knight, Jason; Krishnan, Mahadevan; Lee, Susan; Parks, Donald; Thompson, John; Wilson, Kristi

2004-11-01

197

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

PubMed

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. PMID:22181284

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

2011-10-01

198

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

199

Radiation Symmetry Control for ICF Capsule Implosions in Double Z-Pinch Hohlraums on Z  

NASA Astrophysics Data System (ADS)

The double z-pinch hohlraum high-yield concept [Phys. Plasmas 6, 2129 (1999)] utilizes two 60-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 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 [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 (see G. R. Bennett, this session). Using the backlit capsule distortion as a symmetry diagnostic, we have demonstrated the ability to predictably tune symmetry at the <10in fluence by modifying the hohlraum geometry. Systematic control of the time-integrated P2 Legendre mode asymmetry coefficient at the +/-3length of the cylindrical secondary hohlraum containing the capsule, in agreement with viewfactor and radiation-hydrodynamics simulations. Simulations predict that both P2 and P4 can be further minimized on Z by proper hohlraum design to a level that satisfies the scaled high yield requirement. These same simulation methods indicate that adequate implosion symmetry can be attained for a high-yield (400 MJ) capsule driven at 220 eV in a hohlraum of the same scale.

Vesey, Roger A.

2002-11-01

200

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

201

Aluminum-doped lithium nickel cobalt oxide electrodes for high-power lithium-ion batteries.  

SciTech Connect

Non-doped and aluminum-doped LiNi{sub 0.8}Co{sub 0.2}O{sub 2} cathodes from three industrial developers coupled with graphite anodes were made into lithium-ion cells for high-power applications. The powder morphology of the active cathode materials was examined by a scanning electron microscope. The electrochemical performance of these cells was investigated by hybrid pulse power characterization (HPPC) testing, accelerated aging, and AC impedance measurement of symmetric cells. Although all of the fresh cells are found to meet and exceed the power requirements set by PNGV, the power capability of those cells with non-doped LiNi {sub 0.8}Co{sub 0.2}O{sub 2} cathodes fades rapidly due to the rise of the cell impedance. Al-doping is found very effective to suppress the cell impedance rise by stabilizing the charge-transfer impedance on the cathode side. The stabilization mechanism may be related to the low average oxidation state of nickel ions in the cathode. The powder morphology also plays a secondary role in determining the impedance stabilization.

Chen, C. H.; Liu, J.; Stoll, M. E.; Henriksen, G.; Vissers, D. R.; Amine, K.; Chemical Engineering; Univ. of Science and Technology of China

2004-04-05

202

Aluminum-doped lithium nickel cobalt oxide electrodes for high-power lithium-ion batteries  

NASA Astrophysics Data System (ADS)

Non-doped and aluminum-doped LiNi 0.8Co 0.2O 2 cathodes from three industrial developers coupled with graphite anodes were made into lithium-ion cells for high-power applications. The powder morphology of the active cathode materials was examined by a scanning electron microscope. The electrochemical performance of these cells was investigated by hybrid pulse power characterization (HPPC) testing, accelerated aging, and AC impedance measurement of symmetric cells. Although all of the fresh cells are found to meet and exceed the power requirements set by PNGV, the power capability of those cells with non-doped LiNi 0.8Co 0.2O 2 cathodes fades rapidly due to the rise of the cell impedance. Al-doping is found very effective to suppress the cell impedance rise by stabilizing the charge-transfer impedance on the cathode side. The stabilization mechanism may be related to the low average oxidation state of nickel ions in the cathode. The powder morphology also plays a secondary role in determining the impedance stabilization.

Chen, C. H.; Liu, J.; Stoll, M. E.; Henriksen, G.; Vissers, D. R.; Amine, K.

203

Increasing the K-shell yield of line radiation in Z-pinch implosions using alloyed Al/Mg wire-arrays  

SciTech Connect

The variation of the K-shell yield of pure aluminum wire-array Z-pinch implosions with load parameters is discussed. The mechanism and the efficiency of increasing the K-shell yield using alloyed Al/Mg wire-arrays are numerically investigated. It has been shown that the maximum K-shell yield from a pure aluminum wire-array Z-pinch implosion can be obtained at an optimal load mass for a given generator and at a fixed initial wire-array radius. This optimal load mass is determined by the load energy coupling with the generator, the capability of Z-pinch plasmas to emit the K-shell radiation, and the self absorption of K-shell lines. For different generators, the optimal load mass increases as the drive current increases, and the line absorption limits the further increase of K-shell radiation. The coupled energy per ion is likely decreasing with increased mass, so the plasma might not be able to ionize into the K-shell. Also, the ability of the plasma to radiatively cool can increase with mass, thus, making it difficult for the plasma to ionize into and remain in the K-shell during the stagnation phase of the implosion. Alloyed Al/Mg wire-arrays were thus suggested to be used to decrease the opacity of K-shell lines and to increase the overall K-shell yield. In this paper, we show that using alloyed Al/Mg wire-arrays will decrease the opacity and increase the K-shell yield remarkably if the plasma is optically thick. We will also show that the efficiency of increasing the K-shell yield with alloyed Al/Mg wire-arrays cannot increase indefinitely. The ratio of K-shell yield from an alloyed Al/Mg wire-array to that from a pure aluminum wire-array reaches a limit. For example, we show that when the mass share of magnesium is 10% then this limit is 1.2, and for a 50% mass share, the limit is 1.3.

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

2013-01-15

204

Increasing the K-shell yield of line radiation in Z-pinch implosions using alloyed Al/Mg wire-arrays  

NASA Astrophysics Data System (ADS)

The variation of the K-shell yield of pure aluminum wire-array Z-pinch implosions with load parameters is discussed. The mechanism and the efficiency of increasing the K-shell yield using alloyed Al/Mg wire-arrays are numerically investigated. It has been shown that the maximum K-shell yield from a pure aluminum wire-array Z-pinch implosion can be obtained at an optimal load mass for a given generator and at a fixed initial wire-array radius. This optimal load mass is determined by the load energy coupling with the generator, the capability of Z-pinch plasmas to emit the K-shell radiation, and the self absorption of K-shell lines. For different generators, the optimal load mass increases as the drive current increases, and the line absorption limits the further increase of K-shell radiation. The coupled energy per ion is likely decreasing with increased mass, so the plasma might not be able to ionize into the K-shell. Also, the ability of the plasma to radiatively cool can increase with mass, thus, making it difficult for the plasma to ionize into and remain in the K-shell during the stagnation phase of the implosion. Alloyed Al/Mg wire-arrays were thus suggested to be used to decrease the opacity of K-shell lines and to increase the overall K-shell yield. In this paper, we show that using alloyed Al/Mg wire-arrays will decrease the opacity and increase the K-shell yield remarkably if the plasma is optically thick. We will also show that the efficiency of increasing the K-shell yield with alloyed Al/Mg wire-arrays cannot increase indefinitely. The ratio of K-shell yield from an alloyed Al/Mg wire-array to that from a pure aluminum wire-array reaches a limit. For example, we show that when the mass share of magnesium is 10% then this limit is 1.2, and for a 50% mass share, the limit is 1.3.

Delong, Xiao; Ning, Ding; Chuang, Xue; Jun, Huang; Yang, Zhang; Cheng, Ning; Shunkai, Sun

2013-01-01

205

Experimental Study of a Z-Pinch Driven High-Yield Inertial Confinement Fusion Target Concept  

NASA Astrophysics Data System (ADS)

Wire array Z-pinches on the Z accelerator are the most intense laboratory source of soft x-rays in the world. This source provides a unique combination of a near-Planckian radiation source with: high x-ray production efficiency (15% wall plug), large x-ray powers and energies (>100 TW, >0.7 MJ in 7 ns), large characteristic hohlraum volumes (up to 10 cm^3), long pulse-lengths (4 to 20 ns), x-ray energy scaling with I^2 through 20 MA, good reproducibility (better than ±10% demonstrated) and low cost (25$/Joule). These characteristics make Z-pinches a good match to the requirements for driving high-yield (>200 MJ) ICF capsules with adequate radiation symmetry and margin. Experiments have been performed with this source to characterize the Z-pinch driven hohlraum (ZPDH) approach of Hammer and Porter [Phys. Plasmas, 6, 2129(1999)]. In this concept, the Z-pinch is produced in a primary hohlraum. Radiation is transported into a high-yield scale secondary hohlraum through a transparent Beryllium radial-spoke-electrode and shine shield that isolates the capsule from the pinch plasma, magnetic field, and direct x-ray shine. Experiments have shown that the hohlraum energetics is understood to within ±15% in flux, based on several models, and scale to high-yield. We have demonstrated adequate Be-spoke transparency for high-yield (>60%), in agreement with 2-D radiation MHD simulations. Wall re-emission spectra in the secondary are Planckian for at least 20 ns. We have also demonstrated a single-sided power feed, double-sided Z-pinch radiation source with a potential for 2-5% total radiation symmetry experiments on Z, which would scale to the required 1-2% at a high-yield scale secondary temperature. These experiments have shown the promise of the ZPDH to provide a conservative and robust solution to the requirements for high yield.

Cuneo, M. E.

2000-10-01

206

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

207

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

SciTech Connect

{ital Z}-pinch experiments have been performed on the SATURN and {ital 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 {ital 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 {ital 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 {ital 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 {approx_gt}30 eV, which is somewhat hotter than the foam electron temperatures predicted from the 2D MHD simulations at early times. {copyright} {ital 1999 American Institute of Physics.}

MacFarlane, J.J. [Prism Computational Sciences, Inc., Madison, Wisconsin 53703 (United States)] [Prism Computational Sciences, Inc., Madison, Wisconsin 53703 (United States); Derzon, M.S.; Nash, T.J.; Chandler, G.A. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Peterson, D.L. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1999-01-01

208

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

NASA Astrophysics Data System (ADS)

This recently developed diagnostic was designed to allow for time-gated spectroscopic study of the EUV radiation (4 nm < ? < 15 nm) present during harsh wire array z-pinch implosions. The spectrometer utilizes a 25 ?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 the 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.

2011-09-01

209

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

PubMed

This recently developed diagnostic was designed to allow for time-gated spectroscopic study of the EUV radiation (4 nm < ? < 15 nm) present during harsh wire array z-pinch implosions. The spectrometer utilizes a 25 ?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 the 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. PMID:21974586

Williamson, K M; Kantsyrev, V L; Safronova, A S; Wilcox, P G; Cline, W; Batie, S; LeGalloudec, B; Nalajala, V; Astanovitsky, A

2011-09-01

210

Steady-state radiation ablation in the wire-array Z pinch  

SciTech Connect

The mass ablation phase of a wire-array Z pinch is investigated using steady-state (r,{theta}) simulations. By identifying the dominant physical mechanisms governing the ablation process, a simple scaling relation is derived for the mass ablation rate m with drive current I, in the case where radiation is the primary energy transport mechanism to the wire core. In order to investigate the dependence of m on wire core size, a simplified analytical model is developed involving a wire core placed in a heat bath and ablating due to radiation. Results of the model, simulation, and experiment are compared.

Yu, Edmund P.; Oliver, B. V.; Sinars, D. B.; Mehlhorn, T. A.; Cuneo, M. E.; Sasorov, P. V.; Haines, M. G.; Lebedev, S. V. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185-1193 (United States); Institute of Theoretical and Experimental Physics, Moscow 117218, Russia (Russian Federation); Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom)

2007-02-15

211

Z-Pinch Generated X-Rays Demonstrate Indirect-Drive ICF Potential  

SciTech Connect

Hohlraums (measuring 6-mm in diameter by 7-mm in height) have been heated by x-rays from a z-pinch. Over measured x-ray input powers P of 0.7 to 13 TW, the hohlraum radiation temperature T increases from {approximately}55 to {approximately}130 eV, and is in agreement with the Planckian relation P-T{sup 4}. The results suggest that indirect-drive ICF studies involving NIF relevant pulse shapes and <2-mm diameter capsules can he studied using this arrangement.

Bowers, R.L.; Chandler, G.A.; Derzon, M.S.; Hebron, D.E.; Leeper, R.J.; Matzen, M.K.; Mock, R.C.; Nash, T.J.; Olson, R.E.; Peterson, D.L.; Ruggles, L.E.; Sanford, T.W.L.; Simpson, W.W.; Struve, K.W.; Vesey, R.A.

1999-06-16

212

Z -Pinch-Generated X Rays Demonstrate Potential for Indirect-Drive ICF Experiments  

SciTech Connect

Hohlraums measuring 6 mm in diameter by 7 mm in height have been heated by x rays from a Z pinch. Over the measured x-ray input powers P of 0.7 to 13 TW, the hohlraum radiation temperature T increases from {approx}55 to {approx}130 eV , and is in agreement with the Planckian relation T{approx}P{sup 1/4} . The results suggest that indirect-drive inertial-confinement-fusion experiments involving National Ignition Facility relevant pulse shapes and <2 mm diameter capsules can be studied using this arrangement. (c) 1999 The American Physical Society.

Sanford, T. W. L. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States); Olson, R. E. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States); Bowers, R. L. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545-0010 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545-0010 (United States); Chandler, G. A. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States); Derzon, M. S. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States); Hebron, D. E. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States); Leeper, R. J. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States); Mock, R. C. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States); Nash, T. J. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States); Peterson, D. L. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545-0010 (United States)] (and others) [Los Alamos National Laboratory, Los Alamos, New Mexico 87545-0010 (United States)

1999-12-27

213

Analysis of x-ray spectra obtained in foam Z-pinch experiments  

SciTech Connect

Foam Z-pinch experiments have recently been performed on SATURN to study issues associated with the initiation, acceleration, and stagnation phases of the pinch. Time-integrated x-ray crystal spectra have been recorded from experiments with 5 mg/cc Si aerogel loads and 10 mg/cc agar loads. In this article, we describe results from collisional-radiative equilibrium calculations performed to analyze the Si, Na, and S K-shell emission observed in the spectra. Particular attention is paid to density and opacity effects on intensity ratios involving He{sub {alpha}}, He intercombination, and Li-like satellite lines. {copyright} {ital 1997 American Institute of Physics.}

MacFarlane, J.J.; Wang, P. [Fusion Technology Institute, University of Wisconsin, Madison, Wisconsin 53706 (United States)] [Fusion Technology Institute, University of Wisconsin, Madison, Wisconsin 53706 (United States); Nash, T.J.; Derzon, M.S.; Allshouse, G.A.; Deeney, C. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

1997-01-01

214

Shock model description of the interaction radiation pulse in nested wire array z-pinches  

NASA Astrophysics Data System (ADS)

Bow shock structures are observed in a nested wire array z-pinch as ablation streams from the outer array pass the inner array. The jump in plasma conditions across these shocks results in an enhancement of snowplow emission from the imploding plasma piston. Results from a snowplow model modified to account for the shock jumps are discussed and compared to experimental data from MAGPIE. Magnetohydrodynamic simulations indicate that this is the primary heating mechanism responsible for the interaction pulse recorded on the Z generator, which is required for pulse shaping for inertial confinement fusion.

Ampleford, D. J.; Jennings, C. A.; Lebedev, S. V.; Bland, S. N.; Cuneo, M. E.; Sinars, D. B.; Bott, S. C.; Hall, G. N.; Suzuki-Vidal, F.; Palmer, J. B. A.; Chittenden, J. P.

2012-12-01

215

Linear analysis of magnetic and flow shear stabilization of Z-pinch instabilities  

SciTech Connect

A global normal mode stability analysis on the effect of radially sheared azimuthal flow and radially sheared magnetic fields on magnetohydrodynamic (MHD) instabilities in Z-pinch plasmas is presented. A linearized set of ideal MHD equations allows the investigation of plasmas with both magnetic shear and flow shear included in the plasma equilibrium. The stabilizing effects of sheared azimuthal flow and sheared axial magnetic field are presented. Here we show that radial shear in the functional form of a vortex is particularly efficient at reducing instability growth rates.

Wanex, L.F.; Sotnikov, V.I.; Leboeuf, J.N. [University of Nevada, Reno, Nevada 89557 (United States); University of California, Los Angeles, California 90095 (United States)

2005-04-15

216

One-dimensional hybrid simulations of the imploding large Larmor radius Z pinch  

NASA Astrophysics Data System (ADS)

The interaction of an imploding plasma-vacuum boundary (PVB) with a collisionless Z pinch for the case where the ions have orbits comparable to the radius is studied. Two principal results are found. First, the development of sheared axial ion flow occurs as a result of large Larmor radius (LLR) ions interacting with the moving PVB. This contrasts strongly with the equivalent case in ideal magnetohydrodynamics (MHD). The second result is a modification to current density profiles. These are smoother (due to LLR effects) than those from ideal MHD.

Channon, S. W.; Coppins, M.; Arber, T. D.

1999-10-01

217

Structure of Stagnated Plasma in Aluminium Wire Array Z-pinches  

NASA Astrophysics Data System (ADS)

Experiments with aluminium wire array Z-pinches have been carried out on the MAGPIE generator (1MA, 240ns) at Imperial College London. It has been shown that in these arrays there are two intense sources of radiation during stagnation: line emission from a precursor-sized object and continuum radiation from bright-spots of significantly higher temperature randomly distributed around this object such as to produce a hollow emission profile. Spatially resolved spectra produced by spherically-bent crystals were recorded, both time-integrated and time-resolved, and were used to show that these two sources of radiation peak at the same time.

Hall, G. N.; Pikuz, S. A.; Shelkovenko, T. A.; Bland, S. N.; Lebedev, S. V.; Ampleford, D. J.; Palmer, J. B. A.; Bott, S. C.; Rapley, J.; Chittenden, J. P.

2006-01-01

218

Shock model description of the interaction radiation pulse in nested wire array z-pinches  

SciTech Connect

Bow shock structures are observed in a nested wire array z-pinch as ablation streams from the outer array pass the inner array. The jump in plasma conditions across these shocks results in an enhancement of snowplow emission from the imploding plasma piston. Results from a snowplow model modified to account for the shock jumps are discussed and compared to experimental data from MAGPIE. Magnetohydrodynamic simulations indicate that this is the primary heating mechanism responsible for the interaction pulse recorded on the Z generator, which is required for pulse shaping for inertial confinement fusion.

Ampleford, D. J.; Jennings, C. A.; Cuneo, M. E.; Sinars, D. B. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1106 (United States); Lebedev, S. V.; Bland, S. N.; Hall, G. N.; Suzuki-Vidal, F.; Palmer, J. B. A.; Chittenden, J. P. [Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom); Bott, S. C. [Center for Energy Research, University of California, San Diego, La Jolla, CA 92093 (United States)

2012-12-15

219

Doppler measurement of implosion velocity in fast Z-pinch x-ray sources  

NASA Astrophysics Data System (ADS)

The observation of Doppler splitting in K-shell x-ray lines emitted from optically thin dopants is used to infer implosion velocities of up to 70 cm/?s in wire-array and gas-puff Z pinches at drive currents of 15-20 MA. These data can benchmark numerical implosion models, which produce reasonable agreement with the measured velocity in the emitting region. Doppler splitting is obscured in lines with strong opacity, but red-shifted absorption produced by the cooler halo of material backlit by the hot core assembling on axis can be used to diagnose velocity in the trailing mass.

Jones, B.; Jennings, C. A.; Bailey, J. E.; Rochau, G. A.; Maron, Y.; Coverdale, C. A.; Yu, E. P.; Hansen, S. B.; Ampleford, D. J.; Lake, P. W.; Dunham, G.; Cuneo, M. E.; Deeney, C.; Fisher, D. V.; Fisher, V. I.; Bernshtam, V.; Starobinets, A.; Weingarten, L.

2011-11-01

220

Optical Thomson scattering measurements of plasma parameters in the ablation stage of wire array Z pinches.  

PubMed

A Thomson scattering diagnostic has been used to measure the parameters of cylindrical wire array Z pinch plasmas during the ablation phase. The scattering operates in the collective regime (?>1) allowing spatially localized measurements of the ion or electron plasma temperatures and of the plasma bulk velocity. The ablation flow is found to accelerate towards the axis reaching peak velocities of 1.2-1.3×10(7) cm/s in aluminium and ?1×10(7) cm/s in tungsten arrays. Precursor ion temperature measurements made shortly after formation are found to correspond to the kinetic energy of the converging ablation flow. PMID:22540799

Harvey-Thompson, A J; Lebedev, S V; Patankar, S; Bland, S N; Burdiak, G; Chittenden, J P; Colaitis, A; De Grouchy, P; Doyle, H W; Hall, G N; Khoory, E; Hohenberger, M; Pickworth, L; Suzuki-Vidal, F; Smith, R A; Skidmore, J; Suttle, L; Swadling, G F

2012-04-01

221

Development of a sodium z -pinch load for use on the Saturn accelerator  

SciTech Connect

A reliable sodium wire-array {ital z}-pinch load has been developed for use on the Saturn accelerator. This load routinely produces implosions with {ge}200 GW of power in the heliumlike sodium 1{ital s}{sup 2}--1{ital s}2{ital p} {sup 1}{ital P}{sub 1} line at 11 A. Our best shots have used a 12.5-mm-diam, 20-mm-long annular array of 16 75-{mu}m-diam pure sodium wires. This load will allow us to test predictions of gain in the sodium/neon resonant photoexcitation x-ray laser system.

Porter, J.L.; Spielman, R.B.; Vargas, M.F.; Matzen, M.K. (Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States))

1992-12-01

222

Demonstration of Radiation Symmetry Control for Inertial Confinement Fusion in Double Z-Pinch Hohlraums  

NASA Astrophysics Data System (ADS)

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.

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.

2003-01-01

223

Hybrid Simulation of the Nonlinear Evolution of a Collisionless, Large Larmor Radius {ital Z} Pinch  

SciTech Connect

A two-dimensional, quasineutral hybrid code has been used to study the evolution of a {ital Z} pinch in which the ions are collisionless and have Larmor radii comparable to the pinch radius. The ions are treated as in a particle-in-cell model while the electrons are included through a simple fluid equation. {ital m}=0 instabilities are observed with the correct linear growth rates. These instabilities continue to grow exponentially, i.e., without saturation, until the plasma column is disrupted. {copyright} {ital 1996 The American Physical Society.}

Arber, T.D. [Physics Department, Imperial College, London SW7 2BZ (United Kingdom)] [Physics Department, Imperial College, London SW7 2BZ (United Kingdom)

1996-08-01

224

Experimental investigation of phase explosion by irradiating thin aluminum targets with high power pulsed laser beam  

NASA Astrophysics Data System (ADS)

In this paper phase explosion in aluminum targets induced by Nd:YAG pulsed laser beam is studied. The phase explosion occurs in ablation process when the Nd:YAG laser beam (single pulse) is focused on the surface of target in ambient air. The phase explosion was investigated by monitoring the transmission of a cw laser probe beam through the ablating region. Two different aluminum targets were used in this study; a thin film aluminum on a quartz substrate, and a thick aluminum foil. The results show that the probe beam transmission through the ablated region is enhanced significantly when the laser fluence is enough for the phase explosion to be occurred.

Mahdieh, M. H.; Akbari Jafarabadi, M.; Firozyar, Sh.; Hajiani, Sh.

2012-01-01

225

On the possibility of neutron generation in an imploding TiD{sub 2} puff Z pinch  

SciTech Connect

Simulation of implosion of a TiD{sub 2} 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 TiD{sub 2} 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 × 10{sup 9} neutrons/shot.

Baksht, Rina B. [Institutes of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk (Russian Federation) [Institutes of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk (Russian Federation); Tel-Aviv University, Tel Aviv (Israel); Oreshkin, Vladimir I. [Institutes of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk (Russian Federation) [Institutes of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk (Russian Federation); Tomsk Polytechnic University, Tomsk (Russian Federation); Rousskikh, Alexander G. [Institutes of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk (Russian Federation)] [Institutes of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk (Russian Federation)

2013-08-15

226

Z pinches as intense x-ray sources for inertial confinement fusion applications  

SciTech Connect

Fast z-pinch implosions can convert more than 10% of the stored electrical energy in a pulsed-power accelerator into x-rays. On the Saturn pulsed-power accelerator at Sandia National Laboratories, currents of 6 to 8 MA with a risetime of less than 50 ns have been used to drive cylindrically-symmetric arrays of wires, producing x-ray energies greater than 400 kJ with x-ray pulsewidths less than 5 ns and peak x-ray powers of 75 {+-} 10 TW. Using similar loads, PBFA Z has produced > 1.5 MJ and > 150 TW of x-rays in the first four months of operation in the z-pinch mode. These x-ray energies and powers are records for laboratory x-ray production. The x-ray output can be thermalized into a near-Planckian x-ray source by containing it within a cylindrical radiation case (a hohlraum). These energetic, intense, large volume, long-lived hohlraum x-ray sources have recently been used for ICF-relevant ablator physics experiments and offer the potential for performing many new basic physics and fusion-relevant experiments.

Matzen, M.K.

1997-05-01

227

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

228

Three-dimensional electromagnetic model of the pulsed-power Z-pinch accelerator  

NASA Astrophysics Data System (ADS)

A three-dimensional, fully electromagnetic model of the principal pulsed-power components of the 26-MA ZR accelerator [D. H. McDaniel , in Proceedings of the 5th International Conference on Dense Z-Pinches (AIP, New York, 2002), p. 23] has been developed. This large-scale simulation model tracks the evolution of electromagnetic waves through the accelerator’s intermediate-storage capacitors, laser-triggered gas switches, pulse-forming lines, water switches, triplate transmission lines, and water convolute to the vacuum insulator stack. The insulator-stack electrodes are coupled to a transmission-line circuit model of the four-level magnetically insulated vacuum-transmission-line section and double-post-hole convolute. The vacuum-section circuit model is terminated by a one-dimensional self-consistent dynamic model of an imploding z-pinch load. The simulation results are compared with electrical measurements made throughout the ZR accelerator, and are in good agreement with the data, especially for times until peak load power. This modeling effort demonstrates that 3D electromagnetic models of large-scale, multiple-module, pulsed-power accelerators are now computationally tractable. This, in turn, presents new opportunities for simulating the operation of existing pulsed-power systems used in a variety of high-energy-density-physics and radiographic applications, as well as even higher-power next-generation accelerators before they are constructed.

Rose, D. V.; Welch, D. R.; Madrid, E. A.; Miller, C. L.; Clark, R. E.; Stygar, W. A.; Savage, M. E.; Rochau, G. A.; Bailey, J. E.; Nash, T. J.; Sceiford, M. E.; Struve, K. W.; Corcoran, P. A.; Whitney, B. A.

2010-01-01

229

Calibrated areal density measurements of cable-array Z-pinch plasmas at 1 MA  

NASA Astrophysics Data System (ADS)

We present areal density measurements of multi-wire cable-array Z-pinch plasmas obtained using X-pinch x-ray backlighter radiographs. The elements of a cable array are made by twisting 2 - 4 wires into a cable with a twist wavelength ranging from 0.5mm to 4mm. In experiments on the 1 MA COBRA pulsed power generator, the radiographs of the cables displayed density structure not observed in standard wire-array z-pinches, including sharp density gradients in the form of spirals that follow the twisting wires and small scale striations that are the result of an undetermined mechanism. The X-ray radiographs were produced using the 3-5 keV spectral band of Mo X-pinches, which was obtained using 12.5 micron Ti filters. Ag, Ni, Cu and W cable-arrays have been tested, and film exposure was converted to plasma areal density using calibrated step wedges of the test material that were deposited on the Ti filter. X-pinch timing was monitored with 12.5 micron Ti filtered silicon diodes. Laser shadowgraphy and XUV self-emission diagnostics were also employed. This research is supported by the NNSA SSAA program under DOE Cooperative Agreement DE-FC03-02NA00057.

Hoyt, C. L.; Knapp, P. F.; Pikuz, S. A.; Shelkovenko, T. A.; Gourdain, P.-A.; Greenly, J. B.; Hammer, D. A.

2010-11-01

230

Effects of Wire Ablation on Foam Targets in Wire Array Z-pinches  

NASA Astrophysics Data System (ADS)

Cylindrical foam targets can be placed on the axis of wire array z-pinches, in particular Dynamic Hohlraum (DH) and Double Ended Drive Hohlraum (DEDH); Z-pinch configurations used for ICF experiments on Z, Sandia National Laboratory. Precursor plasma produced by array wires prior to array implosion is accelerated to the axis and impacts the foam target. This can modify the target prior to the implosion of the wire array. Kinetic pressure and thermal heating of the foam are two mechanisms that will affect the foam. Experiments have been preformed with non-imploding wire arrays on the 1 MA MAGPIE generator at Imperial College London. Over-massed arrays injected precursor plasma into the array for the duration of the current pulse; absence of the x-ray pulse an imploding array emits permits radiography of the array axis. The entire width of the array has been radiographed for the first time. Diagnostics included point-projection radiography with x-pinches and x-ray emission framing cameras. Results show ablation of low-density plasma from the foam surface and compression of the foam by precursor pressure.

Palmer, J. B. A.; Bott, S. N.; Bland, S. C.; Lebedev, S. V.; Chittenden, J. P.; Hall, G.; Suzuki, F.; Ampleford, D. J.; Rapley, J.; Sherlock, M.; Haines, M. G.

2006-10-01

231

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

NASA Astrophysics Data System (ADS)

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

Chittenden, Jeremy

2005-10-01

232

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

233

Kinetic simulation of neutron production in a deuterium z-pinch  

NASA Astrophysics Data System (ADS)

Fully kinetic particle-in-cell (PIC) modeling of a deuterium gas puff z-pinch can provide insight into the physical mechanisms for D-D fusion neutron production. Experiments with 15-MA current pinches on the Z accelerator have suggested that the dominant neutron-production mechanism is thermonuclear. The non-linear evolution of the Rayleigh Taylor instability as the pinch coalesces on axis, however, induces large electric fields capable of driving a significant number of high energy ions similar to that reported in dense plasma focus machines where measured ion spectra exhibit power-law dependence. In order to gain further insight, we have performed 2D PIC simulations of deuterium z-pinch implosions that permit non-Maxwellian particle distributions, finite mean-free-path effects, self-consistent anomalous resistivity, and charge separation. The calculated neutron yields largely follow the predicted thermonuclear I^ 4 current scaling [A. L. Velikovich, et. al, Phys. of Plasmas 14, 022701 (2007)], but also exhibit the power law ion distribution and significant non-thermal neutron production. We will discuss both production mechanisms and impact on the scaling of neutron yield at higher current.

Welch, Dale; Rose, David; Stygar, William; Leeper, Ramon

2009-11-01

234

Development of a Non-LTE model for Z-pinch simulations  

NASA Astrophysics Data System (ADS)

Predicting the energetic and spectral characteristics of Z-pinch sources is a delicate task. It requires solving the Atomic Physics equations for plasmas in a wide range of conditions. In addition, the increasing optical depth of the plasma at stagnation can have a strong influence on its own dynamics, suggesting that simultaneous solution of both the magneto-hydrodynamic and radiative response is required. This constraint places a special emphasis on code optimization. We introduce a simple atomic model that can be run inline with the three dimensional resistive Eulerian MHD code GORGON developed at Imperial College. Based on a Screened-Hydrogenic Model (SHM) with nl splitting and making use of an inexpensive modification of the SAHA equation, this code has demonstrated a good ability to mimic Non-LTE plasma conditions. Preliminary results obtained with the standalone version of the model have shown good agreement with commercial packages (PrismSpect). Comparisons of predictions produced by the inline version with data from High Energy Density Plasma Physics (HEDP) experiments at Imperial College, Sandia National Laboratory and Centre d'Études de Gramat are presented. Synthetic Z-pinch XUV images and time dependant spectra are produced.

Niasse, Nicolas; Chittenden, Jeremy

2010-11-01

235

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

236

Comparison Between Laser Initiated Hollow Gas Embedded Z-pinches with Different Initial Radius  

SciTech Connect

An experimental study of the effect of the initial radius on the formation of hollow gas embedded z-pinches is presented. These hollow pinches are formed using a ring precursor plasma generated by focussing a 10ns, 0.2J, 1064nm, Nd:YAG laser pulse onto the cathode surface. The laser pulse is focussed into a ring shape, by using a combination of a converging lens and an axicon. Ring radius variation give place to different initial radius of hollow z-pinches. The experiments were carried out on the Gepopu generator at 110kA, 50ns rise time using flat electrodes. The anode had a central hole, allowing the laser to be focussed onto the cathode surface. Experiments were performed in hydrogen at 1/3 of atmosphere. Schlieren and interferometry are the main plasma diagnostics using the second harmonic of the same laser. Comparison between initial radius of 2 and 3mm are presented, where electron densities on the order of 1018 cm-3 were measured in both cases. Temperature estimates using Bennett relation are of 185 eV and 75 eV respectively. Pinch effect was observed for current density {approx} 5MA/cm2.

Veloso, Felipe; Chuaqui, Hernan; Aliaga-Rossel, Raul; Favre, Mario; Mitchell, Ian; Wyndham, Edmund [Departamento de Fisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile)

2006-12-04

237

Dynamic Z-pinches for high-gradient, high-current acceleration  

NASA Astrophysics Data System (ADS)

In this talk, we discuss planned experiments on acceleration of an injected ion beam in a Z-pinch plasma with MV/cm gradients and the first fully kinetic simulations of such beam-plasma systems. Multi-MeV, kilo-Ampere ion beams have been produced by 100 kJ class, centimeter scale, Dense Plasma Focus (DPF) Z-pinches. We have now demonstrated similar acceleration gradients in a 1 kJ DPF using a fast capacitive driver. Understanding the mechanisms behind these high gradients is essential for optimizing the device for unique compact accelerator applications. We have an RFQ accelerator producing a 4 MeV deuteron beam for probing the DPF plasma. Using this beam we can directly measure the gradients and demonstrate acceleration of an injected ion beam for the first time. Our fully kinetic particle-in-cell simulations have reproduced observed DPF ion beams. Direct comparisons between the experiment and simulations enhance our understanding of these plasmas and provide predictive design capability. These are the first steps to enabling a technologically simple, compact, high-current, plasma-based accelerator.

Tang, V.; Schmidt, A.; Ellsworth, J.; Falabella, S.; Rusnak, B.; Guethlein, G.; Akana, G.; Cook, E.; Hawkins, S.; Welch, D.

2012-10-01

238

Monochromatic Soft X-Ray Self-Emission Imaging in Dense Z Pinches  

NASA Astrophysics Data System (ADS)

The Z machine at Sandia National Laboratories drives 20 MA in 100 ns through a cylindrical array of fine wires which implodes due to the strong j × B force, generating up to 250 TW of soft x-ray radiation when the z-pinch plasma stagnates on axis. The copious broadband self-emission makes the dynamics of the implosion well suited to diagnosis with soft x-ray imaging and spectroscopy. A monochromatic self-emission imaging instrument has recently been developed on Z which reflects pinhole images from a multilayer mirror onto a 1 ns gated microchannel plate detector. The multilayer can be designed to provide narrowband (~10 eV) reflection in the 100-700 eV photon energy range, allowing observation of the soft emission from accreting mass as it assembles into a hot, dense plasma column on the array axis. In the present instrument configuration, data at 277 eV photon energy have been obtained for plasmas ranging from Al to W, and the z-pinch implosion and stagnation will be discussed along with > 1 keV self-emission imaging and spectroscopy. Collisional-radiative simulations are currently being pursued in order to link the imaged emissivity to plasma temperature and density profiles and address the role of opacity in interpreting the data.

Jones, B.; Deeney, C.; Meyer, C. J.; Coverdale, C. A.; Lepell, P. D.; Apruzese, J. P.; Clark, R. W.; Davis, J.; Peterson, K. J.

2007-08-01

239

Kinetic simulations of a deuterium-tritium z pinch with >10^16 neutron yield  

NASA Astrophysics Data System (ADS)

Fully kinetic, collisional, and electromagnetic simulations of the time evolution of an imploding z-pinch plasma have been performed as first reported in D. R. Welch, et al. [Phys. Rev. Lett. 103, 255002 (2009)]. Using the implicit particle-in-cell (PIC) code Lsp, multi-dimensional (1-3D) simulations of deuterium and deuterium-tritium z-pinches provide insight into the mechanisms of neutron production. The PIC code allows non-Maxwellian particle distributions, simulates finite mean-free-path effects, performs self-consistent calculations of anomalous resistivity, and permits charge separation. At pinch current I < 7 MA, neutron production is dominated by high energy ions driven by instabilities. The instabilities produce a power-law ion-energy distribution function in the distribution tail. At higher currents, roughly half of the neutrons are thermonuclear in origin and follow a I ^4 neutron yield scaling. High-current, multi-dimension simulations (> 40 MA with > 10^16 neutron yield) suggest that the fraction of thermonuclear neutrons is not sensitive to I, and the strong dependence of neutron yield on current will continue at still higher currents. Scenarios for fusion breakeven and possible ignition will be discussed.

Welch, Dale

2010-11-01

240

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

241

Z-Pinch Magneto-Inertial Fusion Propulsion Engine Design Concept  

NASA Technical Reports Server (NTRS)

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 spaceflight missions. Magneto-Inertial Fusion (MIF) is an approach which has been shown to potentially lead to a low cost, small fusion reactor/engine assembly (1). The Z-Pinch dense plasma focus method is an MIF concept in which a column of gas is compressed to thermonuclear conditions by an estimated axial current of approximately 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) (2). The magnetic field resulting from the large current compresses the plasma to fusion conditions, and this is repeated over short timescales (10(exp -6) sec). This plasma formation is widely used in the field of Nuclear Weapons Effects (NWE) testing in the defense industry, as well as in fusion energy research. There is a wealth of literature characterizing Z-Pinch physics and existing models (3-5). In order to be useful in engineering analysis, a simplified Z-Pinch fusion thermodynamic model was developed to determine the quantity of plasma, plasma temperature, rate of expansion, energy production, etc. to calculate the parameters that characterize a propulsion system. The amount of nuclear fuel per pulse, mixture ratio of the D-T and nozzle liner propellant, and assumptions about the efficiency of the engine, enabled the sizing of the propulsion system and resulted in an estimate of the thrust and Isp of a Z-Pinch fusion propulsion system for the concept vehicle. MIF requires a magnetic nozzle to contain and direct the nuclear pulses, as well as a robust structure and radiation shielding. The structure, configuration, and materials of the nozzle must meet many severe requirements. The configuration would focus, in a conical manner, the Deuterium-Tritium (D-T) fuel and Lithium-6/7 liner fluid to meet at a specific point that acts as a cathode so the Li-6 can serve as a current return path to complete the circuit. In addition to serving as a current return path, the Li liner also serves as a radiation shield. The advantage to this configuration is the reaction between neutrons and Li-6 results in the production of additional Tritium, thus adding further fuel to the fusion reaction and boosting the energy output. 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, radiation shielding, and structural subsystems of a vehicle. The design reference mission is the transport of crew and cargo to Mars and back, with the intention that the vehicle be reused for other missions. Several aspects of this vehicle are based on a previous crewed fusion vehicle study called Human Outer Planet Exploration (HOPE), which employed a Magnetized Target Fusion (MTF) propulsion concept. Analysis of this propulsion system concludes that a 40-fold increase of Isp over chemical propulsion is predicted. This along with a greater than 30% predicted payload mass fraction certainly warrants further development of enabling technologies. The vehicle is designed for multiple interplanetary missions and conceivably may be suited for an automated one-way interstellar voyage.

Miernik, Janie H.; Statham, Geoffrey; Adams, Robert B.; Polsgrove, Tara; Fincher, Sharon; Fabisinski, Leo; Maples, C. Dauphne; Percy, Thomas K.; Cortez, Ross J.; Cassibry, Jason

2011-01-01

242

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

243

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 4 to 16 mm 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 (300-500 GW) and total energy yields (6-10 kJ) 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 1.6 mm to 785 ?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

244

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

NASA Astrophysics Data System (ADS)

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.; Liu, L.; Cai, D.

2014-06-01

245

Design, simulation, and application of quasi-spherical 100 ns z-pinch implosions driven by tens of mega-amperes  

SciTech Connect

A quasi-spherical z-pinch may directly compress foam or deuterium and tritium in three dimensions as opposed to a cylindrical z-pinch, which compresses an internal load in two dimensions only. Because of compression in three dimensions the quasi-spherical z-pinch is more efficient at doing pdV work on an internal fluid than a cylindrical pinch. Designs of quasi-spherical z-pinch loads for the 28 MA 100 ns driver ZR, results from zero-dimensional (0D) circuit models of quasi-spherical implosions, and results from 1D hydrodynamic simulations of quasi-spherical implosions heating internal fluids will be presented. Applications of the quasi-spherical z-pinch implosions include a high radiation temperature source for radiation driven experiments, a source of neutrons for treating radioactive waste, and a source of fusion energy for a power generator.

Nash, T.J.; McDaniel, D.H.; Leeper, R.J.; Deeney, C.D.; Sanford, T.W.L.; Struve, K.; DeGroot, J.S. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

2005-05-15

246

The study of hard x-ray emission and electron beam generation in wire array Z-pinch and X-pinch plasmas at university-scale generators  

NASA Astrophysics Data System (ADS)

The studies of hard x-ray (HXR) emission and electron beam generation in Z-pinch plasmas are very important for Inertial Confinement Fusion (ICF) research and HXR emission application for sources of K-shell and L-shell radiation. Energetic electron beams from Z-pinch plasmas are potentially a problem in the development of ICF. The electron beams and the accompanying HXR emission can preheat the fuel of a thermonuclear target, thereby preventing the fuel compression from reaching densities required for the ignition of a fusion reaction. The photons above 3-4 keV radiated from a Z pinch can provide detailed information about the high energy density plasmas produced at stagnation. Hence, the investigation of characteristics of hard x-rays and electron beams produced during implosions of wire array loads on university scale-generators may provide important data for future ICF, sources of K-shell and L-shell radiations and basic plasma research. This dissertation presents the results of experimental studies of HXR and electron beam generation in wire-array and X-pinch on the 1.7 MA, 100-ns current rise time Zebra generator at University of Nevada, Reno and 1-MA 100-ns current rise-time Cornell Beam Research Accelerator (COBRA) at Cornell University. The experimental study of characteristics of HXR produced by multi-planar wire arrays, compact cylindrical wire array (CCWA) and nested cylindrical wire array (NCWA) made from Al, Cu, Mo, Ag, W and Au were analyzed. The dependence of the HXR yield and power on geometry of the load, the wire material, and load mass was observed. The presence of aluminum wires in the load with the main material such as stainless steel, Cu, Mo, Ag, W or Au in combined wire array decreases HXR yield. The comparison of emission characteristics of HXR and generation of electron beams in CCWA and NCWA on both the high impedance Zebra generator and low impedance COBRA generator were investigated. Some of the "cold" K- shell spectral lines (0.7-2.3Á) and cold L-shell spectral lines (1-1.54Á) in the HXR region were observed only during the interaction of electron beam with load material and anode surface. These observations suggest that the mechanism of HXR emission should be associated with non-thermal mechanisms such as the interaction of the electron beam with the load material. In order to estimate the characteristics of the high-energetic electron beam in Z-pinch plasmas, a hard x-ray polarimeter (HXP) has been developed and used in experiments on the Zebra generator. The electron beams (energy more than 30keV) have been investigated with measurements of the polarization state of the emitted bremsstrahlung radiation from plasma. We also analyzed characteristics of energetic electron beams produced by implosions of multi-planar wire arrays, compact cylindrical and nested wire arrays as well as X-pinches. Direct indications of electron beams (electron cutoff energy EB from 42-250 keV) were obtained by using the measured current of a Faraday cup placed above the anode or mechanical damage observed in the anode surface. A comparison of total electron beam energy and the spatial and spectral analysis of the parameters of plasmas were investigated for different wire materials. The dependences of the total electron beam energy (E b) on the wire material and the geometry of the wire array load were studied.

Shrestha, Ishor Kumar

247

Application of 2-D simulations to hollow Z-pinch implosions  

SciTech Connect

The application of simulations of z-pinch implosions should have at least two goals: first, to properly model the most important physical processes occurring in the pinch allowing for a better understanding of the experiments and second, provide a design capability for future experiments. Beginning with experiments fielded at Los Alamos on the Pegasus I and Pegasus II capacitor banks, we have developed a methodology for simulating hollow z-pinches in two dimensions which has reproduced important features of the measured experimental current drive, spectrum, radiation pulse shape, peak power and total radiated energy (1,2,3). This methodology employs essentially one free parameter, the initial level of the random density perturbations imposed at the beginning of the 2-D simulation, but in general no adjustments to other parameters (such as the resistivity) are required (1). Limitations in the use of this approach include the use of the 3-T, gray diffusion treatment of radiation and the fact that the initial perturbation conditions are not known a priori. Nonetheless, the approach has been successful in reproducing important experimental features of such implosions over a wide variety of timescales (tens of nanoseconds to microseconds), current drives (3 to 16 MA), masses (submilligram to tens of milligrams), initial radii (<1 cm to 5 cm), materials (Al and W) and initial configurations (thin foils and wire arrays with 40 to 240 wires). Currently we are applying this capability to the analysis of recent Saturn and PBFA-Z experiments (4,5). The code results provide insight into the nature of the pinch plasma prior to arrival on-axis, during thermalization and development after peak pinch time. Among other things, the simulation results provide an explanation for the production of larger amounts of radiated energy than would be expected from a simple slug-model kinetic energy analysis and the appearance of multiple peaks in the radiation power. The 2-D modeling has also been applied to the analysis of Saturn ''dynamic hohlraum'' experiments and is being used in the design of this and other Z-Pinch applications on PBFA-Z.

Peterson, D. L.; Bowers, R. L.; Brownell, J. H.; Lund, C.; Matuska, W.; McLenithan, K.; Oona, H.; Deeney, C.; Derzon, M.; Spielman, R. B.; Nash, T. J.; Chandler, G.; Mock, R. C.; Sanford, T. W. L.; Matzen, M. K.; Roderick, N. F. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); University of New Mexico, Albuquerque, New Mexico 87131 (United States)

1997-05-05

248

Application of 2-D simulations to hollow Z-pinch implosions  

SciTech Connect

The application of simulations of z-pinch implosions should have at least two goals: first, to properly model the most important physical processes occurring in the pinch allowing for a better understanding of the experiments and second, provide a design capability for future experiments. Beginning with experiments fielded at Los Alamos on the Pegasus I and Pegasus II capacitor banks, we have developed a methodology for simulating hollow z-pinches in two dimensions which has reproduced important features of the measured experimental current drive, spectrum, radiation pulse shape, peak power and total radiated energy (1,2,3). This methodology employs essentially one free parameter, the initial level of the random density perturbations imposed at the beginning of the 2-D simulation, but in general no adjustments to other parameters (such as the resistivity) are required (1). Limitations in the use of this approach include the use of the 3-T, gray diffusion treatment of radiation and the fact that the initial perturbation conditions are not known {ital a priori}. Nonetheless, the approach has been successful in reproducing important experimental features of such implosions over a wide variety of timescales (tens of nanoseconds to microseconds), current drives (3 to 16 MA), masses (submilligram to tens of milligrams), initial radii ({lt}1cm to 5 cm), materials (Al and W) and initial configurations (thin foils and wire arrays with 40 to 240 wires). Currently we are applying this capability to the analysis of recent Saturn and PBFA-Z experiments (4,5). The code results provide insight into the nature of the pinch plasma prior to arrival on-axis, during thermalization and development after peak pinch time. Among other things, the simulation results provide an explanation for the production of larger amounts of radiated energy than would be expected from a simple slug-model kinetic energy analysis and the appearance of multiple peaks in the radiation power. The 2-D modeling has also been applied to the analysis of Saturn {open_quotes}dynamic hohlraum{close_quotes} experiments and is being used in the design of this and other Z-Pinch applications on PBFA-Z. {copyright} {ital 1997 American Institute of Physics.}

Peterson, D.L.; Bowers, R.L.; Brownell, J.H.; Lund, C.; Matuska, W.; McLenithan, K.; Oona, H. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Deeney, C.; Derzon, M.; Spielman, R.B.; Nash, T.J.; Chandler, G.; Mock, R.C.; Sanford, T.W.; Matzen, M.K. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Roderick, N.F. [University of New Mexico, Albuquerque, New Mexico 87131 (United States)

1997-05-01

249

Application of 2-D simulations to hollow Z-pinch implosions  

NASA Astrophysics Data System (ADS)

The application of simulations of z-pinch implosions should have at least two goals: first, to properly model the most important physical processes occurring in the pinch allowing for a better understanding of the experiments and second, provide a design capability for future experiments. Beginning with experiments fielded at Los Alamos on the Pegasus I and Pegasus II capacitor banks, we have developed a methodology for simulating hollow z-pinches in two dimensions which has reproduced important features of the measured experimental current drive, spectrum, radiation pulse shape, peak power and total radiated energy (1,2,3). This methodology employs essentially one free parameter, the initial level of the random density perturbations imposed at the beginning of the 2-D simulation, but in general no adjustments to other parameters (such as the resistivity) are required (1). Limitations in the use of this approach include the use of the 3-T, gray diffusion treatment of radiation and the fact that the initial perturbation conditions are not known a priori. Nonetheless, the approach has been successful in reproducing important experimental features of such implosions over a wide variety of timescales (tens of nanoseconds to microseconds), current drives (3 to 16 MA), masses (submilligram to tens of milligrams), initial radii (<1 cm to 5 cm), materials (Al and W) and initial configurations (thin foils and wire arrays with 40 to 240 wires). Currently we are applying this capability to the analysis of recent Saturn and PBFA-Z experiments (4,5). The code results provide insight into the nature of the pinch plasma prior to arrival on-axis, during thermalization and development after peak pinch time. Among other things, the simulation results provide an explanation for the production of larger amounts of radiated energy than would be expected from a simple slug-model kinetic energy analysis and the appearance of multiple peaks in the radiation power. The 2-D modeling has also been applied to the analysis of Saturn ``dynamic hohlraum'' experiments and is being used in the design of this and other Z-Pinch applications on PBFA-Z.

Peterson, D. L.; Bowers, R. L.; Brownell, J. H.; Lund, C.; Matuska, W.; McLenithan, K.; Oona, H.; Deeney, C.; Derzon, M.; Spielman, R. B.; Nash, T. J.; Chandler, G.; Mock, R. C.; Sanford, T. W. L.; Matzen, M. K.; Roderick, N. F.

1997-05-01

250

Discovery and Study on Plasma Turbulence in Z-Pinch According to the Stark Broadening of Deuterium Spectral Lines.  

National Technical Information Service (NTIS)

The hydrogen spectral line diagnostics of turbulent plasma is extended to an analysis of shapes of Dsub( alpha ), Dsub( beta ), Dsub( gamma ) lines emitted from the cylindric Z-pinch. The presence of the Lengmuire and even lower frequency electrostatic no...

E. A. Oks V. A. Rantsev-Kartinov

1979-01-01

251

Indirect Drive Inertial Confinement Fusion Hohlraum Physics Using A 1-2 MJ Z-pinch X-ray Source  

Microsoft Academic Search

An indirect drive inertial confinement fusion (ICF) research program using Z-pinch driven hohlraums is being pursued at Sandia National Laboratories (SNL). Indirect drive ICF uses a soft x-ray radiation field located in a radiation cavity or hohlraum to drive a DT capsule implosion. This research is being conducted on SNL's Z facility, which is capable of driving peak currents of

R. J. Leeper

2003-01-01

252

Development of a visible framing camera diagnostic for the study of current initiation in z-pinch plasmas  

Microsoft Academic Search

The authors assembled and tested a visible framing camera system to take 5 ns FWHM images of the early time emission from a z-pinch plasma. This diagnostic was used in conjunction with a visible streak camera allowing early time emissions measurements to diagnose current initiation. Individual frames from gated image intensifiers were proximity coupled to charge injection device (CID) cameras

D. J. Muron; M. J. Hurst; M. S. Derzon

1996-01-01

253

Development of a visible framing camera diagnostic for the study of current initiation in z-pinch plasmas  

Microsoft Academic Search

We assembled and tested a visible framing camera system to take 5 ns FWHM images of the early time emission from a z-pinch plasma. This diagnostic was used in conjunction with a visible streak camera allowing early time emissions measurements to diagnose current initiation. Individual frames from gated image intensifiers were proximity coupled to charge injection device cameras and read

D. J. Muron; M. J. Hurst; M. S. Derzon

1997-01-01

254

The True Symmetry of Double Z Pinch Driven Imploding Shells Using Multiresolution Denoising Techniques on X Ray Backlighting Generated Images  

Microsoft Academic Search

We have used various advanced image processing and denoising techniques based on multiresolution analysis to obtain useful X ray images of Double Z Pinch driven imploding shells. The shell thickness averaged (highest density) radius (STAR) is defined for a number of asymmetric shots and STAR curves vs angle are Legendre polynomial decomposed in order to characterize the asymmetry in traditional

Kirk Won; B. Afeyan; J. L. Stark; M. Cuneo; G. Bennet; R. Vesey

2003-01-01

255

Role of Z-pinches in magnetic reconnection in space plasmas  

NASA Astrophysics Data System (ADS)

A generally accepted scenario of magnetic reconnection in space plasmas is the breakage of magnetic field lines in X-points. In laboratory, reconnection is widely 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. The X-points are relatively stable, and no substantial energy dissipation is associated with them. On the contrary, turbulent magnetic reconnection driven by kinking of the pinches causes the magnetic energy to decay at a rate of 1.5% per ion gyro period. Current channels and twisted magnetic fields are ubiquitous in turbulent space plasmas, so pinches can be responsible for the observed high magnetic reconnection rates.

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

2014-06-01

256

Exact self-similar solutions for the magnetized Noh Z pinch problem  

NASA Astrophysics Data System (ADS)

A self-similar solution is derived for a radially imploding cylindrical plasma with an embedded, azimuthal magnetic field. The plasma stagnates through a strong, outward propagating shock wave of constant velocity. This analysis is an extension of the classic Noh gasdynamics problem to its ideal magnetohydrodynamics (MHD) counterpart. The present exact solution is especially suitable as a test for MHD codes designed to simulate linear Z pinches. To demonstrate the application of the new solution to code verification, simulation results from the cylindrical R-Z version of Mach2 and the 3D Cartesian code Athena are compared against the analytic solution. Alternative routines from the default ones in Athena lead to significant improvement of the results, thereby demonstrating the utility of the self-similar solution for verification.

Velikovich, A. L.; Giuliani, J. L.; Zalesak, S. T.; Thornhill, J. W.; Gardiner, T. A.

2012-01-01

257

Current initiation in low-density foam z-pinch plasmas  

SciTech Connect

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

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

1996-07-01

258

Current initiation in low-density foam z-pinch plasmas  

SciTech Connect

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

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

1997-01-01

259

Design of Z-Pinch and Dense Plasma Focus Powered Vehicles  

NASA Technical Reports Server (NTRS)

Z-pinch and Dense Plasma Focus (DPF) are two promising techniques for bringing fusion power to the field of in-space propulsion. A design team comprising of engineers and scientists from UAHuntsville, NASA's George C. Marshall Space Flight Center and the University of Wisconsin developed concept vehicles for a crewed round trip mission to Mars and an interstellar precursor mission. Outlined in this paper are vehicle concepts, complete with conceptual analysis of the mission profile, operations, structural and thermal analysis and power/avionics design. Additionally engineering design of the thruster itself is included. The design efforts adds greatly to the fidelity of estimates for power density (alpha) and overall performance for these thruster concepts

Polsgrove, Tara; Fincher, Sharon; Adams, Robert B.; Cassibry, Jason; Cortez, Ross; Turner, Matthew; Maples, C. Daphne; Miermik, Janie N.; Statham, Geoffrey N.; Fabisinski, Leo; Santarius, John; Percy, Tom

2011-01-01

260

Dynamics of quasi-spherical Z-pinch implosions with mass redistribution and displacement modification  

SciTech Connect

Implosions of (quasi-)spherical loads with mass redistribution and displacement modification are investigated numerically. Both methods can theoretically counterbalance the nonuniformity of magnetic pressure along the load surface and realize quasi-spherical Z-pinch implosions. Mass redistribution is feasible for spherical loads with large radius and weight, while the displacement modification is more suitable for light loads, such as those composed of wire arrays. Simulation results suggest that, for mass redistributed spherical loads, wall instabilities induced by polar mass flows will deform the imploding shell. For prolate spherical loads, in which the wall instability cannot develop, the kinetic energy distribution is disturbed at high latitude. These passive behaviors and their possible mitigation methods, such as reshaping the electrode, are investigated numerically in this paper.

Zhang Yang [Institute of Applied Physics and Computational Mathematics, P. O. Box 8009-09, Beijing 100094 (China); Institute of Nuclear Physics and Chemistry, P. O. Box 919-212, Mianyang 621900 (China); Ding Ning; Sun Shunkai; Xue Chuang; Ning Cheng; Xiao Delong; Huang Jun [Institute of Applied Physics and Computational Mathematics, P. O. Box 8009-09, Beijing 100094 (China); Li Zhenghong [Institute of Nuclear Physics and Chemistry, P. O. Box 919-212, Mianyang 621900 (China)

2012-12-15

261

MAIZE: a 1 MA LTD-Driven Z-Pinch at The University of Michigan  

SciTech Connect

Researchers at The University of Michigan have constructed and tested a 1-MA Linear Transformer Driver (LTD), the first of its type to reach the USA. The Michigan Accelerator for Inductive Z-pinch Experiments, (MAIZE), is based on the LTD developed at the Institute of High Current Electronics in collaboration with Sandia National Labs and UM. This LTD utilizes 80 capacitors and 40 spark gap switches, arranged in 40 'bricks,' to deliver a 1 MA, 100 kV pulse with 100 ns risetime into a matched resistive load. Preliminary resistive-load test results are presented for the LTD facility.Planned experimental research programs at UM include: a) Studies of Magneto-Raleigh-Taylor instability of planar foils, and b) Vacuum convolute studies including cathode and anode plasma.

Gilgenbach, R. M.; Gomez, M. R.; Zier, J. C.; Tang, W. W.; French, D. M.; Lau, Y. Y. [Plasma, Pulsed Power and Microwave Lab, University of Michigan, Ann Arbor, MI 48109-2104 (United States); Mazarakis, M. G.; Cuneo, M. E.; Johnston, M. D.; Oliver, B. V.; Mehlhorn, T. A. [Sandia National Laboratories, Albuquerque, NM (United States); Kim, A. A.; Sinebryukhov, V. A. [Institute of High Current Electronics Tomsk (Russian Federation)

2009-01-21

262

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

263

Experimental r-? density profiles of wire-array and cylindrical foil Z-pinches on COBRA  

NASA Astrophysics Data System (ADS)

Calibrated r-? ion density profiles from wire-array and cylindrical foil experiments on the 1-MA COBRA machine will be presented. Profiles are axially averaged over the 1-cm height of the array. The data was gathered using an axial X pinch backlighter.ootnotetextI.C. Blesener et al., ``Axial x-ray backlighting of wire-array Z-pinches using X pinches'', Rev. Sci. Instrum. 80, 123505 (2009). Images have better than 5-micron resolution with calibrated ion densities from 10^18 to 10^20 cm-3. The latest data will be presented, comparing the timing and development of ablation streams and precursor formation between wire-arrays and cylindrical foils. Experimental data will also be compared to simulation results.

Blesener, Isaac; Greenly, John; Pikuz, Sergey; Shelkovenko, Tatiana; Kusse, Bruce; Seyler, Charles

2010-11-01

264

250 kA compact linear transformer driver for wire array z-pinch loads  

NASA Astrophysics Data System (ADS)

We present the application of a short rise (˜150ns) 250 kA linear transformer driver (LTD) to wire array z-pinch loads for the first time. The generator is a modification of a previous driver in which a new conical power feed provides a low inductance coupling to wire loads. Performance of the new design using both short circuit and plasma loads is presented and discussed. The final design delivers ˜200kA to a wire array load which is in good agreement with SCREAMER calculations using a simplified representative circuit. Example results demonstrate successful experiments using cylindrical, conical, and inverse wire arrays as well as previously published work on x-pinch loads.

Bott, S. C.; Haas, D. M.; Madden, R. E.; Ueda, U.; Eshaq, Y.; Collins, G., IV; Gunasekera, K.; Mariscal, D.; Peebles, J.; Beg, F. N.; Mazarakis, M.; Struve, K.; Sharpe, R.

2011-05-01

265

Investigation of the interaction pulse in nested wire array z-pinches  

NASA Astrophysics Data System (ADS)

Radiation pulse shaping is vital for z-pinch driven ICF concepts. One method to achieve such pulse shaping is to use the foot pulse generated by the interaction between two nested wire arrays. We present data from experiments investigating this interaction pulse on the MAGPIE generator (1MA, 240ns) at Imperial College London. On MAGPIE, the current through the inner array is suppressed by enhancing its inductance, leading to a similar current fraction to that observed on the Z-generator. In these experiments time gated imaging of photon energies >30eV indicates that radiation is emitted as leading bubbles of the imploding outer array reach and pass the inner array. Experiments using novel configurations to eliminate possible heating mechanisms will also be discussed, and data will be compared to simulations from the Gorgon 3D MHD code.

Ampleford, D. J.; Jennings, C. A.; Cuneo, M. E.; Deeney, C.; Bland, S. N.; Lebedev, S. V.; Bott, S. C.; Hall, G. N.; Suzuki, F.; Chittenden, J. P.

2006-10-01

266

End-On Laser Interferometry of Wire Array Z-Pinch Implosions on the MAGPIE Generator  

NASA Astrophysics Data System (ADS)

New end-on measurements have taken of the areal electron density distribution of wire array z-pinches during the ablation phase. These measurements have been used to investigate the differences in dynamics between aluminium and tungsten arrays. The experiments were carried out on the 1.4 MA peak current, 240ns rise-time MAGPIE generator at Imperial College, London. The measurements were taken using a two colour Mach-Zender style imaging interferometer. Probing is provided by the 2nd and 3rd harmonics (532nm and 355nm) of a pulsed Nd:YAG laser with a pulse duration of 500ps. Analysis of the results is presented and comparisons made to both the rocket model and simulations produced using the GORGON MHD code.

Swadling, George; Lebedev, Sergey; Chittenden, Jeremy; Hall, Gareth; Suzuki-Vidal, Francisco; Harvey-Thompson, Adam; Niasse, Nicolas; Burdiak, Guy; Khoory, Essa; Pickworth, Louisa; de Grouchi, Philip; Suttle, Lee

2011-11-01

267

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

268

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

269

Radiative Properties and Diagnostic Potential of a Low Atomic Number Z-Pinch Driven Hohlraum  

NASA Astrophysics Data System (ADS)

We investigate the radiative properties and diagnostic potential of a Z-pinch driven hohlraum. The radiation incident on the hohlraum walls is assumed to be a geometrically diluted Planckian with a radiation temperature of 200-300 eV. The hohlraum walls are initially assumed to be Al, but could also be composed of a low-z cocktail such as Al, Cl and Ti. The hohlraum is treated in 1-D and consists of two facing Al walls irradiated on the inside by a Planckian source for 3-4 ns to represent the yield and spectral content supposedly obtained from imploding a W or Au multi-wire array. The simulations are carried out with a 1-D non-LTE radiation-magnetohydrodynamic model with online self-consistent treatment of the radiation transport.

Davis, J.; Apruzese, J. P.; Clark, R. W.

1999-11-01

270

Symmetric inertial-confinement-fusion-capsule implosions in a double-z-pinch-driven hohlraum.  

PubMed

An inertial-confinement-fusion (ICF) concept using two 60-MA Z pinches to drive a cylindrical hohlraum to 220 eV has been recently proposed. The first capsule implosions relevant to this concept have been performed at the same physical scale with a lower 20-MA current, yielding a 70+/-5 eV capsule drive. The capsule shell shape implies a polar radiation symmetry, the first high-accuracy measurement of this type in a pulsed-power-driven ICF configuration, within a factor of 1.6-4 of that required for scaling to ignition. The convergence ratio of 14-21 is to date the highest in any pulsed-power ICF system. PMID:12484951

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

2002-12-01

271

Hot dense capsule-implosion cores produced by Z-pinch dynamic Hohlraum radiation.  

PubMed

Hot dense capsule implosions driven by Z-pinch x rays have been measured using a approximately 220 eV dynamic Hohlraum to implode 1.7-2.1 mm diameter gas-filled CH capsules. The capsules absorbed up to approximately 20 kJ of x rays. Argon tracer atom spectra were used to measure the T(e) approximately 1 keV electron temperature and the n(e) approximately 1-4 x 10(23) cm(-3) electron density. Spectra from multiple directions provide core symmetry estimates. Computer simulations agree well with the peak emission values of T(e), n(e), and symmetry, indicating reasonable understanding of the Hohlraum and implosion physics. PMID:14995784

Bailey, J E; Chandler, G A; Slutz, S A; Golovkin, I; Lake, P W; MacFarlane, J J; Mancini, R C; Burris-Mog, T J; Cooper, G; Leeper, R J; Mehlhorn, T A; Moore, T C; Nash, T J; Nielsen, D S; Ruiz, C L; Schroen, D G; Varnum, W A

2004-02-27

272

Mapping kA Return Currents in Laser-generated Z-pinch Plasmas  

NASA Astrophysics Data System (ADS)

During capsule irradiation ``hot'' electrons leave the capsule and a residual positive charge is left on the target. The positive potential, of order 10^6 V, drives a return current through the supporting stalk structure. The first measurements of the spatial extent and magnitude of these return currents were conducted using monoenergetic proton deflectometry. From the measured proton fluence radiographs an absolute current was inferred and shown to increase from ˜2 kA to ˜7 kA during a picketed laser pulse. These images also demonstrate that current begins near the stalk surface and move outward in a similar manner to a single exploding wire Z-pinch. The work described here was done as part of the first author's PhD thesis and supported in part by NLUF (DE-NA0000877), FSC/UR (415023-G), DoE (DE-FG52-09NA29553), LLE (414090-G), and LLNL (B580243).

Manuel, M. J.-E.; Sinenian, N.; Séguin, F. H.; Li, C. K.; Frenje, J. A.; Rinderknecht, H. G.; Casey, D. T.; Zylstra, A. B.; Petrasso, R. D.; Fatenejad, M.; Beg, F. N.

2012-10-01

273

The LLNL High-gradient Z-pinch Ion Probe Experiment  

NASA Astrophysics Data System (ADS)

Dense Plasma Focus (DPF) Z-pinches are copious sources of neutrons and MeV level particle beams. Deuterons up to 10 MeV have been observed from centimeter-scale long pinches indicating gradients up to 1 GV/m. These beams contribute significantly to the DPF's radiation output. The mechanisms behind these gradients are not understood and a true predictive capability required for optimization or application is not currently available. At LLNL we are assembling a DPF experiment with a 4 MeV ion probe beam to measure these gradients directly. These unique data can be used to validate kinetic simulations. Here we discuss how the probe beam can measure the acceleration gradients in the plasma and present first experimental DPF results.

Tang, V.; Falabella, S.; Guethlein, G.; Schmidt, A.; Blackfield, D.; Cook, E.; Hawkins, S.; Rusnak, B.; Adams, M.; Akana, G.; Anaya, E.; Holmes, C.; McLean, H.; Houck, T.; Watson, J.; Chen, Y.-J.; Caporaso, G.; Welch, D.; Rose, D.

2011-11-01

274

Wavelet Denoising of and X-Ray Power Extraction from Bolometry Data from fast Z Pinches  

NASA Astrophysics Data System (ADS)

Bolometry data consists of X-ray energy vs time as released during a Z-pinch implosion. It is typically quite noisy and hence the extraction of power vs time is challenging (since it involves differentiating a noisy signal). Wavelet analysis can overcome these difficulties by nonlinear thresholding techniques. Both largest coefficient and level thresholding techniques are demonstrated on X-ray energy signals which denoise the data and allow power extraction. Mathematica notebooks dedictated to the performance of these tasks will be demonstrated and various Sandia Z machine bolometry data from single and double shell implosions analyzed using these new techniques. When the data is excessively noisy, the successive application of mild low pass filtering and then wavelet largest coefficients thresholding works best. Future applications of these tools to radiography data analysis and combined low order Legendre polynomial and wavelet analysis will also be discussed.

Afeyan, Bedros; Cuneo, Michael; Spielman, Rick

2001-10-01

275

Wavelets, curvelets, and multiresolution analysis techniques in fast Z-pinch research  

NASA Astrophysics Data System (ADS)

Z pinches produce an X ray rich plasma environment where backlighting imaging of imploding targets can be quite challenging to analyze. What is required is a detailed understanding of the implosion dynamics by studying snapshot images of its in flight deformations away from a spherical shell. We have used wavelets, curvelets and multiresolution analysis techniques to address some of these difficulties and to establish the Shell Thickness Averaged Radius (STAR) of maximum density, r*(N,?) where N is the percentage of the shell thickness over which we average. The non-uniformities of r*(N,?) are quantified by a Legendre polynomial decomposition in angle, ?, and the identification of its largest coefficients. Undecimated wavelet decompositions outperform decimated ones in denoising and both are surpassed by the curvelet transform. In each case, hard thresholding based on noise modeling is used.

Afeyan, Bedros; Won, Kirk; Starck, Jean-Luc; Cuneo, Michael

2003-11-01

276

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

277

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

278

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.

Silterra, J; Holber, W

2009-01-01

279

Time of Neutron Production on Z-Pinch and Plasma Focus Devices  

SciTech Connect

In this paper we present the results obtained on the plasma focus PF-1000 in IPPLM Warsaw and on the z-pinch S-300 in RRC Kurchatov Institute in Moscow using a deuterium load. On the PF-1000 plasma-focus device with deuterium filling gas the energy of neutrons and time of their generation are determined by time-of-flight method from seven scintillation detectors positioned in the axial direction. The neutron signals (total yield {approx}1011 neutrons per shot) correlate with hard x-rays and their maximum occur {approx}150-200 ns after the pinch phase. The initial portion of neutron pulse has beam-target origin with downstream energies up to 2.8-3.2 MeV and the final portion of neutrons has isotropic distribution of energies in the range of 2.2-2.7 MeV. The z-pinch experiments were performed on the S-300 generator with the load formed from a deuterated CD2 fibre in the axis of a tungsten wire array. The energy of neutrons and time of their generation are determined by time-of-flight method from 5 scintillation detectors positioned in the axial and side-on direction. The neutrons with total yield up to 3x109 per shot are produced in the energy range of 1.8-3.2 MeV at 10-30 ns after the pinch phase represented by dip in the current waveform, peak of the voltage and minimum of the pinch diameter. The distribution of neutron velocities is random within the total solid angle. The neutrons in both devices are produced by a non-thermal mechanism with deuterons accelerated to the energies above 100 keV partially in anode-cathode direction and partially with almost isotropic distribution of velocities at the time of the plasma expansion, i.e. after the pinch phase.

Kubes, P.; Kravarik, J.; Klir, D. [CTU Prague, Technicka 2, 166 27 Prague (Czech Republic); Scholz, M.; Paduch, M.; Tomaszewski, K.; Ivanova-Stanik, I.; Bienkowska, B.; Karpinski, L. [Institute of Plasma Physics and Laser Microfusion, 23 Hery, 00-908 Warsaw (Poland); Sadowski, M. [The Andrzej Soltan Institute of Nuclear Studies, 05-400 Otwock- Swierk (Poland); Schmidt, H. [ICDMP, 23 Hery, 00908 Warsaw (Poland); Bakshaev, Y. L.; Blinov, P. I.; Chernenko, A. S.; Kazakov, E. D.; Korelsky, A. V.; Kravchenko, E. V.; Korolev, V. D.; Shashkov, A. Y.; Ustroev, G. I. [RRC Kurchatov Institute, 1 Kurchatov Sq., 123182 Moscow (Russian Federation)] (and others)

2006-12-04

280

Deuterium gas puff Z-pinch at currents of 2 to 3 mega-ampere  

NASA Astrophysics Data System (ADS)

Deuterium gas-puff experiments have been carried out on the GIT-12 generator at the Institute of High Current Electronics in Tomsk. The emphasis was put on the study of plasma dynamics and neutron production in double shell gas puffs. A linear mass density of deuterium (D2) varied between 50 and 85 ?g/cm. Somewhat problematic was a spread of the D2 gas at a large diameter in the central anode-cathode region. The generator operated in two regimes, with and without a plasma opening switch (POS). When the POS was used, a current reached a peak of 2.7 MA with a 200 ns rise time. Without the POS, a current rise time approached 1500 ns. The influence of different current rise times on neutron production was researched. Obtained results were important for comparison of fast deuterium Z-pinches with plasma foci. Average DD neutron yields with and without the POS were about 1011. The neutron yield seems to be dependent on a peak voltage at the Z-pinch load. In all shots, the neutron emission started during stagnation. At the beginning of the neutron production, the neutron emission correlated with soft x-rays and a significant fraction of neutrons could be explained by the thermonuclear mechanism. Nevertheless, a peak of the neutron emission occurred 40 ns after a soft x-ray peak. At this very moment, hard x-rays above 1 MeV were detected and a rapid expansion with a velocity of 3×105 m/s was observed. In the case of the POS, 1 MeV widths of radial neutron spectra implied that there are deuterons with the energy above 200 keV moving in the radial direction. On the basis of D2 gas puff experiments in the 0.3-17 MA region, the neutron yield dependence on a current as Y~I3.0+/-0.2 was proposed.

Klir, D.; Shishlov, A. V.; Kubes, P.; Rezac, K.; Fursov, F. I.; Kokshenev, V. A.; Kovalchuk, B. M.; Kravarik, J.; Kurmaev, N. E.; Labetsky, A. Yu.; Ratakhin, N. A.

2012-03-01

281

Manufacturability of high power ultraviolet-C light emitting diodes on bulk aluminum nitride substrates  

NASA Astrophysics Data System (ADS)

As the technological challenges in obtaining high power ultraviolet-C light emitting diodes (LEDs) on bulk AlN substrates are being overcome, the next challenge faced is the manufacturability. One of these challenges consists of introducing a 10 × 10 mm substrate into a fabrication facility that is processing 2" and larger diameter substrates. This has been successfully carried out using a standard visible LED production facility that is involved in high volume manufacturing of blue LEDs. By introducing specifications on the substrates, the epitaxial wafers, and the fabrication process, the establishment of a pilot production process with pathways to high volume manufacturing has been established.

Grandusky, James R.; Zhong, Zhibai; Chen, Jasson; Leung, Charles; Schowalter, Leo J.

2012-12-01

282

A Experimental Study of the Dynamics of X-Pinch and Z-Pinch Plasmas  

NASA Astrophysics Data System (ADS)

X-pinch experiments have been carried out using 12 to 100 ?m diameter Al wires with peak currents of 330 to 380 kA. Two wires were placed between the output electrodes of a low inductance pulser so as to cross and touch at a single point, resulting in intense K-shell soft x-ray radiation from a sub-millimeter high temperature (300 to 700 eV) and density (2 times 10^{19} to 1 times 10^{21 } cm^{-3}) plasma at the cross point. Single wire z-pinch experiments were conducted for comparison. Additional x-pinch experiments were carried out using up to eight wires at peak currents from 280 kA to 1.0 MA. Intense soft x-ray emission from the cross region occurs in short bursts. Filtered GaAs:Cr photoconducting diodes and streaked x-ray pinhole images show individual bursts lasting <=1 ns. Time-integrated K-shell spectra obtained with a curved KAP crystal spectrograph were used to determine the electron temperature and density for individual bright spots. A sub-ns pulsed nitrogen laser was used for time -resolved schlieren and interferometry measurements of the unstable expansion of a coronal plasma that develops around the wires. The implosion and re-expansion of the corona at the x-pinch cross region was observed immediately prior to x-ray emission. Jets of plasma were ejected along the axis, as recorded in schlieren images and visible light frame images. Late in the pulse, gaps formed along the axis with electron density <=5 times 10^{17} cm^{-3}. Spectra indicated the presence of electron beams carrying the current in these gaps. Interferometry measurements provided the electron density profile late in the current pulse. Individual bursts of x-ray emission from one x -pinch were used to record a shadow of the dense core plasma at the initial wire position of a parallel x-pinch or z -pinch. This core expanded uniformly within the corona, surviving until it was disrupted by the implosion of the corona prior to soft x-ray emission. The Bennett relation is used to estimate the thickness of the layer on the wire surface that is ionized to form the coronal plasma. The instability growth in the corona, and lack of it in the dense core is consistent with theoretical predictions.

Kalantar, Daniel Husayn

283

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

284

The True Symmetry of Double Z Pinch Driven Imploding Shells Using Multiresolution Denoising Techniques on X Ray Backlighting Generated Images  

NASA Astrophysics Data System (ADS)

We have used various advanced image processing and denoising techniques based on multiresolution analysis to obtain useful X ray images of Double Z Pinch driven imploding shells. The shell thickness averaged (highest density) radius (STAR) is defined for a number of asymmetric shots and STAR curves vs angle are Legendre polynomial decomposed in order to characterize the asymmetry in traditional ICF parlance. The powerful hybrid techniques utilizd in this study include wavelets, curvelets and variational minimization iterations to obtain highly reliable denoising based on data extracted noise modeling as well. Pattern detection based on multiresolution analysis hold very good promise in various applications associated with Z pinches and ICF symmetry studies. STAR performance of various implosions can be optimally tuned using these techniques.

Won, Kirk; Afeyan, B.; Stark, J. L.; Cuneo, M.; Bennet, G.; Vesey, R.

2003-10-01

285

Double Z-Pinch Hohlraum Drive with Excellent Temperature Balance for Symmetric Inertial Confinement Fusion Capsule Implosions  

Microsoft Academic Search

A double Z pinch driving a cylindrical secondary hohlraum from each end has been developed which can indirectly drive intertial confinement fusion capsule implosions with time-averaged radiation fields uniform to 2%-4%. 2D time-dependent view factor and 2D radiation hydrodynamic simulations using the measured primary hohlraum temperatures show that capsule convergence ratios of at least 10 with average distortions from sphericity

M. E. Cuneo; R. A. Vesey; J. L. Porter; G. R. Bennett; D. L. Hanson; L. E. Ruggles; W. W. Simpson; G. C. Idzorek; W. A. Stygar; J. H. Hammer; J. J. Seamen; J. A. Torres; J. S. McGurn; R. M. Green

2002-01-01

286

Analyses in Support of Z-Pinch IFE and Actinide Transmutation - LLNL Progress Report for FY-06  

SciTech Connect

This report documents results of LLNL's work in support of two studies being conducted by Sandia National Laboratories (SNL): the development of the Z-pinch driven inertial fusion energy (Z-IFE), and the use of Z-pinch driven inertial fusion as a neutron source to destroy actinides from fission reactor spent fuel. LLNL's efforts in FY06 included: (1) Development of a systems code for Z-IFE and use of the code to examine the operating parameter space in terms of design variables such as the Z-pinch driver energy, the chamber pulse repetition rate, the number of chambers making up the power plant, and the total net electric power of the plant. This is covered in Section 3 with full documentation of the model in Appendix A. (2) Continued development of innovative concepts for the design and operation of the recyclable transmission line (RTL) and chamber for Z-IFE. The work, which builds on our FY04 and FY05 contributions, emphasizes design features that are likely to lead to a more attractive power plant including: liquid jets to protect all structures from direct exposure to neutrons, rapid insertion of the RTL to maximize the potential chamber rep-rate, and use of cast flibe for the RTL to reduce recycling and remanufacturing costs and power needs. See Section 4 and Appendix B. (3) Description of potential figures of merit (FOMs) for actinide transmutation technologies and a discussion of how these FOMs apply and can be used in the ongoing evaluation of the Z-pinch actinide burner, referred to as the In-Zinerator. See Section 5. (4) A critique of, and suggested improvements to, the In-Zinerator chamber design in response to the SNL design team's request for feedback on its preliminary design. This is covered in Section 6.

Meier, W R; Moir, R W; Abbott, R

2006-09-19

287

Efficient production of 100 keV deuterons in deuterium gas puff Z-pinches at 2 MA current  

NASA Astrophysics Data System (ADS)

Deuterium gas puff experiments were carried out on the S-300 Z-pinch at the Kurchatov Institute in Moscow. Gas puffs imploded onto the axis before a current peak at about 100 ns. Fusion neutrons were generated after the gas puff implosion during global expansion of a plasma column. Neutron emission lasted on average 35 ± 5 ns (full width half maximum, FWHM). In the downstream direction (on the Z-pinch axis behind the cathode), a mean neutron energy was 2.6 ± 0.1 MeV. Side-on neutron energy spectra peaked at 2.40 ± 0.05 MeV with about 600 ± 150 keV FWHM. A broad width of side-on neutron spectra implied a high radial component of deuteron velocities. An average kinetic energy of fast deuterons, which produced fusion neutrons, was 150 keV. A peak neutron yield reached a value of 6 × 1010 on a current level of 1.5 MA. It was by one order higher in comparison with other deuterated loads used on the same current generator. On the basis of experimental observations, we concluded that a total energy of deuterons accelerated to fusion energies was above 1.5 kJ. It is more than 15% of the energy input into a plasma. Therefore gas puff Z-pinches seem to be not only powerful sources of x-ray radiation but also efficient sources of 100 keV deuterons. Such a result is consistent with high neutron yields observed on the Angara Z-pinch and plasma foci with similar currents.

Klir, D.; Kravarik, J.; Kubes, P.; Rezac, K.; Cikhardt, J.; Litseva, E.; Hyhlik, T.; Ananev, S. S.; Bakshaev, Yu L.; Bryzgunov, V. A.; Chernenko, A. S.; Kalinin, Yu G.; Kazakov, E. D.; Korolev, V. D.; Ustroev, G. I.; Zelenin, A. A.; Juha, L.; Krasa, J.; Velyhan, A.; Vysin, L.; Sonsky, J.; Volobuev, I. V.

2010-06-01

288

Monochromatic X-ray self-emission imaging of imploding wire array Z-pinches on the Z accelerator  

Microsoft Academic Search

A monochromatic X-ray self-emission imaging diagnostic has been developed for the Z accelerator, which drives 20 MA in 100 ns to implode wire array Z-pinches, generating up to 250 TW of soft X-ray radiation. This instrument reflects eight pinhole images from a flat Cr\\/C multilayer mirror (MLM) onto a 1-ns time-resolved microchannel plate detector. The MLM reflects 277-eV photons with

Brent Jones; Christopher Deeney; Christine A. Coverdale; Charles Julius Meyer; P. David LePell

2006-01-01

289

Study of the effect of preliminary wire explosion on X-ray generation during wire array Z-pinch implosion  

Microsoft Academic Search

Results are presented from experimental studies and numerical simulations of the effect of preliminary wire explosion on the parameters of X-ray emission generated during wire array Z-pinch implosion. The wire array implosion was driven by a current pulse with an amplitude of 0.5 MA and a rise time of 0.5 mus, while the preliminary wire explosion was produced by a

P. B. Repin; V. D. Selemir; V. T. Selyavskii; R. V. Savchenko; A. P. Orlov; B. G. Repin; M. Sh. Ibragimov

2009-01-01

290

Study of the effect of preliminary wire explosion on X-ray generation during wire array Z-pinch implosion  

Microsoft Academic Search

Results are presented from experimental studies and numerical simulations of the effect of preliminary wire explosion on the\\u000a parameters of X-ray emission generated during wire array Z-pinch implosion. The wire array implosion was driven by a current\\u000a pulse with an amplitude of 0.5 MA and a rise time of 0.5 ?s, while the preliminary wire explosion was produced by a

P. B. Repin; V. D. Selemir; V. T. Selyavski?; R. V. Savchenko; A. P. Orlov; B. G. Repin; M. Sh. Ibragimov

2009-01-01

291

Effects of various axial flow profiles on the magneto-Rayleigh-Taylor instability in Z-pinch implosions  

NASA Astrophysics Data System (ADS)

The stabilizing effect of different axial flow profiles on the magneto-Rayleigh-Taylor (MTR) instability in Z-pinch implosions is investigated with a compressible skin-current model. The numerical results show that the mitigation effect of the axial flow on the MRT instability is caused by the radial velocity shear, and it is highly susceptible to the shear value nearby the plasma outer surface. By adjusting the flow profile, the mitigation effect can be improved markedly.

Zhang, Y.; Ding, N.

2006-06-01

292

Effects of various axial flow profiles on the magneto-Rayleigh-Taylor instability in Z-pinch implosions  

SciTech Connect

The stabilizing effect of different axial flow profiles on the magneto-Rayleigh-Taylor (MTR) instability in Z-pinch implosions is investigated with a compressible skin-current model. The numerical results show that the mitigation effect of the axial flow on the MRT instability is caused by the radial velocity shear, and it is highly susceptible to the shear value nearby the plasma outer surface. By adjusting the flow profile, the mitigation effect can be improved markedly.

Zhang, Y.; Ding, N. [Institute of Applied Physics and Computational Mathematics, P.O. Box 8009, Beijing 100088 (China); Institute of Applied Physics and Computational Mathematics, P.O. Box 8009, Beijing 100088 (China); CCAST (World Lab.), P. O. Box 8730, Beijing 100080 (China)

2006-06-15

293

Grazing-incidence mirror streak camera diagnostic for emission measurements of imploding z pinches on the Sandia Z-machine  

Microsoft Academic Search

A soft x-ray (0.1-1 keV) streak camera using a grazing-incidence mirror has been developed for the Sandia Z facility, a 20 MA, 100 ns rise-time accelerator that can generate >200 TW,2 MJ, x-ray pulses. The streak camera is used to measure with one dimension of spatial resolution the continuous time history of sub-kilo-electron-volts emission from z-pinch and radiation flow experiments.

D. F. Wenger; D. B. Sinars; K. L. Keller; R. A. Aragon; L. E. Ruggles; W. W. Simpson; P. H. Primm; J. L. Porter

2004-01-01

294

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

Microsoft Academic Search

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)

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

2003-01-01

295

X-ray emission from z pinches at 107 A: Current scaling, gap closure, and shot-to-shot fluctuations  

Microsoft Academic Search

We have measured the x-ray power and energy radiated by a tungsten-wire-array z pinch as a function of the peak pinch current and the width of the anode-cathode gap at the base of the pinch. The measurements were performed at 13- and 19-MA currents and 1-, 2-, 3-, and 4-mm gaps. The wire material, number of wires, wire-array diameter, wire-array

W. A. Stygar; H. C. Ives; D. L. Fehl; M. E. Cuneo; M. G. Mazarakis; J. E. Bailey; G. R. Bennett; D. E. Bliss; G. A. Chandler; R. J. Leeper; M. K. Matzen; D. H. McDaniel; J. S. McGurn; J. L. McKenney; L. P. Mix; D. J. Muron; J. L. Porter; J. J. Ramirez; L. E. Ruggles; J. F. Seamen; W. W. Simpson; C. S. Speas; R. B. Spielman; K. W. Struve; J. A. Torres; R. A. Vesey; T. C. Wagoner; T. L. Gilliland; M. L. Horry; D. O. Jobe; S. E. Lazier; J. A. Mills; T. D. Mulville; J. H. Pyle; T. M. Romero; J. J. Seamen; R. M. Smelser

2004-01-01

296

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

Microsoft Academic Search

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

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

2003-01-01

297

Use of microsecond current prepulse for dramatic improvements of wire array Z-pinch implosion  

SciTech Connect

The Sphinx machine [F. Lassalle et al., 'Status on the SPHINX machine based on the 1microsecond LTD technology'] based on microsecond linear transformer driver (LTD) technology is used to implode an aluminium wire array with an outer diameter up to 140 mm and maximum current from 3.5 to 5 MA. 700 to 800 ns implosion Z-pinch experiments are performed on this driver essentially with aluminium. Best results obtained before the improvement described in this paper were 1-3 TW radial total power, 100-300 kJ total yield, and 20-30 kJ energy above 1 keV. An auxiliary generator was added to the Sphinx machine in order to allow a multi microsecond current to be injected through the wire array load before the start of the main current. Amplitude and duration of this current prepulse are adjustable, with maxima {approx}10 kA and 50 {mu}s. This prepulse dramatically changes the ablation phase leading to an improvement of the axial homogeneity of both the implosion and the final radiating column. Total power was multiplied by a factor of 6, total yield by a factor of 2.5 with a reproducible behavior. This paper presents experimental results, magnetohydrodynamic simulations, and analysis of the effect of such a long current prepulse.

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

2008-01-15

298

A Concept for Containing Inertial Fusion Energy Pulses in a Z-Pinch-Driven Power Plant  

SciTech Connect

The Z-Pinch Power Plant (ZP-3) is the first concept to use the results at Sandia National Laboratories' Z accelerator in a power plant application. Assuming high-yield fusion pulses (of 1 to 20 GJ per shot at a rate of 0.1 Hz), we consider a unique shock and energy absorbing system to contain the energy. One concept answers the need for system standoff from the fusion reaction with a replaceable mechanical cartridge manufactured on-site. System studies suggest integrated blanket designs for absorbing the fusion energy, cartridge manufacture of recycled materials, and cartridge installation/replacement to maintain a reasonable duty cycle. An effective system design for ZP-3 requires an integrated blanket to shield the permanent structures from the high-energy neutron flux and strong shock wave, breed tritium, and simultaneously absorb the released fusion energy. We investigate the feasibility of this integrated blanket concept and explore the principles of a containment chamber - a crucible - and the containment mechanisms. An operational cycle is proposed to physically load hardware in 10-s intervals while maintaining operational conditions. Preliminary pressure and shock calculations demonstrate that high-yield inertial fusion energy pulses can be contained if the appropriate energy-absorbing materials are used.

Rochau, Gary E. [Sandia National Laboratories (United States); Morrow, Charles W. [Sandia National Laboratories (United States); Pankuch, Peter J. [EG and G Technical Services, Inc. (United States)

2003-05-15

299

ZaP Flow Z-pinch EUV Light Source for Lithography  

NASA Astrophysics Data System (ADS)

The density of features on semiconductor integrated chips (ICs) can increase as the wavelength of the light used for lithography decreases. Present lithography operates at 193 nanometer (nm) wavelength to produce ICs with features at the 90 nm node. By 2015, the semiconductor industry's goal is to operate lithography at the 44 nm node. To accomplish this, an extreme ultraviolet (EUV) light source operating at 13.5 nm wavelength is required, at a power of at least 115 Watts. Using a xenon gas, the ZaP experiment is expected to produce plasma that will emit EUV radiation at the 13.5 nm wavelength. The ZaP Flow Z-Pinch Experiment is presently studying the effect of sheared flow on gross plasma stability. In the experiment, hydrogen gas has been used to produce plasma with quiescent periods in the magnetic mode activity which are 2000 times longer than other plasma concepts for creating EUV light, with 300 times the volume. Similar results have been found with xenon gas. Presently, an EUV detector is being designed using an AXUV100, Silicon/Zirconium filtered photodiode with an 11-18 nm band pass to detect any EUV emissions within that spectrum and the total power of the emissions. The design allows for other photodiodes with narrower band passes to be installed. The design of the detector and initial results will be presented.

Munson, K. A.; Shumlak, U.; Nelson, B. A.

2006-10-01

300

Dynamics of cylindrically converging precursor plasma flow in wire-array Z -pinch experiments  

NASA Astrophysics Data System (ADS)

This paper summarizes the present understanding of the processes leading to precursor column formation in cylindrical wire arrays on the 1MA MAGPIE generator at Imperial College London. Direct experimental measurements of the diameter variation during the collapse and formation phase of the precursor column are presented, along with soft x-ray emission, and quantitative radiography. In addition, data from twisted cylindrical arrays are presented which give additional information on the behavior of coronal plasma generated in wire array z pinches. Three stages in precursor column formation are identifiable from the data: broad initial density profile, rapid contraction to small diameter, and slow expansion after formation. The correlation of emission to column diameter variation indicates the contraction phase is a nonlinear collapse resulting from the increasing on-axis density and radiative cooling rate. The variation in the minimum diameter is measured for several array materials, and data show good agreement with a pressure balance model. Comparison of column expansion rates to analytical models allows an estimate of column temperature variation, and estimates of the current in the column are also made. Formation data are in good agreement with both fluid and kinetic modeling, but highlight the need to include collisionless flow in the early time behavior.

Bott, S. C.; Lebedev, S. V.; Ampleford, D. J.; Bland, S. N.; Chittenden, J. P.; Ciardi, A.; Haines, M. G.; Jennings, C.; Sherlock, M.; Hall, G.; Rapley, J.; Beg, F. N.; Palmer, J.

2006-10-01

301

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

302

Control of instabilities and thermonuclear fusion in Staged Z-pinch  

NASA Astrophysics Data System (ADS)

A Staged Z-pinch, configured for discharge parameters characteristic of multi-megajoule facilities, is studied using the 2 and 1/2 D, radiation-MHD code, MACH2. In this configuration a cylindrical, xenon plasma shell implodes radially onto a co-axial,deuterium-tritium plasma target. During implosion shock fronts are formed in both plasma. The shock waves in the DT plasma preheats the plasma up to several hundred eV before adiabatic compression takes over. In the outer region of the liner plasma,a shock front forms causing Xe mass to accumulate at the outer surface of the DT region. This causes the formation of a conduction channel that the discharge current transfers into. The outer surface of Xe liner then becomes Rayleigh-Taylor (RT)unstable while the shock front that compresses the DT target remains stable. The compression ratio of about 25 can achieve the parameters at the peak compression that can produce a thermonuclear yield from fusion neutrons more then breakeven and beyond. The interesting feature is the inner pinch remains stable even with 1% perturbation level and only become unstable when it explodes.

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

2006-10-01

303

Innovative Approach for Enhancing Shaped X-ray Production in Z-pinches*  

NASA Astrophysics Data System (ADS)

Among z-pinch loads tested at 1.7 MA Zebra generator, planar wire arrays (PWAs) were found to be the best x-ray radiators. PWAs were recently highlighted (PRL 104, 125001, 2010) as potential sources for a new ICF multisource compact hohlraum setup at multi-MA generators. Recent performance optimization of PWA, which exhibits a large resistive energy/power gain and a small, mm-scale size, is reviewed. The anisotropy of radiation yields from single- and double-PWAs that might be caused by opacity effects was observed: higher yield was orthogonally to an array plane or along wire rows in single- and double-PWA (DPWA), respectively. Skewed DPWA implosions, which produce an axial magnetic field to reduce instabilities, generate higher Te/Ne compared to a standard DPWA. Feasible x-ray pulse shaping was demonstrated with DPWA and triple-PWA by varying array composition and parameters. The studies were supported by non-LTE kinetic, WADM, and MHD simulations. * This work was supported by NNSA under DOE Cooperative Agreements DE-FC52-06NA27586, DE-FC52-06NA27588, and in part by DE-FC52-06NA27616.

Kantsyrev, V. L.; Safronova, A. S.; Esaulov, A. A.; Kindel, J. M.; Williamson, K. M.; Shrestha, I.; Osborne, G. C.; Weller, M. E.; Ouart, N. D.; Shlyaptseva, V.; Chuvatin, A. S.; Rudakov, L. I.; Velikovich, A. L.

2010-11-01

304

Theoretical prediction of {beta} and {tau}{sub E} in a hard core Z pinch  

SciTech Connect

The energy confinement time and maximum achievable pressure are critical figures of merit for any proposed magnetic fusion concept. The present work focuses on these issues for a hard core Z pinch, which is the cylindrical limit of a large aspect ratio levitated dipole configuration. An analysis is presented that theoretically predicts both {tau}{sub E} and {beta} for this configuration. The model makes the optimistic assumption that transport is purely classical in the region of the profile that is magnetohydrodynamically (MHD) stable against interchange modes. In the interchange-unstable region use is made of the quasilinear theory described in the accompanying paper [A. Kouznetsov, J. Freidberg, and J. Kesner, Phys. Plasmas 14, 102501 (2007)] which shows that the plasma pressure relaxes to the MHD marginally stable profile while the density evolves to n{proportional_to}[{integral}dl/B]{sup -1}. Analytic and numerical calculations lead to explicit scaling relations for {tau}{sub E} and {beta} which can be tested in future LDX experiments.

Kouznetsov, A.; Freidberg, J. P.; Kesner, J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2007-10-15

305

Z-pinch implosion for ICF physics study on Angara-5-1  

SciTech Connect

Recent development of soft X-ray sources based on super-fast Z-pinch implosion has demonstrated the great promise of pulsed power for ICF physics study. The main direction of the 'Angara-5-1' program is oriented toward using the double liner scheme to confine radiation inside a cavity in order to enhance its intensity significantly. Collision of the external liner shell onto the inner leads to radiation penetration through the inner liner and a decrease in the radiation pulse duration to 3-5 ns. Testing this scheme on 'Angara-5-1' with current 3.5-5 MA demonstrates a flux intensity up to 3 TW/cm{sup 2}. In spite of the fact that results of the experiment and a 1D-simulation are close, there are many issues with external liner stability during current sheath formation and implosion. Recent experimental efforts on Angara-5-1 focused on the 'cold start' problem and on the Rayleigh-Taylor instability for thick (gas-puff) and thin (doped foam) shells. Preionization makes the liner's plasma more homogeneous. The method also works in a plasma focus, according to the first results of a joint Polish-Russian experiment. A high current convolute increases ANGARA-5's load current from about 4 MA to 5.8 MA, which moves the radiation temperature toward the region of interest. We also outline a new approach to a generator intended to produce tens of MA, ANGARA-5-2.

Branitsky, A. V.; Fedulov, M. V.; Grabovsky, E. V.; Nedoseev, S. L.; Olejinik, G. M.; Smirnov, V. P.; Zakharov, S. V. [Troitsk Institute for Innovations and Thermonuclear Investigations, TRINITI, 142092, Troitsk, Moscow region (Russian Federation)

1997-05-05

306

The Physics of Long-Pulse Wire Array Z-Pinch Implosions  

SciTech Connect

Recent improvements in z-pinch wire array load design at Sandia National Laboratories have led to a substantial increase in pinch performance as measured by radiated powers of up to 280 TW in 4 ns and 1.8 MJ of total radiated energy. Next generation, higher current machines will allow for larger mass arrays and comparable or higher velocity implosions to be reached, possibly extending these result.dis the current is pushed above 20 MA, conventional machine design based on a 100 ns implosion time results in higher voltages, hence higher cost and power flow risk. Another approach, which shifts the risk to the load configuration, is to increase the implosion time to minimize the voltage. This approach is being investigated in a series of experimental campaigns on the Saturn and Z machines. In this paper, both experimental and two dimensional computational modeling of the fist long implosion Z experiments will be presented. The experimental data shows broader pulses, lower powers, and larger pinch diameters compared to the corresponding short pulse data. By employing a nested array configuration, the pinch diameter was reduced by 50% with a corresponding increase in power of > 30%. Numerical simulations suggest load velocity is the dominating mechanism behind these results.

DOUGLAS,MELISSA R.; DEENEY,CHRISTOPHER; SPIELMAN,RICK B.; COVERDALE,CHRISTINE A.; RODERICK,N.F.; PETERSON,D.L.

1999-12-14

307

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

308

Model of Enhanced Energy Deposition in a Z-Pinch Plasma  

NASA Astrophysics Data System (ADS)

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 dissipation based on the concept of macroscopic 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 surface m = 0 RT and MHD instability development. As the bubbles converge to the pinch axis, their magnetic energy is converted to the thermal energy of the plasma through pdV work. We present explicit formulas for the average enhanced dissipation rate and the corresponding contribution to the resistance of the load unit, which are favorably compared to the experimental data and simulation results. The possibility of using the enhanced dissipation mechanism to power novel PRS intended to produce high K-shell yields in the long pulse regime will be discussed.

Velikovich, A. L.; Rudakov, L. I.; Davis, J.; Thornhill Giuliani, J. W., Jr.; Clark, R. W.

1999-11-01

309

Numerical Simulations of Z-pinch Experiments to Create Supersonic Differentially Rotating Plasma Flows  

NASA Astrophysics Data System (ADS)

The physics of accretion disks is of fundamental importance for understanding of a wide variety of astrophysical sources that includes protostars, X-ray binaries, and active galactic nuclei. The interplay between hydrodynamic flows and magnetic fields and the potential for turbulence-producing instabilities is a topic of active research that would benefit from the support of dedicated experimental studies. Such efforts are in their infancy, but in an effort to push the enterprise forward we propose an experimental configuration which employs a modified cylindrical wire array Z-pinch to produce a rotating plasma flow relevant to accretion disks. We present three-dimensional resistive magnetohydrodynamic simulations which show how this approach can be implemented. In the simulations, a rotating plasma cylinder or ring is formed, with typical rotation velocity ~30 km s-1, Mach number ~4, and Reynolds number in excess of 107. The plasma is also differentially rotating. Implementation of different external magnetic field configurations is discussed. It is found that a modest uniform vertical field of 1 T can affect the dynamics of the system and could be used to study magnetic field entrainment and amplification through differential rotation. A dipolar field potentially relevant to the study of accretion columns is also considered.

Bocchi, M.; Ummels, B.; Chittenden, J. P.; Lebedev, S. V.; Frank, A.; Blackman, E. G.

2013-04-01

310

Two-dimensional radiation-magnetohydrodynamic simulations of SATURN imploding Z pinches  

SciTech Connect

Z-pinch implosions driven by the SATURN device [D. D. Bloomquist {ital et} {ital al}., {ital Proceedings} {ital of} {ital the} 6{ital th} {ital Institute} {ital of} {ital Electrical} {ital and} {ital Electronics} {ital Engineers} ({ital IEEE}) {ital Pulsed} {ital Power} {ital Conference}, Arlington, VA, edited by P. J. Turchi and B. H. Bernstein (IEEE, New York, 1987), p. 310] at Sandia National Laboratory are modeled with a two-dimensional radiation magnetohydrodynamic (MHD) code, showing strong growth of the magneto-Rayleigh{endash}Taylor (MRT) instability. Modeling of the linear and nonlinear development of MRT modes predicts growth of bubble-spike structures that increase the time span of stagnation and the resulting x-ray pulse width. Radiation is important in the pinch dynamics, keeping the sheath relatively cool during the run-in and releasing most of the stagnation energy. The calculations give x-ray pulse widths and magnitudes in reasonable agreement with experiments, but predict a radiating region that is too dense and radially localized at stagnation. We also consider peaked initial density profiles with constant imploding sheath velocity that should reduce MRT instability and improve performance. Krypton simulations show an output x-ray power {approx_gt}80 TW for the peaked profile. {copyright} {ital 1996 American Institute of Physics.}

Hammer, J.H.; Eddleman, J.L.; Springer, P.T.; Tabak, M.; Toor, A.; Wong, K.L.; Zimmerman, G.B. [Lawrence Livermore National Laboratory, Livermore , California 94526 (United States)] [Lawrence Livermore National Laboratory, Livermore , California 94526 (United States); Deeney, C.; Humphreys, R.; Nash, T.J.; Sanford, T.W.; Spielman, R.B. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); De Groot, J.S. [University of California, Davis, California 95616 (United States)] [University of California, Davis, California 95616 (United States)

1996-05-01

311

Long implosion time tungsten wire array Z pinches on the Saturn generator  

SciTech Connect

Recent success on the Saturn [C. Deeney et al., Phys. Rev. E 56, 5945 (1997)] and Z [R. B. Spielman et al., Phys. Plasmas 5, 2105 (1998)] 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 diam 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 rise times on the order of 4.5-6.5 ns. Experimental data will be presented, along with two-dimensional radiation magnetohydrodynamic simulations used to explain and reproduce the experiment. (c) 2000 American Institute of Physics.

Douglas, M. R. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Deeney, C. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Spielman, R. B. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Coverdale, C. A. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Roderick, N. F. [University of New Mexico, Albuquerque, New Mexico 87102 (United States)] [University of New Mexico, Albuquerque, New Mexico 87102 (United States); Haines, M. G. [The Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom)] [The Blackett Laboratory, Imperial College, London SW7 2BZ, (United Kingdom)

2000-07-01

312

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

313

NUMERICAL SIMULATIONS OF Z-PINCH EXPERIMENTS TO CREATE SUPERSONIC DIFFERENTIALLY ROTATING PLASMA FLOWS  

SciTech Connect

The physics of accretion disks is of fundamental importance for understanding of a wide variety of astrophysical sources that includes protostars, X-ray binaries, and active galactic nuclei. The interplay between hydrodynamic flows and magnetic fields and the potential for turbulence-producing instabilities is a topic of active research that would benefit from the support of dedicated experimental studies. Such efforts are in their infancy, but in an effort to push the enterprise forward we propose an experimental configuration which employs a modified cylindrical wire array Z-pinch to produce a rotating plasma flow relevant to accretion disks. We present three-dimensional resistive magnetohydrodynamic simulations which show how this approach can be implemented. In the simulations, a rotating plasma cylinder or ring is formed, with typical rotation velocity {approx}30 km s{sup -1}, Mach number {approx}4, and Reynolds number in excess of 10{sup 7}. The plasma is also differentially rotating. Implementation of different external magnetic field configurations is discussed. It is found that a modest uniform vertical field of 1 T can affect the dynamics of the system and could be used to study magnetic field entrainment and amplification through differential rotation. A dipolar field potentially relevant to the study of accretion columns is also considered.

Bocchi, M.; Ummels, B.; Chittenden, J. P.; Lebedev, S. V. [Plasma Physics, Imperial College, London SW7 2BW (United Kingdom)] [Plasma Physics, Imperial College, London SW7 2BW (United Kingdom); Frank, A.; Blackman, E. G., E-mail: mbocchi@imperial.ac.uk [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627-0171 (United States)

2013-04-10

314

Time- and space-resolved Si emission measurements of the Z-pinch dynamic hohlraum  

NASA Astrophysics Data System (ADS)

Simulations of the Z-pinch dynamic hohlraum predict a radiating shock in the 14mg/cc CH2 foam that reaches Te> 600eV with a peak hohlraum temperature of Tr> 200eV. To test these simulations, an advanced diagnostic technique has been developed that relies on the measurement of time- and space- resolved Si line emission in combination with 2-D collisional- radiative calculations to infer the conditions of the dynamic hohlraum interior. The line emission originates from Si atoms doped over the central 3 - 6mm height of the foam, and is recorded on an elliptical spectrometer with 1-D spatial resolution imaging through a slot aperture on the top of the dynamic hohlraum. The 2-D calculations assume a 2 or 3 region model of the Si-doped CH2 foam conditions, and include non- local photo-pumping processes that are determined to have an important influence on the observed spectra. The time- and space-resolved conditions of the dynamic hohlraum interior inferred from this technique are presented and compared with 2- D rad-hydro simulations.

Rochau, Gregory A.; Macfarlane, J. J.; Maron, Y.

2005-10-01

315

Kinetic simulation of thermonuclear-neutron production by a 107-A deuterium Z pinch  

NASA Astrophysics Data System (ADS)

Fully kinetic simulations have demonstrated that at sufficiently high currents, half of the neutrons produced by a deuterium Z-pinch are thermonuclear in origin. At 150-kA pinch current, O. A. Anderson et al. [Phys. Rev. 110, 1375 (1958)] clearly shows that essentially all of the neutrons produced by a deuterium pinch are not thermonuclear, but are initiated by an instability that creates beam-target neutrons. Since this paper, many subsequent authors have supported this result while others have claimed that pinch neutrons are, on the contrary, thermonuclear. To resolve this issue, fully kinetic, collisional, and electromagnetic simulations of the complete time evolution of a deuterium pinch have been performed. The simulations were performed with the implicit particle-in-cell code LSP, as described in D. R. Welch et al. [Phys. Rev. Lett. 103, 255002 (2009)]. At 106 -A pinch currents, most of the neutrons are, indeed, beam-target in origin. At 15-MA current, half of the neutrons are thermonuclear and half are beam-target driven by instabilities that produce a power law fall off in the ion energy distribution function at large energy. Simulation results suggest that from 7- to 15-MA current, the fraction of thermonuclear neutrons is not sensitive to current and that the strong dependence of neutron yield on current will continue at currents greater than 15 MA.

Welch, D. R.; Rose, D. V.; Thoma, C.; Clark, R. E.; Mostrom, C. B.; Stygar, W. A.; Leeper, R. J.

2010-07-01

316

The Role of Strong Coupling in Z-Pinch-Driven Approaches to High Yield Inertial Confinement Fusion  

SciTech Connect

Peak x-ray powers as high as 280 {+-} 40 TW have been generated from the implosion of tungsten wire arrays on the Z Accelerator at Sandia National Laboratories. The high x-ray powers radiated by these z-pinches provide an attractive new driver option for high yield inertial confinement fusion (ICF). The high x-ray powers appear to be a result of using a large number of wires in the array which decreases the perturbation seed to the magnetic Rayleigh-Taylor (MRT) instability and diminishes other 3-D effects. Simulations to confirm this hypothesis require a 3-D MHD code capability, and associated databases, to follow the evolution of the wires from cold solid through melt, vaporization, ionization, and finally to dense imploded plasma. Strong coupling plays a role in this process, the importance of which depends on the wire material and the current time history of the pulsed power driver. Strong coupling regimes are involved in the plasmas in the convolute and transmission line of the powerflow system. Strong coupling can also play a role in the physics of the z-pinch-driven high yield ICF target. Finally, strong coupling can occur in certain z-pinch-driven application experiments.

MEHLHORN,THOMAS A.; DESJARLAIS,MICHAEL P.; HAILL,THOMAS A.; LASH,JOEL S.; ROSENTHAL,STEPHEN E.; SLUTZ,STEPHEN A.; STOLTZ,PETER H.; VESEY,ROGER A.; OLIVER,B.

1999-11-08

317

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

SciTech Connect

Inertial confinement fusion capsule implosions absorbing up to 35 kJ of x-rays from a {approx}220 eV dynamic hohlraum on the Z accelerator at Sandia National Laboratories have produced thermonuclear D-D neutron yields of (2.6 {+-} 1.3) x 10{sup 10}. Argon spectra confirm a hot fuel with Te {approx} 1 keV and n{sub e} {approx} (1-2) x 10{sup 23} cm{sup -3}. Higher performance implosions will require radiation symmetry control improvements. Capsule implosions in a {approx}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 P{sub 2} 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.

Bailey, James E.; Chandler, Gordon Andrew; Vesey, Roger Alan; Hanson, David Lester; Olson, Craig Lee; Nash, Thomas J.; Matzen, Maurice Keith; Ruiz, Carlos L.; Porter, John Larry, Jr.; Cuneo, Michael Edward; Varnum, William S.; Bennett, Guy R. (K-tech Corporation, Albuquerque, NM); Cooper, Gary Wayne; Schroen, Diana Grace (Schafer Gorp., Livermore, CA); Slutz, Stephen A.; MacFarlane, Joseph John (Prism Computational Sciences, Madison, WI); Leeper, Ramon Joe; Golovkin, I. E. (Prism Computational Sciences, Madison, WI); Mehlhorn, Thomas Alan; Mancini, Roberto Claudio (University of Nevada, Reno, NV)

2003-07-01

318

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

319

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

320

Evolution of the 3D structure of the magneto Rayleigh-Taylor instability in imploding liner Z-pinch fusion schemes  

NASA Astrophysics Data System (ADS)

Imploding aluminum or beryllium Z-pinch liners provide a method of directly compressing fusion fuel to high densities and temperatures, with excellent energy coupling efficiency. The presence of large magnetic fields also provides a method of suppressing thermal conduction losses and increasing alpha particle confinement, significantly reducing the rho-R criterion required for ignition. A critical requirement is the final integrity of the inside surface of the liner which is used to compress the fusion fuel and which would be significantly degraded should the Rayleigh-Taylor instability grow to large amplitude. Recent experiments at Sandia National Laboratory have provided high quality radiography data which can be used to test the ability of MHD codes to model the Rayleigh-Taylor instability in such liners. We present three dimensional resistive magneto-hydrodynamic simulation results which examine the characteristic Rayleigh-Taylor wavelengths and growth rates and the sensitivity of these results to assumptions of the model. The differences between the Rayleigh-Taylor growth in 2D and 3D are highlighted. Departures from azimuthal symmetry are found to be increasingly important as the implosion approaches the axis and play a pivotal role in determining the peak energy density of the fuel.

Chittenden, Jeremy; Vickers, Simon; Sinars, Daniel; McBride, Ryan

2010-11-01

321

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

322

Soldered contact and current risetime effects on negative polarity wire array Z pinches  

NASA Astrophysics Data System (ADS)

The experimental results described in this paper were motivated by earlier, low current, single wire experiments. In these experiments, single 10-25 ?m diameter wires were driven by 1-5 kA current pulses with variable dI/dt from 5 to 60 A/ns. The amount of energy deposited in the wires, the expansion rate, and expansion uniformity that occurred before a plasma induced voltage collapse were found to depend on the polarity, dI/dt, and the quality of the contacts between the wires and the electrodes. This paper reports the results of experiments with cylindrical wire arrays driven by Cornell Beam Research Accelerator (COBRA) [J. B. Greenly, J. D. Douglas, D. A. Hammer et al., Rev. Sci. Instrum. 79, 073501 (2008)] current pulses that reached 1 MA. The pulse lengths were varied from 100 to 200 ns. These larger current pulses drove the wires of the array through the initiation phase studied in the single wire experiments and through ablation and Z-pinch implosion to stagnation on the cylindrical axis of the array. Regardless of the current pulse length, the COBRA dI/dt per wire during initiation reached approximately 175 A/ns and resistive voltage breakdown occurred at ~13 ns. Wire-electrode contacts were modified by soldering the cathode ends of the wires to the brass electrode. With the 100 ns COBRA pulse, voltage monitor data suggested that soldering produced a smaller radius pinch, but bolometer data showed that this did not affect the total energy emitted from the array compared to nonsoldered contacts. With the 200 ns COBRA pulse and soldered contacts, the bolometer data showed an average of 69% increase in time integrated x-ray emission and the photoconducting detector data showed an increase in x-ray power and yield compared with nonsoldered contacts. Under these same conditions the four-frame extreme ultraviolet images showed a more pronounced ``Christmas tree'' effect at the cathode.

Chalenski, D. A.; Kusse, B. R.; Greenly, J. B.

2009-08-01

323

Oblique shock structures formed during the ablation phase of aluminium wire array z-pinches  

NASA Astrophysics Data System (ADS)

A series of experiments has been conducted in order to investigate the azimuthal structures formed by the interactions of cylindrically converging plasma flows during the ablation phase of aluminium wire array Z pinch implosions. These experiments were carried out using the 1.4 MA, 240 ns MAGPIE generator at Imperial College London. The main diagnostic used in this study was a two-colour, end-on, Mach-Zehnder imaging interferometer, sensitive to the axially integrated electron density of the plasma. The data collected in these experiments reveal the strongly collisional dynamics of the aluminium ablation streams. The structure of the flows is dominated by a dense network of oblique shock fronts, formed by supersonic collisions between adjacent ablation streams. An estimate for the range of the flow Mach number (M = 6.2-9.2) has been made based on an analysis of the observed shock geometry. Combining this measurement with previously published Thomson Scattering measurements of the plasma flow velocity by Harvey-Thompson et al. [Physics of Plasmas 19, 056303 (2012)] allowed us to place limits on the range of the ZTe of the plasma. The detailed and quantitative nature of the dataset lends itself well as a source for model validation and code verification exercises, as the exact shock geometry is sensitive to many of the plasma parameters. Comparison of electron density data produced through numerical modelling with the Gorgon 3D MHD code demonstrates that the code is able to reproduce the collisional dynamics observed in aluminium arrays reasonably well.

Swadling, G. F.; Lebedev, S. V.; Niasse, N.; Chittenden, J. P.; Hall, G. N.; Suzuki-Vidal, F.; Burdiak, G.; Harvey-Thompson, A. J.; Bland, S. N.; De Grouchy, P.; Khoory, E.; Pickworth, L.; Skidmore, J.; Suttle, L.

2013-02-01

324

Oblique shock structures formed during the ablation phase of aluminium wire array z-pinches  

SciTech Connect

A series of experiments has been conducted in order to investigate the azimuthal structures formed by the interactions of cylindrically converging plasma flows during the ablation phase of aluminium wire array Z pinch implosions. These experiments were carried out using the 1.4 MA, 240 ns MAGPIE generator at Imperial College London. The main diagnostic used in this study was a two-colour, end-on, Mach-Zehnder imaging interferometer, sensitive to the axially integrated electron density of the plasma. The data collected in these experiments reveal the strongly collisional dynamics of the aluminium ablation streams. The structure of the flows is dominated by a dense network of oblique shock fronts, formed by supersonic collisions between adjacent ablation streams. An estimate for the range of the flow Mach number (M = 6.2-9.2) has been made based on an analysis of the observed shock geometry. Combining this measurement with previously published Thomson Scattering measurements of the plasma flow velocity by Harvey-Thompson et al.[Physics of Plasmas 19, 056303 (2012)] allowed us to place limits on the range of the ZT{sub e} of the plasma. The detailed and quantitative nature of the dataset lends itself well as a source for model validation and code verification exercises, as the exact shock geometry is sensitive to many of the plasma parameters. Comparison of electron density data produced through numerical modelling with the Gorgon 3D MHD code demonstrates that the code is able to reproduce the collisional dynamics observed in aluminium arrays reasonably well.

Swadling, G. F.; Lebedev, S. V.; Niasse, N.; Chittenden, J. P.; Hall, G. N.; Suzuki-Vidal, F.; Burdiak, G.; Harvey-Thompson, A. J.; Bland, S. N.; De Grouchy, P.; Khoory, E.; Pickworth, L.; Skidmore, J.; Suttle, L. [Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom)

2013-02-15

325

Symmetric ICF Capsule Implosions in Double Z-Pinch Hohlraums on Z*  

NASA Astrophysics Data System (ADS)

Detailed calculations indicate that with a sufficiently uniform radiation drive, correct pulse shaping, and minimal capsule preheat, the dual-60-MA z-pinch high-yield (HY) ICF concept [Phys. Plasmas 6, 2129 (1999).] may release 400 MJ of fusion yield. Using an advanced, 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 first of these issues, radiation symmetry, is under detailed investigation. The time-averaged polar radiation asymmetry, /I, is inferred from direct measurements of the convergence ratio and distortion of an imploding capsules limb-darkened ("backlit") shell, via 6.7 keV point projection x-ray imaging. In this pursuit, the image analysis techniques and the new Z-Beamlet Laser (ZBL), generating the x-ray source for imaging, are being continually enhanced so that sufficiently small distortions, representative of acceptable symmetry for HY scaling, can be detected. In the first experiment with modest spatial resolution the polar symmetry was within 1.7-3x of that required for scaling to HY; the peak gas cavity convergence ratio was 14-21 (38 g/cc predicted peak shell density); and the implosion trajectory was mapped. The close agreement between simulation and data for the trajectory suggests that the hohlraum energetics and first order capsule physics are well understood. In a second recent series the resolution was improved 3x to 50 ?m, thus reducing the measurement uncertainty in /I. These higher resolution images, in a similar near-optimum hohlraum, are undergoing analysis for /I. In both experiments the hohlraum length was tuned to modify the P2 Legendre mode (see R. A. Vesey, this session), thus validating simulations from which a P_2-optimized hohlraum can be predicted.

Bennett, Guy R.

2002-11-01

326

Stability analysis and numerical simulation of a hard-core diffuse z pinch during compression with Atlas facility liner parameters  

NASA Astrophysics Data System (ADS)

In the 'metal liner' approach to magnetized target fusion (MTF), a preheated magnetized plasma target is compressed to thermonuclear temperature and high density by externally driving the implosion of a flux conserving metal enclosure, or liner, which contains the plasma target. As in inertial confinement fusion, the principal fusion fuel heating mechanism is pdV work by the imploding enclosure, called a pusher in ICF. One possible MTF target, the hard-core diffuse z pinch, has been studied in MAGO experiments at VNIIEF and is one possible target being considered for experiments on the Atlas pulsed power facility. Numerical MHD simulations show two intriguing and helpful features of the diffuse z pinch with respect to compressional heating. First, in two-dimensional simulations the m = 0 interchange modes, arising from an unstable pressure profile, result in turbulent motions and self-organization into a stable pressure profile. The turbulence also gives rise to convective thermal transport, but the level of turbulence saturates at a finite level, and simulations show substantial heating during liner compression despite the turbulence. The second helpful feature is that pressure profile evolution during compression tends towards improved stability rather than instability when analysed according to the Kadomtsev criteria. A liner experiment is planned for Atlas to study compression of magnetic flux without plasma, as a first step. The Atlas geometry is compatible with a diffuse z pinch, and simulations of possible future experiments show that kiloelectronvolt temperatures and useful neutron production for diagnostic purposes should be possible if a suitable plasma injector is added to the Atlas facility.

Siemon, R. E.; Atchison, W. L.; Awe, T.; Bauer, B. S.; Buyko, A. M.; Chernyshev, V. K.; Cowan, T. E.; Degnan, J. H.; Faehl, R. J.; Fuelling, S.; Garanin, S. F.; Goodrich, T.; Ivanovsky, A. V.; Lindemuth, I. R.; Makhin, V.; Mokhov, V. N.; Reinovsky, R. E.; Ryutov, D. D.; Scudder, D. W.; Taylor, T.; Yakubov, V. B.

2005-09-01

327

Numerical studies of the effects of precursor plasma on the performance of wire-array Z-pinches  

SciTech Connect

This paper is to numerically investigate, in one dimension, the effects of precursor plasma resulted from wire-array ablation on the performance of its following implosion after the ablation. The wire-array ablation is described by an analytic model, which consists of a rocket model or Sasorov's expression of wire-array mass ablation rate, the evolution equation of magnetic field, and several roughly reasonable assumptions. The following implosion is governed by the radiation magnetohydrodynamics. The implosion processes of wire-array Z-pinch from plasma shells prefilled and un-prefilled by the low-density plasma inside them are studied, and that from the wire-array ablations, which may be changed through varying the ablation time, ablation rate, and ablation velocity V{sub abl}, are also simulated. The obtained results reveal that the prefilled low-density plasma and the precursor plasma from the wire-array ablation help to enhance the plasma shell pinch and the final implosion of the wire array, respectively, compared to the pinch of un-prefilled plasma shell. With the same plasma masses, which are distributed in the interior of the array and the shell, and modified Spitzer resistivity, the implosions that start from the wire ablation develop faster than that from the plasma shell with the prefill. If more substance ablates from the wire array before the start of its implosion, the final Z-pinch performance could be better. The Z-pinch plasma is highly magnetized with driven current more than 3 MA.

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

2010-06-15

328

Enhanced keV peak power and yield using twisted pair 'cables' in a z-pinch  

SciTech Connect

Individual wires in a z-pinch were replaced with twisted pair 'cables' of similar linear mass on the COBRA pulsed power generator, resulting in peak power and yield increases in radiation above 1 keV. A cable is defined here as two or more fine wires twisted together to form a continuous strand with a wavelength ({lambda}{sub t}) dependent on the twists per unit length. The magnitude of {lambda}{sub t} appears to play a strong role in these increases, with the largest gains found for a {lambda}{sub t} of Almost-Equal-To 0.75 mm.

Hoyt, C. L.; Knapp, P. F.; Pikuz, S. A.; Shelkovenko, T. A.; Cahill, A. D.; Gourdain, P.-A.; Greenly, J. B.; Kusse, B. R.; Hammer, D. A. [Laboratory of Plasma Studies, Cornell University, 439 Rhodes Hall, Ithaca, New York 14853 (United States)

2012-06-11

329

Development of novel techniques to study the magnetic field evolution in wire array Z-pinches and X pinches  

NASA Astrophysics Data System (ADS)

Understanding the magnetic field topology in wire-array Z-pinches is of great significance for their ultimate application to stockpile stewardship and inertial confinement fusion. We have developed and tested several novel techniques involving material-based sensors to measure magnetic fields as a function of space and time in high energy density plasmas on pulsed power machines. We first briefly introduce a technique that was used to measure a lower limit of the maximum magnetic field of a sub-microsecond duration pulse using magnetic reversal in CoPt thin films. The time-varying magnetic field was generated by an exploding wire array plasma called an X pinch produced on the 0.5 MA, 100 ns pulse duration, XP pulsed power generator. We then introduce a technique based on Faraday rotation that was used to measure magnetic fields in wire-array Z-pinches produced on the 1 MA, 100 ns rise time, COBRA pulsed power generator as well as on the XP generator. This technique measures 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. We have measured fields > 10 T with 100 ns rise times outside of a wire-array Z-pinch for the entire duration (˜250 ns) of the current pulse and as much as ˜2 T inside a wire-array for ˜40 ns from the start of current. This is the first time that such rapidly varying and large fields have been measured using the terbium borate glass. The third method, also based on Faraday rotation of SLM laser light utilized an integrated optical fiber sensor (a fiber-sensor-fiber assembly) on the XP pulsed power generator that also yielded a measurement of the magnetic field of a wire-array Z-pinch for part of the current pulse. Finally, we repeated the third method by fabricating a "thin film waveguide" of terbium borate glass to increase the spatial resolution of the measurement. The thin film waveguide was then coupled to an optical fiber system. Although we successfully fabricated thin film nanowaveguides of terbium borate glass, the first time such waveguides have been made, due to poor coupling efficiency of light between components, preliminary Faraday rotation measurements were unsuccessful. The technique developed in this dissertation is potentially viable for magnetic field measurements in high current pulsed power systems if the device is protected from intimate interaction with the high energy density plasma during the time that a magnetic field measurement is to be made.

Syed, Wasif

330

Enhanced keV peak power and yield using twisted pair ``cables'' in a z-pinch  

NASA Astrophysics Data System (ADS)

Individual wires in a z-pinch were replaced with twisted pair ``cables'' of similar linear mass on the COBRA pulsed power generator, resulting in peak power and yield increases in radiation above 1 keV. A cable is defined here as two or more fine wires twisted together to form a continuous strand with a wavelength (?t) dependent on the twists per unit length. The magnitude of ?t appears to play a strong role in these increases, with the largest gains found for a ?t of ~0.75 mm.

Hoyt, C. L.; Knapp, P. F.; Pikuz, S. A.; Shelkovenko, T. A.; Cahill, A. D.; Gourdain, P.-A.; Greenly, J. B.; Kusse, B. R.; Hammer, D. A.

2012-06-01

331

Measurements of energy fluctuations of a saturated 46.9 nm Ar laser produced in Z-pinch capillary discharges  

NASA Astrophysics Data System (ADS)

We report on the achievement of significant energy stability in a 46.9 nm soft x-ray laser pumped by fast Z-pinch capillary discharges. The energy stability, investigated over, hundreds of shots, is optimized by operating the laser in the highly saturated regime using capillary discharges with length up to 45 cm. We demonstrate standard deviation on the energy fluctuations smaller than +/-5% and an energy/pulse of 300 ?J at 0.2 Hz. These results demonstrate the reliability of this soft x-ray laser for its widespread use for the development of applications.

Ritucci, A.; Tomassetti, G.; Reale, A.; Reale, L.; Flora, F.; Mezi, L.

2005-03-01

332

Measurement of magnetic fields in a high-current Z pinch in Angara-5-1 using Faraday rotation  

SciTech Connect

Faraday rotation is used to study the magnetic-field structure in the plasma of a high-current Z pinch. It is shown that most of the discharge current, amounting to 3 MA, flows in an axial region of the pinch with diameter {approximately}6 mm. The magnetic-field profile implies that a distance of 3-4 mm from the axis there are local peripheral induced currents of 0.3-0.5 MA around the main pinch, flowing in the reverse direction. The maximum mean magnetic-field strength localized near the peripheral currents is equal to {approximately}5.6 MG. 15 refs., 4 figs.

Branitskii, A.V.; Vikharev, V.D.; Kasimov, A.G.; Nedoseev, S.L.; Rupasov, A.A.; Sarkisov, G.S.; Smirnov, V.P.; Tsarfin, V.Ya.; Shikanov, A.A.

1992-09-01

333

Mass profile and instability growth measurements for 300-wire z-pinch implosions driven by 14-18, MA.  

SciTech Connect

We present the first comprehensive study of high wire-number, wire-array Z-pinch dynamics at 14-18 MA using x-ray backlighting and optical shadowgraphy diagnostics. The cylindrical arrays retain slowly expanding, dense wire cores at the initial position up to 60% of the total implosion time. Azimuthally correlated instabilities at the array edge appear during this stage which continue to grow in amplitude and wavelength after the start of bulk motion, resulting in measurable trailing mass that does not arrive on axis before peak x-ray emission.

Cuneo, Michael Edward; Yu, Edmund P.; Nash, Thomas J.; Bliss, David Emery; Porter, John Larry, Jr.; Sinars, Daniel Brian

2004-07-01

334

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

SciTech Connect

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, producing implosions velocities as high as 100 cm/{mu}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 8 a radiation 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. These large volume, long-lived radiation sources have recently been used for ICF-relevant ablator physics experiments as well as astrophysical opacity and radiation-material interaction experiments. Hydromagnetic Rayleigh-Taylor instabilities and cylindrical load symmetry are critical, limiting factors in determining the assembled plasma densities and temperatures, and thus in the x-ray pulse widths 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, Zn reproducibility, and x-ray output power. X-ray pulse widths 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 Saturn n accelerator, and are a record for x-ray powers in the laboratory.

Matzen, M.K.

1997-02-01

335

Deuterium Gas-Puff Z-Pinch Implosions on the Z accelerator  

NASA Astrophysics Data System (ADS)

The generation of neutrons via current driven sources, including z-pinch driven hohlraums, deuterium gas puffs, deuterium fiber pinches, deuterium liners, and dense plasma foci, has been studied for many years. Experiments with methods other than inertial confinement fusion have produced significant neutron output (up to ˜10^12) from experiments with current drives < 8 MA. In this paper, the results of experiments at the Z Accelerator to study the neutron production and implosion characteristics of a deuterium gas puff will be presented. Two current levels (12MA and 15MA) were fielded to evaluate the scaling of the neutron output; neutron outputs of 1 x 10^13 and 3 x 10^13 were measured. The neutron output measured was the first with a load of this type at this current level and has been demonstrated to be repeatable, with side-on time-of-flight measurements showing 2.34 MeV. While the mechanism for the neutrons has not been identified experimentally, this neutron output is 100 times more than previously observed from neutron producing experiments at Z. Comparison of the neutron output with previous experiments at 7 MA shows that the neutron output scales approximately as I^4. Time-of-flight measurements from multiple directions, as well as the results of activation diagnostics will be presented. The experimental results will be compared with 1D, 2D, and 3D magneto-hydrodynamic (MHD) calculations, which have shown that thermal neutron outputs from Z could be expected to be in the (0.3 to 1.0) x 10^14 range. Dopant gases were added to track the implosion characteristics of the gas through x-ray yield measurements and spectroscopy. X-ray diagnostics have shown that the stagnated deuterium plasma achieved electron temperatures of 2.2 keV and ion densities of 2 x 10^20 cm-3, in agreement with the MHD calculations. **Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000. NRL work was supported by DTRA. **in collaboration with C. Deeney, C. Ruiz, Sandia National Labs, G. Cooper, Univ. of New Mexico, A.L. Velikovich, J. Davis, R.W. Clark, Y.K. Chong, and J.P. Apruzese, Naval Research Lab, J.Franklin, S. Chantrenne, and P.D. LePell, Ktech, J. Chittenden, Imperial College, J.Levine and J. Banister, L-3 Communications.

Coverdale, Christine A.

2006-10-01

336

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

SciTech Connect

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 {mu}g/cm{sup 3} 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 {mu}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 x 10{sup 9} neutrons per shot. The scenario of hot spot formation is adequately described by two-dimensional MHD simulations.

Akunets, A. A. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); 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. [Russian Research Centre Kurchatov Institute (Russian Federation); Pimenov, V. G. [Russian Academy of Sciences, Zelinsky Institute of Organic Chemistry (Russian Federation); Smirnova, E. A.; Ustroev, G. I.; Chernenko, A. S.; Shchagin, V. A. [Russian Research Centre Kurchatov Institute (Russian Federation)

2010-08-15

337

Capsule symmetry sensitivity and hohlraum symmetry calculations for the z-pinch driven hohlraum high-yield concept  

NASA Astrophysics Data System (ADS)

Capsule radiation symmetry is a crucial issue in the design of the z-pinch driven hohlraum approach to high-yield inertial confinement fusion [1]. Capsule symmetry may be influenced by power imbalance of the two z-pinch x-ray sources, and by hohlraum effects (geometry, time-dependent albedo, wall motion). We have conducted two-dimensional radiation-hydrodynamics calculations to estimate the symmetry sensitivity of the 220 eV beryllium ablator capsule that nominally yields 400 MJ in this concept. These estimates then determine the symmetry requirements to be met by the hohlraum design (for even Legendre modes) and by the top-bottom pinch imbalance and mistiming (for odd Legendre modes). We have used a combination of 2- and 3-D radiosity ("viewfactor"), and 2-D radiation-hydrodynamics calculations to identify hohlraum geometries that meet these symmetry requirements for high-yield, and are testing these models against ongoing Z foam ball symmetry experiments. 1. J. H. Hammer et al., Phys. Plas. 6, 2129 (1999).

Vesey, Roger; Cuneo, M. E.; Hanson Porter, D. L., Jr.; Mehlhorn, T. A.; Ruggles, L. E.; Simpson, W. W.; Hammer, J. H.; Landen, O.

2000-10-01

338

Polar Radiation-Flux Symmetry Measurements in Z-Pinch-Driven Hohlraums with Symmetric Double-Pinch Drive  

NASA Astrophysics Data System (ADS)

We are currently exploring symmetry requirements of the z-pinch-driven hohlraum concept [1] for high-yield inertial confinement fusion. In experiments on the Z accelerator, the burnthrough of a low-density self-backlit foam ball has been used to diagnose the large time-dependent flux asymmetry of several single-sided-drive hohlraum geometries [2]. We are currently applying this technique to study polar radiation flux symmetry in a symmetric double z-pinch geometry. Wire arrays on opposite ends of the hohlraum, connected in series to a single current drive of 18 MA, implode and stagnate on axis, efficiently radiating about 100 TW of x rays which heat the secondary to 75 eV. Comparisons with 3-D radiosity and 2-D rad-hydro models of hohlraum symmetry performance will be presented. 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. 1 J. H. Hammer et al., Phys. Plasmas 6, 2129 (1999). 2 D. L. Hanson et al., Bull. Am. Phys. Soc. 44, 40 (1999).

Hanson, D. L.; Vesey, R. A.; Cuneo Porter, M. E., Jr.; Chandler, G. A.; Ruggles, L. E.; Simpson, W. W.; Seamen, H.; Primm, P.; Torres, J.; McGurn, J.; Gilliland, T. L.; Reynolds, P.; Hebron, D. E.; Dropinski, S. C.; Schroen-Carey, D. G.; Hammer, J. H.; Landen, O.; Koch, J.

2000-10-01

339

Study of the effect of preliminary wire explosion on X-ray generation during wire array Z-pinch implosion  

SciTech Connect

Results are presented from experimental studies and numerical simulations of the effect of preliminary wire explosion on the parameters of X-ray emission generated during wire array Z-pinch implosion. The wire array implosion was driven by a current pulse with an amplitude of 0.5 MA and a rise time of 0.5 {mu}s, while the preliminary wire explosion was produced by a current pulse with an amplitude of 0.5-1 kA per wire, a rise time of 100 ns, and a full width at half maximum of {approx}200 ns. The experiments showed that the current prepulse significantly impaired the parameters of X-ray pulses. In particular, along with a decrease in the amplitude and an increase in the duration of the X-ray pulse, its spiky structure became more pronounced. The results of numerical simulations with the use of a one-dimensional radiative MHD code are in good agreement with the parameters of Z-pinch emission in experiments with and without a current prepulse.

Repin, P. B.; Selemir, V. D.; Selyavskii, V. T.; Savchenko, R. V.; Orlov, A. P.; Repin, B. G.; Ibragimov, M. Sh. [Russian Federal Nuclear Center All-Russia Research Institute of Experimental Physics (Russian Federation)

2009-01-15

340

Grazing-incidence mirror streak camera diagnostic for emission measurements of imploding z pinches on the Sandia Z-machine  

SciTech Connect

A soft x-ray (0.1-1 keV) streak camera using a grazing-incidence mirror has been developed for the Sandia Z facility, a 20 MA, 100 ns rise-time accelerator that can generate >200 TW,2 MJ, x-ray pulses. The streak camera is used to measure with one dimension of spatial resolution the continuous time history of sub-kilo-electron-volts emission from z-pinch and radiation flow experiments. Radiation >1 keV is eliminated by the use of a grazing-incidence mirror and transmission filters. The diagnostic has a magnification of 1.22, a 20 mm field-of-view and a spatial resolution of {approx}350 {mu}m. The recording length of the instrument is variable in duration up to a maximum of 33 ns, making it well suited for the typical 100 ns Z pinch implosion times. The spatial resolution can readily be changed to be along either the axial or the radial direction.

Wenger, D.F.; Sinars, D.B.; Keller, K.L.; Aragon, R.A.; Ruggles, L.E.; Simpson, W.W.; Primm, P.H.; Porter, J.L. [Sandia National Laboratories, P.O. Box 5800, MS 1193, Albuquerque, New Mexico 87185 (United States)

2004-10-01

341

Long implosion time (240 ns) Z-pinch experiments with a large diameter (12 cm) double-shell nozzle  

NASA Astrophysics Data System (ADS)

Recently, an 8 cm diameter double-shell nozzle has produced argon Z pinches with high K-shell yields with implosion time of 210 ns. To produce even longer implosion time Z pinches for facilities such as Decade Quad [D. Price, et al., ``Electrical and Mechanical Design of the Decade Quad in PRS Mode,'' in Proceedings of the 12th IEEE Pulsed Power Conference, Monterey, CA, edited by C. Stallings and H. Kirbie (IEEE, New York, 1999), p. 489] (9 MA short circuit current at 300 ns), a larger nozzle (12 cm outer diameter) was designed and fabricated. During initial testing on Double-EAGLE [P. Sincerny et al., Proceedings of the 5th IEEE Pulsed Power Conference, Arlington, VA, edited by M. F. Rose and P. J. Turchi (IEEE, New York, 1985), p. 151], 9 kJ of argon K-shell radiation in a 6 ns full width at half maximum pulse was produced with a 240 ns implosion. The initial gas distributions produced by various nozzle configurations have been measured and their impact on the final radiative characteristics of the pinch are presented. The addition of a central jet to increase the initial gas density near the axis is observed to enhance the pinch quality, increasing K-shell yield by 17% and power by 40% in the best configuration tested.

Levine, J. S.; Banister, J. W.; Failor, B. H.; Qi, N.; Song, Y.; Sze, H. M.; Fisher, A.

2004-05-01

342

Studies of the distribution of the Z-pinch radiance during the implosion of wire arrays in the angara-5-1 facility  

SciTech Connect

Results are presented from time-integrated measurements of soft X-ray emission from Z-pinches during the implosion of simple and nested wire arrays. The blackening density distribution obtained with the help of a pinhole camera is recalculated into the time-integrated Z-pinch radiance. It is found that, in the case of a simple wire array, up to 70% of the total SXR energy emitted during a discharge is radiated from the axial region, the rest of energy being radiated from plasma jets, whereas in the case of a nested wire array, more than 90% of the SXR energy is radiated from the axial region.

Grabovskii, E. V.; Oleinik, G. M.; Porofeev, I. Yu. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)

2006-06-15

343

Issledovanie sverkhbystrogo dejterievogo Z-pincha na ustanovke ANGARA-5-1. (Study on superfast deuterium Z-pinch at the ANGARA-5-1 device).  

National Technical Information Service (NTIS)

2-3 MA superfast deuterium Z-pinch with 100 ns pulse rise time is investigated at the ANGARA-5-1 device. The neutron yield in the experiments reaches 10(sup 12) per pulse. A high axial gradient of the ion number per unit length dN/dx(approx equal)10(sup 1...

A. V. Batyunin A. N. Bulatov V. D. Vikharev

1989-01-01

344

Propulsion application of non-neutronic fusion chain reactions in Petawatt laser ignited shear flow stabilized dense plasma z-pinches  

Microsoft Academic Search

Shear flow stabilized z-pinches promise the attainment of very high densities. At these high densities non-neutronic fusion chain reactions, ideally suited for propulsion, can be ignited with petawatt lasers. To drive the dense pinch discharges large capacitors with short discharge times are required, favoring high voltages. To reduce the weight of the capacitors, and at the same time to have

F. Winterberg

2000-01-01

345

Efficient radiation production in long implosions of structured gas-puff Z pinch loads from large initial radius.  

PubMed

We have proposed and demonstrated successfully a new approach for generating high-yield K-shell radiation with large-diameter gas-puff Z pinches. The novel load design consists of an outer region plasma that carries the current and couples energy from the driver, an inner region plasma that stabilizes the implosion, and a high-density center jet plasma that radiates. It increased the Ar K-shell yield at 3.46 MA in 200 ns implosions from 12 cm initial diameter by a factor of 2, to 21 kJ, matching the yields obtained earlier on the same accelerator with 100 ns implosions. A new "pusher-stabilizer-radiator" physical model is advanced to explain this result. PMID:16196936

Sze, H; Banister, J; Failor, B H; Levine, J S; Qi, N; Velikovich, A L; Davis, J; Lojewski, D; Sincerny, P

2005-09-01

346

Optimization of nickel L-shell radiation from a wire array Z-pinch using initial array radius scaling  

NASA Astrophysics Data System (ADS)

Time-resolved diagnostics have been used to study nickel wire array Z-pinch experiments on the DNA/Double-EAGLE generator. When 4 MA currents are used to implode arrays of different initial diameters, a maximum yield of 40 kJ, around 1 keV from the nickel L-shell, is produced by an array with a diameter of 15 mm. Filtered X-ray pinhole photography and time-resolved crystal X-ray spectroscopy reveal that increasing the diameter beyond 15 mm causes a higher temperature but lower density plasma with the net effect of reducing the L-shell radiation. At diameters less than the optimum, the bulk plasma is too cold to produce nickel L-shell line emission except from localized hot spots.

Deeney, C.; Nash, T.; Lepell, P. D.; Krishnan, M.; Childers, K.

1989-12-01

347

Physics of Multi-Planar and Compact Cylindrical Wire Arrays Implosions on University-Scale Z-pinch Generators  

NASA Astrophysics Data System (ADS)

The presented research focuses on investigation of Z-pinch plasma formation, implosion, and radiation characteristics as a function of the load configuration. The single planar and multi-planar wire arrays as well as compact cylindrical wire arrays were studied on the 1.3 MA UNR Zebra and 1 MA Cornell COBRA generators. The largest yields and powers were found for W and Mo double planar and compact wire arrays. A possibility of radiation pulse shaping was demonstrated. Two types of bright spots were observed in plasmas. A comparison of Mo double planar and compact wire array data indicates the possibility that the same heating mechanism operates during the final implosion and stagnation stages.

Kantsyrev, V. L.; Safronova, A. S.; Esaulov, A. A.; Williamson, K. M.; Shrestha, I.; Ouart, N. D.; Yilmaz, M. F.; Wilcox, P. G.; Osborne, G. C.; Weller, M. E.; Shlyaptseva, V. V.; Chuvatin, A. S.; Rudakov, L. I.; Greenly, J. B.; McBride, R. D.; Knapp, P. F.; Blessener, I. C.; Bell, K. S.; Chalenski, D. A.; Hammer, D. A.; Kusse, B. R.

2009-01-01

348

Fusion neutron detector for time-of-flight measurements in z-pinch and plasma focus experiments.  

PubMed

We have developed and tested sensitive neutron detectors for neutron time-of-flight measurements in z-pinch and plasma focus experiments with neutron emission times in tens of nanoseconds and with neutron yields between 10(6) and 10(12) per one shot. The neutron detectors are composed of a BC-408 fast plastic scintillator and Hamamatsu H1949-51 photomultiplier tube (PMT). During the calibration procedure, a PMT delay was determined for various operating voltages. The temporal resolution of the neutron detector was measured for the most commonly used PMT voltage of 1.4 kV. At the PF-1000 plasma focus, a novel method of the acquisition of a pulse height distribution has been used. This pulse height analysis enabled to determine the single neutron sensitivity for various neutron energies and to calibrate the neutron detector for absolute neutron yields at about 2.45 MeV. PMID:21456735

Klir, D; Kravarik, J; Kubes, P; Rezac, K; Litseva, E; Tomaszewski, K; Karpinski, L; Paduch, M; Scholz, M

2011-03-01

349

Fusion neutron detector for time-of-flight measurements in z-pinch and plasma focus experiments  

SciTech Connect

We have developed and tested sensitive neutron detectors for neutron time-of-flight measurements in z-pinch and plasma focus experiments with neutron emission times in tens of nanoseconds and with neutron yields between 10{sup 6} and 10{sup 12} per one shot. The neutron detectors are composed of a BC-408 fast plastic scintillator and Hamamatsu H1949-51 photomultiplier tube (PMT). During the calibration procedure, a PMT delay was determined for various operating voltages. The temporal resolution of the neutron detector was measured for the most commonly used PMT voltage of 1.4 kV. At the PF-1000 plasma focus, a novel method of the acquisition of a pulse height distribution has been used. This pulse height analysis enabled to determine the single neutron sensitivity for various neutron energies and to calibrate the neutron detector for absolute neutron yields at about 2.45 MeV.

Klir, D.; Kravarik, J.; Kubes, P.; Rezac, K.; Litseva, E. [Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, 16627 Prague 6 (Czech Republic); Tomaszewski, K. [ACS Ltd., Advanced Diagnostics Laboratory, Warsaw (Poland); Karpinski, L.; Paduch, M.; Scholz, M. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland)

2011-03-15

350

Laser probing non-cylindrical Z-pinch in near-isolator region of a discharged chamber  

NASA Astrophysics Data System (ADS)

Physical processes reducing the effectiveness of radiation characteristics of the non-cylindrical Z-pinch are considered. One of the processes studied is the secondary break-down of discharge space with the formation of a current channel shunting the main current of the discharge circuit and spatially localized along insulator surface. The experiments are performed using the plasma focus type device. Deuterium and xenon mixture with partial pressures ratio is the working gas. The working pressure of the mixture varied within 0.4 to 0.7 Torr. The probing is performed by ruby laser with modulated quality factor included into the circuit of interferometric measurements. The main attention is paid to the processes in the near-insulator discharge chamber region.

Mikhajlov, V. I.; Orlov, M. M.

351

Z-pinch research at the Chilean Nuclear Energy Commission: from basic research to portable devices for field applications  

NASA Astrophysics Data System (ADS)

Research in pinch discharges at the Chilean Nuclear Energy Commission includes: a) experimental studies in plasma dynamics, stability, X-ray and particles radiation, fusion mechanisms using gas embedded z-pinch, wire arrays and plasma foci; b) development of transportable and portable non radioactive sources based upon plasma focus devices for field applications; c) development and improvements of diagnostics suitable for the extreme conditions of this research. This work will present an overview of recent results in coupling studies of SPEED 2 generator (2.4MA achieved in 450ns) working in cylindrical wire array configuration, as well as the main conclusions from the scalability work in plasma focus devices from MJ to less than 1J. Ultimate results in a 2J portable PF device as non radioactive neutron source for field applications are presented.

Avaria, Gonzalo; Moreno, Jose; Pavez, Cristian; Tarifeno-Saldivia, Ariel; Zambra, Marcelo; Soto, Leopoldo

2012-10-01

352

One- and two-dimensional modeling of argon K-shell emission from gas-puff Z-pinch plasmas  

NASA Astrophysics Data System (ADS)

In this paper, a theoretical model is described and demonstrated that serves as a useful tool for understanding K-shell radiating Z-pinch plasma behavior. Such understanding requires a self-consistent solution to the complete nonlocal thermodynamic equilibrium kinetics and radiation transport in order to realistically model opacity effects and the high-temperature state of the plasma. For this purpose, we have incorporated into the MACH2 two-dimensional magnetohydrodynamic (MHD) code [R. E. Peterkin et al., J. Comput. Phys. 140, 148 (1998)] an equation of state, called the tabular collisional radiative equilibrium (TCRE) model [J. W. Thornhill et al., Phys. Plasmas 8, 3480 (2001)], that provides reasonable approximations to the plasma's opacity state. MACH2 with TCRE is applied toward analyzing the multidimensional implosion behavior that occurred in Decade Quad (DQ) [D. Price et al., Proceedings of the 12th IEEE Pulsed Power Conference, Monterey, CA, edited by C. Stallings and H. Kirbie (IEEE, New York, 1999), p. 489] argon gas puff experiments that employed a 12 cm diameter nozzle with and without a central gas jet on axis. Typical peak drive currents and implosion times in these experiments were ~6 MA and ~230 ns. By using Planar Laser Induced Fluorescence measured initial density profiles as input to the calculations, the effect these profiles have on the ability of the pinch to efficiently produce K-shell emission can be analyzed with this combined radiation-MHD model. The calculated results are in agreement with the experimental result that the DQ central-jet configuration is superior to the no-central-jet experiment in terms of producing more K-shell emission. These theoretical results support the contention that the improved operation of the central-jet nozzle is due to the better suppression of instabilities and the higher-density K-shell radiating conditions that the central-jet configuration promotes. When we applied the model toward projecting argon K-shell yield behavior for Sandia National Laboratories' ZR machine (~25 MA peak drive currents, ~100 ns implosion times) [D. McDaniel et al., Proceedings of the 5th International Conference on Dense Z-Pinches, Albuquerque, NM, 2002, edited by J. Davis, C. Deeney, and N. R. Pereira (American Institute of Physics, New York, 2002), Vol. 651, p. 23] for experiments that utilize the 12 cm diameter central-jet nozzle configuration, it predicts over 1 MJ of K-shell emission is attainable.

Thornhill, J. W.; Chong, Y. K.; Apruzese, J. P.; Davis, J.; Clark, R. W.; Giuliani, J. L.; Terry, R. E.; Velikovich, A. L.; Commisso, R. J.; Whitney, K. G.; Frese, M. H.; Frese, S. D.; Levine, J. S.; Qi, N.; Sze, H.; Failor, B. H.; Banister, J. W.; Coleman, P. L.; Coverdale, C. A.; Jones, B.; Deeney, C.

2007-06-01

353

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: x-Ray spectroscopic investigation of the stabilisation of a plasma column in a composite Z pinch  

NASA Astrophysics Data System (ADS)

An experimental x-ray spectroscopic investigation was made of the stabilisation of a Z pinch with a composite load in the GAEL (225 kA, 50 ns) accelerator. Kinetic calculations of the intensities of the L lines in the spectrum of copper were used for the first time to determine the parameters of a plasma [Ne approx (1-2)×1020 cm-3, Te approx 300 keV] formed by injection of a cylindrical aluminium-plasma jet imploding onto an axial copper wire. Quantitative and qualitative analyses were made of the stabilisation of the Z pinch with a composite load. Spectroscopic methods were used to demonstrate the stabilising influence of the plasma jet. The results indicated that it should be possible to construct a homogeneous high-temperature plasma column.

Shelkovenko, T. A.; Skobelev, I. Yu; Pikuz, S. A.; Etlicher, B.; Faenov, A. Ya; Attelan, S.; Romanova, V. M.; Chuvatin, A. S.

1996-02-01

354

Soft X-ray emission from the gas-puff Z-pinch plasma produced by an inductive pulsed power generator  

Microsoft Academic Search

An inductive pulsed power generator which has copper wire fuses used as an opening switch has been developed at Kyushu University (Japan) as the power source of a gas-puff Z-pinch. The inductive pulsed power generator has a capacitor of 11 ?F and 19.8 kJ as a primary energy source and can supply a driving current with a rise time of

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

1997-01-01

355

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

356

X-ray backlighting of developments of X-pinches and wire-array Z-pinches using an X-pinch  

Microsoft Academic Search

A pulsed power generator (PPG-I) with a current of 400 kA in amplitude and 100 ns in pulse width was constructed. The development of X-pinches and the early stages of wire-array Z-pinches were investigated by X-ray backlighting using the X-pinch driven by PPG-I as X-ray source. The plasma explosion and implosion near the cross point of the X-shape wires can

T. Zhao; X. Zou; X. Wang; Y. Zhao; Y. Du; R. Zhang

2009-01-01

357

X-ray generation from a gas-puff z-pinch driven by a pulsed power generator with a self-crowbar switch  

Microsoft Academic Search

A self-crowbar switch was operated on the pulsed power generator LIMAY-I and applied to a gas-puff z-pinch load. The radial collapse of the plasma is demonstrated to occur with the aid of the self-crowbar switch after the applied power pulse has turned off. X-ray emission was observed to coincide with radial collapse of the plasma, and the pinched plasma was

K. Takasugi; H. Akiyama; N. Shimomura; M. Sato; T. Tazima

1993-01-01

358

Studying Radiation from Z-pinch Wire Array and X-Pinch Plasmas: K-shell Mg to M-shell Mo  

NASA Astrophysics Data System (ADS)

University-scale Z-pinch generators are able to produce plasmas with a broad range of temperatures, densities, and opacity properties depending on the type, size, and mass of wire-array loads and wire materials. Experiments with very different Z-pinch loads were performed on the 1 MA Zebra generator at UNR and analyzed during the last five years including Single and Nested Cylindrical, Conical, and various types of Planar Wire Arrays. It is shown that such wire arrays are good sources of x-rays and that they produce significant radiation yield (up to 25 kJ) on a ns time scale, and generate bright spots of sub-mm size. They can be used for studying radiative properties of moderate density (between 1018 cm-3 and 5×1021 cm-3) and temperature (<=1.5 keV) plasmas. In addition, X-pinches generated higher density (>1022 cm-3) and temperature (>2 keV) plasmas on scales as small as a few ?m to several mm in size. Wire materials with a broad range of nuclear charge Z were used, ranging from low-Z, such as alloyed Al wires with varying concentrations of Mg, to mid-Z, such as Stainless steel, Cu, Brass, and Mo. Uniform (made from one wire material) as well as combined (made from two wire materials with almost equal wire masses) wire arrays were considered. Uniform, combined, symmetric and asymmetric X-pinches (some of which included a small fraction of tracer Al wires) were also considered. Non-LTE kinetic models to account for K- and L-shell radiation were employed to understand radiative properties of Z-pinch and X-pinch plasmas. Implosion characteristics of such loads are discussed using the wire dynamics and MHD models. Opacity effects of Z-pinch plasmas are studied and benefits of using alloyed and tracer wires are highlighted.

Safronova, A. S.; Kantsyrev, V. L.; Safronova, U. I.; Esaulov, A. A.; Yilmaz, M. F.; Ouart, N. D.; Shrestha, I.; Williamson, K. W.; Osborne, G. C.; Wilcox, P. G.; Weller, M. E.; Shlyaptseva, V.; Coverdale, C. A.; Jones, B.; Ampleford, D. J.; Lepell, P. D.; Deeney, C.

2009-09-01

359

Development of a visible framing camera diagnostic for the study of current initiation in z-pinch plasmas  

SciTech Connect

The authors assembled and tested a visible framing camera system to take 5 ns FWHM images of the early time emission from a z-pinch plasma. This diagnostic was used in conjunction with a visible streak camera allowing early time emissions measurements to diagnose current initiation. Individual frames from gated image intensifiers were proximity coupled to charge injection device (CID) cameras and read out at video rate and 8-bit resolution. A mirror was used to view the pinch from a 90-degree angle. The authors observed the destruction of the mirror surface, due to the high surface heating, and the subsequent reduction in signal reflected from the mirror. Images were obtained that showed early time ejecta and a nonuniform emission from the target. This initial test of the equipment highlighted problems with this measurement. They observed non-uniformities in early time emission. This is believed to be due to either spatially varying current density or heating of the foam. Images were obtained that showed early time ejecta from the target. The results and suggestions for improvement are discussed in the text.

Muron, D.J.; Hurst, M.J.; Derzon, M.S.

1996-07-01

360

Dynamics of a Z Pinch X Ray Source for Heating ICF Relevant Hohlraums to 120-160eV  

SciTech Connect

A z-pinch radiation source has been developed that generates 60 {+-} 20 KJ of x-rays with a peak power of 13 {+-} 4 TW through a 4-mm diameter axial aperture on the Z facility. The source has heated NIF (National Ignition Facility)-scale (6-mm diameter by 7-mm high) hohlraums to 122 {+-} 6 eV and reduced-scale (4-mm diameter by 4-mm high) hohlraums to 155 {+-} 8 eV -- providing environments suitable for indirect-drive ICF (Inertial Confinement Fusion) studies. Eulerian-RMHC (radiation-hydrodynamics code) simulations that take into account the development of the Rayleigh-Taylor instability in the r-z plane provide integrated calculations of the implosion, x-ray generation, and hohlraum heating, as well as estimates of wall motion and plasma fill within the hohlraums. Lagrangian-RMHC simulations suggest that the addition of a 6 mg/cm{sup 3} CH{sub 2} fill in the reduced-scale hohlraum decreases hohlraum inner-wall velocity by {approximately}40% with only a 3--5% decrease in peak temperature, in agreement with measurements.

SANFORD,THOMAS W. L.; OLSON,RICHARD E.; MOCK,RAYMOND CECIL; CHANDLER,GORDON A.; LEEPER,RAMON J.; NASH,THOMAS J.; RUGGLES,LAURENCE E.; SIMPSON,WALTER W.; STRUVE,KENNETH W.; PETERSON,D.L.; BOWERS,R.L.; MATUSKA,W.

2000-07-10

361

Development of a visible framing camera diagnostic for the study of current initiation in z-pinch plasmas  

SciTech Connect

We assembled and tested a visible framing camera system to take 5 ns FWHM images of the early time emission from a z-pinch plasma. This diagnostic was used in conjunction with a visible streak camera allowing early time emissions measurements to diagnose current initiation. Individual frames from gated image intensifiers were proximity coupled to charge injection device cameras and read out at video rate and 8-bit resolution. A mirror was used to view the pinch from a 90{degree} angle. We observed the destruction of the mirror surface, due to the high surface heating, and the subsequent reduction in signal reflected from the mirror. Images were obtained that showed early time ejecta and a non-uniform emission from the target. This initial test of the equipment highlighted problems with this measurement. We observed nonuniformities in early time emission. This is believed to be due to either spatially varying current density or heating of the foam. Images were obtained that showed early time ejecta from the target. The results and suggestions for improvement are discussed in the text. {copyright} {ital 1997 American Institute of Physics.}

Muron, D.J.; Hurst, M.J.; Derzon, M.S. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1196 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185-1196 (United States)

1997-01-01

362

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

363

Initial magnetic field compression studies using gas-puff Z-pinches and thin liners on COBRA  

NASA Astrophysics Data System (ADS)

This magnetic compression of cylindrical liners filled with DT gas has promise as an efficient way to achieve fusion burn using pulsed-power machines. However, to avoid rapid cooling of the fuel by transfer of heat to the liner an axial magnetic field is required. This field has to be compressed during the implosion since the thermal insulation is more demanding as the compressed DT plasma becomes hotter and its volume smaller. This compression of the magnetic field is driven both by the imploding liner and plasma. To highlight how this magnetic field compression by the plasma and liner evolves we have separately studied Z-pinch implosions generated by gas puff and liner loads. The masses of the gas puff and liner loads were adjusted to match COBRA's current rise times. Our results have shown that Ne gas-puff implosions are well described by a snowplow model where electrical currents are predominately localized to the outer surface of the imploding plasma and the magnetic field is external to the imploding plasma. Liner implosions are dominated by the plasma ablation process on the inside surface of the liner and the electrical currents and magnetic fields are advected into the inner plasma volume; the sharp radial gradient associated with the snowplow process is not present.

Gourdain, P.-A.; Concepcion, R. J.; Evans, M. T.; Greenly, J. B.; Hammer, D. A.; Hoyt, C. L.; Kroupp, E.; Kusse, B. R.; Maron, Y.; Novick, A. S.; Pikuz, S. A.; Qi, N.; Rondeau, G.; Rosenberg, E.; Schrafel, P. C.; Seyler, C. E.; Shelkovenko, T. C.

2013-08-01

364

Nonlinear Interaction Between the Radiation and Multidimensional Plasma in Large Diameter Structured Argon Gas Puff Z-Pinch Loads  

NASA Astrophysics Data System (ADS)

It has recently been demonstrated that one can efficiently produce K-shell x-ray radiation with z pinches imploded from larger initial diameters, by longer current pulses than previously thought possible, using a ``pusher-stabilizer-radiator'' load formed by a supersonic nozzle injecting outer and inner annular shells and a high-density central jet between the cathode and the anode [1]. We present a detailed numerical investigation of the implosions of such loads. Our simulations were performed with the 2D RMHD Mach2 code incorporating the dynamical domain tabular collisional radiative equilibrium (DDTCRE) radiation transport model [2]. This model provides a realistic description of the self-consistent multidimensional non-local non-LTE ionization dynamics and radiation transport physics in a computationally efficient manner. A numerical simulation analysis of various nozzle load configurations, with/without the central jet and/or shells, is used to further assess and validate the physical model by simulating the experimental spectra, plasma images and radiation emission characteristics. [1] H. Sze et al., PRL 95, 105001(2005). [2] Y. K. Chong et al., ICOPS 2005, Monterey, CA.

Chong, Y. K.; Thornhill, J. W.; Velikovich, A. L.; Apruzese, J. P.; Davis, J.; Qi, N.; Sze, H.; Levine, J. S.; Failor, B. H.

2006-10-01

365

The plasma z-pinch effect on the I-V characteristic of fast discharge flash tubes  

NASA Astrophysics Data System (ADS)

The effects of plasma z-pinch on the I-V characteristics of a short-pulse, high-current flash lamp are investigated. The formula of Goncz (1965), in which the voltage across the arc is equal to the product of a lamp constant and the 0.5 power of i, is derived from Spitzer's resistivity by considering electron-ion collisions at sufficiently small fields, while the empirical formula presented by Marotta (1978), in which voltage is equal to the product of a constant and the 0.85 power of i, is obtained using the anomalous resistivity of Sadeev and Galeev (1969) and the Boltzmann transport equation. Experimental results show that for flash lamps operating in the prepulse mode in a Nd:YAG laser, the relation of Marotta holds for peak currents of 2 kA/sq cm and that of Goncz applies at a peak current of 0.6 kA/sq cm. A shape factor of 1.3 is found to be optimal for a lamp circuit discharge system in a preionized mode at high current density, while simultaneous solution of the plasma pinch and Kirkwood equations, which determine the current, indicates plasma pinch influences circuit optimization only in submicrosecond discharge systems.

Lue, J. T.; Song, D. Y.; Yeh, C.-K.

1980-09-01

366

Measurements of Ion Beam Production and Neutron Yields in the LLNL High Gradient Z-Pinch Experiment  

NASA Astrophysics Data System (ADS)

Dense plasma focus (DPF) z-pinch plasmas are known to produce abundant neutrons and particle beams, but the mechanisms behind the high gradient fields in DPFs are not well understood. We have a 4 MeV deuteron beam that can be used to probe the electric field gradients produced by the DPF experiment at LLNL. This information can be used in conjunction with fully kinetic simulations of DPF plasmas to further our understanding of the mechanisms that produce these beams. This knowledge allows us to optimize the gradients in the DPF for next generation compact accelerators. The beam and neutron output from the LLNL DPF have been characterized. We present measurements of beam and neutron production for a variety of pinch currents. Acceleration gradients greater than 0.5 MV/cm have been achieved, a record for sub-kJ DPFs. Our upgraded gun design allows a probe beam to pass through the plasma, allowing for the first-ever measurements of DPF gradients. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and supported by the Laboratory Directed Research and Development Program (11-ERD-063) at LLNL.

Ellsworth, J. L.; Falabella, S.; Rusnak, B.; Schmidt, A.; Tang, V.

2012-10-01

367

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

368

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

369

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

PubMed

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. PMID:19044561

Jones, B; Coverdale, C A; Nielsen, D S; Jones, M C; Deeney, C; Serrano, J D; Nielsen-Weber, L B; Meyer, C J; Apruzese, J P; Clark, R W; Coleman, P L

2008-10-01

370

Generation of episodic magnetically driven plasma jets in a radial foil Z-pinch  

NASA Astrophysics Data System (ADS)

We present experimental results of the formation of magnetically driven plasma jets, showing for the first time a way of producing episodic jet/ouflows in the laboratory. The jets are produced using a 6.5 ?m thick aluminum disk (a radial foil), which is subjected to the 1 MA, 250 ns current pulse from the MAGPIE generator [I. H. Mitchell et al., Rev. Sci. Instrum. 67, 1533 (1996)]. The early time motion of the foil is characterized by the bulk motion of the mass due to the magnetic pressure, together with the formation of a surface plasma following the direction of the J×B force. A low density plasma fills the region above the foil preceding the formation of subsequent magnetically driven jets on the axis of expanding magnetic bubbles. The outflows emerge in timescales of ~30-40 ns and their episodic nature is the result of current reconnection in the foil, aided by the formation of current-driven instabilities in the jet and the distribution of mass available from the foil. The additional inductance due to the new current path inside the cavities was measured using an inductive probe, allowing to estimate the energy balance associated with the episodes. The measured temperature of the compressed jet resulted in Te~300 eV and a magnetic Reynolds number of ReM~200-1000, allowing the experiments to be in the regime relevant for scaled representations of astrophysical outflows.

Suzuki-Vidal, Francisco; Lebedev, Sergey V.; Bland, Simon N.; Hall, Gareth N.; Swadling, George; Harvey-Thompson, Adam J.; Chittenden, Jeremy P.; Marocchino, Alberto; Ciardi, Andrea; Frank, Adam; Blackman, Eric G.; Bott, Simon C.

2010-11-01

371

Beryllium liner z-pinches for Magneto-Rayleigh-Taylor studies on Z  

NASA Astrophysics Data System (ADS)

Magnetic Liner Inertial Fusion (MagLIF) [S. A. Slutz, et al., Phys. Plasmas 17 056303 (2010)] is a promising new concept for achieving >100 kJ of fusion yield on Z. The greatest threat to this concept is the Magneto-Rayleigh-Taylor (MRT) instability. Thus an experimental campaign has been initiated to study MRT growth in fast-imploding (<100 ns) cylindrical liners. The first sets of experiments studied aluminum liner implosions with prescribed sinusoidal perturbations (see talk by D. Sinars). By contrast, this poster presents results from the latest sets of experiments that used unperturbed beryllium (Be) liners. The purpose for using Be is that we are able to radiograph ``through'' the liner using the 6-keV photons produced by the Z-Beamlet backlighting system. This has enabled us to obtain time-resolved measurements of the imploding liner's density as a function of both axial and radial location throughout the field of view. This data is allowing us to evaluate the integrity of the inside (fuel-confining) surface of the imploding liner as it approaches stagnation.

McBride, R.; Slutz, S.; Jennings, C.; Sinars, D.; Lemke, R.; Martin, M.; Vesey, R.; Cuneo, M.; Herrmann, M.

2010-11-01

372

X-ray emission from z pinches at 107 A: Current scaling, gap closure, and shot-to-shot fluctuations  

NASA Astrophysics Data System (ADS)

We have measured the x-ray power and energy radiated by a tungsten-wire-array z pinch as a function of the peak pinch current and the width of the anode-cathode gap at the base of the pinch. The measurements were performed at 13- and 19-MA currents and 1-, 2-, 3-, and 4-mm gaps. The wire material, number of wires, wire-array diameter, wire-array length, wire-array-electrode design, normalized-pinch-current time history, implosion time, and diagnostic package were held constant for the experiments. To keep the implosion time constant, the mass of the array was increased as I2 (i.e., the diameter of each wire was increased as I), where I is the peak pinch current. At 19 MA, the mass of the 300-wire 20-mm-diam 10-mm-length array was 5.9 mg. For the configuration studied, we find that to eliminate the effects of gap closure on the radiated energy, the width of the gap must be increased approximately as I. For shots unaffected by gap closure, we find that the peak radiated x-ray power Pr?I1.24±0.18, the total radiated x-ray energy Er?I1.73±0.18, the x-ray-power rise time ?r?I0.39±0.34, and the x-ray-power pulse width ?w?I0.45±0.17. Calculations performed with a time-dependent model of an optically thick pinch at stagnation demonstrate that the internal energy and radiative opacity of the pinch are not responsible for the observed subquadratic power scaling. Heuristic wire-ablation arguments suggest that quadratic power scaling will be achieved if the implosion time ?i is scaled as I-1/3. The measured 1? shot-to-shot fluctuations in Pr, Er, ?r, ?w, and ?i are approximately 12%, 9%, 26%, 9%, and 2%, respectively, assuming that the fluctuations are independent of I. These variations are for one-half of the pinch. If the half observed radiates in a manner that is statistically independent of the other half, the variations are a factor of 21/2 less for the entire pinch. We calculate the effect that shot-to-shot fluctuations of a single pinch would have on the shot-success probability of the double-pinch inertial-confinement-fusion driver proposed by Hammer et al. [Phys. Plasmas 6, 2129 (1999)]. We find that on a given shot, the probability that two independent pinches would radiate the same peak power to within a factor of 1±? (where 0???1) is equal to erf(?/2?), where ? is the 1? fractional variation of the peak power radiated by a single pinch. Assuming ? must be ?7% to achieve adequate odd-Legendre-mode radiation symmetry for thermonuclear-fusion experiments, ? must be <3% for the shot-success probability to be ?90%. The observed (12/21/2)%=8.5% fluctuation in Pr would provide adequate symmetry on 44% of the shots. We propose that three-dimensional radiative-magnetohydrodynamic simulations be performed to quantify the sensitivity of the x-ray emission to various initial conditions, and to determine whether an imploding z pinch is a spatiotemporal chaotic system.

Stygar, W. A.; Ives, H. C.; Fehl, D. L.; Cuneo, M. E.; Mazarakis, M. G.; Bailey, J. E.; Bennett, G. R.; Bliss, D. E.; Chandler, G. A.; Leeper, R. J.; Matzen, M. K.; McDaniel, D. H.; McGurn, J. S.; McKenney, J. L.; Mix, L. P.; Muron, D. J.; Porter, J. L.; Ramirez, J. J.; Ruggles, L. E.; Seamen, J. F.; Simpson, W. W.; Speas, C. S.; Spielman, R. B.; Struve, K. W.; Torres, J. A.; Vesey, R. A.; Wagoner, T. C.; Gilliland, T. L.; Horry, M. L.; Jobe, D. O.; Lazier, S. E.; Mills, J. A.; Mulville, T. D.; Pyle, J. H.; Romero, T. M.; Seamen, J. J.; Smelser, R. M.

2004-04-01

373

Characterization of Axially-Directed X-Rays Generated from a Target within a Z-Pinch  

NASA Astrophysics Data System (ADS)

X-ray powers on the order of 10 TW over an area of 4.5 mm2 are produced in the axial direction from the compression of a low-density foam target centered within a z-pinch on the Z generator. The x-rays from this source are used for high-energy-density physics experiments, including the heating of hohlraums for ICF studies [1]. In this paper, detailed characteristics of this radiation source measured using an upgraded axial-radiation-diagnostic suite [2] together with other on- and off-axis diagnostics are summarized and discussed in terms of Eulerian and Lagrangian radiation-magnetohydrodynamic code simulations. The source, characterized here, employs a nested array of 10-mm-long tungsten wires, at radii of 20 and 10 mm, having a total masses of 2 and 1 mg, and wire numbers of 240 and 120, respectively. The target is a 14 mg/cc CH2 foam cylinder of 5-mm diameter. The codes take into account the development of the Rayleigh-Taylor instability in the r-z plane, and provide integrated calculations of the implosion together with the x-ray generation. [1] T. W. L. Sanford, R. E. Olson, R. L. Bowers, et al, Phys. Rev. Lett 83, 5511 (1999). [2] T. J. Nash, M. S. Derzon, G. A. Chandler, et al, Rev. Sci. Instrum. 70, 464 (1999). Sandia is a multiprogram laboratory operated by the Sandia Corporation, a Lockheed Martin Company, for the U.S. Department of Energy under Contract No. DE-AC04-94AL85000.

Sanford, T. W. L.; Chandler, G. A.; Cuneo, M. E.; Fehl, D. L.; Hebron, D. E.; Leeper, R. J.; Lemke, R. W.; Mock, R. C.; Olson, R. E.; Nash, T. J.; Porter, J. L.; Ruggles, L. E.; Ruiz, C. L.; Simpson, W. W.; Peterson, D. L.; Chrien, R. E.; Idzorek, G. C.; Watt, R. G.

2000-10-01

374

The high-density Z-pinch as a pulsed fusion neutron source for fusion nuclear technology and materials testing  

SciTech Connect

The dense Z-pinch (DZP) is one of the earliest and simplest plasma heating and confinement schemes. Recent experimental advances based on plasma initiation from hair-like (10s ..mu..m in radius) solid hydrogen filaments have so far not encountered the usually devastating MHD instabilities that plagued early DZP experiments. These encouraging results along with debt of a number of proof-of principle, high-current (1--2 MA in 10--100 ns) experiments have prompted consideration of the DZP as a pulsed source of DT fusion neutrons of sufficient strength (/dot S//sub N/ greater than or equal to 10/sup 19/ n/s) to provide uncollided neutron fluxes in excess of I/sub ..omega../ = 5--10 MW/m/sup 2/ over test volumes of 10--30 litre or greater. While this neutron source would be pulsed (100s ns pulse widths, 10--100 Hz pulse rate), giving flux time compressions in the range 10/sup 5/--10/sup 6/, its simplicity, near-time feasibility, low cost, high-Q operation, and relevance to fusion systems that may provide a pulsed commercial end-product (e.g., inertial confinement or the DZP itself) together create the impetus for preliminary considerations as a neutron source for fusion nuclear technology and materials testings. The results of a preliminary parametric systems study (focusing primarily on physics issues), conceptual design, and cost versus performance analyses are presented. The DZP promises an expensive and efficient means to provide pulsed DT neutrons at an average rate in excess of 10/sup 19/ n/s, with neutron currents I/sub ..omega../ /approx lt/ 10 MW/m/sup 2/ over volumes V/sub exp/ greater than or equal to 30 litre using single-pulse technologies that differ little from those being used in present-day experiments. 34 refs., 17 figs., 6 tabs.

Krakowski, R.A.; Sethian, J.D.; Hagenson, R.L.

1989-01-01

375

Evidence and mechanisms of axial-radiation asymmetry in dynamic hohlraums driven by wire-array Z pinches  

SciTech Connect

Dynamic hohlraums driven by arrays consisting of large numbers of tungsten wires in Z pinches exhibit differences in radiation emitted from REHs (radiation exit holes) symmetrically located at either end of the hohlraum [Sanford et al., Phys. Plasmas 10, 1187 (2003)]. Significantly greater peak power is radiated from the top (anode) REH relative to the bottom (cathode) REH. Spectral measurements of tungsten M-shell emission (2-2.4 keV) indicate the peak radiated power from either REH anticorrelates with the fraction of wire-array tungsten plasma inferred to sweep across (or into the field of view of) the REH near the time of peak axial emission. In all cases, greater M-shell emission relative to the total emission in the band 1.4-4 keV is measured at the bottom REH in comparison to the top REH. The decrease in peak power radiated from the bottom REH relative to the top appears to be due, in part, to an increase in localized opacity arising from the presence of increased wire-array tungsten plasma near the bottom REH. The asymmetry in both peak axial power and pulse shape is largely removed by adding two thin annular pedestals extending 3 mm into the anode-cathode gap from either electrode, just radially outboard of the REHs. The pedestals are designed to prevent the radial flow of tungsten plasma from prematurely crossing the REHs. A polarity effect [Sarkisov et al., Phys. Rev. E 66, 046413(6) (2002)] during wire initiation may offer one possible explanation for the underlying cause of such a tungsten-related axial power asymmetry.

Sanford, T.W.L.; Nash, T.J.; Mock, R.C.; Peterson, D.L.; Watt, R.G.; Chrien, R.E.; Apruzese, J.P.; Clark, R.W.; Roderick, N.F.; Sarkisov, G.S.; Haines, M.G. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Naval Research Laboratory, Washington, DC 20375 (United States); University of New Mexico, Albuquerque, New Mexico 87131 (United States); Ktech Corporation, Albuquerque, 1030 Eubank Boulevard, Albuquerque, New Mexico 87123 (United States); Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)

2005-02-01

376

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

377

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

NASA Astrophysics Data System (ADS)

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; Ye, Fan; Ning, Jiamin; Hu, Qingyuan; Chen, Faxin; Qin, Yi; Xu, Rongkun; Li, Zhenghong; Sun, Shunkai

2014-04-01

378

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

379

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 target 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 {minus}85 eV for a duration of {approximately} 10 ns, while a solid cylindrical target of 5-mm diameter and 14-mg/cm{sup 3} CH generates first-step-pulse conditions of {approximately} 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 {approximately} 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-(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.

Sandord, T.W.L.; Olson, R.E.; Chandler, G.A.; Hebron, D.E.; Mock, R.C.; Leeper, R.J.; Nash, T.J.; Ruggles, L.E.; Simpson, W.W.; Struve, K.W.; Vesey, R.A.; Bowers, R.L.; Matuska, W.; Peterson, D.L.; Peterson, R.R.

1999-08-25

380

Pulsed current wave shaping with a transmission line by utilizing superposition of a forward and a backward voltage wave for fast capillary Z-pinch discharge  

NASA Astrophysics Data System (ADS)

By using a water transmission line, current wave shaping was demonstrated for a fast capillary Z-pinch discharge recombination soft x-ray laser study. The pulsed power system consists of a water capacitor, a gap switch, a transmission line, and a capillary plasma load. A voltage wave initiated at the water capacitor propagates toward the capillary load through the transmission line. Control of the pulse delay that occurred in the transmission line provides the superposition of the forward and the backward voltage waves effectively in order to perform current wave shaping with higher current amplitude and rapid current decay.

Sakai, Y.; Takahashi, S.; Watanabe, M.; Kim, G.-H.; Hotta, E.

2010-04-01

381

Observations of Modified Three-Dimensional Instability Structure for Imploding z-Pinch Liners that are Premagnetized with an Axial Field  

NASA Astrophysics Data System (ADS)

Novel experimental data are reported that reveal helical instability formation on imploding z-pinch liners that are premagnetized with an axial field. Such instabilities differ dramatically from the mostly azimuthally symmetric instabilities that form on unmagnetized liners. The helical structure persists at nearly constant pitch as the liner implodes. This is surprising since, at the liner surface, the azimuthal drive field presumably dwarfs the axial field for all but the earliest stages of the experiment. These fundamentally 3D results provide a unique and challenging test for 3D-magnetohydrodynamics simulations.

Awe, T. J.; McBride, R. D.; Jennings, C. A.; Lamppa, D. C.; Martin, M. R.; Rovang, D. C.; Slutz, S. A.; Cuneo, M. E.; Owen, A. C.; Sinars, D. B.; Tomlinson, K.; Gomez, M. R.; Hansen, S. B.; Herrmann, M. C.; McKenney, J. L.; Nakhleh, C.; Robertson, G. K.; Rochau, G. A.; Savage, M. E.; Schroen, D. G.; Stygar, W. A.

2013-12-01

382

Observation of emission process in hydrogen-like nitrogen Z-pinch discharge with time integrated soft X-ray spectrum pinhole image  

NASA Astrophysics Data System (ADS)

The emission spectra of hydrogen-like nitrogen Balmer at the wavelength of 13.4 nm in capillary Z-pinch discharge plasma are experimentally examined. Ionization to fully strip nitrogen at the pinch maximum, and subsequent rapid expansion cooling are required to establish the population inversion between the principal quantum number of n = 2 and n = 3. The ionization and recombination processes with estimated plasma parameters are evaluated by utilizing a time integrated spectrum pinhole image containing radial spatial information. A cylindrical capillary plasma is pinched by a triangular pulsed current with peak amplitude of 50 kA and pulse width of 50 ns.

Sakai, Y.; Rosenzweig, J.; Kumai, H.; Nakanishi, Y.; Ishizuka, Y.; Takahashi, S.; Komatsu, T.; Xiao, Y.; Bin, H.; Quishi, Z.; Hayashi, Y.; Song, I.; Kawamura, T.; Watanabe, M.; Hotta, E.

2013-02-01

383

Mass-profile and instability-growth measurements for 300-wire Z-pinch implosions driven by 14-18 MA.  

PubMed

We present the first comprehensive study of high wire-number, wire-array Z-pinch dynamics at 14-18 MA using x-ray backlighting and optical shadowgraphy diagnostics. The cylindrical arrays retain slowly expanding, dense wire cores at the initial position up to 60% of the total implosion time. Azimuthally correlated instabilities at the array edge appear during this stage which continue to grow in amplitude and wavelength after the start of bulk motion, resulting in measurable trailing mass that does not arrive on axis before peak x-ray emission. PMID:15524803

Sinars, D B; Cuneo, M E; Yu, E P; Bliss, D E; Nash, T J; Porter, J L; Deeney, C; Mazarakis, M G; Sarkisov, G S; Wenger, D F

2004-10-01

384

Measurements of the mass distribution and instability growth for wire-array Z-pinch implosions driven by 14-20 MA  

SciTech Connect

The mass distribution and axial instability growth of wire-array Z-pinch implosions driven by 14-20 MA has been studied using high-resolution, monochromatic x-ray backlighting diagnostics. A delayed implosion is consistently observed in which persistent, dense wire cores continuously ablate plasma until they dissipate and the main implosion begins. In arrays with small interwire gaps, azimuthally correlated axial instabilities appear during the wire ablation stage and subsequently seed the early growth of magneto-Rayleigh-Taylor instabilities. The instabilities create a distributed implosion front with trailing mass that may limit the peak radiation power.

Sinars, D.B.; Cuneo, M.E.; Jones, B.; Coverdale, C.A.; Nash, T.J.; Mazarakis, M.G.; Porter, J.L.; Deeney, C.; Wenger, D.F.; Adams, R.G.; Yu, E.P.; Bliss, D.E.; Sarkisov, G.S. [Sandia National Laboratories, P. O. Box 5800, Albuquerque, New Mexico 87185 (United States)

2005-05-15

385

Observation of emission process in hydrogen-like nitrogen Z-pinch discharge with time integrated soft X-ray spectrum pinhole image  

SciTech Connect

The emission spectra of hydrogen-like nitrogen Balmer at the wavelength of 13.4 nm in capillary Z-pinch discharge plasma are experimentally examined. Ionization to fully strip nitrogen at the pinch maximum, and subsequent rapid expansion cooling are required to establish the population inversion between the principal quantum number of n = 2 and n = 3. The ionization and recombination processes with estimated plasma parameters are evaluated by utilizing a time integrated spectrum pinhole image containing radial spatial information. A cylindrical capillary plasma is pinched by a triangular pulsed current with peak amplitude of 50 kA and pulse width of 50 ns.

Sakai, Y.; Kumai, H.; Nakanishi, Y.; Ishizuka, Y.; Takahashi, S.; Komatsu, T.; Xiao, Y.; Bin, H.; Quishi, Z.; Hayashi, Y.; Song, I.; Kawamura, T.; Watanabe, M.; Hotta, E. [Department of Energy Sciences, Tokyo Institute of Technology, Nagatsuta, Midoriku, Yokohama, Kanagawa 226-8502 (Japan); Rosenzweig, J. [Department of Physics and Astronomy, University of California Los Angeles, 405 Hilgard Ave., Los Angeles, California 90095 (United States)

2013-02-15

386

Propulsion application of non-neutronic fusion chain reactions in Petawatt laser ignited shear flow stabilized dense plasma z-pinches  

NASA Astrophysics Data System (ADS)

Shear flow stabilized z-pinches promise the attainment of very high densities. At these high densities non-neutronic fusion chain reactions, ideally suited for propulsion, can be ignited with petawatt lasers. To drive the dense pinch discharges large capacitors with short discharge times are required, favoring high voltages. To reduce the weight of the capacitors, and at the same time to have high voltages, use can be made of the high vacuum of space which in combination with magnetic insulation has the potential for gigajoule, gigavolt capacitors.

Winterberg, F.

2000-04-01

387

Observations of modified three-dimensional instability structure for imploding z-pinch liners that are premagnetized with an axial field.  

PubMed

Novel experimental data are reported that reveal helical instability formation on imploding z-pinch liners that are premagnetized with an axial field. Such instabilities differ dramatically from the mostly azimuthally symmetric instabilities that form on unmagnetized liners. The helical structure persists at nearly constant pitch as the liner implodes. This is surprising since, at the liner surface, the azimuthal drive field presumably dwarfs the axial field for all but the earliest stages of the experiment. These fundamentally 3D results provide a unique and challenging test for 3D-magnetohydrodynamics simulations. PMID:24476283

Awe, T J; McBride, R D; Jennings, C A; Lamppa, D C; Martin, M R; Rovang, D C; Slutz, S A; Cuneo, M E; Owen, A C; Sinars, D B; Tomlinson, K; Gomez, M R; Hansen, S B; Herrmann, M C; McKenney, J L; Nakhleh, C; Robertson, G K; Rochau, G A; Savage, M E; Schroen, D G; Stygar, W A

2013-12-01

388

Time and space resolved measurements of visible-light and soft x-ray emission from foam z-pinch plasmas and implosions  

SciTech Connect

We have developed a time-resolved imaging capability to make measurements of the emission profile or spot size for low density foam z-pinch targets on the Saturn accelerator. By lens-coupling visible emission from the z-pinch target to an array of fiber optics, we obtained an emission profile as a function of time with radial resolution of 200 {mu}m. To measure the emission at temperatures greater than {approx}40 eV, x rays from the source were slit-imaged or pinhole-imaged onto a scintillator. The emission was filtered to select 50{endash}80, 200{endash}280, and 400{endash}450 eV x rays. Nonuniformities were observed in both visible and x-ray emissions for solid foam targets. For wire array on foam targets, on-axis x-ray emission-spot implosion velocities calculated for the three spectral regions differed from the mass-implosion velocity. We describe the diagnostics, the image-unfold process, and results from the instrument for both visible and x-ray measurements. {copyright} {ital 1997 American Institute of Physics.}

Lazier, S.E.; Barber, T.L. [Ktech Corporation, Albuquerque, New Mexico 87110 (United States)] [Ktech Corporation, Albuquerque, New Mexico 87110 (United States); Derzon, M.S.; Kellogg, J.W. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

1997-01-01

389

Simulation and mitigation of the magneto-Rayleigh-Taylor instabilities in Z-pinch gas discharge extreme ultraviolet plasma radiation sources  

NASA Astrophysics Data System (ADS)

The development and use of a single-fluid two-temperature approximated 2-D Magneto-Hydrodynamics code is reported. Z-pinch dynamics and the evolution of Magneto-Rayleigh-Taylor (MRT) instabilities in a gas jet type Extreme Ultraviolet (EUV) source are investigated with this code. The implosion and stagnation processes of the Z-pinch dynamics and the influence of initial perturbations (single mode, multi- mode, and random seeds) on MRT instability are discussed in detail. In the case of single mode seeds, the simulation shows that the growth rates for mm-scale wavelengths up to 4 mm are between 0.05 and 0.065 ns-1. For multi-mode seeds, the mode coupling effect leads to a series of other harmonics, and complicates MRT instability evolution. For perturbation by random seeds, the modes evolve to longer wavelengths and finally converge to a mm-scale wavelength approximately 1 mm. MRT instabilities can also alter the pinch stagnation state and lead to temperature and density fluctuations along the Z axis, which eventually affects the homogeneity of the EUV radiation output. Finally, the simulation results are related to experimental results to discuss the mitigations of MRT instability.

Huang, B.; Tomizuka, T.; Xie, B.; Sakai, Y.; Zhu, Q.; Song, I.; Okino, A.; Xiao, F.; Watanabe, M.; Hotta, E.

2013-11-01

390

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

391

Simulation and mitigation of the magneto-Rayleigh-Taylor instabilities in Z-pinch gas discharge extreme ultraviolet plasma radiation sources  

SciTech Connect

The development and use of a single-fluid two-temperature approximated 2-D Magneto-Hydrodynamics code is reported. Z-pinch dynamics and the evolution of Magneto-Rayleigh-Taylor (MRT) instabilities in a gas jet type Extreme Ultraviolet (EUV) source are investigated with this code. The implosion and stagnation processes of the Z-pinch dynamics and the influence of initial perturbations (single mode, multi- mode, and random seeds) on MRT instability are discussed in detail. In the case of single mode seeds, the simulation shows that the growth rates for mm-scale wavelengths up to 4 mm are between 0.05 and 0.065 ns{sup ?1}. For multi-mode seeds, the mode coupling effect leads to a series of other harmonics, and complicates MRT instability evolution. For perturbation by random seeds, the modes evolve to longer wavelengths and finally converge to a mm-scale wavelength approximately 1 mm. MRT instabilities can also alter the pinch stagnation state and lead to temperature and density fluctuations along the Z axis, which eventually affects the homogeneity of the EUV radiation output. Finally, the simulation results are related to experimental results to discuss the mitigations of MRT instability.

Huang, B.; Tomizuka, T.; Xie, B.; Sakai, Y.; Zhu, Q.; Song, I.; Okino, A.; Xiao, F.; Watanabe, M.; Hotta, E. [Department of Energy Sciences, Tokyo Institute of Technology, 4259 J2-35 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan)] [Department of Energy Sciences, Tokyo Institute of Technology, 4259 J2-35 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan)

2013-11-15

392

Travel to the UK to attend the third international conference on dense z pinches and to discuss new soft x-ray test capabilities at the Atomic Weapons Establishment. Foreign trip report, April 17--24, 1993.  

National Technical Information Service (NTIS)

This trip report describes a visit by Rick B. Spielman to the Imperial College in London, UK and to the Atomic Weapons Establishment in Aldermastron. The Third International Conference on Dense Z Pinches was sponsored by the Imperial College. This is the ...

R. B. Spielman

1993-01-01

393

Insight into mechanism of neodymium: Yttrium-aluminum-garnet laser prostatectomy utilizing the high-power contact-free beam technique  

Microsoft Academic Search

ObjectivesThe objective of this study was to define the actual mechanism of neodymium: yttrium-aiuminum-garnet (Nd:YAG) laser prostatectomy achieved with the previously described contact-free beam technique using the Ultraline delivery system at high-power settings.

John N. Kabalin; Michael Gong; Muta M. Issa; Robert Sellers

1995-01-01

394

Numerical evaluation of hard x-ray line yield emitted from aluminum plasma produced by high power sub-nanosecond laser pulses  

NASA Astrophysics Data System (ADS)

In this paper line x-ray emission from aluminum plasma at wavelength within range of 5 - 7 angstrom was studied numerically. The plasma was assumed to be produced by irradiating of aluminum target by long laser pulses (1000 ps >= ?p >= 50 ps) at intensities up to I = 5×1016Wcm-2. The plasma hydrodynamics was simulated by EHYBRID code. Using the data from this code and Saha-Boltzmann equation; the x-ray spectrum and total x-ray yield of the plasma were calculated within the time scale of irradiation. The influences of laser intensity as well as pulse duration on the total yield of x-ray line emission were investigated. The results show that, the emitted x-ray lines at the above wavelength range has duration similar to that of the laser pulse and the total x-ray yield can be increased by increasing laser intensity and pulse duration.

Mahdieh, M. H.; Hosseini, S.; Daei A., A.

2010-09-01

395

K-shell and extreme ultraviolet spectroscopic signatures of structured Ar puff Z-pinch loads with high K-shell x-ray yield  

NASA Astrophysics Data System (ADS)

Structured 12-cm-diam Ar gas-puff loads have recently produced Z-pinch implosions with reduced Rayleigh-Taylor instability growth and increased K-shell x-ray yield [H. Sze, J. Banister, B. H. Failor, J. S. Levine, N. Qi, A. L. Velikovich, J. Davis, D. Lojewski, and P. Sincerny, Phys. Rev. Lett. 95, 105001 (2005)]. To better understand the dynamics of these loads, we have measured the extreme ultraviolet (XUV) emission resolved radially, spectrally, and axially. Radial measurements indicated a compressed diameter of ~3 mm, consistent with the observed load inductance change and an imploded-mass consisting of a ~1.5-mm-diam, hot, K-shell-emitting core and a cooler surrounding blanket. Spectral measurements indicate that, if the load is insufficiently heated, then radiation from the core will rapidly photoheat the outer blanket, producing a strong increase in XUV emission. Also, adding a massive center jet (>=20% of load mass) increases the rise and fall times of the XUV emission to >=40 ns, consistent with a more adiabatic compression and heating of the load. Axial measurements show that, despite differences in the XUV and K-shell emission time histories, the K-shell x-ray yield is insensitive to axial variations in load mass.

Failor, B. H.; Sze, H. M.; Banister, J. W.; Levine, J. S.; Qi, N.; Apruzese, J. P.; Lojewski, D. Y.

2007-02-01

396

Comparative 2D Radiation MHD Simulations of Argon Gas Puff Z-pinch Plasma Experiments on the Sandia Z Machine Using the Radiative Diffusion and CRE Transport Models  

NASA Astrophysics Data System (ADS)

The recent development of the computationally efficient tabulated collisional radiative equilibrium (TCRE) radiation transport model(J.W. Thornhill, J.P. Apruzese, J. Davis, R.W. Clark, A.L. Velikovich, J.L. Giuliani, Jr., Y.K. Chong, K.G. Whitney, C. Deeney, C.A. Coverdale and F.L. Cochran, Phys. Plasmas 7, 3480 (2001).) has made possible full multidimensional radiation MHD simulations of hot dense Z-pinch plasmas with a realistic description of the non-LTE ionization dynamics and radiation transport physics. In this study, we focus on the implementation of the TCRE radiation transport model in the Mach2 2D radiation MHD code. An application of the model is made through a full dynamical simulation of an argon gas puff pinch driven by a circuit model of the Z generator. An analysis of the simulation, in particular, the K- and L-shell radiation yields, as well as the spectral and spatial characteristics of the radiation will be presented. In addition, a comparison of this multidimensional transport method will be made with the existing radiative diffusion model.

Chong, Y. K.; Thornhill Giuliani, J. W., Jr.; Apruzese, J. P.; Terry, R. E.; Davis, J.

2001-10-01

397

Multidimensional Radiation Emission and Absorption Processes in a Large Diameter Krypton Gas Puff Z-Pinch Plasma on the ZR Simulator  

NASA Astrophysics Data System (ADS)

In a hot and dense plasma environment, such as that expected to be produced in a large diameter krypton gas puff load implosion on the ZR simulator, the radiation plays a significant and influential role on the time and space evolution of the plasma. An investigation of the multidimensional radiation emission, absorption, and transfer processes as well as their effects on the energetics & dynamics of the krypton Z-pinch plasma on the simulator, is made using the mach2 2D radiation MHD code. The incorporation of the dynamical domain tabular collisional radiative equilibrium (DDTCRE) radiation transport model [Y. K. Chong, et. al., ICOPS 2005, Monterey, CA.] into mach2 affords a realistic description of the self-consistent non-local non-LTE ionization dynamics & radiation transport physics in a computationally efficient manner. An extensive krypton atomic structure model including the M-, L-, and K-shells forms the basis for the transport model. In addition, the K- and L-shell radiation yield and power signatures, as well as their spectral & spatial characteristics are highlighted through a detailed postprocess analysis of the plasma during various stages of the implosion process using the AXSTRAN 2D non-LTE radiation ionization dynamics code & the SPECAM 3D multifrequency non-LTE spectra/image synthesizer code. *Work supported by DTRA.

Chong, Y.; Thornhill, J. W.; Clark, R. W.; Dasgupta, A.; Apruzese, J. P.; Davis, J.

2006-10-01

398

Bow shocks in ablated plasma streams for nested wire array z-pinches: A laboratory astrophysics testbed for radiatively cooled shocks  

SciTech Connect

Astrophysical observations have demonstrated many examples of bow shocks, for example, the head of protostellar jets or supernova remnants passing through the interstellar medium or between discrete clumps in jets. For such systems where supersonic and super-Alfvenic flows and radiative cooling are all important, carefully scaled laboratory experiments can add insight into the physical processes involved. The early stage of a wire array z-pinch implosion consists of the steady ablation of material from fine metallic wires. Ablated material is accelerated toward the array axis by the JxB force. This flow is highly supersonic (M>5) and becomes super-Alfvenic (M{sub A}>2). Radiative cooling is significant in this flow and can be controlled by varying the material in the ablated plasma. The introduction of wires as obstructions in this steady flow leads to the formation of bow shocks, which can be used as a laboratory testbed for astrophysical bow shocks. The magnetic field associated with this obstruction wire can be controlled by varying the current through it. Differences in the shock for different cooling rates and different magnetic fields associated with the obstruction will be discussed, along with comparisons of dimensionless parameters in the experiments to astrophysical systems.

Ampleford, D. J.; Jennings, C. A.; Cuneo, M. E. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1106 (United States); Hall, G. N.; Lebedev, S. V.; Bland, S. N.; Suzuki-Vidal, F.; Palmer, J. B. A.; Chittenden, J. P. [Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom); Bott, S. C. [Center for Energy Research, University of California, San Diego, La Jolla, California 92093 (United States); Frank, A.; Blackman, E. G. [Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States) and Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14627 (United States); Ciardi, A. [LERMA, Universite Pierre et Marie Curie, Observatoire de Paris, 5 Place Jules Janssen, Meudon 92195 (France)

2010-05-15

399

Spatiotemporal behavior of X-ray emission above 20 keV from a Z-pinch produced by wire-array implosion  

SciTech Connect

Results are presented from experimental studies of hard X-ray (HXR) emission in the photon energy range above 20 keV from dense radiating Z-pinch plasmas. The work is aimed at revealing the nature of fast-electron (electron beam) generation during the implosion of cylindrical and conical wire arrays in the Angara-5-1 facility at currents of up to 3 MA. It is found that the plasma implosion zippering caused by the inclination of wires affects the parameters of the HXR pulse emitted during the implosion of a conical array. It is shown that HXR emission correlates well with the decay of the plasma column near the cathode in the stagnation phase. HXR images of the pinch are produced by the bremsstrahlung of fast electrons generated during plasma column decay and interacting with plasma ions and the anode target. It is found that the use of conical arrays makes it possible to control the direction of plasma implosion zippering and the spatiotemporal and energy parameters of the pinch X-ray emission, in particular the X-ray yield. For wire array with diameters of 12 mm and linear masses of 200-400 {mu}g/cm, the current of the fast electron beam is 20 kA and its energy is 60 J, which is about 1/500 of the energy of the main soft X-ray pulse.

Aleksandrov, V. V.; Grabovski, E. V.; Gribov, A. N.; Gritsuk, A. N.; Medovshchikov, S. F.; Mitrofanov, K. N.; Oleinik, G. M. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)

2009-02-15

400

Spatiotemporal behavior of X-ray emission above 20 keV from a Z-pinch produced by wire-array implosion  

NASA Astrophysics Data System (ADS)

Results are presented from experimental studies of hard X-ray (HXR) emission in the photon energy range above 20 keV from dense radiating Z-pinch plasmas. The work is aimed at revealing the nature of fast-electron (electron beam) generation during the implosion of cylindrical and conical wire arrays in the Angara-5-1 facility at currents of up to 3 MA. It is found that the plasma implosion zippering caused by the inclination of wires affects the parameters of the HXR pulse emitted during the implosion of a conical array. It is shown that HXR emission correlates well with the decay of the plasma column near the cathode in the stagnation phase. HXR images of the pinch are produced by the bremsstrahlung of fast electrons generated during plasma column decay and interacting with plasma ions and the anode target. It is found that the use of conical arrays makes it possible to control the direction of plasma implosion zippering and the spatiotemporal and energy parameters of the pinch X-ray emission, in particular the X-ray yield. For wire array with diameters of 12 mm and linear masses of 200-400 ?g/cm, the current of the fast electron beam is 20 kA and its energy is 60 J, which is about 1/500 of the energy of the main soft X-ray pulse.

Aleksandrov, V. V.; Grabovski, E. V.; Gribov, A. N.; Gritsuk, A. N.; Medovshchikov, S. F.; Mitrofanov, K. N.; Oleinik, G. M.

2009-02-01

401

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

402

Operational aspects of an externally driven neutron multiplier assembly concept using a Z-pinch 14-MeV Neutron Source (ZEDNA).  

SciTech Connect

This report documents the key safety and operational aspects of a Z-pinch Externally Driven Nuclear Assembly (ZEDNA) reactor concept which is envisioned to be built and operated at the Z-machine facility in Technical Area IV. Operating parameters and reactor neutronic conditions are established that would meet the design requirements of the system. Accident and off-normal conditions are analyzed using a point-kinetics, one-dimensional thermo-mechanical code developed specifically for ZEDNA applications. Downwind dose calculations are presented to determine the potential dose to the collocated worker and public in the event of a hypothetical catastrophic accident. Current and magnetic impulse modeling and the debris shield design are examined for the interface between the Z machine and the ZEDNA. This work was performed as part of the Advanced Fusion Grand Challenge Laboratory Directed Research and Development Program. The conclusion of this work is that the ZEDNA concept is feasible and could be operated at the Z-machine facility without undue risk to collocated workers and the public.

Smith, David Lewis; Heames, Terence John (Alion Science and Technology, Albuquerque, NM); Parma, Edward J., Jr.; Peters, Curtis D.; Suo-Anttila, Ahti Jorma (Alion Science and Technology, Albuquerque, NM)

2007-09-01

403

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

404

Z-Pinch Fusion Propulsion.  

National Technical Information Service (NTIS)

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...

J. Miernik

2011-01-01

405

High power fiber lasers  

Microsoft Academic Search

High power fiber lasers are one of the hot topics in laser science and technology in recent years. The clad pumping of double clad fiber lasers was the key issue for high power performance in the last decade. The clad pumping scheme demonstrated more than 100 W from a single core fiber. A new concept of high power fiber lasers,

K. Ueda

2001-01-01

406

High power coaxial ubitron  

Microsoft Academic Search

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

Adam J. Balkcum

1998-01-01

407

High power fiber lasers  

Microsoft Academic Search

We discuss fundamental aspects of high-power fiber lasers and describe their recent dramatic advances and prospects including our up-to-date experimental results with particular attention to kilowatt-class, refined power amplifier regimes.

Y. Jeong; J. Nilsson; J. K. Sahu; P. Dupriez; C. A. Codemard; D. B. S. Soh; C. Farrell; J. Kim; D. J. Richardson; D. N. Payne

2005-01-01

408

High power fiber lasers  

Microsoft Academic Search

In this review article, the development of the double cladding optical fiber for high power fiber lasers is reviewed. The\\u000a main technology for high power fiber lasers, including laser diode beam shaping, fiber laser pumping techniques, and amplification\\u000a systems, are discussed in detail. 1050 W CW output and 133 W pulsed output are obtained in Shanghai Institute of Optics and

Qi-Hong Lou; Jun Zhou

2007-01-01

409

High Power Hall Thrusters  

NASA Technical Reports Server (NTRS)

The development of Hall thrusters with powers ranging from tens of kilowatts to in excess of one hundred kilowatts is considered based on renewed interest in high power. high thrust electric propulsion applications. An approach to develop such thrusters based on previous experience is discussed. It is shown that the previous experimental data taken with thrusters of 10 kW input power and less can be used. Potential mass savings due to the design of high power Hall thrusters are discussed. Both xenon and alternate thruster propellant are considered, as are technological issues that will challenge the design of high power Hall thrusters. Finally, the implications of such a development effort with regard to ground testing and spacecraft intecrati'on issues are discussed.

Jankovsky, Robert; Tverdokhlebov, Sergery; Manzella, David

1999-01-01

410