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1

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

2

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

3

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

4

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

SciTech Connect

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

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

2014-03-15

5

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

6

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

7

Z-Pinch Discharge in Laser Produced Plasma  

SciTech Connect

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

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

2010-10-08

8

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

9

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

10

The X-1 Z-pinch driver  

Microsoft Academic Search

X-1 is a program initiative to develop the next-generation laboratory X-ray source using fast Z-pinch drivers. X-1 will provide unique applications utility to high-energy density physics, inertial confinement fusion, and radiation effects simulation research. The advent in the 1980's of pulsed power accelerators capable of delivering tens of terawatts to imploding plasma loads led to a quantum improvement in Z-pinch

Juan J. Ramirez

1997-01-01

11

The physics of fast Z pinches  

SciTech Connect

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

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

1998-07-01

12

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

13

A supersonic nozzle for gas-puff Z-pinch  

Microsoft Academic Search

Summary form only given. In this paper Z-pinch plasma implosion was numerically simulated based on one-dimensional snow-plow model with differently presumed gas shells. An equivalent circuit of Z-pinch discharge was also established for calculating Z-pinch current. In the circuit model the plasma column of Z-pinch was considered as an inductor with variable inductance depending on the decreasing radius of the

Wei Li; Xinxin Wang; Xiaobing Zou; Ruili Ma; Min Han; Guixin Zhang

2004-01-01

14

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

15

Gas-puff Z-pinch experiment  

Microsoft Academic Search

The fast linear Z-pinch was experimentally investigated using a high-current pulse generator (10·8 µF, 5–10 kJ, 150–250 kA) and pulse injection of argon and neon. Measured electrical characteristics of the discharge (current shape and risetime, inductance) and calculated dynamic parameters of plasma implosion (accelerated mass, radial plasma velocity) are presented. X-ray diagnostics with temporal resolution (vacuum X-ray diodes, semiconductor detectors)

A. Krejcí

1990-01-01

16

Radial foil Z-pinch experiments on the MAGPIE generator  

NASA Astrophysics Data System (ADS)

The dynamics of plasma formation in a radial foil Z-pinch are presented. The experimental setup consists of a ?m-thick aluminum disc held between two concentric electrodes and subjected to a 1.4 MA, 250 ns current pulse from the MAGPIE generator. The JxB force acts on the ablated plasma from the foil forming a region of enhanced density on the axis. This precedes the pinching of plasma from current-driven magnetic ``bubbles''. The interaction of these features with an argon ambient (N˜10^16-17 cm-3) from a supersonic gas nozzle (Mach˜9), particularly the formation of several shock structures will be presented and discussed.

de Grouchy, P.; Suzuki-Vidal, F.; Lebedev, S. V.; Swadling, G.; Burdiak, G.; Bland, S. N.; Hall, G. N.; Harvey-Thompson, A. J.; Khoory, E.; Pickworth, L.; Skidmore, J.; Chittenden, J. P.; Bocchi, M.; Ciardi, A.; Krishnan, M.

2010-11-01

17

Applications of high-power diode lasers for aluminum welding  

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

18

Progress in Z-pinch inertial fusion energy  

Microsoft Academic Search

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

Weed; John Woodruff

2010-01-01

19

NRL capillary Z-pinch experiment  

SciTech Connect

The current renewed interest in the dense linear z-pinch is due in large part to a recent Los Alamos Study which concluded that a z- pinch based reactor could produce 4.4 KJ of fusion energy per pulse for the modest input of 140 kJ per pulse, if a straight pinch could be maintained for 2 {mu}sec. Early attempts to achieve suitable high density z-pinches were of the implosion type which produced hollow pressure profiles that quickly resulted in disruptive m = 0 instabilities. These instabilities are not found in the gas embedded pinch in which an initially small diameter plasma is kept in radial equilibrium by following a prescribed current waveform. Unfortunately, these pinches are prone to a rapid accretion of the surrounding gas during the early stages of formation. Our approach is to form the pinch inside small diameter quartz capillaries filled with neutral hydrogen. This fixes the line density. By driving currents through the pinch at a rate that exceeds that necessary for radial equilibrium, we expect the pinch to contract away from the walls and be subject to compressional, as well as ohmic heating. This contraction will, of course, produce a plasma between the pinch and the capillary wall, but we anticipate this ``corona`` will be kept at a low temperature (i.e., high resistance) by radiation and hence shunt only a small fraction of the pinch current. We also expect negligible impurities in the pinch as the classical mixing time will be much longer than the pinch duration at the densities (10{sup 21}- 10{sup 22} ions/cm{sup 3}) and magnetic fields (1 - 10 MG) involved. However, we do expect the presence of the dense corona to reduce the growth rate of the m = 1 instability. Our results demonstrate that a z-pinch can be formed inside a capillary, but our limited current rise rates and peak current have limited our test abilities. Planned improvements in electrical equipment should yield successful testing results.

Sethian, J.D.; Gerber, K.A.; Robson, A.E. [Naval Research Lab., Washington, DC (United States); DeSilva, A.W. [Sachs/Freeman Associates, Inc., Landover, MD (United States)]|[Maryland Univ., College Park, MD (United States)

1984-12-31

20

Soft x ray emission from a gas-puff z-pinch plasma  

Microsoft Academic Search

Soft x ray emission or radiation was studied by using a gas-puff z-pinch device, which has no triggered switch. A PIN-photodiode covered by aluminum was used for the detection of soft x rays. Three kinds of spatial emission patterns were observed from measurement using a pinhole camera. Hot spots were observed near the middle of the discharge. In order to

S. Ueda; S. Maeda; H. Akiyama

1991-01-01

21

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

22

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

23

Z-pinch plasma neutron sources  

SciTech Connect

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 {approx}3x10{sup 13}, 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 Y{sub n}{approx}I{sub m}{sup 4}, where I{sub m} 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 {approx}5x10{sup 16} and {approx}10{sup 18}, 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. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Chemical and Nuclear Engineering Department, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Ktech Corporation, Albuquerque, New Mexico 87185 (United States); Icarus Research, Inc., Bethesda, Maryland 20824-0780 (United States)

2007-02-15

24

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 2.5-14MeV 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

25

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

26

Contraction phase of a gas-puff z-pinch  

Microsoft Academic Search

The dynamics of a gas-puff z-pinch plasma was investigated using a Kerr-cell camera. A large amplitude Rayleigh-Taylor instability was observed to develop during the contraction of the plasma. Two types of gas nozzles were examined to reduce axial nonuniformity, and it was confirmed that the uniform z-pinch was produced by the choice of the nozzle.

Kinya Moriyama; Keiichi Takasugi; Tetsu Miyamoto; Koichi Sato

1994-01-01

27

Experimental study of gas-puff z-pinch plasma  

Microsoft Academic Search

A small neon gas-puff z-pinch device was constructed, and the plasma implosion and its radiation characteristics were studied experimentally. The plasma implosion was investigated using a three-frame Mach-Zehnder interferometer (TFMZI) that is capable of taking three pictures (5 ns exposure and 13 ns interpicture delay) within a single z-pinch shot. Thermopiles were also used in the experiments with the TFMZI

Xiaobing Zou; Xinxin Wang; Chengmu Luo; Min Han

2005-01-01

28

Magnetic Flux Compression with a Gas Puff Z Pinch  

Microsoft Academic Search

The dynamics of a hollow gas puff z pinch imploding with a trapped, initially uniform, axial magnetic field is studied on the 0.45 MA, 1.2 mu s rise-time U.C. Irvine z pinch. The primary purpose is to ascertain the feasibility of producing short pulsed ultrahigh magnetic fields with this geometry. Data is taken primarily for Ne and Kr plasmas with

Edward Lee Ruden

1988-01-01

29

Rotating plasma disks in dense Z-pinch experiments  

NASA Astrophysics Data System (ADS)

We present data from the first z-pinch experiments aiming to simulate aspects of accretion disk physics in the laboratory. Using off axis ablation flows from a wire array z-pinch we demonstrate the formation of a hollow disk structure that rotates at 60 kms-1 for 150 ns. By analysing the Thomson scattered spectrum we make estimates for the ion and electron temperatures as Ti ˜ 60 eV and ZTe ˜ 150 to 200 eV.

Bennett, M. J.; Lebedev, S. V.; Hall, G. N.; Suttle, L.; Burdiak, G.; Suzuki-Vidal, F.; Hare, J.; Swadling, G.; Patankar, S.; Bocchi, M.; Chittenden, J. P.; Smith, R.; Frank, A.; Blackman, E.; Drake, R. P.; Ciardi, A.

2014-12-01

30

Thermal Analysis of the Z-Pinch Power Plant Concept  

Microsoft Academic Search

In this work, a preliminary thermal model for the Z-Pinch Power Plant is presented. This power plant utilizes fusion energy to generate electric energy in the GW range. The Z-Pinch Technology consists of compressing high-density plasma to produce X-rays to indirectly heat to ignition a deuterium\\/tritium fusion capsule. This ignition releases a minimum of 3 GJ every 10 seconds. The

M. A. Modesto; E. R. Lindgren; C. W. Morrow

2005-01-01

31

Wire array initiation at 1MA z-pinch ZEBRA  

NASA Astrophysics Data System (ADS)

The initial stage of W and Al wire array explosions on the 1MA z-pinch installation ZEBRA was investigated. Data from breakdown light emission, B-dot and axial/peripheral V-dots were obtained. Observation of the resistive voltage and the moment of corona generation allow calculation of the condition of the wire core after breakdown. With a current prepulse of 300ns duration, we observed plasma formation at 200ns before the main current. At this moment a first light emission and V-dot signals was observed. During the next 5-10 ns fast plasma components arrive at the center of the wire array and shunt the axial V-dot. After shunting, the axial V-dot shows signals correlated to axial current. Analyzing mass-velocity ratios, we determined that for the Al wire array hydrogen plasma arrived first at the center with velocity 666km/s, followed by carbon plasma with velocity 200km/s and later, the aluminum plasma with velocity 130km/s. Hence, before the main current starts the internal volume of the array is filled by low-density plasma. The axial V-dot signal indicates that the main current initially flows though the entire wire array cross-section, but it is rapidly rejected to the periphery. During the compression stage we observed that the current again flows through the center of the wire array.

Sarkisov, G. S.; Ivanov, V. V.; Cowan, T. E.; Rosenthal, S. E.; Struve, K. W.; Morozov, A.; Haboub, A.; Astanovitskiy, A.; La Galloudec, B.

2006-10-01

32

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

33

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

34

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

35

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

36

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.

37

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

Microsoft Academic Search

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

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

2011-01-01

38

A Z-Pinch Driven Fusion Reactor Concept  

NASA Astrophysics Data System (ADS)

Recent z-pinch target physics progress has encouraged us to consider how a power reactor could be configured based on a fast z-pinch driver. Initial cost estimates show that recyclable transmission lines (RTLs) are economically viable. Providing 'standoff' between the primary power supply and the target, which is what disposable RTLs provide, has historically been the main obstacle to the consideration of pinches as fusion drivers. We will be introducing basic reactor scaling in terms of shot rate, yield, tritium breeding and neutron flux, etc. This concept has advantages in that z-pinches provide a robust mechanical environment, as well as a chamber which does not require low-pressure pumping between shots and the wall lifetime is expected to be limited factors other than neutron damage. 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.

Derzon, Mark; Rochau, Gregory; Spielman, Rick; Slutz, Stephen; Rochau, G. E.; Peterson, R. R.; Peterson, P. F.

1999-11-01

39

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

40

Diagnostics for studying the dynamics of wire array Z pinches  

NASA Astrophysics Data System (ADS)

The evolution of a wire array Z pinch encompasses a huge range of conditions—with spatial dimensions varying from micrometers to centimeters, densities from solid metal through plasmas of 1015-1022e-cm-3, and temperatures from sub-eV to many 100eV. We present a summary of the diagnostics developed and used at the Imperial College MAGPIE facility to study the formation and dynamics of plasma in wire array Z pinches, describing the plasma conditions for which they are useful, their various limitations, and some of the novel diagnostic techniques applied.

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

2006-10-01

41

Measurement and analysis of x-ray absorption in Al and MgF2 plasmas heated by Z-pinch radiation.  

PubMed

High-power Z pinches on Sandia National Laboratories' Z facility can be used in a variety of experiments to radiatively heat samples placed some distance away from the Z-pinch plasma. In such experiments, the heating radiation spectrum is influenced by both the Z-pinch emission and the re-emission of radiation from the high-Z surfaces that make up the Z-pinch diode. To test the understanding of the amplitude and spectral distribution of the heating radiation, thin foils containing both Al and MgF2 were heated by a 100-130 TW Z pinch. The heating of these samples was studied through the ionization distribution in each material as measured by x-ray absorption spectra. The resulting plasma conditions are inferred from a least-squares comparison between the measured spectra and calculations of the Al and Mg 1s-->2p absorption over a large range of temperatures and densities. These plasma conditions are then compared to radiation-hydrodynamics simulations of the sample dynamics and are found to agree within 1sigma to the best-fit conditions. This agreement indicates that both the driving radiation spectrum and the heating of the Al and MgF2 samples is understood within the accuracy of the spectroscopic method. PMID:16486068

Rochau, Gregory A; Bailey, J E; Macfarlane, J J

2005-12-01

42

Formation and Sustainment of a Sheared Flow in a Z-pinch  

Microsoft Academic Search

The ZaP Flow Z-Pinch Experiment has forms Z-pinches that are stable for 700 times the kink growth time of a nonflowing Z-pinch. The pinch is formed using a coaxial accelerator. During the acceleration phase, the attachment region of the current widens. The leading edge travels down the outer electrode, initiating the Z-pinch, while the trailing edge travels towards the insulator.

R. P. Golingo; S. L. Jackson; B. A. Nelson; U. Shumlak; D. J. den Hartog

2002-01-01

43

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

E-print Network

Measurement and Control of Current Waveform in an Ablative Z-Pinch Pulsed Plasma Thruster" Reducing Current Ringing in the AZPPT2 Circuit Abstract The second Ablative Z-Pinch Pulsed Plasma Thruster AZPPT2 and Applications . . . . . . . . . . . . . . . . 3 2.2 Ablative Z-Pinch Pulsed Plasma Thruster

Choueiri, Edgar

44

Bifurcation of current within gas puff Z-pinches  

Microsoft Academic Search

Summary form only given. We have found numerical evidence that large amplitude waves resulting from the Rayleigh-Taylor instability in gas puff Z-pinches may grow until individual magnetic field structures form, creating separatices between them. In the computational model used the plasma was described by collisional MHD equations (single fluid and temperature) in axisymmetric geometry. The magnetic field perpendicular to the

A. Wilson; P. Steen

2004-01-01

45

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

46

Resolving microstructures in Z pinches with intensity interferometry  

SciTech Connect

Nearly 60 years ago, Hanbury Brown and Twiss [R. Hanbury Brown and R. Q. Twiss, Nature 178, 1046 (1956)] succeeded in measuring the 30 nrad angular diameter of Sirius using a new type of interferometry that exploited the interference of photons independently emitted from different regions of the stellar disk. Its basis was the measurement of intensity correlations as a function of detector spacing, with no beam splitting or preservation of phase information needed. Applied to Z pinches, X pinches, or laser-produced plasmas, this method could potentially provide spatial resolution under one micron. A quantitative analysis based on the work of Purcell [E. M. Purcell, Nature 178, 1449 (1956)] reveals that obtaining adequate statistics from x-ray interferometry of a Z-pinch microstructure would require using the highest-current generators available. However, using visible light interferometry would reduce the needed photon count and could enable its use on sub-MA machines.

Apruzese, J. P. [Consultant to NRL through Engility Corp., Chantilly, Virginia 20151 (United States)] [Consultant to NRL through Engility Corp., Chantilly, Virginia 20151 (United States); Kroupp, E.; Maron, Y. [Weizmann Institute of Science, Rehovot 76100 (Israel)] [Weizmann Institute of Science, Rehovot 76100 (Israel); Giuliani, J. L.; Thornhill, J. W. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States)] [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States)

2014-03-15

47

Stagnation dynamics of a ne gas puff z pinch  

Microsoft Academic Search

Detailed spatially resolved spectroscopic analysis of a neon gas puff z pinch on the Weizmann 1 MA generator indicates that the radius of the K-shell emitting region grows to a maximum and then decreases during the radiation pulse1,2. ID Lagrangian simulations show the opposite trend because the emission arises from the inside surface of a dense shell that bounces off

J. L. Giuliani; J. W. Thornhill; A. Velikovich; J. P. Apruzese; A. Dasgupta; J. Davis; S. Zalesak; R. Clark; E. Kroupp; D. Osin; A. Starobinets; E. Stambulchik; V. Bernshtam; V. Fisher; Y. Maron; A. Fisher; C. Deeney

2010-01-01

48

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

49

Fiber ablation in the solid deuterium Z pinch  

SciTech Connect

We have performed one-dimensional magnetohydrodynamic computer calculations of the formation and evolution of the solid deuterium fiber Z pinch. With use of tabulated atomic data base and ''cold start'' initial conditions, our computations show that current is carried by hot plasma which has been ablated from the solid fiber. The computations suggest that the experimentally observed instability growth may coincide with the complete ablation of the central fiber.

Lindemuth, I.R.; McCall, G.H.; Nebel, R.A.

1989-01-16

50

Radiating Shock Measurements in the Z-Pinch Dynamic Hohlraum  

Microsoft Academic Search

The Z-pinch dynamic hohlraum is an x-ray source for high energy-density physics studies that is heated by a radiating shock to radiation temperatures >200eV. The time-dependent 300 400 eV electron temperature and 15 35mg\\/cc density of this shock have been measured for the first time using space-resolved Si tracer spectroscopy. The shock x-ray emission is inferred from these measurements to

G. A. Rochau; J. E. Bailey; Y. Maron; G. A. Chandler; G. S. Dunham; D. V. Fisher; V. I. Fisher; R. W. Lemke; J. J. Macfarlane; K. J. Peterson; D. G. Schroen; S. A. Slutz; E. Stambulchik

2008-01-01

51

Power scaling of a Z-pinch extreme ultraviolet source  

Microsoft Academic Search

A xenon Z-pinch generating extreme ultraviolet radiation at the Mo-Si mirror wavelength of 13.5 nm has been scaled to emit increased power at a higher repetition frequency. The 25 mm long by 3.0 mm (FWHM) diameter pinch produces 1.5 W of EUV radiation (2.5% bandwidth) into an axial 0.1 sr solid angle when operated at 100 Hz (100 J stored).

Malcolm W. McGeoch

2000-01-01

52

Capsule implosions driven by a z-pinch dynamic hohlraum  

Microsoft Academic Search

Capsule implosions driven by z-pinch dynamic hohlraums are a promising avenue for ICF research. The goal of the experiments described here is to produce Ar K-shell x-rays that can be used to constrain implosion simulations and be exploited in future symmetry measurements. The configuration uses a 2-mm-diameter CH capsule filled with 12 atm D2\\/ 0.012 atm Ar, embedded in a

J. E. Bailey; G. R. Bennett; G. A. Chandler; G. Cooper; D. E. Hebron; J. S. Lash; T. J. Nash; C. L. Ruiz; S. A. Slutz; R. A. Vesey; P. Lake; D. S. Nielson; R. Smelser; D. G. Schroen-Carey; J. J. Macfarlane

2000-01-01

53

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

54

The Study of a Fibre Z-Pinch  

E-print Network

This thesis presents the results of fibre Z-pinch experiments carried out on the Z-150 device at the CTU in Prague. The generator that was used to drive the experiments consisted of one capacitor of 3e-6 F capacitance. In the case of 20 kV charging voltage, the current was peaking at 80 kA with a 850 ns quarter period. The Z-pinch was formed from carbon fibres of 15 micrometer diameter and 1 cm length. The discharge was observed by a large number of diagnostic tools. This comprehensive set of diagnostics enabled us to describe the gross dynamics of the Z-pinch. It was found out that after the breakdown a low density coronal plasma was formed while the fibre diameter remained almost unchanged. This low density corona was carrying almost all the current of the order of 10 kA. When the current had built up, the implosion of the corona onto the central fibre occurred. The implosion velocity approached the value of 2e5 m/s. When the imploded corona had reached the fibre, the dip in dI/dt, voltage peak up to 10 kV,...

Klir, D

2005-01-01

55

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

56

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

SciTech Connect

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

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

1996-08-01

57

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

58

Development of laser-based diagnostics for 1-MA z-pinch plasmas  

NASA Astrophysics Data System (ADS)

The 50 TW Leopard laser coupled with the 1-MA Zebra generator was used for development of new diagnostics of z-pinch plasmas. Two plasma diagnostics are presented: an x-ray broadband backlighting for z-pinch absorption spectroscopy and parametric two-plasmon decay of the laser beam in dense z-pinch plasma. Implementation of new diagnostics on the Zebra generator and the first results are discussed. The absorption spectroscopy is based on backlighting of z-pinch plasma with a broadband x-ray radiation from a Sm laser plasma. Detailed analysis of the absorption spectra yields the electron temperature and density of z-pinch plasma at the non-radiative stage. The parametric two-plasmon decay of intensive laser radiation generates 3/2? and 1/2? harmonics. These harmonics can be used to derive a temperature of z-pinch plasma with the electron density near the quarter of critical plasma density.

Ivanov, V. V.; Hakel, P.; Mancini, R. C.; Wiewior, P.; Presura, R.; Kindel, J. M.; Shevelko, A. P.; Chalyy, O.; Astanovitskiy, A.; Haboub, A.; Altemara, S. D.; Papp, D.; Durmaz, T.

2009-11-01

59

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

Microsoft Academic Search

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

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

2001-01-01

60

SPEED2 Driven A Gas Embedded Z-Pinch Preliminary Results  

SciTech Connect

Preliminary results in a gas embedded Z-pinch driven by the SPEED2 generators are presented. A 0-D model for a quasi static z-pinch with variable line density has been applied to determined the initial conditions to produce a gas embedded z-pinch to be driven by SPEED2 generator. Initial conditions to produce a gas embedded z-pinch with enhanced stability by means resistive effects and by finite Larmor radius effects were obtained. Using these results the electrodes were designed and constructed.

Soto, Leopoldo; Moreno, Jose; Sylvester, Gustavo; Silva, Patricio; Zambra, Marcelo [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile); Pavez, Cristian [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile); Universidad de Concepcion (Chile)

2006-01-05

61

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

62

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

63

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

64

High energy density Z-pinch plasmas using flow stabilization  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

65

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

66

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

67

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

68

Investigation of trailing mass in Z-pinch implosions and comparison to experiment  

NASA Astrophysics Data System (ADS)

Wire-array Z pinches represent efficient, high-power x-ray sources with application to inertial confinement fusion, high energy density plasmas, and laboratory astrophysics. The first stage of a wire-array Z pinch is described by a mass ablation phase, during which stationary wires cook off material, which is then accelerated radially inwards by the JxB force. The mass injection rate varies axially and azimuthally, so that once the ablation phase concludes, the subsequent implosion is highly 3D in nature. In particular, a network of trailing mass and current is left behind the imploding plasma sheath, which can significantly affect pinch performance. In this work we focus on the implosion phase, electing to model the mass ablation via a mass injection scheme. Such a scheme has a number of injection parameters, but this freedom also allows us to gain understanding into the nature of the trailing mass network. For instance, a new result illustrates the role of azimuthal correlation. For an implosion which is 100% azimuthally correlated (corresponding to an azimuthally symmetric 2D r-z problem), current is forced to flow on the imploding plasma sheath, resulting in strong Rayleigh-Taylor (RT) growth. If, however, the implosion is not azimuthally symmetric, the additional azimuthal degree of freedom opens up new conducting paths of lower magnetic energy through the trailing mass network, effectively reducing RT growth. Consequently the 3D implosion experiences lower RT growth than the 2D r-z equivalent, and actually results in a more shell-like implosion. A second major goal of this work is to constrain the injection parameters by comparison to a well-diagnosed experimental data set, in which array mass was varied. In collaboration with R. Lemke, M. Desjarlais, M. Cuneo, C. Jennings, D. Sinars, E. Waisman

Yu, Edmund

2007-11-01

69

Current scaling of optimum K-shell X-ray yield and load mass applied to argon gas-puff z-pinches  

Microsoft Academic Search

Summary form only given, as follows. A simple radiation-scaling model based on two-level atomic physics and plasma energy balance was developed to guide selection of load parameters and estimate K-shell x-ray yields for z-pinch drivers. The model agrees with neon gas-puff experiments at 0.7 MA and aluminum wire-array experiments at 7 MA. It predicts the current scaling of peak K-shell

D. Mosher; M. Krishnan; N. Qi; P. Coleman; H. Y. Se; E. Waisman

2001-01-01

70

D-D fusion experiments using fast Z pinches  

SciTech Connect

The development of high current (I > 10 MA) drivers provides the authors with a new tool for the study of neutron-producing plasmas in the thermal regime. The imploded deuterium mass (or collisionality) increases as I{sup 2} and the ability of the driver to heat the plasma to relevant fusion temperatures improves as the power of the driver increases. Additionally, fast (<100 ns) implosions are more stable to the usual MHD instabilities that plagued the traditional slower implosions. The authors describe experiments in which deuterium gas puffs or CD{sub 2} fiber arrays were imploded in a fast z-pinch configuration on Sandia`s Saturn facility generating up to 3 {times} 10{sup 12} D-D neutrons. These experiments were designed to explore the physics of neutron-generating plasmas in a z-pinch geometry. Specifically, the authors intended to produce neutrons from a nearly thermal plasma where the electrons and ions have a nearly Maxwellian distribution. This is to be clearly differentiated from the more usual D-D beam-target neutrons generated in many dense plasma focus (DPF) devices.

Spielman, R.B.; Baldwin, G.T.; Cooper, G. [and others

1998-03-01

71

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

72

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

73

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

74

Caterpillar structures in single-wire Z-pinch experiments  

NASA Astrophysics Data System (ADS)

A series of experiments have been performed on single-wire Z pinches (1-2 kA, 20 kV, pulse length 500 ns; Al, Ag, W, or Cu wire of diameter 7.5-50 ?m, length 2.5 cm). Excimer laser absorption photographs show expansion of metallic plasmas on a time scale of order 100 ns. The edge of this plasma plume begins to develop structures resembling a caterpillar only after the current pulse reaches its peak value. The growth of these caterpillar structures is shown to be consistent with the Rayleigh-Taylor instability of the decelerating plasma plume front at the later stage of the current pulse.

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

2003-12-01

75

Plasma dynamics in an inverse wire array z-pinch  

NASA Astrophysics Data System (ADS)

We describe experiments on the MAGPIE facility (1MA, 250ns) with inverse wire array z-pinches, in which the wires act as a return current cage placed around a central current conductor. In this configuration the plasma ablated from the wires is pushed by the JxB force in the radially outward direction and expands into the region free of the magnetic field. The parameters of the coronal plasma were measured using laser interferometry, X-ray and XUV imaging. The experimental set-up also allows addition of axial and radial magnetic fields, and we study the effects of these fields on the plasma dynamics and the ablation rate. The complete ablation of the wires triggers radial ``explosion'' of the plasma which proceeds through formation of gaps in the wire cores, similar to the dynamics of standard wire arrays. The opening of the current path in the final stages could potentially be used as a plasma opening switch.

Lebedev, Sergey; Bland, S. N.; Bott, S. C.; Chittenden, J. P.; Hall, G. N.; Suzuki, F. A.; Ciardi, A.; Palmer, J. B. A.

2006-10-01

76

Calculation of neutron yield from a dense Z pinch  

SciTech Connect

Measurements of neutron yield from a Z pinch formed from a solid deuterium fiber have been reported recently. The scaling of yield with applied current was a surprising I/sup 10/. Although the neutrons were believed to result from a plasma instability, no explanation for the magnitude or scaling of the yield with current was suggested. A model of a sausage, or m = 0, instability has been generated which gives the observed yield to a multiplicative constant and the scaling of yield with current. It is predicted that the yield can be increased by increasing the applied current, but the model indicates that yields from this mechanism may be limited to 10/sup 12/ unless tritium is added to the pinch.

McCall, G.H.

1989-04-24

77

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

78

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

79

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

80

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

81

Experimental study of implosion plasma physical characteristics in a small puff-gas z-pinch  

SciTech Connect

This paper presents the physical characteristics of the z-pinch implosion plasma. Experiments were carried out on a small gas-puff z-pinch plasma device. A three-frame Mach-Zehnder interferometer was developed to measure implosion plasma. Some important physical parameters of plasma implosion process were obtained. At the same time, the soft x-ray energy spectra range from 0.2 {approx} 1.5 keV and the energy spectra of ion beam emitted from the z-pinch plasma were measured.

Zou, X.B.; Wang, X.X.; Han, M.; Luo, C.M.; Zhang, G.X.; Liu, Z. [Gas Discharge and Plasma Laboratory, Dept. of Electrical Engineering, Tsinghua University, Beijing 100084 (China)

2006-01-05

82

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

83

EQ-10 electrodeless Z-pinch EUV source for metrology applications  

NASA Astrophysics Data System (ADS)

With EUV Lithography systems shipping, the requirements for highly reliable EUV sources for mask inspection and resist outgassing are becoming better defined, and more urgent. The sources needed for metrology applications are very different than that needed for lithography; brightness (not power) is the key requirement. Suppliers for HVM EUV sources have all resources working on high power and have not entered the smaller market for metrology. Energetiq Technology has been shipping the EQ-10 Electrodeless Z-pinchTM light source since 19951. The source is currently being used for metrology, mask inspection, and resist development2-4. These applications require especially stable performance in both output power and plasma size and position. Over the last 6 years Energetiq has made many source modifications which have included better thermal management to increase the brightness and power of the source. We now have introduced a new source that will meet requirements of some of the mask metrology first generation tools; this source will be reviewed.

Gustafson, Deborah; Horne, Stephen F.; Partlow, Matthew J.; Besen, Matthew M.; Smith, Donald K.; Blackborow, Paul A.

2011-11-01

84

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

85

Azimuthal wire motion and ablation dynamics in z-pinches  

NASA Astrophysics Data System (ADS)

This dissertation describes theoretical, simulation, and experimental work to study ablation dynamics and azimuthal 'clumping' of wires in multi-wire z-pinch arrays. First, a resistive-inductive model of discrete filamentary conductors is developed to model wires in multi-wire z-pinches. These equations have been shown to decrease computation times over similar models in literature by as much as 5 orders of magnitude. From these new equations, a simulation code called REIN (REsistive-INductive) was developed to simulate discrete wire arrays. REIN simulations revealed that wires 'clumped' azimuthally when an initial random azimuthal perturbation was placed on the wire positions. Theory was developed to describe the observed clumping. The fastest growing clumping mode was found to be the pairing of neighboring wires (pi-mode). Experiments were conducted by the author on the COBRA accelerator (1 MA, 100 ns risetime) at Cornell University to look for azimuthal wire clumping in closely spaced wires. Radiography of wire cores did not demonstrate azimuthal wire clumping. However, based on the lack of motion, the major conclusion of the experiment is that less than 7% of the total current was flowing in the wire cores. Another calculation indicated that for wire cores to remain unvaporized by resistive heating, less than 1% of the current could have flowed in the cores. The other 93--99% of the current must therefore have flowed in the coronal plasma. Results also indicated presence of axial non-uniform ablation. Experiments performed at the University of Michigan on the MIZ-3 (9-10 kA, 400 ns risetime) and MIZ-4 (18 kA, 150 ns risetime) facilities are also described. On MIZ-4, plasma electron temperatures of ablated 30 mum Al wires were measured by emission spectroscopy to be 1.5-2 eV. Comparing results to previous experiments, it is observed that electron temperature scales very weakly with current (more than 10 times increase in current amplitude resulted in less than 2 times increase in electron temperature). On MIZ-3, more intense optical emission from wires preheated with DC currents indicated greater energy deposition than in slightly preheated wires.

Strickler, Trevor S.

86

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

E-print Network

Convective Cell Formation in a Z-Pinch J. Kesner Plasma Science and Fusion Center Massachusetts and the MHD time scales, 3 /(acs) with the thermal diffusivity, cs the sound speed and a the characteristic

87

Optical observation of the instability in microsecond gas-puff z-pinch plasmas  

Microsoft Academic Search

Summary form only given. The occurrence and growth of fluid instabilities in gas-puff z-pinch plasmas have been investigated by using laser diagnostic systems. A schlieren system was employed to investigate the temporal evolution of the structure in the plasma during the pinch. The z-pinch plasma was driven by a fast bank, which provided a current of 150 kA at 1.55s

Murayama; S. Katsuki; H. Akiyama; I. Fukudome

2001-01-01

88

Three-dimensional hydromagnetic simulation of a high-velocity gas-puff Z-pinch  

Microsoft Academic Search

Experiments on the Sandia National Laboratories Saturn pulsed power machine have produced high-velocity Z-pinch plasma implosions of krypton gas puffs from a circular nozzle. We use the three-dimensional (3-D), time-dependent MACH3 magnetohydrodynamics code to simulate these experiments. Generally, the quality of Z-pinch implosions is degraded by hydromagnetic Rayleigh-Taylor instabilities. The images displayed in this paper illustrate the growth in time

Robert E. Peterkin; Norman F. Roderick; Shari Colella; Dennis E. Lileikis

1999-01-01

89

Experimental study of a small gas-puff Z-pinch plasma device  

Microsoft Academic Search

An experiment was carried out on a small gas-puff Z-pinch plasma device with capacitor bank of 16 ?F and charging voltage 22 kV. Discharge current was measured by Rogowski coil. A compact Thomson ion energy analyzer was installed in the discharge chamber for determining the energy spectra of ion beam emitted from the Z-pinch plasma. The energy spectra of argon

Chengmu Luo; Chengrong Li; Xinxin Wang; Zhifeng Xie; X. M. Guo; Min Han

1999-01-01

90

Energy Transfer and X-Ray Radiation Characteristics of a Gas-Puff Z-Pinch  

Microsoft Academic Search

The characteristics of energy transfer and X-ray radiation from an Ar gas-puff z-pinch plasma have been investigated in the z-pinch discharge region. The input energy reached approximately 10% of the bank energy at maximum. The input energy had a little more than square dependence for the pinch current. The average energy distributed to each particle had a decreasing tendency with

Keiichi Takasugi; Hisashi Akiyama

2004-01-01

91

Numerical Studies of Neon Gas-puff Z-pinch Dynamic Process  

Microsoft Academic Search

The dynamic process of neon gas-puff Z-pinch, which may produce high temperature and density plasma, were numerically studied by one-dimensional lagrangian radiation magneto-hydrodynamic code developed by the authors. The spatio-temporal distributions of some plasma parameters in the process were obtained, and the dynamic process was reproduced. The results also show the zippering effect in gas-puff Z-pinch, and suggest that the

Cheng Ning; Zhenhua Yang; Ning Ding

2002-01-01

92

Optical observation of the instability in microsecond gas-puff z-pinch plasmas  

Microsoft Academic Search

The occurrence of fluid instabilities in gas-puff z-pinch plasmas have been investigated using laser diagnostic systems. An interferometer system was employed to investigate the temporal evolution of the structure in the plasma column during the pinch. The z-pinch plasma was driven by a fast bank, which provided a current of 160 kA at 1.5 µs (T\\/4). Initially the plasma was

Sunao Katsuki; Koichi Murayama; Hidenori Akiyama

2000-01-01

93

Magnetic Rayleigh-Taylor instability mitigation in large-diameter gas puff Z-pinch implosions  

Microsoft Academic Search

Recently, a new approach for efficiently generating K-shell x-rays in large-diameter, long-implosion time, structured argon gas Z-pinches has been demonstrated based on a ``pusher-stabilizer-radiator'' model. In this paper, direct observations of the Rayleigh-Taylor instability mitigation of a 12-cm diameter, 200-ns implosion time argon Z-pinch using a laser shearing interferometer (LSI) and a laser wavefront analyzer (LWA) are presented. Using a

N. Qi; H. Sze; B. H. Failor; J. Banister; J. S. Levine; J. C. Riordan; P. Steen; P. Sincerny; D. Lojewski

2008-01-01

94

Diagnostics for a small gas-puff Z-pinch plasma device  

Microsoft Academic Search

Experiments were carried out on a small gas-puff Z-pinch plasma device with a capacitor bank of 16 ?F and a charging voltage of 22 kV. A compact Thomson ion energy analyzer was installed on the device for determining the energy spectra of ion beam emitted from the Z-pinch plasma. The energy spectra of Argon ion beams with single, double, and

Chengmu Luo; Xinxin Wang; Min Han; Chengrong Li

2000-01-01

95

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

Microsoft Academic Search

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 Omega 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

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

1989-01-01

96

Gas-puff Z-pinch driven by inductive energy storage pulsed power generator ASO2  

Microsoft Academic Search

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

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

1994-01-01

97

EUV radiation characteristics of Ar gas-puff Z-pinch plasma with axial magnetic field  

Microsoft Academic Search

The axial magnetic field was applied to the Ar gas-puff Z-pinch plasma for the control of soft X-ray and EUV emission. The reduction of soft X-ray and increase of EUV emission were again confirmed. EUV spectroscopic measurement was made on the Z-pinch plasma, and Ar IX and Ar X lines were observed. By applying axial magnetic field of 950 G,

Keiichi Takasugi; Fuminari Kobayashi

2004-01-01

98

Ultrahigh magnetic fields produced in a gas-puff Z pinch  

Microsoft Academic Search

Controlled, ultrahigh axial magnetic fields have been produced and measured in a gas-puff Z pinch. A 0.5-MA, 2-cm-radius annular gas-puff Z pinch with a 3-min repetition rate was imploded radially onto an axial seed field, causing the field to compress. Axial magnetic field compressions up to 180 and peak magnetic fields up to 1.6 MG were measured. Faraday rotation of

F. S. Felber; F. J. Wessel; N. C. Wild; H. U. Rahman; A. Fisher; C. M. Fowler; M. A. Liberman; A. L. Velikovich

1988-01-01

99

Optical Observation of the Instability in Microsecond Gas-Puff Z-Pinch Plasmas  

Microsoft Academic Search

The occurrence of fluid instabilities in gas-puff z-pinch plasmas have been investigated using laser diagnostic systems. An interferometer system was employed to investigate the temporal evolution of the structure in the plasma column during the pinch. The z-pinch plasma was driven by a fast bank, which provided a current of 160 kA for 1.5 mus quarter period of oscillation. Initially

Sunao Katsuki; Koichi Murayama; Hidenori Akiyama

2001-01-01

100

Gas puff Z-pinch x-ray source: a new approach  

Microsoft Academic Search

Gas puff Z-pinches have been operated successfully with peak currents of 100 kA to more than 10 MA. Very little effort has been developed to study long life rep-rated systems. The scaling laws of the gas puff Z-pinch show that up to a few MA (peak pinch current), the neon k-line yield is proportional to I4. In these machines the

Amnon Fisher

1991-01-01

101

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

102

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

103

Fusion propulsion with a sheared helical flow stabilized z-pinch  

Microsoft Academic Search

A shear flow stabilized z-pinch has in the past been proposed as a propulsion device for space travel. In high density plasmas non-neutronic fusion chain reactions are possible, which are ideally suited for propulsion. In z-pinches, high densities are only possible if the magnetically confined plasma can be stabilized, but it has been shown that sheared helical flow has a

L. F. Wanex; F. Winterberg

2009-01-01

104

Effect of Radiation Cooling and Plasma Atomic Number on Z-Pinch Dynamics  

Microsoft Academic Search

A gas puff z-pinch is operated by injecting a gas annulus into the space between two electrodes, then applying a voltage pulse (supplied by a 5 KJ, 30 KV capacitor bank) to initiate a z-pinch discharge. During the pinched stage, the plasma electron density reaches 10('20)cm(' -3) and T(,e) (DBLTURN) 100 eV. At these parameters, moderate atomic number atoms emit

James Edward Bailey

1984-01-01

105

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

NASA Astrophysics Data System (ADS)

The Cornell University COBRA pulser is a nominal 1 MA machine, capable of driving up to 32 wire cylindrical Z-pinch arrays. COBRA can operate with variable current risetimes ranging from 100 ns to 200 ns (short and long pulse, respectively). Wires are typically strung with a "press" contact to the electrode hardware, where the wire is loosely pulled against the hardware and held there to establish electrical contact. The machine is normally negative, but a bolt-on convolute can be used to modify the current path and effectively produce positive polarity operation at the load. Previous research with single wires on a 1-5 kA pulser [1] has shown that soldering the wire, thereby improving the wire/electrode contact, and operating in positive polarity can improve the energy deposition into the wire and enhance wire core expansion. Negative polarity showed no difference. Previous experiments on the negative polarity, 20 MA, 100 ns Z accelerator [2] have shown that improving the contact improved the x-ray yield. Cornell data were collected on 16-wire Aluminum Z-pinch arrays in negative polarity. Experiments were conducted with both short and long current pulses with soldered and no-soldered wire/electrode contacts. The initiation, ablation, implosion and stagnation phases were compared for these four conditions. Time dependent x-ray signals were measured using diodes and diamond detectors. An inductive voltage monitor was used to infer minimum current radius achieved, as defined by a uniform shell of current moving radially inward, producing a time dependent inductance. Total energy data were collected with a metal-strip bolometer. Self-emission data were collected by an XUV 4-frame camera and an optical streak camera. In negative polarity and with short pulses, soldering appeared to produce a smaller radius pinch and decrease variations in the x-ray pulse shape. The bolometer, laser backlighter, 4-frame and streak cameras showed negligible differences in the initiation ablation and implosion phases. X-ray yield was increased with soldered arrays in negative polarity with long pulses. The bolometer also showed a 50% increase in radial power emitted for soldered arrays. 4-frame images showed soldered arrays have a more pronounced "Christmas Tree" effect originating from the cathode. The inductive voltage monitor showed, with both long and short pulses, that soldered and no-solder arrays reached the same minimum current radius at the same time. However, with long pulses soldered arrays radiate x-rays at the time of minimum current radius while no-solder array x-ray output is delayed by ˜20 ns, resulting in decreased x-ray yield.

Chalenski, D. A.; Kusse, B. R.; Greenly, J. B.; Blesener, I. C.; McBride, R. D.; Hammer, D. A.; Knapp, P. F.

2009-01-01

106

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

SciTech Connect

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

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

1996-07-01

107

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

108

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

109

The NRL frozen deuterium fiber Z-pinch experiment  

SciTech Connect

Previous experiments at NRL have shown z-pinches formed from 60 to 125 micron diameter frozen D{sub 2} fibers were stable as long as the current was rising. At current peak the pinch went rapidly {ital m}=0 unstable and emitted 2.45 MeV neutrons whose total number scaled as {ital I}{sup 10}. The maximum current was 640 kA with a rise time of 130 nsec. A new generator, called ZFX, has been built to increase the current through the pinch to up to 2 MA. In preliminary experiments with ZFX at currents of 450 kA, streak photos again shown the pinch is stable as long as the current is rising, except that the stable period has been extended to 300 nsec. X-ray pinhole photos also show a straight, uniform pinch. The number of neutrons produced by the pinch when it goes unstable is consistent with the previously observed {ital I}{sup 10} scaling.

Sethian, J.D.; Robson, A.E.; Gerber, K.A.; DeSilva, A.W. (Naval Research Laboratory, Washington, DC (USA))

1989-12-01

110

Azimuthal Clumping Instabilities in a Z-pinch Wire Array  

NASA Astrophysics Data System (ADS)

Recent simulations of a high wire-number array Z-pinch reveal a strong azimuthal clumping instability [1]. This instability is found to be entirely analogous to the Jeans instability in a self-gravitating disk, where the mutual attraction of gravity is replaced by the mutual attraction of neighboring wires that carry currents in the same direction. The unstable modes are heavily crowded. We have studied the temporal evolution of initial perturbations which are randomly and uniformly distributed among all modes, i.e., the spectral equivalent of white noise. An analytic scaling law is derived, which shows that randomly seeded perturbations evolve at the rate of the fastest unstable mode, almost from the start. Extension to a coronal plasma, and the coupling of this clumping instability to the magnetic Rayleigh-Taylor instability, will be reported. [1] T. Strickler et al., Phys. Plasmas 12, 052701 (2005). * This work was supported by U. S. DoE through Sandia National Laboratories award number 240985 to the University of Michigan. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.

Tang, W.; Garasi, C.

2005-10-01

111

Spectroscopic measurements of an imploding z-pinch plasma  

SciTech Connect

The structure of an imploding plasma in an annular gas-puffed 1.2 {micro}sec, 350 kA Z-pinch is investigated. Absolute intensities and spectral profiles of lines of ions up to the sixth ionization stage are observed along the chord and along the axial direction. The magnetic field distribution in the plasma is determined from Zeeman splitting by discrimination against the Stark and Doppler broadenings, using polarization spectroscopy. Ionization times and line ratios, together with the time dependent CR calculations, are used to determine the electron temperature. The ion velocity distributions are observed in the radial and the axial directions from Doppler broadenings and shifts. The electron density is determined from Stark broadening and the continuum. The current density and the skin depth are obtained from the magnetic field distribution, also giving the plasma conductivity. This yields the Ohmic heating as a function of time and radius. The measurements of the electron temperature, the conductivity, and the ion velocities allow the various heating contributions to be calculated. The line intensities of various charge states and the electron density and temperature allow the energy losses due to ionization and radiation to be estimated. Here, the different mechanisms of the acceleration are obtained quantitatively across the plasma shell.

Davara, G.; Gregorian, L.; Kroupp, E.; Markus, Y.; Peter, W.; Maron, Y. [Weizmann Inst. of Science, Rehovot (Israel). Dept. of Particle Physics

1995-12-31

112

The physics of the high density Z-pinch  

SciTech Connect

The fiber-initiated High-Density Z-Pinch (HDZP) is a novel concept in which fusion plasma could be produced by applying 2 MV along a thin filament of frozen deuterium, 20-30 ..mu..m in diameter, 5-10 cm long. The megamp-range currents that result would ohmically heat the fiber to fusion temperatures in 100 ns while maintaining nearly constant radius. The plasma pressure would be held stably by the self-magnetic field for many radial sound transit times during the current-rise phase while, in the case of D-T, a significant fraction of the fiber undergoes thermonuclear fusion. This paper presents results of Los Alamos HDZP studies. Existing and new experiments are described. A succession of theoretical studies, including 1D self-similar and numerical studies of the hot plasma phase, 1D and 2D numerical studies of the cold startup phase, and 3D numerical studies of stability in the hot regime, are then presented. 9 refs., 4 figs.

Glasser, A.H.; Hammel, J.E.; Lewis, H.R.; Lindemuth, I.R.; McCall, G.H.; Nebel, R.A.; Scudder, D.W.; Schlachter, J.S.; Lovberg, R.H.; Rosenau, P.; Sheehey, P.T.

1988-01-01

113

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

114

Diagnostics for Z-pinch implosion experiments on PTS  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

115

Study of gas-puff Z-pinches on COBRA  

NASA Astrophysics Data System (ADS)

Gas-puff Z-pinch experiments were conducted on the 1 MA, 200 ns pulse duration Cornell Beam Research Accelerator (COBRA) pulsed power generator in order to achieve an understanding of the dynamics and instability development in the imploding and stagnating plasma. The triple-nozzle gas-puff valve, pre-ionizer, and load hardware are described. Specific diagnostics for the gas-puff experiments, including a Planar Laser Induced Fluorescence system for measuring the radial neutral density profiles along with a Laser Shearing Interferometer and Laser Wavefront Analyzer for electron density measurements, are also described. The results of a series of experiments using two annular argon (Ar) and/or neon (Ne) gas shells (puff-on-puff) with or without an on- (or near-) axis wire are presented. For all of these experiments, plenum pressures were adjusted to hold the radial mass density profile as similar as possible. Initial implosion stability studies were performed using various combinations of the heavier (Ar) and lighter (Ne) gasses. Implosions with Ne in the outer shell and Ar in the inner were more stable than the opposite arrangement. Current waveforms can be adjusted on COBRA and it was found that the particular shape of the 200 ns current pulse affected on the duration and diameter of the stagnated pinched column and the x-ray yield.

Qi, N.; Rosenberg, E. W.; Gourdain, P. A.; de Grouchy, P. W. L.; Kusse, B. R.; Hammer, D. A.; Bell, K. S.; Shelkovenko, T. A.; Potter, W. M.; Atoyan, L.; Cahill, A. D.; Evans, M.; Greenly, J. B.; Hoyt, C. L.; Pikuz, S. A.; Schrafel, P. C.; Kroupp, E.; Fisher, A.; Maron, Y.

2014-11-01

116

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

117

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

Microsoft Academic Search

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

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

2001-01-01

118

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

119

Absorption coefficient of aluminum near the critical point and the consequences on high-power nanosecond laser ablation  

NASA Astrophysics Data System (ADS)

During nanosecond laser ablation, the absorption coefficient determines the laser energy deposition in the target, the accurate knowledge of which near the material critical point is crucial for understanding the fundamental physics of high-power nanosecond laser ablation. In this letter, the absorption coefficient of aluminum near the critical point is calculated through the Drude model based on the measured electrical conductivity data, and its effect on laser ablation is investigated numerically using a heat transfer model. The result supports the experimental observations that phase explosion occurs for the ablation of aluminum by sufficiently intense laser pulses, and the model predicted phase explosion threshold is consistent with experimental measurements.

Wu, Benxin; Shin, Yung C.

2006-09-01

120

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

121

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

PubMed

For the first time, a geometry has been developed to allow for an axial imaging system for wire-array Z-pinch experiments that produce high-resolution x-ray images. The new geometry required a significant redesign of the electrode hardware. Calibrated areal density measurements of the Z-pinch plasma including wire cores, coronal plasma, streaming plasma, and the precursor were obtained. The system used eight-wire molybdenum (Mo) X pinches in series with and directly below the Z-pinch axis to provide micron-scale x-rays sources for point-projection radiography. The images formed on the x-ray sensitive film had a 15 mm diameter field of view at the center height of the array and a magnification of about 7.5:1. Titanium (Ti) filters in front of the film transmitted radiation in the spectral range of 3-5 keV. For calibration, a separate film with the same thickness Ti filter was placed the same distance from the X pinch. This film had an unobstructed path that bypasses the Z-pinch but included step wedges for calibration of the Z-pinch plasma. The step wedges had thicknesses of tungsten (W) ranging from 0.015 to 1.1 microm to obtain areal density measurements of the W plasma from the wire-array. Images had subnanosecond temporal resolution and about 10 microm spatial resolution. PMID:20059143

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

2009-12-01

122

Study of instabilities in wire-array Z pinches at stagnation  

NASA Astrophysics Data System (ADS)

Stagnation of the wire array Z pinches was studied at a 1 MA generator with imaging UV and x-ray diagnostics. Cylindrical, linear, and star wire-array Z pinches present different sets of instabilities seeded to the pinch during implosion. Compact cylindrical wire arrays implode to Z-pinches with m=0 necks associated with bright spots on x-ray images. The electron temperature of bright spots measured with K-shell spectroscopy is higher by 20-40% compared to cold areas. Maximum x-ray power is generated by Z pinches with strong instabilities. Fast plasma motion with a velocity >100 km/s was observed in the Z pinch at stagnation with two-frame shadowgraphy. Plasma instabilities may present a mechanism for conversion of magnetic energy to kinetic energy. Comparison of the implosions in small-diameter cylindrical and star wire array shows that the secondary implosion of non-imploded peripheral plasma prolongs the stagnation stage and provides the enhanced x-ray production. Development of instabilities in wire arrays is in agreement with 3D MHD Gorgon simulations.

Ivanov, V. V.; Chittenden, J. P.; Mancini, R. C.; Papp, D.; Niasse, N.; Altemara, S. D.; Anderson, A. A.

2012-10-01

123

X ray emission scaling and energy balance of small gas-puff Z-pinch  

Microsoft Academic Search

Gas-puff Z-pinch is discussed as an intensive pulsed source of soft x-rays. Measurements of total x-ray yield Y(sub T) and the yield Y(sub K) from K-shells of highly-ionized atoms of argon, neon, and nitrogen are presented. The radiation produced by small (4.3 kJ) gas-puff Z-pinch confirmed the Y(sub K) approximately equal to I(sup 4) scaling (well-known from large devices) also

Ales Krejci

1992-01-01

124

X-ray emission scaling and energy balance of small gas-puff Z-pinch  

Microsoft Academic Search

Gas-puff Z-pinch is discussed as an intensive pulsed source of soft X-rays. Measurements of total X-ray yield YT and the yield YK from K shells of highly ionized atoms af argon, neon, and nitrogen are presented. The radiation produced by a small-scale (4.3 kJ) gas-puff Z-pinch confirmed the YK approximately=I4 scaling (well known from large devices) for pinch currents I=120-200

A. Krejci

1992-01-01

125

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

126

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

127

Recent Wire-Array Z-Pinch Experiments at Imperial College  

NASA Astrophysics Data System (ADS)

Recent wire-array Z-pinch experiments performed on the MAGPIE generator at Imperial College are presented. Experiments have been conducted using a variety of array configurations, including radial wire arrays, cylindrical arrays, and coiled arrays. This research was sponsored by Sandia National Laboratories, Albuquerque; and the NNSA under DOE Cooperative Agreement DE-F03-02NA00057.

Hall, Gareth; Lebedev, Sergey; Chittenden, Jeremy; Bland, Simon; Suzuki-Vidal, Francisco; Harvey-Thompson, Adam; Swadling, George; Niasse, Nicolas; Palmer, James

2008-11-01

128

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

129

Deuteron Acceleration and Fusion Neutron Production in Z-pinch plasmas  

SciTech Connect

Fusion neutron measurements were carried out on the S-300 generator (Kurchatov Institute, Moscow). We tried deuterated fibers, various types of wire arrays imploding onto a deuterated fiber, and deuterium gas puffs as Z-pinch loads. On the current level of 2 MA, the peak neutron yield of 10{sup 10} was achieved with a deuterium gas-puff. The neutron and deuteron energy spectra were quite similar in various types of Z-pinch configurations. The broad width of radial neutron spectra implied a high radial component of deuteron velocity. On the basis of neutron measurements, we concluded that neutron production mechanism is connected with the study of plasma voltage. It means that the acceleration of fast deuterons is not a secondary process but it reflects the global dynamics of Z-pinch plasmas. For this reason it is useful to add deuterium as a 'tracer' in Z-pinch loads more often. For instance, it seems attractive to prepare wire-arrays from deuterated metal wires such as Pd.

Klir, D.; Kravarik, J.; Kubes, P.; Rezac, K. [Czech Technical University, Faculty of Electrical Engineering, Department of Physics, Technicka 2, 166 27 Prague 6 (Czech Republic); Ananeev, S. S.; Bakshaev, Yu. L.; Blinov, P. I.; Chernenko, A. S.; Kazakov, E. D.; Korolev, V. D.; Ustroev, G. I. [Russian Research Center Kurchatov Institute, 1 Kurchatov Sq., 123182 Moscow (Russian Federation)

2009-01-21

130

Magnetic Rayleigh-Taylor instability mitigation in large-diameter gas puff Z-pinch implosions  

SciTech Connect

Recently, a new approach for efficiently generating K-shell x-rays in large-diameter, long-implosion time, structured argon gas Z-pinches has been demonstrated based on a 'pusher-stabilizer-radiator' model. In this paper, direct observations of the Rayleigh-Taylor instability mitigation of a 12-cm diameter, 200-ns implosion time argon Z-pinch using a laser shearing interferometer (LSI) and a laser wavefront analyzer (LWA) are presented. Using a zero-dimensional snowplow model, the imploding plasma trajectories are calculated with the driver current waveforms and the initial mass distributions measured using the planar laser induced fluorescence method. From the LSI and LWA images, the plasma density and trajectory during the implosion are measured. The measured trajectory agrees with the snowplow calculations. The suppression of hydromagnetic instabilities in the ''pusher-stabilizer-radiator'' structured loads, leading to a high-compression ratio, high-yield Z-pinch, is discussed. For comparison, the LSI and LWA images of an alternative load (without stabilizer) show the evolution of a highly unstable Z-pinch.

Qi, N.; Sze, H.; Failor, B. H.; Banister, J.; Levine, J. S.; Riordan, J. C.; Steen, P.; Sincerny, P. [L-3 Communications Pulse Sciences, San Leandro, California 94577 (United States); Lojewski, D. [Defense Threat Reduction Agency, Albuquerque, New Mexico 87117 (United States)

2008-02-15

131

Fully electromagnetic particle-in-cell simulations of a deuterium gas puff z-pinch  

Microsoft Academic Search

A deuterium gas puff z-pinch has been shown to be a significant source of neutrons. Early experiments measured neutron yields that were not thermonuclear in origin but likely driven by instabilities. Subsequent experiments including recent 15 MA experiments on the Z accelerator2 have suggested that the dominant process is thermonuclear. The neutron yield has been shown to scale strongly with

D. R. Welch; D. V. Rose; W. A. Stygar; R. J. Leeper

2008-01-01

132

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

Microsoft Academic Search

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

Christine A. Coverdale

2006-01-01

133

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

Microsoft Academic Search

The Cornell University COBRA pulser is a nominal 1 MA machine, capable of driving up to 32 wire cylindrical Z-pinch arrays. COBRA can operate with variable current risetimes ranging from 100 ns to 200 ns (short and long pulse, respectively). Wires are typically strung with a “press” contact to the electrode hardware, where the wire is loosely pulled against the

D. A. Chalenski; B. R. Kusse; J. B. Greenly; I. C. Blesener; R. D. McBride; D. A. Hammer; P. F. Knapp

2009-01-01

134

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

Microsoft Academic Search

The Cornell University COBRA pulser is a nominal 1 MA machine, capable of driving up to 32 wire cylindrical Z-pinch arrays. COBRA can operate with variable current risetimes ranging from 100 ns to 200 ns (short and long pulse, respectively). Wires are typically strung with a ``press'' contact to the electrode hardware, where the wire is loosely pulled against the

D. A. Chalenski; B. R. Kusse; J. B. Greenly; I. C. Blesener; R. D. McBride; D. A. Hammer; P. F. Knapp

2009-01-01

135

The Effect of Radial Electric Fields on Plasma Formation in Wire Array Z-Pinches  

Microsoft Academic Search

Summary form only given. We will present experimental observations of the effect of the radial electric field on plasma formation and implosion dynamics in wire array Z-pinches. Experiments were performed on the 1 MA MAGPIE generator, with 8 mm diameter Al wire arrays in configurations in which the polarity of the radial electric field was reversed midway along the wires

S. V. Lebedev; S. N. Bland; D. J. Ampleford; S. C. Bott; J. P. Chittenden; C. Jennings; M. G. Haines; G. N. Hall; J. B. A. Palmer; J. A. Gomez; I. H. Mitchell; D. A. Hammer

2005-01-01

136

Thermohydraulic Analysis of the Z-Pinch Power Plant Primary Cycle  

Microsoft Academic Search

In this paper, we investigate the thermohydraulic characteristics of the Z-pinch power plant (ZIFE) primary cycle. The generation of electric energy using a power cycle is possible only if a minimum operating temperature is achieved and maintained in the primary cycle. Many energy losses are associated with the operation of the primary cycle. These thermal and pressure losses have a

M. A. Modesto; C. W. Morrow; E. R. Lindgren; V. L. Vigil

2005-01-01

137

Use of Faraday probing to estimate current distribution in wire array z pinches  

Microsoft Academic Search

In order to understand the formation and dynamics of plasma in wire array z-pinch experiments, measurements of the distribution of current throughout the array are required. We present details of two Faraday probing diagnostics aimed at exploring the magnetic fields and hence distribution of current in an array. An imaging Faraday system utilizes a short laser pulse to make estimates

S. N. Bland; D. J. Ampleford; S. C. Bott; A. Guite; G. N. Hall; S. M. Hardy; S. V. Lebedev; P. Shardlow; A. Harvey-Thompson; F. Suzuki; K. H. Kwek

2006-01-01

138

Development of laser based diagnostics for wire array z-pinch experiments on the MAGPIE generator  

Microsoft Academic Search

End on Interferometric imaging is a useful technique for diagnosing the electron density distribution in the interior of wire array z-pinches during their ablation phase. These measurements are limited as there is often no known density reference point in the image. By using a time resolved, CW line integrated interferometry system, we can measure the electron density for a single

George Swadling; S. V. Lebedev; S. N. Bland; G. N. Hall; F. Suzuki-Vidal; N. Niasse; G. Burdiak; E. Khoory; L. Pickworth; C. Hutchison

2009-01-01

139

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

140

Investigation of the Internal Structure of the Dense Z-Pinch  

NASA Astrophysics Data System (ADS)

UV laser probing at the wavelength of 266 nm was applied for investigation of wire-array Z-pinches at the Zebra generator. A fine structure of the 1 MA stagnated pinch was observed in unprecedented details. Kink instability with loop-like structures, disruptions, and micropinches were observed in Z-pinches at the peak of the x-ray pulse and later in time. Micropinches with the diameters of 60-90 ?m are located inside necks of lower-density plasma. Instability with a period of 70-200 ?m was observed on the edges of Z-pinches. Micron-scale density perturbations were observed in the precursor plasma and in the current carrying areas of the dense pinch. A homogeneous Z pinch plasma column was observed in star wire arrays. Development of instabilities was compared with 3D MHD Gorgon simulations. The Gorgon modeling is in good agreement with implosion and stagnation scenarios observed in two very different cylindrical and star wire arrays.

Ivanov, V. V.; Chittenden, J. P.; Altemara, S. D.; Niasse, N.; Hakel, P.; Mancini, R. C.; Papp, D.; Anderson, A. A.; Astanovitskiy, A. L.; Nalajala, V.

2011-11-01

141

Radiation science using Z-pinch x raysa... J. E. Bailey,1,b)  

E-print Network

Radiation science using Z-pinch x raysa... J. E. Bailey,1,b) G. A. Chandler,1 D. Cohen,2 M. E 200 TW peak power, 5­10 ns duration x-ray bursts that provide new possibilities to advance radiation away from the pinch, where it is heated to 10­100 eV temperatures by the pinch radiation

Cohen, David

142

STARFISH 1 - Towards a compact 1MA pulsed power generator for z-pinch applications  

Microsoft Academic Search

The design and construction of STARFISH, a series of compact compact pulsed power generators to drive advanced z-pinch experiments, for applications such soft X-ray generation and as a high density plasma diagnostic, is being developed in Oxford. The design for these machines is based on the use of many very low impedance distributed pulse forming lines (PFLs) or discrete pulse

Paul W. Smith

2008-01-01

143

Discrete pulse forming lines for a compact z-pinch pulsed power generator  

Microsoft Academic Search

A new design for a 1 MA pulsed power supply to drive a z-pinch is being developed in Oxford. The new design avoids the use of very high voltage Marx generators and water pulse forming lines that are usually used in such designs. It should also be far more reliable and capable of a much higher repetition rate, provided the

Paul W. Smith

2007-01-01

144

Plasma channel and Z-pinch dynamics for heavy ion transport  

SciTech Connect

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

Ponce-Marquez, David

2002-07-09

145

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

SciTech Connect

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

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

2014-06-09

146

K-shell radiation physics in low-to moderate-atomic-number z-pinch plasmas on the Z accelerator.  

SciTech Connect

Dense z-pinches produced by 100 ns implosions of wire arrays or gas puffs produce substantial soft X-ray power. One class of z-pinch radiation sources includes low- to moderate-atomic-number K-shell radiators, such as aluminum and iron. These loads are designed for 1-10 keV K-shell X-ray generation, and offer opportunities for crystal spectroscopy that can reveal fundamental properties of the plasma when studied using plasma spectroscopic modeling. Typically these plasmas are characterized by ion densities of {approx} 10{sup 20} cm{sup -3}, diameters of 1-5 mm, electron temperatures up to several keV, and a range of opacities of the K-shell lines. Measurements from wire arrays on Sandia's 20 MA Z accelerator are presented along with collisional radiative and hydrodynamic simulations. The impact of opacity and 3D structure on non-LTE, non-diffusive radiation transport and X-ray production is discussed.

Clark, Robert W. (Naval Research Laboratory, Washington, DC); Maron, Yitzhak (Weizmann Institute of Science, Rehovot, Israel); Davis, J. (Naval Research Laboratory, Washington, DC); Apruzese, John P. (Naval Research Laboratory, Washington, DC); Whitney, Ken G. (Naval Research Laboratory, Washington, DC); LePell, Paul David (Ktech Corporation, Albuquerque, NM); Velikovich, Aleksandr Lazarevich (Naval Research Laboratory, Washington, DC); Deeney, Christopher E.; McKenney, John Lee; Thornhill, Joseph W. (Naval Research Laboratory, Washington, DC); Oreshkin, V. I. (High Current Electronics Institute, Tomsk, Siberia, Russia); Kantsyrev, Victor Leonidovich (University of Nevada, Reno, NV); Coverdale, Christine Anne; Jones, Brent Manley; Safronova, Alla S. (University of Nevada, Reno, NV)

2004-12-01

147

Numerical simulations of annular wire-array z-pinches in (x,y), (r,{theta}), and (r,z) geometries  

SciTech Connect

The Total Immersion PIC (TIP) code has been used in several two-dimensional geometries to understand better the measured dynamics of annular, aluminum wire-array z-pinches. The areas investigated include the formation of the plasma sheath from current-induced individual wire explosions, the effects of wire number and symmetry on the implosion dynamics, and the dependence of the Rayleigh-Taylor instability growth on initial sheath thickness. A qualitative change in the dynamics with increasing wire number was observed, corresponding to a transition between a z-pinch composed of non-merging, self-pinching individual wires, and one characterized by the rapid formation and subsequent implosion of a continuous plasma sheath. A sharp increase in radiated power with increasing wire number has been observed experimentally near this calculated transition. Although two-dimensional codes have correctly simulated observed power pulse durations, there are indications that three dimensional effects are important in understanding the actual mechanism by which these pulse lengths are produced.

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

1997-12-01

148

Study of implosion dynamics of Z-pinch dynamic hohlraum on the Angara-5-1 facility  

NASA Astrophysics Data System (ADS)

The Z-pinch dynamic hohlraum (ZPDH) is one of high-power X-ray sources that has been used in a variety of high energy-density experiments including inertial confinement fusion (ICF) studies. Dynamic hohlraums driven by a 12-mm and a 18-mm-diameter single tungsten wire arrays embedded with a C16H20O6 foam, respectively, exhibit no visible differences in radiation from the axial exit, although the radial radiation is a little higher in a large array. The analysis of the images suggests that the implosion of a large array is quasi-continuous and has a faster imploding velocity, indicating that the large array is matched to the embedded foam and, oppositely, the small array is mismatched. The analysis also shows that the Rayleigh-Taylor instability develops much harder in implosions of a large array, and this leads to a lower hohlraum temperature. The conclusion was drawn that, for the purpose of enhancing the hohlraum temperature, increasing the conversion efficiency of kinetic energy into thermal energy is more important than increasing the kinetic energy from wire plasma.

Zhang, Faqiang; Xu, Rongkun; Xu, Zeping; Yang, Jianlun; Li, Zhenghong; Xia, Guangxin; Ning, Jiamin; Li, Linbo; Chen, Dingyang; Chen, Jinchuan

2015-02-01

149

Advances in experimental spectroscopy of Z-pinch plasmas and applications  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

150

Comparison of Z-pinch and theta pinch driven solid liner implosions  

NASA Astrophysics Data System (ADS)

An analytic and computational comparison of Z-pinch and theta pinch driven implosions of metal shells (solid liners) is presented. The liners are Al, 30 cm long, 10 cm diameter, and 0.1 cm thick. The circuit parameters are appropriate for the 1300 microfarad Shiva Star capacitor bank, operated at 80 kilovolt charge voltage. The initial inductance used for this study is 35 nanohenries. The series resistance includes a safety fuse and a milliohm external resistance. Both Z and theta schemes are feasible, and have different advantages for compressing plasmas to Magnetized Target Fusion (MTF) conditions. The Z-pinch approach has experimentally demonstrated 35megajoules) to implosion kinetic energy (1.5 megajoules), with 13 times radial convergence of the inner liner surface, with good symmetry. The theta pinch approach has potential for purer and easier injection of Field Reversed Configurations, easier diagnostic access, and may be more easily operated repetitively.

Degnan, J. H.; Turchi, P. J.; Siemon, R. E.

2001-10-01

151

Ablation of wires in an inverse wire array z-pinch  

NASA Astrophysics Data System (ADS)

We describe experiments on the MAGPIE facility (1MA, 250ns) with inverse wire array z-pinches, in which the wires act as a return current cage placed around a central current conductor. In this configuration the plasma ablated from the wires is pushed by the JxB force in the radially outward direction and expands into the region free of the magnetic field. This allows quantitative characterisation of the plasma ablated from an individual wire using laser interferometry, X-ray radiography and XUV imaging. The inverse z-pinch configuration also allows to measure separately the contribution to the inductance coming from the ``private'' magnetic flux of the wires and thus to evaluate the size of the current-carrying region around the wire cores. Quantitative information obtained in these experiments will be compared with results of 3-D MHD computer simulations.

Lebedev, Sergey; Hall, G. N.; Bland, S. N.; Suzuki-Vidal, F. A.; Chittenden, J. P.; Jennings, C.; Harvey-Thompson, A.; Ning, Cheng; Palmer, J. B. A.

2007-11-01

152

Determination of the inductance of imploding wire array Z-pinches using measurements of load voltage  

NASA Astrophysics Data System (ADS)

The inductance of imploding cylindrical wire array z-pinches has been determined from measurements of load voltage and current. A thorough analysis method is presented that explains how the load voltage of interest is found from raw signals obtained using a resistive voltage divider. This method is applied to voltage data obtained during z-pinch experiments carried out on the MAGPIE facility (1.4 MA, 240 ns rise-time) in order to calculate the load inductance and thereafter the radial trajectory of the effective current sheath during the snowplough implosion. Voltage and current are monitored very close to the load, allowing these calculations to be carried out without the need for circuit modelling. Measurements give a convergence ratio for the current of between 3.1 and 5.7 at stagnation of the pinch.

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

2013-03-01

153

Origin of the interaction pulse in Nested Wire Array Z-pinches  

NASA Astrophysics Data System (ADS)

The interaction pulse emitted by nested wire array z-pinches on the Z-generator is critical to achieving the required x-ray pulse shape for z-pinch driven ICF schemes. We discuss data from the MAGPIE generator which indicates this interaction pulse is likely to be caused by the presence of the inner array creating bow shocks in the ablation streams from the outer array, and hence enhancing the prefill density at this location. As the outer array implodes, it snowplows the prefilled material, radiating excess kinetic energy as snowplow radiation. The enhanced density due to shocked prefill around the inner wires boosts the snowplow, and is seen as the interaction radiation pulse. This understanding agrees with data from Z, which indicates that the interaction pulse is independent of the inner array parameters, and decreases with increasing outer array mass. Comparisons of this model to recent data on the refurbished Z generator will also be discussed.

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

2008-11-01

154

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

155

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

156

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

SciTech Connect

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

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

2014-05-15

157

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

158

History of HERMES III diode to z-pinch breakthrough and beyond : learning about pulsed power and z-pinch ICF.  

SciTech Connect

HERMES III and Z are two flagship accelerators of Sandia's pulsed-power program developed to generate intense-ray fields for the study of nuclear radiation effects, and to explore high energy-density physics (including the production of intense x-ray fields for Inertia Confinement Fusion [ICF]), respectively. A diode at the exit of HERMES III converts its 20-MeV electron beam into-rays. In contrast, at the center of Z, a z-pinch is used to convert its 20-MA current into an intense burst of x-rays. Here the history of how the HERMES III diode emerged from theoretical considerations to actual hardware is discussed. Next, the reverse process of how the experimental discovery of wire-array stabilization in a z-pinch, led to a better theory of wirearray implosions and its application to one of the ICF concepts on Z--the DH (Dynamic Hohlraum) is reviewed. Lastly, the report concludes with how the unexpected axial radiation asymmetry measured in the DH is understood. The first discussion illustrates the evolution of physics from theory-to-observationto- refinement. The second two illustrate the reverse process of observationto- theory-to refinement. The histories are discussed through the vehicle of my research at Sandia, illustrating the unique environment Sandia provides for personal growth and development into a scientific leader.

Sanford, Thomas W. L.

2013-04-01

159

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

160

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

Microsoft Academic Search

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

M. G. Haines

1982-01-01

161

The influence of temperature gradients on the distribution of axial current in a large current Z-pinch implosion  

Microsoft Academic Search

General algebraic expressions for the tensor electrical conductivity and heat conductivity are presented that are needed in one-dimensional (1-D) magnetohydrodynamic modeling of Z-pinch implosions. The expressions contain both the ionization state and the magnetic field dependence of these quantities and generalize Braginskii's results. The ionization dependence is important in any description of a Z-pinch's implosion dynamics, since substantial ionization occurs

K. G. Whitney; J. W. Thornhill

1998-01-01

162

Measurement and analysis of argon continuum radiation from a 12CM diameter gas puff Z pinch at 6MA  

Microsoft Academic Search

Summary form only given. Absolute measurement of the free-bound (FB) continuum spectrum above the K-shell from atomic-number Z ges 10 Z-pinches can be a useful diagnostic tool to obtain the electron temperature and the ion density of a hot, radiating Z-pinch. These measurements are also of interest for benchmarking continuum radiation models associated with the use of this high-photon-energy radiation

F. C. Young; J. P. Apruzese; R. J. Commisso; D. Mosher; D. P. Murphy; A. L. Velikovich; P. L. Coleman; J. W. Banister; B. H. Failor; J. S. Levine; N. Qi; H. M. Sze

2006-01-01

163

Influence of gas density distribution on the pinch process in gas-puff Z-pinch scheme  

Microsoft Academic Search

Spatial distribution of the incident gas significantly influences the pinch process in gas-puff Z pinch schemes. This paper shows the dependence of the plasma formation on the distribution of the gas puffed into the discharge region. Temporary and spatially resolved gas density between the Z-pinch electrodes was measured by using a high-sensitive multi-channel laser interferometer. Also, plasma density distribution was

S. Katsuki; K. Murayama; T. Nishi; I. V. Lisitsyn; H. Akiyama

1999-01-01

164

The effect of the puffed gas shell profile on plasma dynamics in a small gas-puff Z-pinch  

Microsoft Academic Search

This paper reports on an argon annular gas-puff Z-pinch that has been experimentally investigated with three different nozzles. The puffed gas shell profiles and the plasma implosion have been measured using a fast ionization gauge and a differential interferometer. These experiments confirm that both the puffed gas density and its distribution may effect the compression process of Z-pinch plasma.

C. R. Li; T. C. Yang; C. M. Luo; M. Han

1992-01-01

165

Reduction of the source size of gas-puff z-pinch plasmas using an inductive pulsed power system  

Microsoft Academic Search

A small scale inductive pulsed power (IPP) generator with copper wire fuses as an opening switch has been applied to an argon gas-puff z-pinch plasma which can be used as a point source for x-ray lithography. The IPP generator with fuses supplies a driving current of 60 kA in 400 ns to the z-pinch plasma. Without fuses, the generator serves

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

2000-01-01

166

Behavior of the gas-puff z-pinch plasma during the initial phase of discharge in IPP method  

Microsoft Academic Search

Previous gas-puff z-pinch experiments in our study showed that spatial stability of hot spots in radial direction was obtained by using an inductive pulsed power generator. However, it was confirmed that the injected gas was expanded to radial direction during initial phase of discharge. Therefore it was thought that the compressing process and z-pinch characteristics were influenced by the shape

K. Imasaka; T. Masaki; K. Kawazoe; J. Suehiro; M. Hara

2000-01-01

167

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

168

Fully Kinetic Particle-in-Cell Simulations of a Deuterium Gas Puff z Pinch  

SciTech Connect

We present the first fully kinetic, collisional, and electromagnetic simulations of the complete time evolution of a deuterium gas puff z pinch. Recent experiments with 15-MA current pinches have suggested that the dominant neutron-production mechanism is thermonuclear. We observe distinct differences between the kinetic and magnetohydrodynamic simulations in the pinch evolution with the kinetic simulations producing both thermonuclear and beam-target neutrons. The kinetic approach demonstrated in this Letter represents a viable alternative for performing future plasma physics calculations.

Welch, D. R.; Rose, D. V.; Clark, R. E.; Mostrom, C. B.; Stygar, W. A.; Leeper, R. J. [Voss Scientific, LLC, Albuquerque, New Mexico 87108 (United States); Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

2009-12-18

169

VUV ablation of polymers by emission from gas-puff Z-pinch plasmas  

Microsoft Academic Search

We have made experiments of the polymer ablation utilizing the gas-puff Z-pinch plasmas which provide a highly bright emission extending over a broad wavelength range from visible lights to X-rays. When the emission was irradiated through a mask onto a polytetrafluoroethylene (PTFE) film, the irradiated area was ablated and a pattern of the mask was copied on the surface of

H. Deno; S. Sugiyama; Y. Kakudate; M. Yoshida; S. Fujiwara

1996-01-01

170

The Plasma Column Evolution in Gas-Puff Z-Pinches on the Yang Accelerator  

Microsoft Academic Search

The plasma column evolution in gas-puff z-pinch was investigated on the Yang accelerator. The pinch process was significantly influenced by the initial gas distribution. Uniformity of the gas-puff distribution resulted in the asymmetry of the initially load current through the main channels of the plasma layer. The zipper velocity and implosion speed under ``trumpet'' distribution was given, it was observed

Jianjun Deng; Libing Yang; Yuanchao Gu; Xianbing Huang; Fengping Li; Zeping Xv; Shican Ye; Guanghua Cheng; Lihua Chang; Shaotong Zhou; Siqun Zhang; Weiping Xie; Bonan Ding; Xianjue Peng

2006-01-01

171

Generation of high magnetic fields using a gas-puff Z pinch  

Microsoft Academic Search

The imploding plasma column of a gas-puff Z pinch was used to compress an embedded axial magnetic field. Field compression ratios up to 180 times and peak compressed fields up to 1.6 MG were measured by Faraday rotation. Field compression by this method has the advantage of high repetition rate for applications in the controlled production of high-energy densities, solid-state

F. J. Wessel; F. S. Felber; N. C. Wild; H. U. Rahman; A. Fisher; E. Ruden

1986-01-01

172

Fully Kinetic Particle-in-Cell Simulations of a Deuterium Gas Puff z Pinch  

Microsoft Academic Search

We present the first fully kinetic, collisional, and electromagnetic simulations of the complete time evolution of a deuterium gas puff z pinch. Recent experiments with 15-MA current pinches have suggested that the dominant neutron-production mechanism is thermonuclear. We observe distinct differences between the kinetic and magnetohydrodynamic simulations in the pinch evolution with the kinetic simulations producing both thermonuclear and beam-target

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

2009-01-01

173

Compression of ultrahigh magnetic fields in a gas-puff Z pinch  

Microsoft Academic Search

Evidence is presented that an axial magnetic field of 100 kG has been compressed to 42 MG by an imploding neon gas-puff Z pinch on a 800 kJ, 7.5 MA, 60 nsec pulsed power generator. Machine electrical diagnostics and x-ray pinhole photographs indicate that this 420-fold field compression was produced by imploding plasma at high magnetic Reynolds number.

F. S. Felber; M. M. Malley; F. J. Wessel; M. K. Matzen; M. A. Palmer; R. B. Spielman; M. A. Liberman; A. L. Velikovich

1988-01-01

174

Kinetic simulation of neutron production in a deuterium z-pinch  

Microsoft Academic Search

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

Dale Welch; David Rose; William Stygar; Ramon Leeper

2009-01-01

175

A small gas puff Z-pinch X-ray source  

Microsoft Academic Search

The gas puff Z-pinch is an intense pulsed plasma X-ray source energized by a capacitor bank. Typically 5-10 percent of the electrical energy stored in the bank is converted into X-ray radiations with wavelengths less than 100 A. Such devices have applications in X-ray microscopy, lithography, spectroscopy and X-ray optics engineering. Here the results of a parametric study of the

P. Choi; A. E. Dangor; C. Deeney

1987-01-01

176

Observation of an Electron Beam in an Annular Gas-Puff Z-Pinch Plasma Device  

Microsoft Academic Search

We report on the first observation of an electron beam formed in an argon gas-puff Z pinch at the time of pinch. An on-axis Faraday cup in conjunction with thin foil filters was used to measure the beam parameters. The beam has a pulse width of 4 ns, a peak current on the order of 10 kA, and an energy

D. R. Kania; L. A. Jones

1984-01-01

177

Soft x-ray spectra from a gas-puff z pinch  

Microsoft Academic Search

XUV and x-ray emission spectra of the elements carbon, oxygen, neon, and argon, in the spectral range 3–300 A?, generated in a gas-puff z pinch, are presented. The spectra are analyzed to give time-integrated measurements of the density, electron temperature, and dimensions of the imploded plasma and the ‘‘hot spots’’ that often occur in the gas-puff pinch. In particular, dielectronic

G. Nave; C. D. Challis; A. E. Dangor; J. G. Lunney

1989-01-01

178

Characterization of 12 cm Diameter Triple-shell Gas Puff Z-pinch Loads  

Microsoft Academic Search

To mitigate the Rayleigh-Taylor instability and thus increase the x-ray yield, shell-on-shell gas puff loads have been studied on high current z-pinch drivers such as Double-EAGLE, DQ and Z. A triple-shell gas puff has been developed, where a gas jet is introduced in the center and the outer and inner gas shell radii are 5.5 and 2.5 cm, respectively. We

Niansheng Qi; Jeff Banister; Sophie Chantrenne; Bruce Failor; Jerry Levine; Paul Steen; Henry Sze; Yuanxu Song

2003-01-01

179

Electromagnetic kinetic simulations of a deuterium gas puff z-pinch  

Microsoft Academic Search

Summary form only given: A deuterium gas puff z-pinch has been shown to be a significant source of neutrons. Recent experiments on the Z accelerator at 15 MA current have suggested that the dominant process is thermonuclear. This process has been shown to have a favorable neutron yield scaling with current Yn~I. In this paper, we present results from 1D

D. R. Welch; D. V. Rose; W. A. Stygar; R. J. Leeper

2009-01-01

180

Two Dimensional Modeling of Double shell Argon Gas Puff Z-Pinch Implosions on Decade Quad  

Microsoft Academic Search

Two dimensional radiation magneto-hydrodynamic simulations of double shell argon gas puff Z-pinch implosions on Decade Quad (DQ) are performed. These calculations utilize the Mach2 hydrodynmics code that has been modified to include a tabular collisional radiative equilibrium (TCRE) treatment of radiation transport and ionization dynamics.(J. W. Thornhill, et al., Phys. of Plasmas 8, 3480 (2001).) This treatment contains more realistic

J. W. Thornhill; Y. K. Chong; J. Giuliani; J. Davis; H. Sze; J. S. Levine; B. H. Failor; C. Deeney; C. A. Coverdale

2002-01-01

181

Gas-puff z-pinch plasmas driven by inductive energy storage pulsed power generator  

Microsoft Academic Search

ASO-II, an inductive energy storage pulsed power generator developed at Kumamoto University, is used as a power source for gas-puff z-pinch plasmas. The plasma characteristics are compared with those generated by a fast capacitive bank that supplies the same energy. Also, solid and mesh cathode electrodes are compared with respect to the pinch behavior. Using ASO-II in the case of

K. Murayama; T. Shinkai; S. Katsuki; H. Akiyama

1997-01-01

182

High-fidelity three dimensional MHD simulations of argon gas-puff Z-pinches  

Microsoft Academic Search

Summary form only given. We have performed 3-D, resistive, magnetohydrodynamic (MHD) simulations with MACH3 of argon gas-puff Z-pinches inside an array of 12 current return posts from realistic initial conditions using a collisional radiative equilibrium (CRE) model to predict K-shell and L-shell radiation output. Initial gas puff conditions, including densities, temperatures, and velocities were imported from a 2-D azimuthally symmetric

M. H. Frese; S. D. Frese

2006-01-01

183

Gas-puff Z-pinch on pulsed power generator with self-crowbar switch  

Microsoft Academic Search

Recent developments in pulsed power technology have increased interest in gas-puff Z-pinches as soft X-ray sources and for nuclear fusion. The pulse width of the pulsed power is extremely short, i.e. several tens of nanosecond, in comparison with the pulse width of the fast bank. Therefore, high current density is necessary to realize pinch phenomena within the pulse width. A

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

1989-01-01

184

Experimental study of a gas-puff Z-pinch plasma  

Microsoft Academic Search

A small gas-puff Z-pinch plasma device driven by a capacitor bank (12 ?f, 3.75 kJ) is reported. The current reaches the maximum of 200 kA in about 2.2 ?s. A supersonic (March 4) flow nozzle is used to feed argon into the discharge chamber. The gas density profile, the discharge current, the rate of current rise, the compression process of

C. R. Li; T. C. Yang; M. Han; C. M. Luo

1989-01-01

185

X-ray results from a modified nozzle and double gas puff z pinch  

Microsoft Academic Search

The nozzle and the anode of the UCI (University of California, Irvine) z-pinch facility were modified to study the influence of the anode-cathode geometrical structure on the stability of the pinch and the x-ray yield of the pinch. The anode was modified from a honey-comb to a hollow cylinder with a 4-cm diameter and a ?3.5-mm wall thickness, placed 2

T-F Chang; A. Fisher; A. Van Drie

1991-01-01

186

Evaluation of the gas puff z pinch as an x-ray lithography and microscopy source  

Microsoft Academic Search

Soft x rays (100–10 000 eV), due to their short wavelength (0.1–10 nm) can play an important role in high resolution microscopy and lithography. The gas puff Z pinch is an intense source of soft x rays. Calorimeter and x ray diode measurements showed that 10% of the stored electrical energy was converted to radiation in the range of 1–10

J. Bailey; Y. Ettinger; A. Fisher; R. Feder

1982-01-01

187

Gas-Puff Z-Pinch Plasmas Driven by Inductive Energy Storage Pulsed Power Generator  

Microsoft Academic Search

An inductive energy storage pulsed power generator is used as a power source of gas-puff z-pinch plasmas to investigate the effect of the steepened current rise on the intensity of soft X-rays and the spatial reproducibility of the hot spots. Furthermore, two kinds of electrodes, which are solid and mesh type, are used to investigate the influence of the incident

Koichi Murayama; Toshinori Shinkai; Sunao Katsuki; Hidenori Akiyama

1998-01-01

188

Overview of Recent Large-Diameter, Gas-Puff Z-Pinch Research  

Microsoft Academic Search

Summary form only given. Large radius implosions of gas-puff Z-pinches are the subject of intense investigation. Such implosions are needed to achieve the high specific energy required to excite K-line radiation from high-atomic-number (e.g. Z>26) radiators, for proper matching with high-current (~10 MA and higher) generators, for continuum radiator concepts that require heating beyond the optimum He\\/H-like state for K-shell

R. J. Commisso; J. P. Apruzese; Y. K. Chong; J. Davis; M. H. Frese; D. Mosher; D. P. Murphy; D. G. Phipps; J. W. Thornhill; A. L. Velikovich; B. V. Weber; F. C. Young; J. W. Banister; B. H. Failor; J. S. Levine; N. Qi; H. Sze; A. Bixler; P. Coleman; M. Krishnan; J. Thompson; E. Carlson; R. C. Hazelton; E. J. Yadlowsky; F. Davies; C. De La Cruz

2005-01-01

189

Soft X-Ray Images of Krypton Gas-Puff Z-Pinches  

Microsoft Academic Search

A series of experiments has been carried out on Qiang-guang I generator to study the dynamics of krypton gas-puff Z-pinches. The generator was operated at a peak current of 1.5 MA with a rise-time of 80 ns. The specific linear mass of gas liner was about 20 mug\\/cm in these experiments. In the diagnostic system, a four-frame x-ray framing camera

Meng-tong Qiu; Bin Kuai; Zheng-zhong Zeng; Min Lu; Kui-lu Wang; Ai-ci Qiu; Mei Zhang; Jian-hui Luo

2002-01-01

190

Soft X-ray spectra from a gas-puff z pinch  

Microsoft Academic Search

XUV and X-ray emission spectra of the elements carbon, oxygen, neon, and argon, in the spectral range 3-300 A, generated in a gas-puff z pinch, are presented. The spectra are analyzed to give time-integrated measurements of the density, electron temperature, and dimensions of the imploded plasma and the 'hot spots' that often occur in the gas-puff pinch. In particular, dielectronic

G. Nave; C. D. Challis; A. E. Dangor; J. G. Lunney

1989-01-01

191

Control of x-ray spectrum emitted from a gas-puff Z-pinch  

Microsoft Academic Search

The axial magnetic field is applied to an annular gas-puff z-pinch for the control of radial dynamics and x-ray emission from the pinched plasma. K-shell and L-shell radiations of Ar ions are detected separately, and only the K-shell radiation is suppressed significantly by the axial field. The radial motion of the plasma is analyzed assuming a simple circuit model. The

Keiichi Takasugi; Tetsu Miyamoto; Katsuhiro Tatsumi; Takehito Igusa

1997-01-01

192

Soft X-ray spectroscopic study of a gas-puff Z-pinch argon plasma  

Microsoft Academic Search

X-ray radiation characteristics of argon plasma produced by a gas-puff Z-pinch device were investigated using an X-ray crystal spectrometer, an X-ray diode, and an extreme ultraviolet (XUV) spectrometer. Using a germanium crystal we have observed spectral emission from Ar XVII produced by hot spots at the pinched stage. With the help of a 2-m grazing incidence XUV spectrometer, the spectrum

Seong Ho Kim; Dong-Eon Kim; Tong Nyong Lee

1998-01-01

193

Numerical simulation of cold flow for initialization of gas-puff Z-pinches  

Microsoft Academic Search

Summary form only given. The design, development, and optimization of pulsed power machines utilizing Z-pinches of gases could be augmented by numerical simulation of gas-puffs to provide initial flow conditions of gas-puff nozzles. Gas-puff operation typically involves the expansion of a working gas such as argon from a reservoir at ?300 K, 1 atm through a hypersonic nozzle and into

W. M. Scott; K. E. Tatum; E. S. Powell

2004-01-01

194

X-ray results from a modified nozzle and double gas puff z pinch  

Microsoft Academic Search

The nozzle and the anode of the UCI (University of California, Irvine) {ital z}-pinch facility were modified to study the influence of the anode-cathode geometrical structure on the stability of the pinch and the x-ray yield of the pinch. The anode was modified from a honey-comb to a hollow cylinder with a 4-cm diameter and a {similar to}3.5-mm wall thickness,

T.-F. Chang; A. Fisher; A. van Drie

1991-01-01

195

Theoretical modelling of a gas-puff Z-pinch experiment  

Microsoft Academic Search

Summary form only given, as follows. We present theoretical and computational results of the modelling of the CO2 gas-puff Z-pinch experiment at the Weizmann Institute of Science. Experimental data of the motion of the plasma column (pinch radius vs. time) were taken from a visible light framing camera and are in excellent agreement with a zero-dimensional slug model. The pinch

W. Peter; G. Davara; L. Gregorian; A. Velikovich; V. Fisher; Yu. Ralchenko; Y. Maron

1995-01-01

196

An Experimental Study on Kr Gas-puff Z-pinch  

Microsoft Academic Search

Kr gas-puff Z-pinch experiment performed recently on Qiang-guang I pulsed power generator is reported. The generator has a 1.5 MA current with a pulse width of 100 ns. The total x-ray energy as well as its spectrum has been obtained, and the average power of x-ray radiation in 50-700 eV measured by XRDs is 2 TW. The generator configuration, gas-puff

Bin Kuai; Pei-tian Cong; Zheng-zhong Zeng; Ai-ci Qiu; Meng-tong Qiu; Hong Chen; Tian-xue Liang; Wen-lai He; Liang-ping Wang; Zhong Zhang

2002-01-01

197

X ray radiation from a gas-puff z-pinch plasma  

Microsoft Academic Search

A z-pinch experiment was performed with a hollow-shaped Ar gas-puff. Three types of discharge were found depending on the delay time of discharge from gas-puff detection. Strong x ray radiations were emitted from spots, a volume with cloud structure and the anode surface. The number of x ray spikes observed in a scintillation probe signal is correlated with spot images

K. Takasugi; A. Takeuchi; H. Takada; M. Kimura; T. Miyamoto

1991-01-01

198

Evolution of gas-puff Z-pinch during implosion and pinch phase  

Microsoft Academic Search

The four-frame high-speed electrooptical camera backed by an automatic image capturing and processing system has been used to investigate the evolution of the gas-puff Z-pinch. The sequence of four images of the pinch continuum radiation (the exposure of each frame was 1 ns, the time separation of frames was 10 or 20 ns) enabled the study of the pinch-forming phase

A. Krejci; K. Kolacek; J. Kravarik; P. Kubes; M. Paduch; K. Tomaszewski

1996-01-01

199

ALEGRA Modeling of Gas Puff Z-Pinch Experiments at the ZR Facility  

Microsoft Academic Search

Gas puff z-pinch experiments have been proposed for the refurbished Z (ZR) facility for CY2011. Previous gas puff experiments [Coverdale et. al., Phys. Plasmas 14, 056309, 2007] on pre-refurbishment Z established a world record for laboratory fusion neutron yield. New experiments would establish ZR gas puff capability for x-ray and neutron production and could surpass previous yields. We present validation

C. S. Kueny; C. A. Coverdale; D. G. Flicker; M. Krishnan; P. L. Coleman

2010-01-01

200

Observation of an electron beam in an annular gas-puff Z-pinch plasma device  

Microsoft Academic Search

We report on the first observation of an electron beam formed in an argon gas-puff Z pinch at the time of pinch. An on-axis Faraday cup in conjunction with thin foil filters was used to measure the beam parameters. The beam has a pulse width of 4 ns, a peak current on the order of 10 kA, and an energy

D. R. Kania; L. A. Jones

1984-01-01

201

Effect of Initial Conditions on Gas-Puff Z-Pinch Dynamics  

Microsoft Academic Search

This dissertation concerns the effects initial conditions have on the dynamics of an imploded, annular gas-puff z-pinch. The influence of axial magnetic fields, nozzle size and composition, different gases, pre-ionization, and electrode design on pinch quality and x-ray yield is investigated. The experiment uses a 5-kJ capacitor bank to deliver 0.35 MA to the pinch load in 1.4 mu rm

Gus Gordon Peterson

1994-01-01

202

Experiment with a small gas-puff z-pinch plasma device  

Microsoft Academic Search

Summary form only given. A small gas-puff Z-pinch plasma device is composed of a capacitor energy storage bank (capacitance=16.3 ?F, charging voltage=23 kV), field distortion switches, a discharge chamber, vacuum pumping system, fast operation gas valve and diagnostics. The amplitude and the period of discharge current are 230 kA and 9.6 ?s, respectively. Firstly, a hollow gas shell is produced

C. M. Luo; C. R. Li; X. X. Wang; Z. X. Zheng; Z. F. Xie; M. Han

1998-01-01

203

Gas-puff Z pinches with D2 and D2Ar mixtures  

Microsoft Academic Search

Results obtained with the University of California, Irvine gas-puff Z-pinch experiment are described for deuterium and deuterium-argon mixtures. This experiment utilizes a hollow cylindrical gas puff injected between electrodes driven by a 4.8-kJ capacitor bank. Various gas compositions have been tested, including pure deuterium, 90% D2-10% Ar, and up to 10% D2-90% Ar. We have observed the stages of collapse

J. Bailey; Y. Ettinger; A. Fisher; N. Rostoker

1982-01-01

204

Wire-array z-pinch: a powerful x-ray source for ICF  

Microsoft Academic Search

The wire-array z-pinch has in a very short time achieved remarkable performance as a powerful (>200 TW), pulsed soft x-ray source of high efficiency (?15%) and of great relevance to inertial confinement fusion. The underlying physics involves the transformation of wire cores to a plasma corona, the occurrence of uncorrelated axial instabilities, inward flowing low magnetic Reynolds number jets, sometimes

M G Haines; T W L Sanford; V P Smirnov

2005-01-01

205

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

Matzen

1997-01-01

206

Z pinches as intense X-ray sources for inertial confinement fusion 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. On the Saturn pulsed-power accelerator at Sandia National Laboratories, currents of 6–8 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

M. Keith Matzen

1999-01-01

207

The effect of radial electric field on plasma formation in wire array z-pinches  

Microsoft Academic Search

We present the first measurements of the effect of radial electric field on plasma formation and dynamics in wire array z-pinches. Experiments were performed on the 1MA MAGPIE generator, with an 8mm diameter array of Al wires in a configuration where the direction of the radial electric field at the wires was reversed mid-way between the electrodes. The two sections

S. N. Bland; S. V. Lebedev; J. P. Chittenden; D. J. Ampleford; S. C. Bott; G. N. Hall; J. A. Gómez; I. H. Mitchell

2004-01-01

208

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

Microsoft Academic Search

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

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

2001-01-01

209

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

Microsoft Academic Search

We report on the first time-resolved measurements of an imploding capsule radius driven by radiation within a z-pinch dynamic hohlraum (ZPDH). The configuration uses a gas-filled 2-mm-diameter CH capsule embedded in a cylindrical CH foam. The pinch plasma impact with the foam creates radiation that drives the capsule. The radiation is measured with a filtered XRD array and the capsule

J. E. Bailey; G. A. Chandler; G. Cooper; D. E. Hebron; J. S. Lash; R. W. Lemke; J. McGurn; T. J. Nash; C. L. Ruiz; S. A. Slutz; J. Torres; W. Varnum; R. A. Vesey; G. R. Bennett; D. O. Jobe; P. Lake; S. Lazier; T. C. Moore; D. S. Nielson; Smelser; D. G. Schroen; J. J. Macfarlane

2001-01-01

210

MHD simulation of deuterium-fiber-initiated Z-pinches with two-fluid effects  

SciTech Connect

Two-dimensional ``cold-start`` resistive MHD computations of formation and evolution of deuterium-fiber-initiated Z-pinches have been extended to include separate ion and electron energy equations and finite-Larmor-radius ordered terms. In the Ohm`s Law (magnetic field evolution) equation, Hall and diamagnetic pressure terms have been added, and corresponding terms have been added to the energy equations. Comparison is made of the results of these computations with previous computations and with experiments.

Sheehey, P. [California Univ., Los Angeles, CA (United States). Dept. of Physics; Lindemuth, I.R. [Los Alamos National Lab., NM (United States)

1993-05-01

211

MHD simulation of deuterium-fiber-initiated Z-pinches with two-fluid effects  

SciTech Connect

Two-dimensional cold-start'' resistive MHD computations of formation and evolution of deuterium-fiber-initiated Z-pinches have been extended to include separate ion and electron energy equations and finite-Larmor-radius ordered terms. In the Ohm's Law (magnetic field evolution) equation, Hall and diamagnetic pressure terms have been added, and corresponding terms have been added to the energy equations. Comparison is made of the results of these computations with previous computations and with experiments.

Sheehey, P. (California Univ., Los Angeles, CA (United States). Dept. of Physics); Lindemuth, I.R. (Los Alamos National Lab., NM (United States))

1993-01-01

212

On the motion of a z-pinch in an inhomogeneous transverse magnetic field  

Microsoft Academic Search

An analytical treatment of the large scale axisymmetric motion of a z-pinch in an arbitrary transverse magnetic field is given. The analysis is based on an expansion in the non-circularity of the plasma cross-section, but does not involve any assumption of small displacements of the plasma from some equilibrium position. In order to include the effect of a possible internal

H. G. Eriksson; C. Wahlberg

1990-01-01

213

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

NASA Astrophysics Data System (ADS)

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 , Phys. PlasmasPHPAEN1070-664X10.1063/1.2896577 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.; 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

214

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

215

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

SciTech Connect

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

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

2014-08-15

216

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

217

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

SciTech Connect

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

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

2010-03-15

218

The microscopic Z-pinch process of current-carrying rarefied deuterium plasma shell  

NASA Astrophysics Data System (ADS)

For insight into the microscopic mechanism of Z-pinch dynamic processes, a code of two-dimensional particle-in-cell (PIC) simulation has been developed in cylindrical coordinates. In principle, the Z-pinch of current-carrying rarefied deuterium plasma shell has been simulated by means of this code. Many results related to the microscopic processes of the Z-pinch are obtained. They include the spatio-temporal distributions of electromagnetic field, current density, forces experienced by the ions and electrons, positions and energy distributions of particles, and trailing mass and current. In radial direction, the electric and magnetic forces exerted on the electrons are comparable in magnitude, while the forces exerted on the ions are mainly the electric forces. So in the Z-pinch process, the electrons are first accelerated in Z direction and get higher velocities; then, they are driven inwards to the axis at the same time by the radial magnetic forces (i.e., Lorentz forces) of them. That causes the separations between the electrons and ions because the ion mass is much larger than the electron's, and in turn a strong electrostatic field is produced. The produced electrostatic field attracts the ions to move towards the electrons. When the electrons are driven along the radial direction to arrive at the axis, they shortly move inversely due to the static repellency among them and their tiny mass, while the ions continue to move inertially inwards, and later get into stagnation, and finally scatter outwards. Near the stagnation, the energies of the deuterium ions mostly range from 0.3 to 6 keV, while the electron energies are mostly from 5 to 35 keV. The radial components, which can contribute to the pinched plasma temperature, of the most probable energies of electron and ion at the stagnation are comparable to the Bennett equilibrium temperature (about 1 keV), and also to the highest temperatures of electron and ion obtained in one dimensional radiation magnetohydrodynamic simulation of the plasma shell Z-pinch. The trailing mass is about 20% of the total mass of the shell, and the maximum trailing current is about 7% of the driven current under our trailing definition. Our PIC simulation also demonstrates that the plasma shell first experiences a snow-plow like implosion process, which is relatively stable.

Ning, Cheng; Feng, Zhixing; Xue, Chuang; Li, Baiwen

2015-02-01

219

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

220

X-ray Spectroscopy of K- and L-shell Z-pinch and Astrophysical Plasmas  

SciTech Connect

In recent years, there have been significant advances in instrumental capabilities for making X-ray spectroscopic measurements of astrophysical plasmas. There have been corresponding improvements in X-ray diagnostics for advanced multi-mega-ampere pulse power machines that produce increasingly large radiative yields from gas-puff and wire array Z pinch plasmas. Analysis used for Z pinches can be used to study ICF and also astrophysical plasmas where laboratory measurements and simulations are the only means to interpret observed data. The astrophysical data for Fe, the most cosmically abundant high Z element, can provide a wealth of information about cosmic plasmas. Fe is also the key element in stainless steel (SS) wire arrays that are investigated as an intense X-ray radiation source at the Z machine at Sandia National Laboratories. The implosion dynamics of an array of wires on the Z and/or refurbished Z accelerator produces an abundance of radiation from the K- and L-shell ionization stages. These dynamic plasmas are inherently non-LTE, with opacity and other factors influencing the X-ray output. As the plasma assembles on axis, a number of time resolved snapshots provide temperature and density profiles and map the emitting region. We will analyze the ionization dynamics and generate K- and L-shell spectra using the conditions generated in the Z and/or refurbished Z accelerator, described by a 1-D non-LTE radiation-hydrodynamics model. Diagnostics based on spectral shape of L-shell emissions are inherently more difficult than those based on K-shell emissions because of more complex multiplet structures and line overlaps. The non-LTE populations are obtained by using detailed atomic models that include all important excitation, ionization, and recombination processes. We will highlight the connection between laboratory Z-pinch plasma simulations and astrophysical plasmas.

Dasgupta, A.; Davis, J.; Giuliani, J. G. [Plasma Physics Division, Naval Research Laboratory, Washington DC 20375 (United States); Clark, R. W. [Berkeley Research Associates, Beltsville, Maryland 20705 (United States)

2009-09-10

221

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

222

ALEGRA modeling of gas puff Z-pinch experiments at the ZR facility.  

SciTech Connect

Gas puff z-pinch experiments have been proposed for the refurbished Z (ZR) facility for CY2011. Previous gas puff experiments [Coverdale et. al., Phys. Plasmas 14, 056309, 2007] on pre-refurbishment Z established a world record for laboratory fusion neutron yield. New experiments would establish ZR gas puff capability for x-ray and neutron production and could surpass previous yields. We present validation of ALEGRA simulations against previous Z experiments including X-ray and neutron yield, modeling of gas puff implosion dynamics for new gas puff nozzle designs, and predictions of X-ray and neutron yields for the proposed gas puff experiments.

Coleman, P. L. (Alameda Applied Sciences); Flicker, Dawn G.; Coverdale, Christine Anne; Kueny, Christopher Shane (Hewlett-Packard Company); Krishnan, Mahadevan (Alameda Applied Sciences)

2010-11-01

223

The Plasma Column Evolution in Gas-Puff Z-Pinches on the Yang Accelerator  

SciTech Connect

The plasma column evolution in gas-puff z-pinch was investigated on the Yang accelerator. The pinch process was significantly influenced by the initial gas distribution. Uniformity of the gas-puff distribution resulted in the asymmetry of the initially load current through the main channels of the plasma layer. The zipper velocity and implosion speed under 'trumpet' distribution was given, it was observed the pinch speed and the temperature of the plasma near cathode increased when the rise time of the load current was shortened.

Deng Jianjun; Yang Libing; Gu Yuanchao; Huang Xianbing; Li Fengping; Xv Zeping; Ye Shican; Cheng Guanghua; Chang Lihua; Zhou Shaotong; Zhang Siqun; Xie Weiping; Ding Bonan; Peng Xianjue [China Academy of Engineer Physics, P.O.Box 919-150, Mianyang, Sichuan, 621900 (China)

2006-01-05

224

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

SciTech Connect

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

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

2008-10-15

225

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

226

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

SciTech Connect

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

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

1999-11-03

227

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

228

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

229

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

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

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

232

Impact of Rayleigh Taylor on neutron production in a deuterium Z-pinch.  

SciTech Connect

A deuterium gas puff z-pinch has been shown to be a significant source of neutrons with yield scaling with current as Y{sub n} {approx} I{sup 3.5}. Recent implicit, electromagnetic and kinetic particle-in-cell simulations with the LSP code have shown that the yield has significant thermonuclear and beam-target components. Beam-target neutron yield is produced from deuterium ion high-energy tails driven by the Rayleigh Taylor instability. In this paper, we present further results from 1-3D simulations of deuterium z-pinches over a wider current range 1.4-20 MA. Preliminary results show that unlike the high current regime above 7 MA, the yield at lower currents is dominated by beam-target fusion reactions from high energy ions consistent with experiment. We will also examine in 3D the impact of the Rayleigh Taylor instability on the ion energy distribution. We discuss the implications of these simulations for neutron yield at still higher currents.

Mostrom, C. (Voss Scientific, Albuquerque, NM); Stygar, William A.; Thoma, Carsten (Voss Scientific, Albuquerque, NM); Welch, Dale Robert (Voss Scientific, Albuquerque, NM); Clark, R. E. (Voss Scientific, Albuquerque, NM); Leeper, Ramon Joe; Rose, David V. (Voss Scientific, Albuquerque, NM)

2010-06-01

233

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

234

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

235

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

SciTech Connect

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

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

1999-04-09

236

Kinetic simulations of a deuterium-tritium Z pinch with >10{sup 16} neutron yield  

SciTech Connect

Fully kinetic, collisional, and electromagnetic simulations of the time evolution of an imploding and burning Z pinch plasma have been performed. Using the implicit particle-in-cell (PIC) code, multidimensional (1D and 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 low pinch current, 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 with deuterium-tritium fuel, the vast majority of the neutrons is thermonuclear in origin and neutron yield follows an I{sup 4} neutron yield scaling with current. High-current, multidimension simulations (up to 40 MA with > 10{sup 16} neutron yield) suggest that the fraction of thermonuclear neutrons increases with current and the strong dependence of neutron yield with current will continue at still higher currents. Scenarios for fusion breakeven and possible ignition in the 40-80 MA regime are discussed.

Welch, D. R.; Rose, D. V.; Thoma, C.; Clark, R. E.; Mostrom, C. B. [Voss Scientific, LLC, Albuquerque, New Mexico 87108 (United States); Stygar, W. A.; Leeper, R. J. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1196 (United States)

2011-05-15

237

Observations of Radial Straight Tubular Channels in Gaseous Z-Pinch and Plasma Focus  

NASA Astrophysics Data System (ADS)

The evidences for the tubular straight long-living filaments (LLFs) of macroscopic size (few centimeter long) are found in a gaseous Z-pinch and plasmas focus. The long-livingness of similar straight filaments was proven in [1(a)] via 3D imaging of their dynamics in a Z-pinch during almost entire discharge. Here, identification of straight LLFs directed radially suggests the possibility of a direct (non-diffusive) transport of magnetic field from external circuit to discharge's axis -- not only on the stage of the formation of a precursor on the axis but at the quasi-steady-state stage (stagnation) as well. The respective typical LLF appears to be a straight cylindrical formation varying in length from few millimeters up to the radius (and even diameter) of the discharge volume. Such an LLF often resembles a cable: it has a distinct inner cylinder of few hundreds of microns in diameter and an axisymmetric tubular sheath, with a distinct boundary. An extension of the interpretation [1(b)] of observations [1(b)] of ``wild cables" in tokamak plasmas to the case of inertially confined plasmas is given. References: [1] Kukushkin A.B. Rantsev-Kartinov V.A. (a) Proc. 26-th EPS conf., Maastricht, Netherlands, 1999, P2-087 (http://epsppd.epfl.ch/cross/p2087.htm); (b) Proc. Innovative Confinement Concepts Workshop, February 2000, Lawrence Berkeley Lab., USA (http://icc2000.lbl.gov/...). format.

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

2000-10-01

238

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

239

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

SciTech Connect

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

NONE

1995-12-01

240

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

SciTech Connect

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

Matuska, W.; Lee, H.

1997-11-01

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

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

SciTech Connect

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

DERZON,MARK S.

2000-03-01

244

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

NASA Astrophysics Data System (ADS)

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

Weller, Michael Eugene

245

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

Microsoft Academic Search

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,

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

2010-01-01

246

Measuring the gas flow from a supersonic nozzle used in a 1.5MA gas puff Z pinch  

Microsoft Academic Search

A supersonic nozzle for a 1.5-MA gas puff Z pinch was designed and the gas flow injected out from the nozzle was measured. A miniature ionization gauge was developed to measure the density profile of the gas shell and two pressure transducers were used for determining the Mach number of the gas flow. It was found that the gas flow

Xiaobing Zou; Xinxin Wang; Chengmu Luo; Min Han

2002-01-01

247

Development of laser based diagnostics for the investigation of wire array Z-pinch dynamics on the MAGPIE generator  

Microsoft Academic Search

Summary form only given. End on Interferometric imaging is a useful technique for diagnosing the electron density distribution in the interior of wire array z-pinches during their ablation phase. These measurements are limited as there is often no known density reference point in the image. By using a time resolved, CW line integrated interferometry system, we can measure the electron

G. Swadling; S. Lebedev; S. Bland; G. Hall; F. Suzuki-Vidal; N. Niasse; G. Burdiak; E. Khoory; L. Pickworth

2010-01-01

248

PHYSICAL REVIEW E 84, 056408 (2011) Doppler measurement of implosion velocity in fast Z-pinch x-ray sources  

E-print Network

black holes in galaxy merger remnants [5]. In the laboratory, the Doppler effect reveals rotation of Doppler effects in these K-shell lines thus provides unique information about the plasma motionPHYSICAL REVIEW E 84, 056408 (2011) Doppler measurement of implosion velocity in fast Z-pinch x

Starobinets, Alexander

249

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

250

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

251

Dense Plasma Focus Z-pinches for High Gradient Particle Acceleration  

SciTech Connect

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

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

2009-07-24

252

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

SciTech Connect

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

Shlachter, J.S.

1982-05-01

253

Magneto-Hydrodynamic Modeling in the Design and Interpretation of Wire Array Z-pinches  

NASA Astrophysics Data System (ADS)

Magneto-hydrodynamic simulations provide a powerful tool for improving our understanding of the complex physical processes underlying the behavior of wire array Z-pinches. We show how, by using large scale parallel 3D simulations of the array as a whole, it is possible to encompass all of the important features of the wire ablation, implosion and stagnation phases and to observe how these phenomena control the X-ray pulse that is achieved. Comparison of code results with experimental data from the 'Z' and MAGPIE pulsed power generators is shown to provide a detailed benchmark test for the models. The simulation results are also used to highlight key areas for future research.

Chittenden, J. P.; Niasse, N. P.; Jennings, C. A.

2009-01-01

254

Development of laser based diagnostics for wire array z-pinch experiments on the MAGPIE generator  

NASA Astrophysics Data System (ADS)

End on Interferometric imaging is a useful technique for diagnosing the electron density distribution in the interior of wire array z-pinches during their ablation phase. These measurements are limited as there is often no known density reference point in the image. By using a time resolved, CW line integrated interferometry system, we can measure the electron density for a single point on the image. This allows us to calculate the density distribution across the remainder of the image. Two new quadrature interferometry systems are discussed, the first free space and the second fiber based. Also discussed is a new fiber based multipoint Heterodyne Velocimetry (HET-V) system, for the time resolved measurement of large velocities and accelerations, and a new faraday rotation current probe system, to measure rapidly rising currents in new switched mode wire arrays.

Swadling, George; Lebedev, S. V.; Bland, S. N.; Hall, G. N.; Suzuki-Vidal, F.; Niasse, N.; Burdiak, G.; Khoory, E.; Pickworth, L.; Hutchison, C.

2009-11-01

255

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

256

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

SciTech Connect

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

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

2011-09-15

257

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

258

Macroscopic Behavior and X-ray Radiation Characteristics of SHOTGUN Z-Pinch Plasma  

NASA Astrophysics Data System (ADS)

Gas-puff z-pinch plasmas were produced using Ne, Ar, Kr and Xe as pinch materials in the SHOTGUN device. The hardening of x-ray radiation with atomic number Z of the operating gas was confirmed. It results from higher energy input into the higher Z plasma due to stronger compression, which is attributed to radiation cooling in the contraction phase. The contracting plasma showed nonuniformity along the axis, which results from m = 0 unstable mode. As the nonuniformity develops, the plasma column is divided into several sections, and each of them collapses by turns from the anode. The x-ray is emitted at several localized spots which corresponds to the nodes of the rippling.

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

1994-03-01

259

Development of absorption spectroscopy for wire-array Z-pinches  

NASA Astrophysics Data System (ADS)

The 50 TW Leopard laser was coupled with the 1 MA Zebra generator for the x-ray backlighting of wire arrays. The Leopard laser is based on the chirped pulse amplification and can operate in subpicosecond or subnanosecond regimes. Several materials were tested in both regimes and samarium was selected for subnanosecond backlighting in the range of 7-9 å. One ray of Al wire-arrays was investigated at the ablation and implosion stages. Two focusing conical spectrometers with mica crystals recorded reference and main spectra on x-ray film. Collimators protected spectrometers against the x-ray burst from the main Z-pinch. Comparison of spectra of backlighting radiation with reference spectra indicates absorption lines in the range of 8.2-8.4 å. The electron temperature of wire-array plasma was estimated from simulations with atomic kinetics models.

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

2010-11-01

260

Experimental study of z-pinch driven radiative shocks in low density gases  

NASA Astrophysics Data System (ADS)

Results of experiments performed on MAGPIE pulsed power facility (1.4MA, 250ns) will be presented. Shocks with velocities of 50-70km/s are driven in Ar, Xe and He gases at density ˜10-5g/cc using radial foil z-pinch configuration [1]. Measurements of the structure of the shocks obtained with laser probing will be presented and observations of the development of instabilities will be discussed. It was found that the structure of the shocks and the development of instabilities strongly depend on the rate of radiative cooling, increasing for gases with higher atomic numbers.[4pt] [1] F. Suzuki-Vidal et al., PoP 19, 022708 (2012)

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

2012-10-01

261

New Exact MHD Solutions Describing the Stagnating Z-pinch plasma  

NASA Astrophysics Data System (ADS)

Recent 3D RMHD simulations at Sandia and experiments at Weizmann Institute of Science have demonstrated that axially and azimuthally averaged dynamics of a strongly radiating stagnated Z-pinch column resembles a self-similar, cylindrically symmetric motion. The cold, rapidly imploding plasma transforms into the hot stagnated plasma heated and compressed in the diverging shock wave that propagates from the pinch axis. The simplest analytical solution describing such flow was given by Noh. Here we discuss generalizations of the classical Noh's solution, which take into account the non-uniform density and velocity profiles in the incident plasma, as well as the presence of azimuthal magnetic field in it. These new solutions are found to be surprisingly close to the observations and simulation results. They have also been used for verification tests of MHD codes.

Velikovich, A. L.; Giuliani, J. L.; Thornhill, J. W.; Zalesak, S. T.; Maron, Y.; Starobinets, A.; Yu, E. P.

2011-11-01

262

Evaluation of the gas puff z pinch as an x-ray lithograhy and microscopy source  

SciTech Connect

Soft x rays (100--10 000 eV), due to their short wavelength (0.1--10 nm) can play an important role in high resolution microscopy and lithography. The gas puff Z pinch is an intense source of soft x rays. Calorimeter and x ray diode measurements showed that 10% of the stored electrical energy was converted to radiation in the range of 1--10 nm. Commercial photoresist polymethyl methacrylate (PMMA) and some new resists: CR 39, nitrocellulose, were exposed to the pinch radiation. The developed images on the resists have been studied with a scanning electron microscope. The resolution was found to be source limited, but a simple modification can improve the resolution by more than an order of magnitude.

Bailey, J.; Ettinger, Y.; Fisher, A.; Feder, R.

1982-01-01

263

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

264

3D MHD Simulations of Radial Wire Array Z-pinches  

SciTech Connect

Recent experiments carried out on the MAGPIE (1 MA, 250 ns), OEDIPE (730 kA, 1.5 {mu}s) and SPHINX (4 MA, 700 ns)[1] facilities have shown the relatively high level of scalability of the Radial Wire Array Z-pinches. These configurations where the wires stretch radially outwards from a central cathode offer numerous advantages over standard cylindrical arrays. In particular, imploding in a very stable and compact way, they seem suitable for coupling to small scale hohlraums. Making use of the 3D resistive magneto-hydrodynamic code GORGON[2] developed at Imperial College, the dynamic of the radial wire arrays is investigated. Influence of the cathode hotspots and wires angle on the x-ray emissions is also discussed. Comparison with experiments is offered to validate the numerical studies.

Niasse, N.; Chittenden, J. P.; Bland, S. N.; Suzuki-Vidal, F. A.; Hall, G. N.; Lebedev, S. V. [Blackett Laboratory, Imperial College, London, SW7 2BW (United Kingdom); Calamy, H.; Zucchini, F.; Lassalle, F.; Bedoch, J. P. [Centre d'Etudes de Gramat, Gramat (France)

2009-01-21

265

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

266

3D MHD Simulations of Radial Wire Array Z-pinches  

NASA Astrophysics Data System (ADS)

Recent experiments carried out on the MAGPIE (1 MA, 250 ns), OEDIPE (730 kA, 1.5 ?s) and SPHINX (4 MA, 700 ns)[1] facilities have shown the relatively high level of scalability of the Radial Wire Array Z-pinches. These configurations where the wires stretch radially outwards from a central cathode offer numerous advantages over standard cylindrical arrays. In particular, imploding in a very stable and compact way, they seem suitable for coupling to small scale hohlraums. Making use of the 3D resistive magneto-hydrodynamic code GORGON[2] developed at Imperial College, the dynamic of the radial wire arrays is investigated. Influence of the cathode hotspots and wires angle on the x-ray emissions is also discussed. Comparison with experiments is offered to validate the numerical studies.

Niasse, N.; Chittenden, J. P.; Bland, S. N.; Suzuki-Vidal, F. A.; Hall, G. N.; Lebedev, S. V.; Calamy, H.; Zucchini, F.; Lassalle, F.; Bedoch, J. P.

2009-01-01

267

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

SciTech Connect

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

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

2010-06-01

268

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

NASA Astrophysics Data System (ADS)

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

Giuliani, J. L.; Thornhill, J. W.; Kroupp, E.; Osin, D.; Maron, Y.; Dasgupta, A.; Apruzese, J. P.; Velikovich, A. L.; Chong, Y. K.; Starobinets, A.; Fisher, V.; Zarnitsky, Yu.; Bernshtam, V.; Fisher, A.; Mehlhorn, T. A.; Deeney, C.

2014-03-01

269

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

PubMed Central

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

Silterra, J; Holber, W

2009-01-01

270

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

SciTech Connect

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

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

2014-03-15

271

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

SciTech Connect

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

Sheehey, P.T.

1994-02-01

272

Methods and results of studies of the radiation spectra of megampere Z-pinches at the angara-5-1 facility  

NASA Astrophysics Data System (ADS)

Methods and results of studies of the radiation spectra of high-current Z-pinches with different elemental compositions are presented. To examine a wide spectral range ( E h? = 30-3000 eV), two diagnostics tools were used—a transmission grating and a reflecting mica crystal. The radiation characteristics of the pinch are determined by its elemental composition. For currents of 2-3 MA and low- Z elements (aluminum), the hard end of the radiation spectrum is represented by spectral lines with clearly pronounced K lines, while for high- Z elements (tungsten), the spectrum lies in the softer photon energy range and is quasi-continuous. Two methods of spectrum processing were used to determine the plasma parameters. The parameters of aluminum plasma were traditionally determined from the intensity ratios of the K lines taking into account the plasma transparency for these lines. The spectra of tungsten plasma were compared with the results of computer simulations of pinch compression with allowance for both magnetohydrodynamic and plasma radiation processes. The applicability of these methods of spectral analysis is discussed.

Boldarev, A. S.; Bolkhovitinov, E. A.; Vichev, I. Yu.; Volkov, G. S.; Gasilov, V. A.; Grabovskii, E. V.; Gritsuk, A. N.; Dan'ko, S. A.; Zaitsev, V. I.; Novikov, V. G.; Oleinik, G. M.; Ol'khovskaya, O. G.; Rupasov, A. A.; Fedulov, M. V.; Shikanov, A. S.

2015-02-01

273

Relationship of laser absorption to keyhole behavior in high power fiber laser welding of stainless steel and aluminum alloy  

Microsoft Academic Search

This study was undertaken in order to assess absorption of a 10kW fiber laser beam with tightly focused spot diameter of 200?m in Type 304 austenitic stainless steel or A5052 aluminum alloy in bead-on-plate welding with a wide range of welding speeds from 17 to 300mm\\/s, by using water-calorimetric measurement. The maximum absorptions of the steel and aluminum were 89

Yousuke Kawahito; Naoyuki Matsumoto; Youhei Abe; Seiji Katayama

2011-01-01

274

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

275

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

Microsoft Academic Search

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

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

1999-01-01

276

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

Microsoft Academic Search

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

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

1999-01-01

277

Study of pulsed soft X-ray source employing a gas-puff Z-pinch plasma device for lithography applications  

Microsoft Academic Search

Employing a gas-puff Z-pinch plasma device, we have developed a bright and reliable X-ray source. The Z-pinch plasma was produced by a capacity discharge, using a fast valve to inject an annulus of Argon gas. The total capacitance of circuit is 24muF, and the peak discharge current is 360kA with a quarter-period of 2mus when the capacitor bank was charged

G. X. Zhang; X. M. Guo; C. M. Luo; S. Lee; X. Feng

1997-01-01

278

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

279

Shear Flow Stabilization of a z-Pinch Plasma in the Presence of a Radial Temperature Gradient  

E-print Network

The previous study regarding the stabilization of a magnetized constant temperature plasma by shear flow with vorticity is extended to a plasma of non-constant temperature, where in the presence of heat source or sinks the thermomagnetic Nernst effect becomes important. Of special interest is what this effect has on the stabilization of a linear z-pinch discharge for which exact solutions are given.

Winterberg, F

2009-01-01

280

Study of Soft X-Ray Spectrum from a Small Gas-Puff Z-Pinch Device  

Microsoft Academic Search

Summary form only given. A Ross filter difference spectrometer was developed to study the soft X-ray radiation emitted from gas-puff Z-pinch plasma. It is composed of PIN detector arrays in combination with front Ross filters. Filter materials and thickness was selected by the desired X-ray spectral energy cuts. To measure softer X-ray energy spectrum, we mainly used the L absorption

Xiaobing Zou; Guixin Zhang; Xinxin Wang; Min Han

2005-01-01

281

Stability enhancement of a low initial density hollow gas-puff z pinch by e - beam preionization  

Microsoft Academic Search

e? beam preionization of the initial gas column of the hollow gas-puff z pinch at the University of California, Irvine is shown to decrease the amplitude of Rayleigh–Taylor instabilities which disrupt the imploding plasma shell of low initial density (<1×1017 cm?3) helium pinches. A 5-ns pulsed nitrogen laser Mach–Zehnder interferometer compares the plasma density profile at various times during the

E. Ruden; H. U. Rahman; A. Fisher; N. Rostoker

1987-01-01

282

The K-shell radiation of a double gas puff z-pinch with an axial magnetic field  

Microsoft Academic Search

A double shell z-pinch with an axial magnetic field is considered as a K-shell plasma radiation source. One-dimensional radiation-hydrodynamics calculations performed suggest that this scheme holds promise for the production of the K-shell radiation of krypton (h[nu] [approximate] 12 17 keV). As a first step in verifying the advantages of this scheme, experiments have been performed to optimize a neon

S. A. Chaikovsky; A. Yu. Labetsky; V. I. Oreshkin; A. V. Shishlov; R. B. Baksht; A. V. Fedunin; A. G. Rousskikh

2003-01-01

283

Efficient Radiation Production in Long Implosions of Structured Gas-Puff Z Pinch Loads from Large Initial Radius  

Microsoft Academic Search

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

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

2005-01-01

284

Magnetic Rayleigh-Taylor Instability Mitigation and Efficient Radiation Production in Gas Puff Z-Pinch Implosions  

Microsoft Academic Search

For a long time it was believed that tightness and uniformity of Z-pinch plasmas imploded from large radii are inherently low because the adverse effect of the magnetic Rayleigh-Taylor (RT) instability that distorts the imploding plasma column is stronger for a longer acceleration path. None of the wire-array implosions from a diameter exceeding 7 cm were successful; a significant decrease

Henry Sze

2006-01-01

285

Magnetic Rayleigh-Taylor instability mitigation and efficient radiation production in gas puff Z-pinch implosions  

Microsoft Academic Search

Large radius Z-pinches are inherently susceptible to the magnetic Rayleigh-Taylor (RT) instability because of their relatively long acceleration path. This has been reflected in a significant reduction of the argon K-shell yield as was observed when the diameter of the load was increased from 2.5 to >4 cm. Recently, an approach was demonstrated to overcome the challenge with a structured

H. Sze; J. S. Levine; J. Banister; B. H. Failor; N. Qi; P. Steen; A. L. Velikovich; J. Davis; A. Wilson

2007-01-01

286

Experimental study on the dynamics of a cylindrical plasma sheath in a gas-puff z-pinch device  

Microsoft Academic Search

The dynamics of a hollow cylindrical plasma sheath produced in a gas-puff Z-pinch device were studied with a differential interferometer. The velocity of the imploding plasma during three stages of compression the minimum radius of the pinched plasma column, the hot spots and the X-ray emissions were measured. The effect of the parameters of the gas cylinder on the plasma

Cheng Rong Li; Tsin Chi Yang

1991-01-01

287

A self-crowbar switch for a gas-puff z-pinch driven by a pulsed power generator  

Microsoft Academic Search

A self-crowbar switch for a gas-puff z-pinch, driven by a pulsed power generator with output voltage 600 kV, pulse width 70 ns, and characteristic impedance of 3 ?, has been built and tested successfully. Discharges with pulsed gas injection are placed into four groups dependent on the delay between the pulsed power generator trigger time and the gas-puff trigger time.

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

1990-01-01

288

Dynamical Domain Tabular Collisional Radiative Equilibrium Radiation Transport Model for Argon Gas-Puff Z-Pinch Plasmas  

Microsoft Academic Search

Summary form only given. The proper treatment of the radiation transport in the multidimensional MHD simulations of large diameter argon gas-puff Z-pinch loads is essential in understanding and predicting accurately the dynamic evolution and the radiative emission characteristics of the plasmas. The tabular collisional radiative equilibrium (TCRE) radiation transport model represents a novel approach to the realistic self-consistent treatment of

Y. K. Chong; J. W. Thornhill; J. P. Apruzese; J. Davis; H. D. Minor

2005-01-01

289

Development and characterization of a Z-pinch-driven hohlraum high-yield inertial confinement fusion target concept  

Microsoft Academic Search

Initial experiments to study the Z-pinch-driven hohlraum high-yield inertial confinement fusion (ICF) concept of Hammer, Tabak, and Porter [Hammer &etal;, Phys. Plasmas 6, 2129 (1999)] are described. The relationship between measured pinch power, hohlraum temperature, and secondary hohlraum coupling (“hohlraum energetics”) is well understood from zero-dimensional semianalytic, and two-dimensional view factor and radiation magnetohydrodynamics models. These experiments have shown the

Michael E. Cuneo; Roger A. Vesey; John L. Porter; Gordon A. Chandler; David L. Fehl; Terrance L. Gilliland; David L. Hanson; John S. McGurn; Paul G. Reynolds; Laurence E. Ruggles; Hans Seamen; Rick B. Spielman; Ken W. Struve; William A. Stygar; Walter W. Simpson; Jose A. Torres; David F. Wenger; James H. Hammer; Peter W. Rambo; Darrell L. Peterson; George C. Idzorek

2001-01-01

290

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

Microsoft Academic Search

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

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

1999-01-01

291

Development and characterization of a Z-pinch-driven hohlraum high-yield inertial confinement fusion target concept  

Microsoft Academic Search

Initial experiments to study the Z-pinch-driven hohlraum high-yield inertial confinement fusion (ICF) concept of Hammer, Tabak, and Porter [Hammer et al., Phys. Plasmas 6, 2129 (1999)] are described. The relationship between measured pinch power, hohlraum temperature, and secondary hohlraum coupling (``hohlraum energetics'') is well understood from zero-dimensional semianalytic, and two-dimensional view factor and radiation magnetohydrodynamics models. These experiments have shown

Michael E. Cuneo; Roger A. Vesey; John L. Porter; Gordon A. Chandler; David L. Fehl; Terrance L. Gilliland; David L. Hanson; John S. McGurn; Paul G. Reynolds; Laurence E. Ruggles; Hans Seamen; Rick B. Spielman; Ken W. Struve; William A. Stygar; Walter W. Simpson; Jose A. Torres; David F. Wenger; James H. Hammer; Peter W. Rambo; Darrell L. Peterson; George C. Idzorek

2001-01-01

292

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

Microsoft Academic Search

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 µm in radius) solid hydrogen filaments have so far not encountered the usually devastating MHD instabilities that plagued early DZP experimenters. These encouraging results along with the debut of a number of proof-of principle,

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

1989-01-01

293

Demonstration of Radiation Pulse Shaping with Nested-Tungsten-Wire-Array Z Pinches for High-Yield Inertial Confinement Fusion  

Microsoft Academic Search

Nested wire-array Z pinches are shown to generate soft x-ray radiation pulse shapes required for three-shock isentropic compression and hot-spot ignition of high-yield inertial confinement fusion capsules. We demonstrate a reproducible and tunable foot pulse (first shock) produced by interaction of the outer and inner arrays. A first-step pulse (second shock) is produced by inner array collision with a central

M. E. Cuneo; R. A. Vesey; D. B. Sinars; E. M. Waisman; R. W. Lemke; D. E. Bliss; W. A. Stygar; J. L. Porter; M. G. Mazarakis; G. A. Chandler; T. A. Mehlhorn; J. P. Chittenden; S. V. Lebedev; D. G. Schroen

2005-01-01

294

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

295

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

NASA Astrophysics Data System (ADS)

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

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

2003-10-01

296

Nonthermal effects on the diagnostics of a collapsing gas shell Z-pinch  

SciTech Connect

The collapsing gas shell Z-pinch at Los Alamos is powered by a 72 kJ - 600 kV Marx bank. This Marx bank consists of twelve six-stage modules which are used to pulse charge a 1 ..cap omega..-90 ns long water line in approx. 500 ns. The plasma produced by this device has been well diagnosed, but rather than present the results of all the diagnostics, we will discuss only those relevant to nonthermal effects. First, we show a spectrum taken with a 1 m VUV spectrograph. A section of the spectrum has been microdensitometered to show that we observe Ar X-XIII in this spectrum. This same instrument was used to image the spectrum both axially and radially. The same portion of the spectrum discussed above is shown along with a time integrated, filtered (1 to 6 keV) x-ray pinhole picture. These pictures show that the collapsed plasma is axially inhomogenous, i.e., He-like argon, represented by the x-ray pinhole picture, forms in hot spots along the axis and lower ionization stages fill in the regions between the hot spots. Next we present a spectrum taken with a curved crystal instrument. This spectrum shows the argon XVII, He-like resonance and intercombination lines, along with satellite structures from argon X to XVI. Another part of the spectrum contains weak H-like lines.

Jones, L.A.; Kania, D.R.

1984-01-01

297

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

298

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

299

Experimental Study of an Inverse Wire Array Z-Pinch Operating as a Current Switch  

NASA Astrophysics Data System (ADS)

We will present experiments on the MAGPIE facility (1.5MA, 250ns) in which an inverse wire array [1] (with the wires acting as a return current cage placed around a central current conductor) operated as a fast current switch. This allowed to significantly reduce the rise-time of the current pulse (<100ns) delivered to a separate, standard imploding wire array z-pinch load. Experimental studies of the operation of this arrangement as a current switch will be discussed and new measurements of current switching into the load array will be presented. We will also discuss how pre-conditioning of the load array wires by the current pre-pulse [2] depends on wire materials (Al, Cu, W) used in the load and the exploding wire arrays. [4pt] [1] A. Harvey-Thompson, S.V. Lebedev, S.N. Bland et al., PoP 16, 022701 (2009).[0pt] [2] A. Harvey-Thompson, S.V. Lebedev, G. Burdiak, et al., PRL 106, 205002 (2011)

Lebedev, Sergey; Harvey-Thomson, A.; Hall, G. N.; Waisman, E. M.; Khoory, E.; Burdiak, G.; Chittenden, J. P.; de Grouchy, P.; Suzuki-Vidal, F. A.; Swadling, G.; Bland, S. N.; Pickworth, L.; Skidmore, J.; Suttle, L.

2011-11-01

300

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

301

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

NASA Astrophysics Data System (ADS)

The implosion dynamics of wire-array Z-pinches are investigated numerically in 2D (r, ?) geometry by using a resistive MHD code. It is assumed that the wires have expanded to plasmas with diameter d0, 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 d0, the effects of the wire expansion degree on the implosion dynamics are analyzed. When d0 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 d0. 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 d0, 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, Shun-Kai; Zhang, Yang; Xiao, De-Long; Xue, Chuang

2012-06-01

302

Characteristics of a Z-pinch produced from a glass optical fiber  

SciTech Connect

A Z-pinch discharge in a quartz fiber (20--125 {mu}m diameter) driven by a 150 kA current with a rise time of 50 nsec has been investigated. The pinch was found to develop an {ital m}=0 instability during the time of current rise and before the whole fiber had been formed into a plasma. No anomalously stable behavior was seen. The bright spots associated with the instability expanded radially and moved in the axial direction with typical velocities of a few 10{sup 6} cm sec{sup {minus}1}. A coronal plasma was found to exist with density 10{sup 16} cm{sup {minus}3} at a radius 500 {mu}m. There was evidence of an energetic (20 keV) electron beam. The observed plasma expansion and ionization agreed well with a one-dimensional magnetohydrodynamic simulation. The simulation showed that the light which was observed to be generated in the core of the optical fiber was due to shock heating. The predicted temperature of the surface of the plasma was also in good agreement with an estimate of the temperature (25{plus minus}8 eV) obtained by assuming that the light emission was blackbody.

Figura, E.S.; McCall, G.H.; Dangor, A.E. (Blackett Laboratory, Imperial College of Science, Technology, and Medicine, London SW7 2BZ (England))

1991-10-01

303

Gas puff Z-pinch implosions with external Bz field on COBRA  

NASA Astrophysics Data System (ADS)

We present preliminary experimental results on mitigating Magneto-Rayleigh-Taylor (MRT) instabilities by applying an external Bz field. The experiments were conducted on the 1-MA, 200-ns COBRA generator at Cornell University. In the experiments, a triple-nozzle was used to produce z-pinch loads from concentric outer and inner annular gas puffs and a center gas puff column. A single coil was used to produce a Bz field in the pinch region. We have used two 4-frame 2-ns gated EUV cameras to obtain images of the imploding plasmas, in which the MRT instabilities were observed. The MRT instabilities can grow when the plasma accelerates toward the axis. With a triple gas puff (outer, inner and center puff), reduced acceleration or de-acceleration of the imploding plasma occurred when the outer puff plasma imploded onto the inner annular puff plasma resulting a relatively stable implosion. In the absent of the inner annular gas puff, the imploding outer annular plasma continued to accelerate toward the axis. Large turbulent flares at the edge of the implosion or pinch plasma were observed. The implosion was not stable. To stabilize the implosion without the inner gas puff, a Bz field was applied. This external Bz field was compressed by the outer imploding plasma shell. A relatively stable implosion was observed. Increasing the Bz field to 2-kG resulted in a relatively fatter pinch plasma.

Qi, N.; de Grouchy, P.; Schrafel, P. C.; Atoyan, L.; Potter, W. M.; Cahill, A. D.; Gourdain, P.-A.; Greenly, J. B.; Hammer, D. A.; Hoyt, C. L.; Kusse, B. R.; Pikuz, S. A.; Shelkovenko, T. A.

2014-12-01

304

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

305

Z-Pinch-Driven Hemispherical Capsule Implosions for Fast Ignitor Fuel Assembly  

NASA Astrophysics Data System (ADS)

Rad-hydro simulations indicate that partial-sphere fusion capsules can be compressed to peak densities of interest for fast ignition experiments with the symmetry control available in a single-ended indirect drive vacuum hohlraum configuration. We are presently investigating this approach to fast ignitor fuel assembly using pulsed-power driver technology. Current from the Sandia Z accelerator implodes a single wire-array z-pinch in the primary hohlraum, efficiently generating thermal x rays to drive the ablative compression of a hemispherical capsule moving on a high density glide surface in the secondary hohlraum. We report on recent work in two areas: (1) x-ray backlighter imaging of 3.0-mm-diam., 110-um-thick GDP hemispherical capsule implosions, complicated at high convergence by gold plasma expansion from the glide surface; and (2) development of a hemispherical liquid cryogenic fusion capsule in which a liquid cryogenic fuel layer is condensed in situ from a low pressure external gas supply and confined between concentric plastic shells mounted on the glide surface. Progress in measurement of shell distortion using high resolution 6.151 keV monochromatic crystal imaging will be discussed. Technology issues for liquid cryogenic fuel capsule development and progress toward demonstration of a working capsule will be presented. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

Hanson, D. L.; Vesey, R. A.; Sinars, D. B.; Cuneo, M. E.; Adams, R. G.; Slutz, S. A.; Porter, J. L.; Johnston, R. R.; Wenger, D. F.; Schroen, D. G.; Russell, C.

2004-11-01

306

Ion viscous heating in a magnetohydrodynamically unstable Z-pinch at over two billion Kelvin.  

SciTech Connect

Pulsed power driven metallic wire-array Z pinches are the most powerful and efficient laboratory x-ray sources. Furthermore, under certain conditions the soft x-ray energy radiated in a 5 ns pulse at stagnation can exceed the estimated kinetic energy of the radial implosion phase by a factor of 3 to 4. A theoretical model is developed here to explain this, allowing the rapid conversion of magnetic energy to a very high ion temperature plasma through the generation of fine scale, fast-growing m=0 interchange MHD instabilities at stagnation. These saturate nonlinearly and provide associated ion viscous heating. Next the ion energy is transferred by equipartition to the electrons and thus to soft x-ray radiation. Recent time-resolved iron spectra at Sandia confirm an ion temperature T{sub i} of over 200 keV (2 x 10{sup 9} degrees), as predicted by theory. These are believed to be record temperatures for a magnetically confined plasma.

Jones, Brent Manley; Coverdale, Christine Anne; LePell, Paul David; Haines, Malcolm G. (Imperial College, London, United Kingdom); Deeney, Christopher

2005-02-01

307

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

308

Large scale parallel computing simulations of wire array Z-pinches  

NASA Astrophysics Data System (ADS)

Until recently simulations of wire array Z-pinches have been undertaken in a piece-wise fashion, modelling either only part of the array volume, or modelling different aspects of the array behaviour separately. Recent simulations of a single wire in the array suggest that the short wavelength modulations of the ablating plasma observed in experiments are the result of a modified m=0 like instability. In order to simulate the growth of magneto-Rayleigh-Taylor instabilities during the implosion phase, a separate calculation is usually performed in which estimates for the structure of the modulated ablation are used to provide the initial seed perturbation for the implosion. Improvements to the parallel computing architecture of the Gorgon 3D resistive MHD code, however, mean that is now possible to run with large enough computational grids to encompass the entire volume of the array whilst retaining sufficient resolution to model the spontaneous development of the modulated ablation structure from microscopic noise. Thus we can model the evolution of the wire array from the point of initial plasma formation, right through the implosion, without imposing any predetermined perturbation or structure. A detailed comparison of synthetic diagnostic images with data from MAGPIE experiments is used to test this method. Preliminary data from similar simulations of Z experiments are also presented.

Chittenden, Jeremy; Niasse, Nicolas; Ciardi, Andrea

2008-11-01

309

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

310

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

NASA Astrophysics Data System (ADS)

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

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

2006-05-01

311

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

SciTech Connect

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

Rahman, H. U. [Magneto-Inertial Fusion Technologies Inc. (MIFTI), Irvine, California 92612 (United States) and Department of Physics, University of California Irvine, Irvine, California 92697 (United States); Wessel, F. J. [Department of Physics, University of California Irvine, Irvine California 92697 (United States); Ney, P. [Mount San Jacinto College, Menifee, California 92584 (United States); Presura, R. [University of Nevada, Reno, 1664 N. Virginia St., Reno, Nevada 89557-0208 (United States); Ellahi, Rahmat [Department of Mathematics and Statistics, FBAS, IIU, Islamabad (Pakistan) and Department of Mechanical Engineering, University of California Riverside, Riverside, California 92521 (United States); Shukla, P. K. [Department of Mechanical and Aerospace Engineering and Center for Energy Research, University of California San Diego, La Jolla, California 92093 (United States)

2012-12-15

312

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

313

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

314

Effects of uneven mass distribution on plasma dynamics in cylindrical wire array Z-pinches  

NASA Astrophysics Data System (ADS)

The formation and dynamics of cylindrical wire array Z-pinch plasmas using uneven mass distribution is studied through experiments and computer simulations. In this study, the initial mass distribution is modified using different wire sizes within the same array, in contrast to the most standard wire arrays. Since the ablation rate of a particular wire material is related to current driver characteristics but not to the wire size, the use of different wires within an array produces time differences for complete ablation of each size. This changes the plasma dynamics and precursor plasma formation as compared to standard arrays. The experiments have been carried out on the Llampudken pulsed power generator (~350kA in ~300ns) using a 1:6 mass ratio among different wires of a single array. Plasma dynamics are studied using time-resolved laser interferometry (532nm, 5ns FWHM) and XUV imaging (5ns exposure time) in both side-on and end-on directions respect to the array. Experimental results show the formation of a dense, precursor plasma column on the array axis at early times, which shifts its position toward the thicker wires at later times at velocities of the order of 104 m/s. Numerical simulations using the 3-D MHD code GORGON are able to reproduce the experimental observations. They show that the larger mass of thicker wires induces modifications in the global magnetic field topology, producing the shifting in the precursor position as observed in the experiments. Further details on the changes of ablation dynamics and precursor formation are presented and discussed.

Veloso, Felipe; Donoso, Luis; Swadling, George; Chittenden, Jeremy; Muñoz, Gonzalo; Valenzuela, Vicente; Suzuki-Vidal, Francisco; Favre, Mario; Wyndham, Edmund

2015-03-01

315

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

NASA Astrophysics Data System (ADS)

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

Papp, Daniel

316

Dense Z-pinch (DZP) as a fusion power reactor: preliminary scaling calculations and sysems energy balance  

SciTech Connect

A conceptual DT fusion reactor concept is described that is based upon the dense Z-pinch (DZP). This study emphasizes plasma modeling and the parametric assessment of the reactor energy balance. To this end simple analytic and numerical models have been developed and evaluated. The resulting optimal reactor operating point promises a high-Q, low-yield system of a scale that may allow the use of conventional high-voltage Marx/water-line technology to drive a potentially very small reactor system.

Hagenson, R.L.; Tai, A.S.; Krakowski, R.A.; Moses, R.W.

1980-01-01

317

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

318

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

319

The dense Z-pinch program at the University of Nevada, Reno  

NASA Astrophysics Data System (ADS)

A new program of research into the physics of dense z-pinches is being initiated around a high-repetition-rate two-terawatt generator (formerly Zebra/HDZP-II: 2MV, 1.2 MA, 100 ns, 200 kJ, 1.9 ? final line impedance) transferred to the University of Nevada. Reno Physics Department from Los Alamos National Laboratory. Areas for study include the early-time evolution of a current-driven wire, the plasma turbulence around and between wires, the suppression or reduction of instabilities, the nature of x-ray bright spots, and the tailoring of the x-ray emission spectrum. Novel loads that introduce a stabilizing velocity shear or density profile will be examined, along with configurations that promise to increase the quantity, hardness, stability, and reproducibility of x-ray emission. A wide variety of diagnostics are being developed, so as to diagnose the plasma thoroughly and make detailed comparisons between experiment, computer simulation, and theory. These include x-ray, soft x-ray, and extreme ultraviolet space- and time-resolved spectroscopy, with polarization measurements; laser interferometry, collective Thomson scattering, Faraday rotation, and laser-induced fluorescence; ion charge spectroscopy with an electrostatic analyzer; and small-angle x-ray diffraction of hard x-rays from the crystal lattice of the solid state load, using a standard x-ray tube and a double crystal monochromator. Quantities to be measured include the ion charge states present in the plasma; the electron density (ne) and temperature (Te); the magnetic field (B); the plasma flow speed (u); extreme ultraviolet (2.5 nm

Bauer, B. S.; Kantsyrev, V. L.; Winterberg, F.; Shlyaptseva, A. S.; Mancini, R. C.; Li, H.; Oxner, A.

1997-05-01

320

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

321

Deconvolution of Stark broadened spectra for multi-point density measurements in a flow Z-pinch  

DOE PAGESBeta

Stark broadened emission spectra, once separated from other broadening effects, provide a convenient non-perturbing means of making plasma density measurements. A deconvolution technique has been developed to measure plasma densities in the ZaP flow Z-pinch experiment. The ZaP experiment uses sheared flow to mitigate MHD instabilities. The pinches exhibit Stark broadened emission spectra, which are captured at 20 locations using a multi-chord spectroscopic system. Spectra that are time- and chord-integrated are well approximated by a Voigt function. The proposed method simultaneously resolves plasma electron density and ion temperature by deconvolving the spectral Voigt profile into constituent functions: a Gaussian function associated with instrument effects and Doppler broadening by temperature; and a Lorentzian function associated with Stark broadening by electron density. The method uses analytic Fourier transforms of the constituent functions to fit the Voigt profile in the Fourier domain. The method is discussed and compared to a basic least-squares fit. The Fourier transform fitting routine requires fewer fitting parameters and shows promise in being less susceptible to instrumental noise and to contamination from neighboring spectral lines. The method is evaluated and tested using simulated lines and is applied to experimental data for the 229.69 nm C III line from multiple chords to determine plasma density and temperature across the diameter of the pinch. These measurements are used to gain a better understanding of Z-pinch equilibria.

Vogman, G. V. [Univ. of California, Berkeley, CA (United States); Shumlak, U. [Univ. of Washington, Seattle, WA (United States)

2011-10-13

322

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

323

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

324

Recent Results for Large Diameter (12 cm) Gas Puff Z-Pinches at Peak Currents of >3 to <6 MA  

SciTech Connect

There is strong interest in many laboratories worldwide in utilizing less expensive, longer rise-time (> 200 ns) pulsed power to drive x-ray producing z-pinches. Based on the idea of a magnetically-driven annular implosion, the emission of K-shell photons requires high energy per ion (implosion velocity above 43 cm/{mu}s for argon) to strip the atoms to the helium-like and hydrogen-like states. This high velocity must be combined with high density in the final hot plasma to produce significant x-ray yield. To first order, implosion velocity correlates with the initial diameter of the z-pinch load in proportion to the implosion time. Thus some effort has been made in the last few years to develop larger diameter z-pinch loads suitable for use with the longer rise-time drivers. Advancing from the <4 cm diameter loads (used for 100 ns implosions) of a decade ago, progress with 8 cm loads was reported at the last DZP meeting. Here we review further progress with 12 cm loads as used to date at peak currents of 3.5 MA to almost 6 MA with >200 ns implosion times. The most interesting result is that implosions from 12 cm diameter have not proven hopelessly unstable. High quality pinches with few millimeter K-shell emitting diameters, <5 ns pulse widths, electron temperatures above 1.7 keV and ion densities >4*1019/cm{sup 3} have been achieved. The observed argon K yield has equaled simple scaling estimates that ignore the expected increase in instabilities for large initial diameters. This more stable result probably occurs because we are using radial mass distributions that are 'snowplow' stabilized, i.e., they are not shell-like but rather have smoothly varying mass with the radial density gradient, d{rho}/dr small or negative over much of the gas flow. Data on yield as a function of the radial distribution suggest that a near or on-axis peak in the initial gas density is probably optimal. Work remains to be done to establish the details of the 'best' mass distribution.

Coleman, P.L.; Krishnan, M.; Thompson, J.R. [Alameda Applied Sciences Corp, 626 Whitney St, San Leandro CA, 94577 (United States); Banister, J.W.; Failor, B.H.; Levine, J.S.; Qi, N.; Sze, H.M. [Titan Pulsed Sciences Division, 2700 Merced St., San Leandro, CA 94577 (United States); Apruzese, J.P.; Davis, J.; Thornhill, J.W.; Velikovich, A.L. [Naval Reearch Laboratory, Code 6720, 4555 Overlook Ave SW, Washington DC 20375 (United States); Commisso, R.J. [Naval Reearch Laboratory, Code 6770, 4555 Overlook Ave SW, Washington DC 20375 (United States); Verma, A. [Defense Threat Reduction Agency, Kirtland AFB, Albuquerque, NM 87117 (United States)

2006-01-05

325

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  

Microsoft Academic Search

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

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

2010-01-01

326

Modifying implosion dynamics of a wire array by using an inverse wire array z-pinch as a current switch  

NASA Astrophysics Data System (ADS)

We will describe experiments on the MAGPIE facility (1.5MA, 250ns) in which an inverse wire array (with the wires acting as a return current cage placed around a central current conductor) operated as a fast current switch. This allowed to significantly reduce the rise-time of the current pulse (<100ns) delivered to a separate, standard imploding wire array z-pinch load. It was found that this arrangement generates a short current pre-pulse (˜5kA, <15ns) through the imploding array, followed by a ˜140ns interval with zero current, before the main fast rising current pulse is switched into the array. This led to a significant change in the implosion dynamics, suppressing the ablation phase, introducing a 0-D-like implosion and reducing the level of trailing mass.

Lebedev, Sergey; Harvey-Thomson, A.; Hall, G. N.; Bland, S. N.; Burdiak, G.; Suzuki-Vidal, F. A.; Swadling, G.; Khoory, E.; Chittenden, J. P.; Pickworth, L.

2009-11-01

327

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

SciTech Connect

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. [Physics Department, University of Nevada, Reno, NV 89557 (United States); Chuvatin, A. S. [Ecole Polytechnique, 91128 Palaiseau (France); Rudakov, L. I. [Icarus Research Inc., Bethesda, MD 20824-0780 (United States); Greenly, J. B.; McBride, R. D.; Knapp, P. F.; Blessener, I. C.; Bell, K. S.; Chalenski, D. A.; Hammer, D. A. [Laboratory of Plasma Studies Cornell University, Ihaca, NY 14853 (United States)] (and others)

2009-01-21

328

Efficient Radiation Production in Long Implosions of Structured Gas-Puff Z Pinch Loads from Large Initial Radius  

SciTech Connect

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.

Sze, H.; Banister, J.; Failor, B.H.; Levine, J.S.; Qi, N.; Sincerny, P. [L-3 Titan Pulse Sciences Division, San Leandro, California, 94577 (United States); Velikovich, A.L.; Davis, J. [Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States); Lojewski, D. [Defense Threat Reduction Agency, Albuquerque, New Mexico 87117 (United States)

2005-09-02

329

Enhanced stability and neutron production in a dense Z-pinch plasma formed from a frozen deuterium fiber  

SciTech Connect

We have formed dense Z pinches from frozen deuterium fibers ranging in diameter from 80 to 125 ..mu..m and at peak currents of up to 640 kA. The pinch remains stable for the entire 130 nsec of the current rise. This anomalously long stable period corresponds to about 100 MHD growth times. As soon as the current peaks, i.e., when dI/dt = 0, the pinch goes rapidly m = 0 unstable and produces nearly 10/sup 12/ neutrons in a 30--60-nsec-wide pulse. The instability occurs only at dI/dt = 0 and is independent of either the current magnitude or the time to peak.

Sethian, J.D.; Robson, A.E.; Gerber, K.A.; DeSilva, A.W.

1987-08-24

330

Gas-puff Z pinches with D/sub 2/ and D/sub 2/-Ar mixtures  

SciTech Connect

Results obtained with the University of California, Irvine gas-puff Z-pinch experiment are described for deuterium and deuterium-argon mixtures. This experiment utilizes a hollow cylindrical gas puff injected between electrodes driven by a 4.8-kJ capacitor bank. Various gas compositions have been tested, including pure deuterium, 90% D/sub 2/-10% Ar, and up to 10% D/sub 2/-90% Ar. We have observed the stages of collapse and its rate, electron density at the pinch, neutron yield, and the time dependence of x-ray and neutron emission. When a 90% D/sub 2/-10% Ar mixture is injected, the plasma annulus is observed to separate into two columns which implode concentrically.

Bailey, J.; Ettinger, Y.; Fisher, A.; Rostoker, N.

1982-03-15

331

Efficient generation of fast neutrons by magnetized deuterons in an optimized deuterium gas-puff z-pinch  

NASA Astrophysics Data System (ADS)

Z-pinch experiments with deuterium gas puffs have been carried out on the GIT-12 generator at 3 MA currents. Recently, a novel configuration of a deuterium gas-puff z-pinch was used to accelerate deuterons and to generate fast neutrons. In order to form a homogeneous, uniformly conducting layer at a large initial radius, an inner deuterium gas puff was surrounded by an outer hollow cylindrical plasma shell. The plasma shell consisting of hydrogen and carbon ions was formed at the diameter of 350 mm by 48 plasma guns. A linear mass of the plasma shell was about 5 µg cm?1 whereas a total linear mass of deuterium gas in single or double shell gas puffs was about 100 µg cm?1. The implosion lasted 700 ns and seemed to be stable up to a 5 mm radius. During stagnation, m = 0 instabilities became more pronounced. When a disruption of necks occurred, the plasma impedance reached 0.4 ? and high energy (>2 MeV) bremsstrahlung radiation together with high energy deuterons were produced. Maximum neutron energies of 33 MeV were observed by axial time-of-flight detectors. The observed neutron spectra could be explained by a suprathermal distribution of deuterons with a high energy tail f?ft({{E}\\text{d}}\\right)\\propto E\\text{d}-(1.8+/- 0.2) . Neutron yields reached 3.6 × 1012 at a 2.7 MA current. A high neutron production efficiency of 6 × 107 neutrons per one joule of plasma energy resulted from the generation of high energy deuterons and from their magnetization inside plasmas.

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

2015-04-01

332

Magnetic Rayleigh-Taylor instability mitigation and efficient radiation production in gas puff Z-pinch implosions  

SciTech Connect

Large radius Z-pinches are inherently susceptible to the magnetic Rayleigh-Taylor (RT) instability because of their relatively long acceleration path. This has been reflected in a significant reduction of the argon K-shell yield as was observed when the diameter of the load was increased from 2.5 to >4 cm. Recently, an approach was demonstrated to overcome the challenge with a structured gas puff load that mitigates the RT instability, enhances the energy coupling, and leads to a high compression, high yield Z-pinch. The novel load consists of a 'pusher', outer region plasma that carries the current and couples energy from the driver, a 'stabilizer', inner region plasma that mitigates the RT growth, and a ''radiator,'' high-density center jet plasma that is heated and compressed to radiate. In 3.5-MA, 200-ns, 12-cm initial diameter implosions, the Ar K-shell yield has increased by a factor of 2, to 21 kJ, matching the yields obtained on the same accelerator with 100-ns, 2.5-cm-diam implosions. Further tests of such structured Ar gas load on {approx}6 MA, 200-ns accelerators have achieved >80 kJ. From laser diagnostics and measurements of the K-shell and extreme ultraviolet emission, initial gas distribution and implosion trajectories were obtained, illustrating the RT suppression and stabilization of the imploding plasma, and identifying the radiation source region in a structured gas puff load. Magnetohydrodynamic simulations, started from actual initial density profiles, reproduce many features of the measurements both qualitatively and quantitatively.

Sze, H.; Levine, J. S.; Banister, J.; Failor, B. H.; Qi, N.; Steen, P.; Velikovich, A. L.; Davis, J.; Wilson, A. [L-3 Pulse Sciences, San Leandro, California 94577 (United States); Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States); Avonia Inc., San Diego, California 92130 (United States)

2007-05-15

333

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

E-print Network

Initial magnetic field compression studies using gas-puff Z-pinches and thin liners on COBRA studies using gas-puff Z-pinches and thin liners on COBRA P.-A. Gourdain1 , R.J. Concepcion1 , M.T. Evans1-pinch implosions generated by gas puff and liner loads. The masses of the gas puff and liner loads were adjusted

Kroupp, Eyal

334

Experimental studies on X-ray and ion beam emitted from a small gas-puff Z-pinch plasma device  

Microsoft Academic Search

Summary form only given. Experimental studies on X-ray emission and energy spectra of the ion beam have been conducted on a small gas-puff Z-pinch plasma device (ZP). The ZP consists of a capacitor bank and a discharge chamber, which includes a fast gas valve, an ultrasonic nozzle, and a pair of electrodes. The effects on the X-ray yield of nozzle

C. M. Luo; C. R. Li; Y. Z. Fu; T. C. Yang; S. T. Pai

1993-01-01

335

Investigation of Ne IX and Ne X line emission from a gas-puff Z-pinch plasma using Ross filter systems  

Microsoft Academic Search

Semiconductor detectors can provide measurements of the X-ray emission spectra from Z-pinch plasmas with spectral, time and spatial resolution simultaneously. PIN detectors working in the current regime (up to 1 A), fast enough (1 nsec rise time), and small enough (1 to 3 mm 2 active area) are suitable, provided the X-ray spectral resolution is achieved by some element external

I. N. Bogatu; L. Gregorian; E. Klodzh; E. Kroupp; Y. Maron; Yu. V. Ralchenko

1998-01-01

336

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

Microsoft Academic Search

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 &etal;, 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

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

2008-01-01

337

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

Microsoft Academic Search

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

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

2008-01-01

338

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

339

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

340

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

341

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

342

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

NASA Astrophysics Data System (ADS)

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.; Serrano, J. D.; Nielsen-Weber, L. B.; Meyer, C. J.; Apruzese, J. P.; Clark, R. W.; Coleman, P. L.

2008-10-01

343

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

344

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

345

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

346

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

347

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

348

Numerical studies of ablated-plasma dynamics and precursor current of wire-array Z-pinches  

NASA Astrophysics Data System (ADS)

The dynamics of ablated plasmas of wire-array Z-pinches are studied numerically in (r,?) geometry by using the magnetohydrodynamic (MHD) simulation model in which the mass injection boundary conditions are presented, and two-dimensional spatio-temporal distributions of magnetic field and precursor current during the ablation phase are obtained. The ablated-plasma dynamics contains four processes: drifting toward the axis, arriving at the axis and forming the precursor column, and contraction and expansion of the precursor column. The relationship among the maximum inward velocity of ablated plasma streams and the initial wire array parameters is analyzed and it is found that this velocity is relatively sensitive to the change of inter-wire separation but weakly depends on the original array radius. The results are in reasonable agreement with the experiments on MAGPIE facility. The origin of the current flow in the precursor plasmas is analyzed from the point of view of the B-field convection in (r,?) plane. The dynamics of ablation streams determine the distribution of magnetic field and the current density Jz inside the wire array. The precursor current can be approximately calculated by the integral of Jz inside the region of a radius near to the column. In this model, the fraction of precursor current is less than 10% of the total current, which is close to the experimental results. When the current waveform is fixed, the increase of the inter-wire gap or decrease of the initial radius will lead to the increase of the precursor current.

Huang, Jun; Sun, Shun-Kai; Ding, Ning; Ning, Cheng; Xiao, De-Long; Zhang, Yang; Xue, Chuang

2011-04-01

349

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

350

Observed Multi-Decade DD and DT Z-Pinch Fusion Rate Scaling in 5 Dense Plasma Focus Fusion Machines  

SciTech Connect

Dense Plasma Focus (DPF) machines are in use worldwide or a wide variety of applications; one of these is to produce intense, short bursts of fusion via r-Z pinch heating and compression of a working gas. We have designed and constructed a series of these, ranging from portable to a maximum energy storage capacity of 2 MJ. Fusion rates from 5 DPF pulsed fusion generators have been measured in a single laboratory using calibrated activation detectors. Measured rates range from ~ 1015 to more than 1019 fusions per second have been measured. Fusion rates from the intense short (20 – 50 ns) periods of production were inferred from measurement of neutron production using both calibrated activation detectors and scintillator-PMT neutron time of flight (NTOF) detectors. The NTOF detectors are arranged to measure neutrons versus time over flight paths of 30 Meters. Fusion rate scaling versus energy and current will be discussed. Data showing observed fusion cutoff at D-D fusion yield levels of approximately 1?1012, and corresponding tube currents of ~ 3 MA will be shown. Energy asymmetry of product neutrons will also be discussed. Data from the NTOF lines of sight have been used to measure energy asymmetries of the fusion neutrons. From this, center of mass energies for the D(d,n)3He reaction are inferred. A novel re-entrant chamber that allows extremely high single pulse neutron doses (> 109 neutrons/cm2 in 50 ns) to be supplied to samples will be described. Machine characteristics and detector types will be discussed.

Hagen, E. C. [National Security Technologies, LLC; Lowe, D. R. [National Security Technologies, LLC; O'Brien, R. [University of Nevada, Las Vegas; Meehan, B. T. [National Security Technologies, LLC

2013-06-18

351

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

352

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

SciTech Connect

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

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

2014-04-15

353

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

354

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

SciTech Connect

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 10{sup 18} cm{sup -3} and 5x10{sup 21} cm{sup -3}) and temperature (<=1.5 keV) plasmas. In addition, X-pinches generated higher density (>10{sup 22} cm{sup -3}) and temperature (>2 keV) plasmas on scales as small as a few mum 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. [University of Nevada, Reno, NV 89557 (United States); Coverdale, C. A.; Jones, B.; Ampleford, D. J. [Sandia National Laboratories Albuquerque, NM 87185 (United States); LePell, P. D. [KTech Corporation, Albuquerque, NM 87123 (United States); Deeney, C. [NNSA/DOE, Headquarters, Washington, DC 20585 (United States)

2009-09-10

355

Dynamics of a Z-pinch x-ray source for heating inertial-confinement-fusion relevant hohlraums to 120-160 eV  

Microsoft Academic Search

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-diam axial aperture on the Z facility. The source has heated National Ignition Facility-scale (6-mm-diam by 7-mm-high) hohlraums to 122+\\/-6 eV and reduced-scale (4-mm-diam by 4-mm-high) hohlraums to 155+\\/-8 eV-providing environments suitable for indirect-drive inertial confinement fusion

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

2000-01-01

356

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

SciTech Connect

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

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

2010-03-26

357

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  

SciTech Connect

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.; Hotta, E. [Department of Energy Sciences, Tokyo Institute of Technology, Nagatsuta, Midoriku, Yokohama, Kanagawa 226-8502 (Japan); Kim, G.-H. [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)

2010-04-15

358

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

359

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

PubMed

A new imaging system for 1 MA scale wire-array Z-pinch experiments that produces up to five high-resolution x-ray images per experimental pulse has been developed. Calibrated areal density measurements of the Z-pinch plasma can be obtained from each pulse. The system substitutes five molybdenum (Mo) X pinches for the normal copper return-current conductors to provide point sources of x-rays for point-projection radiography. Each backlighting X pinch consists of four Mo wires, the x-ray burst timing of which was controlled by varying the wire diameter (mass) from 10.2 to 30 microm in the five X pinches. Typical images have a 16x8 mm2 field of view at the wire array and a magnification of about 6.5:1 on the x-ray-sensitive film. Titanium (Ti) filters in front of the films transmit continuum radiation in the spectral range of 3-5 keV. Inclusion on the Ti of a step wedge having known thickness increments of the same material as the wires enables the calibrated areal density measurements to be made of the exploding wire plasmas. Here, we used tungsten (W) step wedges with step thicknesses ranging from 0.015 to 1.1 microm to obtain accurate (+/-10%) areal density measurements of W plasmas from the spatial profile of film exposure. When imaging arrays that produce intense radiation pulses, a plastic monofilament "quencher" is placed on axis to avoid film saturation. Images have subnanosecond temporal resolution and about 7 microm spatial resolution. PMID:18377006

Douglass, J D; Hammer, D A

2008-03-01

360

K-shell and extreme ultraviolet spectroscopic signatures of structured Ar puff Z-pinch loads with high K-shell x-ray yield  

SciTech Connect

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 {approx_equal}3 mm, consistent with the observed load inductance change and an imploded-mass consisting of a {approx_equal}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. [L-3 Communications/Pulse Sciences, San Leandro, California 94577 (United States); Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States); Defense Threat Reduction Agency, Albuquerque, New Mexico 87117 (United States)

2007-02-15

361

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

362

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

363

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

364

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

365

Viscous Heating of Ions through Saturated Fine-Scale MHD Instabilities in a Z-Pinch at 200-300 KeV Temperature  

NASA Astrophysics Data System (ADS)

Pulsed power driven Z-pinches yield large X-ray powers at stagnation, the energy of which can exceed by up to factors of 3 or 4, the estimated kinetic energy of the implosion. Furthermore, when electron temperatures are measured at stagnation similar in temperatures would not lead to pressure balance. These problems can be resolved by a theoretical model in which short wavelength (ka >> 1, and viscous Lundquist number ˜ 1), fast growing, m=O MHD instabilities reach a saturated amplitude, and the associated viscous dissipation of the vortices leads to ion heating. Equating this heating rate to the equipartition of energy to electrons leads to an estimate of the ion temperature and pinch radius at pressure balance. Extremely high ion temperatures in the range of 200-300 KeV are predicted from this model for stainless steel wire array experiments on Z at Sandia. These have been confirmed from time-resolved Doppler broadening spectroscopic measurements of the optically thin Fe He-? line. This conversion of magnetic energy into ion thermal energy occurs on the nanosecond timescale, and can prevent radiative collapse. Any accompanying loss of magnetic flux in this highly conducting plasma can be explained by the occurrence of a large number of hot spots along the axis, with electron density and temperature variating not exactly in phase. This leads to a significant value of the integral of E.dl. Dl along the axis due to the grad Pe term in Ohm's law, analogous to the magnetic field generating term found in laser-plasma interactions. Ref 1. M.G. Haines, et al; Phys. Rev. Lett. 96, 075003 (2006) Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-ACO4-94AL85000.

Haines, Malcolm; Coverdale, Christine; Deeney, Chris; Lepell, P. David; Jones, Brent; Apruzese, J. P.

2006-10-01

366

Implementation of the thermonuclear process in D3He-9Be plasma on the basis of a Z pinch with an ultrafast laser ignition  

NASA Astrophysics Data System (ADS)

A new concept of inertial-magnetic confinement fusion is proposed. This concept is based on a high-current Z pinch combined with a femtosecond laser. The fusion target is composed of a D3He fuel contained under a high pressure inside a sealed cylindrical capsule made from metallic 9Be. An electric discharge along the capsule preheats the target and transforms it into a state of compressed liner. A subsequent TW femtosecond-laser pulse focused on a target end face causes ultrafast cold ignition of a small portion of the D3He fuel. This laser impact generates energetic electrons and ions, which trigger a nuclear-physics mechanism of a catalytic heating of the fuel and also creates a detonation shock wave capable of propagating along the plasma filament. It is shown that the self-sustaining fusion burn wave can appear in the D3He-9Be plasma, in which case the bulk of the energy release is carried by nonradioactive ions, with the energy gain being in excess of 50. The possibility of probing the fusion process by means of gamma-ray spectroscopy is also discussed. The radiative-capture reactions 3He( d, ?), D( d, ?), and 3He(3He, ?) naturally accompanying the burning of the D3He fuel are shown to serve as a convenient diagnostic tool. A nuclear “marker” of D3He fusion on the basis of the detection of monochromatic gamma rays produced in the reaction 9Be( ?, ?n), which is induced in the liner beryllium shell by energetic fusion alpha particles, is also examined.

Voronchev, V. T.; Kukulin, V. I.

2010-01-01

367

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

368

High Power Cryogenic Targets  

SciTech Connect

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

Gregory Smith

2011-08-01

369

High power density targets  

NASA Astrophysics Data System (ADS)

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

Pellemoine, Frederique

2013-12-01

370

High-power red VCSEL arrays  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

371

High power arcjet  

NASA Technical Reports Server (NTRS)

The activities on the development of the high power arc jet HIPARC, the thrust balance, and plasma diagnostic probes are discussed. Modifications of the HIPARC design and a synopsis of the materials used are given. Further experimental results with the TT30 thruster in the 50 kW range are presented. Some first calibration measurements of the thrust balance are also included. Progress concerning the development of plasma diagnostic devices is documented.

Auweter-Kurtz, M.; Glocker, B.; Goelz, T. M.; Habiger, H.; Kurtz, H. L.; Schrade, H. O.; Wegmann, T.

1990-01-01

372

High power microwave generator  

DOEpatents

A microwave generator efficiently converts the energy of an intense relativistic electron beam (REB) into a high-power microwave emission using the Smith-Purcell effect which is related to Cerenkov radiation. Feedback for efficient beam bunching and high gain is obtained by placing a cylindrical Smith-Purcell transmission grating on the axis of a toroidal resonator. High efficiency results from the use of a thin cold annular highly-magnetized REB that is closely coupled to the resonant structure.

Ekdahl, Carl A. (Albuquerque, NM)

1986-01-01

373

High power microwave generator  

DOEpatents

A microwave generator efficiently converts the energy of an intense relativistic electron beam (REB) into a high-power microwave emission using the Smith-Purcell effect which is related to Cerenkov radiation. Feedback for efficient beam bunching and high gain is obtained by placing a cylindrical Smith-Purcell transmission grating on the axis of a toroidal resonator. High efficiency results from the use of a thin cold annular highly-magnetized REB that is closely coupled to the resonant structure.

Ekdahl, C.A.

1983-12-29

374

Influence of insulating coating on aluminum wire explosions  

SciTech Connect

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

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

2014-10-15

375

High power arcjet  

NASA Technical Reports Server (NTRS)

The activities of the High Power Arcjet Project (HIPARC) from August 1990 to January 1991 are discussed. In this period the HIPARC thruster was ignited for the first time. Power levels up to 140 kW with a mass flow rate of 300 mg/s hydrogen were reached. Specific impulse values of more than 1300 s were shown to be possible. Tests were performed with the baseline thruster version only, which has a 6 mm throat diameter and a conical nozzle with a 20 degree half angle. Measurement data summing up all tests carried out until now is included. All measuring methods are described, including a check on possible error sources.

Goelz, T. M.; Auweter-Kurtz, M.; Kurtz, H. L.; Schrade, H. O.

1991-01-01

376

High power arcjet  

NASA Technical Reports Server (NTRS)

In this period a new mass flow controller was brought into the gas supply system, so that the upper limit for the mass flow rate could be increased up to 500 mg/s with hydrogen. A maximum specific impulse of 1500 s could be achieved with the high powered arcjet (HIPARC) at an efficiency of slightly better than 20 percent. Different nozzle throat diameters had been tested. The 100 kilo-watt input power limit was reached with the 4 mm nozzle throat diameter at a mass flow rate of 400 mg/s. Tests were carried out with different cathode gaps and with three different cathodes. In addition measurements of pressure and gas temperature were taken in the feed line in order to determine the pressure drop in the propellant injectors.

Goelz, T. M.; Auweter-Kurtz, M.; Kurtz, H. L.; Schrade, H. O.

1992-01-01

377

High power connection system  

DOEpatents

A high power connection system adapted for automotive environments which provides environmental and EMI shielding includes a female connector, a male connector, and a panel mount. The female connector includes a female connector base and a snap fitted female connector cover. The male connector includes a male connector base and a snap fitted male connector cover. The female connector base has at least one female power terminal cavity for seatably receiving a respective female power terminal. The male connector base has at least one male power terminal cavity for seatably receiving a respective male power terminal. The female connector is covered by a cover seal and a conductive shroud. A pair of lock arms protrude outward from the front end of the male connector base, pass through the panel mount and interface with a lever of a lever rotatably connected to the shroud to thereby mechanically assist mating of the male and female connectors. Safety terminals in the male and female connectors provide a last-to-connect-first-to-break connection with an HVIL circuit.

Schaefer, Christopher E. (Warren, OH); Beer, Robert C. (Noblesville, IN); McCall, Mark D. (Youngstown, OH)

2000-01-01

378

Silver based batteries for high power applications  

NASA Astrophysics Data System (ADS)

The present status of silver oxide-zinc technology and applications has been described by Karpinski et al. [A.P. Karpinski, B. Makovetski, S.J. Russell, J.R. Serenyi, D.C. Williams, Silver-Zinc: status of technology and applications, Journal of Power Sources, 80 (1999) 53-60], where the silver-zinc couple is still the preferred choice where high specific energy/energy density, coupled with high specific power/power density are important for high-rate, weight or size/configuration sensitive applications. Perhaps the silver oxide cathode can be considered one of the most versatile electrode materials. When coupled with other anodes and corresponding electrolyte management system, the silver electrode provides for a wide array of electrochemical systems that can be tailored to meet the most demanding, high power requirements. Besides zinc, the most notable include cadmium, iron, metal hydride, and hydrogen electrode for secondary systems, while primary systems include lithium and aluminum. Alloys including silver are also available, such as silver chloride, which when coupled with magnesium or aluminum are primarily used in many seawater applications. The selection and use of these couples is normally the result of a trade-off of many factors. These include performance, safety, risk, reliability, and cost. When high power is required, silver oxide-zinc, silver oxide-aluminum, and silver oxide-lithium are the most energetic. For moderate performance (i.e., lower power), silver oxide-zinc or silver-cadmium would be the system of choice. This paper summarizes the suitability of the silver-based couples, with an emphasis on the silver-zinc system, as primary or rechargeable power sources for high energy/power applications.

Karpinski, A. P.; Russell, S. J.; Serenyi, J. R.; Murphy, J. P.

379

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

NASA Astrophysics Data System (ADS)

An in-chamber, mini x-ray imaging instrument employs a pinhole and a logarithmic spiral crystal has been developed for obtaining K-shell line images of the imploding aluminum wire array on the "Yang" accelerator. The logarithmic spiral crystal acts as a monochromator and a non-dispersive mirror that reflects the pinhole image to a x-ray film detector with a very narrow photon energy bandwidth (<1 eV, mainly determined by the width of rocking curve of the crystal). Two imaging configurations with the use of Quartz (10bar{1}0) crystal and Mica (002) crystal are designed, respectively, to image the Al Ly?2 line (1727.7 eV) emission and Al He? intercombination line (1588.3 eV) emission. The primary experimental data corresponding to these two configurations are presented and discussed.

Yang, Qingguo; Li, Zeren; Peng, Qixian; Yang, Libing; Chen, Guanhua; Ye, Yan; Huang, Xianbin; Cai, Hongchun; Li, Jing; Xiao, Shali

2011-09-01

380

High power ferrite microwave switch  

NASA Technical Reports Server (NTRS)

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

Bardash, I.; Roschak, N. K.

1975-01-01

381

High power gas laser amplifier  

DOEpatents

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

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

1981-01-01

382

High power solid state lasers  

SciTech Connect

These proceedings discuss the following subjects: trends in materials processing with laser radiation; slabs and high power systems; glasses and new crystals; solid state lasers at HOYA Corp.; lamps, resonators and transmission; glasses as active materials for high average power solid state lasers; flashlamp pumped GGG-crystals; alexandrite lasers; designing telescope resonators; mode operation of neodymium: YAG lasers; intracavity frequency doubling with KTP crystal and thermal effects in cylinder lasers.

Weber, H.

1988-01-01

383

Anode arc motion in high power arcjets  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

384

High-power pulsed lasers  

SciTech Connect

The ideas that led to the successful construction and operation of large multibeam fusion lasers at the Lawrence Livermore Laboratory are reviewed. These lasers are based on the use of Nd:glass laser materials. However, most of the concepts are applicable to any laser being designed for fusion experimentation. This report is a summary of lectures given by the author at the 20th Scottish University Summer School in Physics, on Laser Plasma Interaction. This report includes basic concepts of the laser plasma system, a discussion of lasers that are useful for short-pulse, high-power operation, laser design constraints, optical diagnostics, and system organization.

Holzrichter, J.F.

1980-04-02

385

Analysis of Z Pinch Shock Wave Experiments  

SciTech Connect

In this paper, we report details of our computational study of two shock wave physics experiments performed on the Sandia Z machine in 1998. The novelty of these particular experiments is that they represent the first successful appli- cation of VISAR interferometry to diagnose shock waves generated in experi- mental payloads by the primary X-ray pulse of the machine. We use the Sandia shock-wave physics code ALEGRA to perform the simulations reported in this study. Our simulations are found to be in fair agreement with the time-resolved VISAR experimental data. However, there are also interesting and important discrepancies. We speculate as to future use of time-resolved shock wave data to diagnose details of the Z machine X-ray pulse in the future.

Asay, James; Budge, Kent G.; Chandler, Gordon; Fleming, Kevin; Hall, Clint; Holland, Kathleen; Konrad, Carl; Lawrence, Jeffery; Trott, Wayne; Trucano, Timothy

1999-05-01

386

Microfabricated wire arrays for Z-pinch.  

SciTech Connect

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

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

2008-10-01

387

High power broadband millimeter wave TWTs  

Microsoft Academic Search

In the early 1980’s the requirement for high power broadband millimeter wave sources encouraged the development of microwave vacuum device amplifiers for radar and communication systems. Many government funded programs were implemented for the development of high power broadband millimeter wave amplifiers that would meet the needs of the high power community. The tube design capable of meeting these goals

Bill G. James

1999-01-01

388

High Power Broadband Millimeter Wave TWTs  

Microsoft Academic Search

In the early 1980's the requirement for high power broadband millimeter wave sources encouraged the development of microwave vacuum device amplifiers for radar and communication systems. Many government funded programs were implemented for the development of high power broadband millimeter wave amplifiers that would meet the needs of the high power community. The tube design capable of meeting these goals

Bill G. James

1998-01-01

389

High power broadband millimeter wave TWTs  

Microsoft Academic Search

In the early 1980's the requirement for high power broadband millimeter wave sources encouraged the development of microwave vacuum device amplifiers for radar and communication systems. Many government funded programs were implemented for the development of high power broadband millimeter wave amplifiers that would meet the needs of the high power community. The tube design capable of meeting these goals

Bill G. James

1999-01-01

390

High-Power Rf Load  

DOEpatents

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

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

1998-09-01

391

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

Microsoft Academic Search

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

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

2011-01-01

392

Broadband High Power Amplifier using Spatial Power Combining Pengcheng Jia 1  

E-print Network

the input power to each element. A new compact coaxial combiner with much smaller size is investigated and convection. Since copper is only inferior to silver in thermal conductivity at room temperature and is 1.6 times better than aluminum, we chose copper as the material for the metal carriers in the high power

393

High Power Window Tests at SLAC  

Microsoft Academic Search

The successful design of high power windows play an essential role in RF power source development in accelerator programs such as the Next Linear Collider (NLC). Different window design approaches have been developed at several institutions to develop a successful high power window design. Some of the design considerations include the utilization of low loss RF modes, multiple RF modes

Vlieks; Arnold E

2002-01-01

394

High-power characteristics of piezoelectric materials  

Microsoft Academic Search

A measuring method of the high-power characteristics of the piezoelectric transducers and some experimental results are described. The vibrational velocity dependences of the equivalent circuit constants and the temperature rise were measured under the constant vibrational velocity control. In addition, when a high-power ultrasonic device such as an ultrasonic motor is practically used, the maximum efficiency is obtained at the

S. Hirose; S. Takahashi; M. Aoyagi; Y. Tomikawa

1994-01-01

395

High power laser perforating tools and systems  

SciTech Connect

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

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

2014-04-22

396

Photoconductive switching for high power microwave generation  

SciTech Connect

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

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

1990-10-01

397

High power rechargeable batteries Paul V. Braun  

E-print Network

High power rechargeable batteries Paul V. Braun , Jiung Cho, James H. Pikul, William P. King storage Secondary batteries High energy density High power density Lithium ion battery 3D battery of rechargeable (second- ary) batteries, as this is critical for most applications. As the penetration

Braun, Paul

398

Aluminum Hydroxide  

MedlinePLUS

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

399

Optical diagnostics for high power pulsed underwater electrical discharge characterization  

NASA Astrophysics Data System (ADS)

In order to evaluate the behavior of a high power pulsed underwater electrical discharge, and especially characterize the pressure generated by such a discharge, we implemented several optical diagnostics. We first observed directly the expansion of the plasma produced by the dielectric breakdown of the water between the electrodes and the resulting gaseous pulsating bubble. This observation led to an estimate of the pressure inside the bubble with respect to time. We then visualized the propagation of the pressure wave generated by the discharge with shadowgraph and Schlieren setup. The obtained velocity was then used to evaluate the theoretical maximum pressure at the pressure front. Finally, we measured the velocity induced by the pressure wave on a thin aluminum disk with a heterodyne velocimeter and used numerical simulation to obtain a temporal form of pressure. These methods and results can be used to develop and assess performances of processes using underwater electrical discharges to generate pressure waves such as electrohydraulic forming.

Deroy, J.; Claverie, A.; Avrillaud, G.; Boustie, M.; Mazanchenko, E.; Assous, D.; Chuvatin, A.

2014-05-01

400

High power millimeter wave source development program  

NASA Technical Reports Server (NTRS)

High power millimeter wave sources for fusion program; ECH source development program strategy; and 1 MW, 140 GHz gyrotron experiment design philosophy are briefly outlined. This presentation is represented by viewgraphs only.

George, T. V.

1989-01-01

401

Very high power THz radiation sources  

SciTech Connect

We report the production of high power (20 watts average, {approx} 1 Megawatt peak) broadband THz light based on coherent emission from relativistic electrons. Such sources are ideal for imaging, for high power damage studies and for studies of non-linear phenomena in this spectral range. We describe the source, presenting theoretical calculations and their experimental verification. For clarity we compare this source to one based on ultrafast laser techniques.

Carr, G.L.; Martin, Michael C.; McKinney, Wayne R.; Jordan, K.; Neil, George R.; Williams, G.P.

2002-10-31

402

High-power LEDs for plant cultivation  

Microsoft Academic Search

We report on high-power solid-state lighting facility for cultivation of greenhouse vegetables and on the results of the study of control of photosynthetic activity and growth morphology of radish and lettuce imposed by variation of the spectral composition of illumination. Experimental lighting modules (useful area of 0.22 m2) were designed based on 4 types of high-power light-emitting diodes (LEDs) with

Gintautas Tamulaitis; Pavelas Duchovskis; Zenius Bliznikas; Kestutis Breive; Raimonda Ulinskaite; Ausra Brazaityte; Algirdas Novickovas; Arturas Zukauskas; Michael S. Shur

2004-01-01

403

High Power Co-Axial Coupler  

SciTech Connect

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

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

2013-12-01

404

A High Power Frequency Doubled Fiber Laser  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reports on the development of a high power 780 nm laser suitable for space applications of laser cooling. A possible solution is to use frequency doubling of high power 1560 nm telecom lasers. The presentation shows a diagram of the frequency conversion, and a graph of the second harmonic generation in one crystal, and the use of the cascading crystals. Graphs show the second harmonic power as a function of distance between crystals, second harmonic power vs. pump power, tunability of laser systems.

Thompson, Robert J.; Tu, Meirong; Aveline, Dave; Lundblad, Nathan; Maleki, Lute

2003-01-01

405

Diagnostics for High Power Targets and Dumps  

E-print Network

High power targets are generally used for neutrino, antiproton, neutron and secondary beam production whereas dumps are needed in beam waste management. In order to guarantee an optimized and safe use of these targets and dumps, reliable instrumentation is needed; the diagnostics in high power beams around targets and dumps is reviewed. The suite of beam diagnostics devices used in such extreme environments is discussed, including their role in commissioning and operation. The handling and maintenance of the instrumentation components in high radiation areas is also addressed.

Gschwendtner, E

2012-01-01

406

High power diode lasers reliability experiment  

NASA Astrophysics Data System (ADS)

In order to evaluate and obtain the actual lifetime data of high power laser diodes, an automated high power laser diodes reliability experiment was developed and reported in this paper. This computer controlled setup operates the laser diodes 24 hours a day, the parameters such as output power, wavelength were test once in one hour. The experiment has 60 work stations, the temperature control range is from 25°C to 70°C, and the output power of the aging device is beyond 20W.

Lu, Guoguang; Xie, Shaofeng; Hao, Mingming; Huang, Yun; En, Yunfei

2013-12-01

407

Aluminum Boats  

NSDL National Science Digital Library

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

Reuben H. Fleet Science Center

1999-01-01

408

Continuous high-power gas lasers  

NASA Technical Reports Server (NTRS)

High power gas laser concepts are discussed with emphasis on the role that fluid mechanics has played in their development. Consideration is given to three types of systems: gasdynamic lasers, HF supersonic diffusion lasers, and electric discharge lasers. Flow effects and aerodynamic windows in such lasers are briefly described. Future directions of research are outlined.

Hertzberg, A.

1979-01-01

409

High-power annular beam klystrons  

Microsoft Academic Search

Summary form only given. Annular beam klystrons are well suited to high power operation. Significantly higher beam current can be transported than in conventional pencil beam klystrons (at the same beam voltage). Furthermore, we have designed cavity configurations that provide strong beam modulation and efficient energy extraction from the bunched electrons. Building on the pioneering work of Friedman and coworkers

J. Pasour; D. Smithe; L. Ludeking; M. Friedman

2000-01-01

410

BEAM INSTRUMENTATION FOR HIGH POWER HADRON BEAMS  

SciTech Connect

This presentation will describe developments in the beam diagnostics which support the understanding and operation of high power hadron accelerators. These include the measurement of large dynamic range transverse and longitudinal beam profiles, beam loss detection, and non-interceptive diagnostics.

Aleksandrov, Alexander V [ORNL] [ORNL

2013-01-01

411

Driver Circuit For High-Power MOSFET's  

NASA Technical Reports Server (NTRS)

Driver circuit generates rapid-voltage-transition pulses needed to switch high-power metal oxide/semiconductor field-effect transistor (MOSFET) modules rapidly between full "on" and full "off". Rapid switching reduces time of overlap between appreciable current through and appreciable voltage across such modules, thereby increasing power efficiency.

Letzer, Kevin A.

1991-01-01

412

Automated System Tests High-Power MOSFET's  

NASA Technical Reports Server (NTRS)

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

Huston, Steven W.; Wendt, Isabel O.

1994-01-01

413

High Power Lasers... Another approach to  

E-print Network

1 High Power Lasers... Another approach to Fusion Energy John Sethian Plasma Physics Division Naval Research Laboratory Washington, DC #12;2 Main points of the talk Fusion Energy based on lasers and direct drive targets Can lead to an attractive electricity generating power plant Developing Laser Fusion

414

Halo formation in high-power klystrons  

SciTech Connect

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

Pakter, R.; Chen, C.

1999-07-01

415

High Power Picosecond Laser Pulse Recirculation  

SciTech Connect

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

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

2010-04-12

416

High power microwave research at SLAC  

Microsoft Academic Search

Summary form only given. This presentation will report on the efforts at SLAC to produce high power microwave sources for the Next Linear Collider (NLC). The NLC as outlined by SLAC will require 4000 X-band klystrons operating at >50 MW with a 1.2 ?s pulsewidth. SLAC has recently developed and tested an X-band klystron up to 75 MW. Design and

G. Scheitrum; G. Caryotakis; R. Phillips; D. Sprehn; R. Fowkes

1996-01-01

417

High-Power -Doped Phosphate Fiber Amplifier  

Microsoft Academic Search

We report on the development of novel high-power light sources utilizing a Yb3+-doped phosphate fiber as the gain element. This host presents several key benefits over silica, particularly much higher Yb2 O3 concentrations (up to 26 wt%), a 50% weaker stimulated Brillouin scattering (SBS) gain cross section, and the absence of observable photodarkening even at high population inversion. These properties

Yin-Wen Lee; Michel J. F. Digonnet; Supriyo Sinha; Karel E. Urbanek; Robert L. Byer; Shibin Jiang

2009-01-01

418

Aluminum Analysis.  

ERIC Educational Resources Information Center

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

Sumrall, William J.

1998-01-01

419

High temperature, high power piezoelectric composite transducers.  

PubMed

Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined. PMID:25111242

Lee, Hyeong Jae; Zhang, Shujun; Bar-Cohen, Yoseph; Sherrit, Stewart

2014-01-01

420

High Power MPD Thruster Performance Measurements  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

421

High Power UV LED Industrial Curing Systems  

SciTech Connect

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

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

2012-05-14

422

High Temperature, High Power Piezoelectric Composite Transducers  

PubMed Central

Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined. PMID:25111242

Lee, Hyeong Jae; Zhang, Shujun; Bar-Cohen, Yoseph; Sherrit, StewarT.

2014-01-01

423

High power impulse magnetron sputtering discharge  

SciTech Connect

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

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

2012-05-15

424

Laser Welding of Aluminum and Aluminum Alloys  

E-print Network

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

Eagar, Thomas W.

425

Beam Stop For High-Power Lasers  

NASA Technical Reports Server (NTRS)

Graphite/aluminum plate absorbs most of light. Beam stop fits on standard optical mounting fixture. Graphite plate thick enough to absorb incident laser beam but thin enough to transfer heat quickly to heat sink. Device used for variety of blocking purposes. For example, blocks laser beam after it passes through experimental setup, or at each stage of setup so stages checked and tested in sequence. Negligible reflectance of device is valuable safety feature, protecting both users and equipment from reflections.

Mcdermid, Iain S.; Williamson, William B.

1990-01-01

426

High-power LEDs for plant cultivation  

NASA Astrophysics Data System (ADS)

We report on high-power solid-state lighting facility for cultivation of greenhouse vegetables and on the results of the study of control of photosynthetic activity and growth morphology of radish and lettuce imposed by variation of the spectral composition of illumination. Experimental lighting modules (useful area of 0.22 m2) were designed based on 4 types of high-power light-emitting diodes (LEDs) with emission peaked in red at the wavelengths of 660 nm and 640 nm (predominantly absorbed by chlorophyll a and b for photosynthesis, respectively), in blue at 455 nm (phototropic function), and in far-red at 735 nm (important for photomorphology). Morphological characteristics, chlorophyll and phytohormone concentrations in radish and lettuce grown in phytotron chambers under lighting with different spectral composition of the LED-based illuminator and under illumination by high pressure sodium lamps with an equivalent photosynthetic photon flux density were compared. A well-balanced solid-state lighting was found to enhance production of green mass and to ensure healthy morphogenesis of plants compared to those grown using conventional lighting. We observed that the plant morphology and concentrations of morphologically active phytohormones is strongly affected by the spectral composition of light in the red region. Commercial application of the LED-based illumination for large-scale plant cultivation is discussed. This technology is favorable from the point of view of energy consumption, controllable growth, and food safety but is hindered by high cost of the LEDs. Large scale manufacturing of high-power red AlInGaP-based LEDs emitting at 650 nm and a further decrease of the photon price for the LEDs emitting in the vicinity of the absorption peak of chlorophylls have to be achieved to promote horticulture applications.

Tamulaitis, Gintautas; Duchovskis, Pavelas; Bliznikas, Zenius; Breive, Kestutis; Ulinskaite, Raimonda; Brazaityte, Ausra; Novickovas, Algirdas; Zukauskas, Arturas; Shur, Michael S.

2004-10-01

427

High-power Ka-band amplifier  

NASA Technical Reports Server (NTRS)

Development of a high-power tube suitable to power a Ka-band (34.5-GHz) antenna transmitter located at the Goldstone, California, tracking station is continuing. The University of Maryland Laboratory for Plasma Research and JPL are conducting a joint effort to test the feasibility of phase locking a second-harmonic gyrotron both by direct injection at the output cavity and by using a priming cavity to bunch the electrons in the beam. This article describes several design options and the results of computer simulation testing.

Cormier, R.

1993-01-01

428

CLIC RF High Power Production Testing Program  

SciTech Connect

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

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

2011-11-02

429

Scaling blackbody laser to high powers  

NASA Technical Reports Server (NTRS)

Lasers pumped by solar heated blackbody cavities have potential for multimegawatt power beaming in space. There are two basic types of blackbody lasers; cavity pumped and transfer system. The transfer system is judged to be more readily scalable to high power. In this system, either N2 or CO is heated by the blackbody cavity then transferred into the laser cavity where CO2 is injected. The N2-CO2 system was demonstrated, but probably has lower efficiency than the CO-CO system. The characteristics of potential transfer laser systems are outlined.

Deyoung, R. J.

1985-01-01

430

High power diode pumped alkali vapor lasers  

NASA Astrophysics Data System (ADS)

Diode pumped alkali lasers have developed rapidly since their first demonstration. These lasers offer a path to convert highly efficient, but relatively low brightness, laser diodes into a single high power, high brightness beam. General Atomics has been engaged in the development of DPALs with scalable architectures. We have examined different species and pump characteristics. We show that high absorption can be achieved even when the pump source bandwidth is several times the absorption bandwidth. In addition, we present experimental results for both potassium and rubidium systems pumped with a 0.2 nm bandwidth alexandrite laser. These data show slope efficiencies of 67% and 72% respectively.

Zweiback, J.; Krupke, B.

2008-05-01

431

High power, high frequency, vacuum flange  

DOEpatents

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

Felker, B.; McDaniel, M.R.

1993-03-23

432

High power 2 µm femtosecond fiber laser.  

PubMed

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

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

2013-09-01

433

High power, high frequency, vacuum flange  

DOEpatents

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

Felker, Brian (Livermore, CA); McDaniel, Michael R. (Manteca, CA)

1993-01-01

434

High-power ultrawideband electromagnetic pulse radiation  

NASA Astrophysics Data System (ADS)

Basing on energetic processes studying in the near-field radiator zone, a new concept of antenna synthesizing for ultrawideband electromagnetic pulse radiation has been suggested. The results of experimental investigations of the antennae developed with using of this concept for high-power applications are presented. The antennae have small dimensions, high electrical strength, cardioid pattern with linear polarization of the pulse radiated and they are ideally adapted to be used as a steering antenna array element. A high-voltage nanosecond bipolar pulse generator design to excite antennae is described.

Koshelev, Vladimir I.; Buyanov, Yuri I.; Koval'chuk, Boris M.; Andreev, Yuri A.; Belichenko, Victor P.; Efremov, Anatoly M.; Plisko, Vyacheslav V.; Sukhushin, Konstantin N.; Vizir, Vadim A.; Zorin, Valery B.

1997-10-01

435

Powersail High Power Propulsion System Design Study  

NASA Astrophysics Data System (ADS)

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

Gulczinski, Frank S., III

2000-11-01

436

High power disk lasers: advances and applications  

NASA Astrophysics Data System (ADS)

Though the genesis of the disk laser concept dates to the early 90's, the disk laser continues to demonstrate the flexibility and the certain future of a breakthrough technology. On-going increases in power per disk, and improvements in beam quality and efficiency continue to validate the genius of the disk laser concept. As of today, the disk principle has not reached any fundamental limits regarding output power per disk or beam quality, and offers numerous advantages over other high power resonator concepts, especially over monolithic architectures. With well over 1000 high power disk lasers installations, the disk laser has proven to be a robust and reliable industrial tool. With advancements in running cost, investment cost and footprint, manufacturers continue to implement disk laser technology with more vigor than ever. This paper will explain important details of the TruDisk laser series and process relevant features of the system, like pump diode arrangement, resonator design and integrated beam guidance. In addition, advances in applications in the thick sheet area and very cost efficient high productivity applications like remote welding, remote cutting and cutting of thin sheets will be discussed.

Havrilla, David; Holzer, Marco

2011-02-01

437

Interest in high power microwave research  

SciTech Connect

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

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

1994-12-31

438

The future of high power laser techniques  

NASA Astrophysics Data System (ADS)

High Power Lasers have been used for years in corresponding applications. Constantly new areas and new processes have been demonstrated, developed and transferred to fruitful use in industry. With the advent of diode pumped solid state lasers in the multi-kW-power regime at beam qualities not far away from the diffraction limit, a new area of applicability has opened. In welding applications speeds could be increased and systems could be developed with higher efficiently leading also to new perspectives for increased productivity, e.g. in combined processing. Quality control is increasingly demanded by the applying industries, however applications still are rare. Higher resolution of coaxial process control systems in time and space combined with new strategies in signal processing could give rise to new applications. The general approach described in this paper emphasizes the fact, that laser applications can be developed more efficiently, more precisely and with higher quality, if the laser radiation is tailored properly to the corresponding application. In applying laser sources, the parameter ranges applicable are by far wider and more flexible compared to heat, mechanical or even electrical energy. The time frame ranges from several fs to continuous wave and this spans approximately 15 orders of magnitude. Spacewise, the foci range from several µm to cm and the resulting intensities suitable for materials processing span eight orders of magnitude from 10 3 to 10 11 W/cm2. In addition to space (power, intensity) and time (pulse) the wavelength can be chosen as a further parameter of optimization. As a consequence, the resulting new applications are vast and can be utilized in almost every market segment of our global economy (Fig. 1). In the past and only partly today, however, this flexibility of laser technology is not exploited in full in materials processing, basically because in the high power regime the lasers with tailored beam properties are not available and consequently many applications are not developed yet or are not operatable at optimized parameters. Because of their systematic flexibility in the sense layed out above, solid state lasers are the class to be considered in this context, diode pumped solid state lasers as well as high power diode lasers. In the past years the intrinsic beam quality of diode lasers in terms of divergence, smile and stability as well as the lifetime increased significantly. Single bars with beam parameter products around BPP=20 mm*mrad have been demonstrated. Lifetimes of 30.000h (90%) @100W cw operation are available /29/, /30/. Consequently the market increasingly accepts this type of lasers and new application domains like welding and metal deposition are investigated. Also the beam quality of high power diode lasers has been increased at many groups working in the field of coherent coupling or incoherent superposition [1]. Corresponding by the direct application of high power high quality diode lasers increasingly enters the markets. For all concepts the key demand is its applicability in terms of the specification of the process the laser is designed for. The characteristics of the laser with respect to power and energy on the one hand and quality in terms of space (spacial coherence, focussability), time (puls e duration and duty cycle) and wavelength have to match the demands of the specific application. Therefore, we face an intense trend for diversification of lasers in the named characteristics. There may be dominant large markets and niches but on the other hand there will not be a "best" laser or laser concept in the general sense.

Poprawe, Reinhart; Loosen, Peter; Hoffmann, Hans-Dieter

2007-05-01

439

Aluminum alloy  

NASA Technical Reports Server (NTRS)

This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

Blackburn, Linda B. (inventor); Starke, Edgar A., Jr. (inventor)

1989-01-01

440

Interaction of a high-power laser beam with metal sheets  

SciTech Connect

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

Boley, C. D.; Cutter, K. P.; Fochs, S. N.; Pax, P. H.; Rotter, M. D.; Rubenchik, A. M.; Yamamoto, R. M. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

2010-02-15

441

Interaction of a High-Power Laser Beam with Metal Sheets  

SciTech Connect

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

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

2009-06-24

442

Aluminum Cans  

NSDL National Science Digital Library

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

2008-01-01

443

Aluminum Pannier  

USGS Multimedia Gallery

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

444

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

SciTech Connect

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

Rosenberg, R.A.; Farrell, W.; Ma, Q. [Argonne National Lab., IL (United States). Advanced Photon Source] [and others

1997-09-01

445

High power density solid oxide fuel cells  

DOEpatents

A method for producing ultra-high power density solid oxide fuel cells (SOFCs). The method involves the formation of a multilayer structure cells wherein a buffer layer of doped-ceria is deposited intermediate a zirconia electrolyte and a cobalt iron based electrode using a colloidal spray deposition (CSD) technique. For example, a cobalt iron based cathode composed of (La,Sr)(Co,Fe)O (LSCF) may be deposited on a zirconia electrolyte via a buffer layer of doped-ceria deposited by the CSD technique. The thus formed SOFC have a power density of 1400 mW/cm.sup.2 at 600.degree. C. and 900 mW/cm.sup.2 at 700.degree. C. which constitutes a 2-3 times increased in power density over conventionally produced SOFCs.

Pham, Ai Quoc; Glass, Robert S.

2004-10-12

446

Feedthrough terminal for high-power cell  

DOEpatents

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

Kaun, T.D.

1982-05-28

447

High power long life superluminescent diode  

NASA Astrophysics Data System (ADS)

High power superluminescent diodes (SLD) have been fabricated from both gain-guided and index-guided AlGaAs/GaAs lasers. The spectral width (FWHM) of 15nm for the gain-guided SLD and 8 nm for the index-guided SLD are typical measured values. An output power of over 30mW/facet is achieved for the SLD at a wavelength of .83 micron. Over 3 mW has been obtained from the core of the pigtailed single-mode polarization-preserving fiber. Life testing of both SLDs on heat sinks and single-mode fiber pigtailed SLDs has been performed at different temperatures. A room-temperature extrapolated lifetime of over 100,000 hours is expected.

Wang, C. S.; Chen, J. S.; Fu, R.; Sunderam, V. S.; Varma, R.

1987-03-01

448

Efficient, monochromatic, high-power microwave generator  

SciTech Connect

Microwave generation by electron beams in virtual cathode configurations can achieve significant power levels. However, most designs inherently have two competing mechanisms generating microwaves; namely the oscillating virtual cathode and the reflexing electrons. These two mechanisms tend to interfere destructively with each other. Specifically, the reflexing electrons subject the electron beam to two-stream instability, causing considerable heating of the electron beam. In addition, the space-charge of the reflexing electrons can cause the diode independence to fluctuate, resulting in oscillations of the electron beam energy. We have investigated a novel idea to remove these undesirable effects and we found that high-power, narrow-band, and monochromatic microwaves could be generated with efficiency of 10 to 20%. 16 refs., 7 figs.

Kwan, T.J.T.; Snell, C.M.

1986-01-01

449

High-Power Options for LANSCE  

SciTech Connect

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

Garnett, Robert W. [Los Alamos National Laboratory

2011-01-01

450

High power transcranial beam steering for ultrasonic brain therapy  

E-print Network

1 High power transcranial beam steering for ultrasonic brain therapy M. Pernot, J.-F. Aubry, M.N.R.S. 7587, 10 rue Vauquelin, 75005 Paris, France Shortened title: High power ultrasonic array for brain-elements corresponding to a new generation of high power transducers developed in collaboration with Imasonic (Besançon

Paris-Sud XI, Université de

451

Surface alloying of silicon into aluminum substrate.  

SciTech Connect

Aluminum alloys that are easily castable tend to have lower silicon content and hence lower wear resistance. The use of laser surface alloying to improve the surface wear resistance of 319 and 320 aluminum alloys was examined. A silicon layer was painted onto the surface to be treated. A high power pulsed Nd:YAG laser with fiberoptic beam delivery was used to carry out the laser surface treatment to enhance the silicon content. Process parameters were varied to minimize the surface roughness from overlap of the laser beam treatment. The surface-alloyed layer was characterized and the silicon content was determined.

Xu, Z.

1998-10-28

452

High-Power Magnetoplasmadynamic Thruster Being Developed  

NASA Technical Reports Server (NTRS)

High-power electromagnetic thrusters have been proposed as primary in-space propulsion options for several of the bold new interplanetary and deep space missions envisioned by the Human Exploration and Development of Space (HEDS) Strategic Enterprise. As the lead center for electric propulsion, the NASA Glenn Research Center is actively involved in the design, development, and testing of high-power electromagnetic technologies to meet these demanding mission requirements. One concept of particular interest is the magnetoplasmadynamic (MPD) thruster, shown schematically in the preceding figure. In its basic form, the MPD thruster consists of a central cathode surrounded by a concentric cylindrical anode. A high-current arc is struck between the anode and cathode, which ionizes and accelerates a gas (plasma) propellant. In the self-field version of the thruster, an azimuthal magnetic field generated by the current returning through the cathode interacts with the radial discharge current flowing through the plasma to produce an axial electromagnetic body force, providing thrust. In applied field-versions of the thruster, a magnetic field coil surrounding the anode is used to provide additional radial and axial magnetic fields that can help stabilize and accelerate the plasma propellant. The following figure shows an experimental megawatt-class MPD thruster developed at Glenn. The MPD thruster is fitted inside a magnetic field coil, which in turn is mounted on a thrust stand supported by thin metal flexures. A calibrated position transducer is used to determine the force provided by the thruster as a function of thrust stand displacement. Power to the thruster is supplied by a 250-kJ capacitor bank, which provides up to 30- MW to the thruster for a period of 2 msec. This short period of time is sufficient to establish thruster performance similar to steady-state operation, and it allows a number of thruster designs to be quickly and economically evaluated. In concert with this experimental research, Glenn is also developing and using advanced numerical simulations to predict the performance of self-field and applied-field MPD thrusters.

LaPointe, Michael R.

2001-01-01

453

High power, high beam quality regenerative amplifier  

DOEpatents

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

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

1993-08-24

454

High power, high beam quality regenerative amplifier  

DOEpatents

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

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

1993-01-01

455

High power THz sources for nonlinear imaging  

SciTech Connect

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

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

2014-02-18

456

Reactive high power impulse magnetron sputtering  

NASA Astrophysics Data System (ADS)

Here we discuss reactive high power impulse magnetron sputtering sputtering (HiPIMS) [1] of Ti target in an Ar/N2 and Ar/O2 atmosphere. The discharge current waveform is highly dependent on both the pulse repetition frequency and discharge voltage. The discharge current increases with decreasing frequency or voltage. This we attribute to an increase in the secondary electron emission yield during the self-sputtering phase of the pulse, as nitride [2] or oxide [3] forms on the target. We also discuss the growth of TiN films on SiO2 at temperatures of 22-600 ^oC. The HiPIMS process produces denser films at lower growth temperature and the surface is much smoother and have a significantly lower resistivity than dc magnetron sputtered films on SiO2 at all growth temperatures due to reduced grain boundary scattering [4].[4pt] [1] J. T. Gudmundsson, N. Brenning, D. Lundin and U. Helmersson, J. Vac. Sci. Technol. A, 30 030801 (2012)[0pt] [2] F. Magnus, O. B. Sveinsson, S. Olafsson and J. T. Gudmundsson, J. Appl. Phys., 110 083306 (2011)[0pt] [3] F. Magnus, T. K. Tryggvason, S. Olafsson and J. T. Gudmundsson, J. Vac. Sci. Technol., submitted 2012[0pt] [4] F. Magnus, A. S. Ingason, S. Olafsson and J. T. Gudmundsson, IEEE Elec. Dev. Lett., accepted 2012

Gudmundsson, J. T.; Magnus, F.; Tryggvason, T. K.; Sveinsson, O. B.; Olafsson, S.

2012-10-01

457

High-power LED package requirements  

NASA Astrophysics Data System (ADS)

Power LEDs have evolved from simple indicators into illumination devices. For general lighting applications, where the objective is to light up an area, white LED arrays have been utilized to serve that function. Cost constraints will soon drive the industry to provide a discrete lighting solution. Early on, that will mean increasing the power densities while quantum efficiencies are addressed. For applications such as automotive headlamps & projection, where light needs to be tightly collimated, or controlled, arrays of die or LEDs will not be able to satisfy the requirements & limitations defined by etendue. Ultimately, whether a luminaire requires a small source with high luminance, or light spread over a general area, economics will force the evolution of the illumination LED into a compact discrete high power package. How the customer interfaces with this new package should be an important element considered early on in the design cycle. If an LED footprint of adequate size is not provided, it may prove impossible for the customer, or end user, to get rid of the heat in a manner sufficient to prevent premature LED light output degradation. Therefore it is critical, for maintaining expected LED lifetime & light output, that thermal performance parameters be defined, by design, at the system level, which includes heat sinking methods & interface materials or methdology.

Wall, Frank; Martin, Paul S.; Harbers, Gerard

2004-01-01

458

High frequency, high power capacitor development  

NASA Astrophysics Data System (ADS)

A program to develop a special high energy density, high power transfer capacitor to operate at frequency of 40 kHz, 600 V rms at 125 A rms plus 600 V dc bias for space operation. The program included material evaluation and selection, a capacitor design was prepared, a thermal analysis performed on the design. Fifty capacitors were manufactured for testing at 10 kHz and 40 kHz for 50 hours at Industrial Electric Heating Co. of Columbus, Ohio. The vacuum endurance test used on environmental chamber and temperature plate furnished by Maxwell. The capacitors were energized with a special power conditioning apparatus developed by Industrial Electric Heating Co. Temperature conditions of the capacitors were monitored by IEHCo test equipment. Successful completion of the vacuum endurance test series confirmed achievement of the main goal of producing a capacitor or reliable operation at high frequency in an environment normally not hospitable to electrical and electronic components. The capacitor developed compared to a typical commercial capacitor at the 40 kHz level represents a decrease in size and weight by a factor of seven.

White, C. W.; Hoffman, P. S.

1983-03-01

459

High frequency, high power capacitor development  

NASA Technical Reports Server (NTRS)

A program to develop a special high energy density, high power transfer capacitor to operate at frequency of 40 kHz, 600 V rms at 125 A rms plus 600 V dc bias for space operation. The program included material evaluation and selection, a capacitor design was prepared, a thermal analysis performed on the design. Fifty capacitors were manufactured for testing at 10 kHz and 40 kHz for 50 hours at Industrial Electric Heating Co. of Columbus, Ohio. The vacuum endurance test used on environmental chamber and temperature plate furnished by Maxwell. The capacitors were energized with a special power conditioning apparatus developed by Industrial Electric Heating Co. Temperature conditions of the capacitors were monitored by IEHCo test equipment. Successful completion of the vacuum endurance test series confirmed achievement of the main goal of producing a capacitor or reliable operation at high frequency in an environment normally not hospitable to electrical and electronic components. The capacitor developed compared to a typical commercial capacitor at the 40 kHz level represents a decrease in size and weight by a factor of seven.

White, C. W.; Hoffman, P. S.

1983-01-01

460

High power THz sources for nonlinear imaging  

NASA Astrophysics Data System (ADS)

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

Tekavec, Patrick F.; Kozlov, Vladimir G.

2014-02-01

461

Improved Collectors for High Power Gyrotrons  

SciTech Connect

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

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

2009-05-20

462

High power diode laser remelting of metals  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

463

High power linear pulsed beam annealer  

DOEpatents

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

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

1983-01-01

464

Considerations for very-high-power accelerators  

NASA Astrophysics Data System (ADS)

A Heavy Ion Fusion powerplant driver, if built today, would become the highest average-power accelerator ever built, probably by at least an order of magnitude. However, if some o