Note: This page contains sample records for the topic high-power aluminum z-pinch from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

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

SciTech Connect

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

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

1996-08-01

2

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

SciTech Connect

Time-resolved x-ray pinhole photographs and time-integrated radially-resolved x-ray crystal spectrometer measurements of azimuthally-symmetric aluminum-wire implosions suggest that the final pinch is composed of a hot dense plasma core surrounded by a cooler plasma halo. The slope of the free-bound x-ray continuum measured using filtered photoconducting diodes, provides a time-resolved, model-independent diagnostic of the core electron temperature. A simultaneous measurement of the time-resolved K-shell line spectra provides a diagnostic to indirectly measure the electron temperature of the plasma halo. Together, measurements from the two diagnostics lend support to a picture that also emerges from a 1-D Rad-Hydro model; namely, that of a plasma whose thermalization on axis produces steep radial gradients in temperature, where the temperatures are substantially in excess of a kilovolt in the core and below a kilovolt in the surrounding plasma halo.

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

1996-06-01

3

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

SciTech Connect

Time-resolved x-ray pinhole photographs and time-integrated radially resolved x-ray crystal-spectrometer measurements of azimuthally symmetric aluminum-wire implosions suggest that the densest phase of the pinch is composed of a hot plasma core surrounded by a cooler plasma halo. The slope of the free-bound x-ray continuum, provides a time-resolved, model-independent diagnostic of the core electron temperature. A simultaneous measurement of the time-resolved K-shell line spectra provides the electron temperature of the spatially averaged plasma. Together, the two diagnostics support a one-dimensional radiation{endash}hydrodynamic model prediction of a plasma whose thermalization on axis produces steep radial gradients in temperature, from temperatures in excess of 1 kV in the core to below 1 kV in the surrounding plasma halo. {copyright} {ital 1997 American Institute of Physics.}

Sanford, T.W.; Nash, T.J.; Mock, R.C.; Spielman, R.B.; Seamen, J.F.; McGurn, J.S.; Jobe, D.; Gilliland, T.L.; Vargas, M. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1193 (United States); Whitney, K.G.; Thornhill, J.W.; Pulsifer, P.E.; Apruzese, J.P. [Naval Research Laboratory, Washington, DC 20375-5000 (United States)

1997-01-01

4

High power z pinches as x ray laser photopumps  

NASA Astrophysics Data System (ADS)

Using Saturn as a driver, we are pursuing both photoresonantly pumped and photoionization/recombination lasers. Our lasing targets are gas cells with thin windows that are pumped by a z pinch 2 cm away radiating 10 TW. In both schemes the lasant and gas fill is neon. To increase our chances of measuring the resonantly photopumped lasing transition we have introduced potassium into a sodium z pinch and have eliminated oxygen from the gas cell windows. We have measured the spatial dependence of ionization balance across the gas cell, and this measurement is consistent with propagation of a shock front across the gas cell target. We have measured blue-shifted satellites to several Li-like neon transitions that may indicate return-current driven jetting a high 1.5e8 cm/sec velocity. Using a gold z-pinch we have shown that key radiation is necessary to excite the He-like lines of neon. An attempt at a single shot gain measurement also indicates that radiation is not the only source of gas cell heating.

Nash, T. J.; Spielman, R. B.; Ruggles, L.; Vargas, M.

5

High power z pinches as x-ray laser photopumps  

SciTech Connect

Using Saturn as a driver, we are pursuing both photoresonantly pumped and photoionization/recombination lasers. Our lasing targets are gas cells with thin windows that are pumped by a z pinch 2 cm away radiating 10 TW. In both schemes the lasant and gas fill is neon. To increase our chances of measuring the resonantly photopumped lasing transition we have introduced potassium into a sodium z pinch and have eliminated oxygen from the gas cell windows. We have measured the spatial dependence of ionization balance across the gas cell, and this measurement is consistent with propagation of a shock front across the gas cell target. We have measured blue-shifted satellites to several Li-like neon transitions that may indicate return-current driven jetting a high 1.5e8 cm/sec velocity. Using a gold z-pinch we have shown that key radiation is necessary to excite the He-like lines of neon. An attempt at a single shot gain measurement also indicates that radiation is not the only source of gas cell heating.

Nash, T.J.; Spielman, R.B.; Ruggles, L.; Vargas, M.

1992-12-31

6

High power z pinches as x-ray laser photopumps  

SciTech Connect

Using Saturn as a driver, we are pursuing both photoresonantly pumped and photoionization/recombination lasers. Our lasing targets are gas cells with thin windows that are pumped by a z pinch 2 cm away radiating 10 TW. In both schemes the lasant and gas fill is neon. To increase our chances of measuring the resonantly photopumped lasing transition we have introduced potassium into a sodium z pinch and have eliminated oxygen from the gas cell windows. We have measured the spatial dependence of ionization balance across the gas cell, and this measurement is consistent with propagation of a shock front across the gas cell target. We have measured blue-shifted satellites to several Li-like neon transitions that may indicate return-current driven jetting a high 1.5e8 cm/sec velocity. Using a gold z-pinch we have shown that key radiation is necessary to excite the He-like lines of neon. An attempt at a single shot gain measurement also indicates that radiation is not the only source of gas cell heating.

Nash, T.J.; Spielman, R.B.; Ruggles, L.; Vargas, M.

1992-01-01

7

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

8

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

9

Radiative characteristics of pulsed power driven Z-pinch aluminum plasmas  

Microsoft Academic Search

In this paper, we study the dynamics of a massive aluminum Z-pinch plasma load and evaluate its performance as a soft X-ray radiator. A radiation hydrodynamic model self-consistently driven by a circuit describes the dynamics. Comparisons are made for the K- and L-shell soft X-ray emission as a function of the ionization dynamic model. The ionization dynamic models are represented

Jack Davis; R. W. Clark; J. W. Thornhill; Christopher Deeney

1998-01-01

10

Diamond photoconducting detectors as high power [ital z]-pinch diagnostics (invited)  

SciTech Connect

Diamond photoconducting detectors (PCDs) are one of the primary x-ray diagnostics for [ital z]-pinch experiments at Sandia National Laboratories' Saturn facility. Diamond PCDs represent a significant advance in the state of the art for electrical x-ray detectors because of their stability of response, overall flatness of response, and ease of use. We have observed no aging effects in detectors used for years. Five PCDs on Saturn experiments where 1--3 TW of keV x-ray power is emitted in 5--20-ns pulses by [ital z]-pinch x-ray sources are routinely fielded. Typical PCDs used at Sandia have dimensions of 1 mm width [times]3 mm long [times]0.5 mm thick. The techniques used in the assembly, fielding, and calibration of diamond PCDs will be described.

Spielman, R.B. (Sandia National Laboratories, Albuquerque, New Mexico 87185-1194 (United States))

1995-01-01

11

High-Power Z Pinches as X-ray Laser Photopumps  

NASA Astrophysics Data System (ADS)

Using Saturn as a driver, we are pursuing both photoresonantly pumped and photoionization/recombination lasers. Our lasing targets are gas cells with thin windows that are pumped by a z pinch 2 cm away radiating 10 TW. In both schemes the lasant and gas fill is neon. To increase our chances of measuring the resonantly photopumped lasing transition we have introduced potassium into a sodium z pinch and have eliminated oxygen from the gas cell windows. We have measured the spatial dependence of ionization balance across the gas cell, and this measurement is consistent with propagation of a shock front across the gas cell target. We have measured blue-shifted satellites to several Li-like neon transitions that may indicate return-current driven jetting a high 1.5e8 cm/sec velocity. Using a gold z-pinch we have shown that keV radiation is necessary to excite the He-like lines of neon. An attempt at a single shot gain measurement also indicates that radiation is not the only source of gas cell heating.

Nash, T. J.; Spielman, R. B.; Ruggles, L.; Vargas, M.

1994-03-01

12

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

NASA Astrophysics Data System (ADS)

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

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

13

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

Microsoft Academic Search

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

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

1997-01-01

14

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

SciTech Connect

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

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

1997-06-13

15

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

16

Computational modeling of long implosion time aluminum z-pinches on the Saturn generator  

Microsoft Academic Search

Summary form only given. Long implosion time aluminum experiments have been carried out on the 7-MA Saturn accelerator at Sandia National Laboratories'. Such experiments are motivated by the incentive that longer implosion times translate to reduced cost and power flow risk to existing and future, high current generators. However, to achieve similar implosion velocities and subsequent powers as in the

M. Douglas; C. Coverdale; C. Deeney; N. Roderick

2000-01-01

17

Characteristics of implosion and radiation for aluminum planar wire array z-pinch at 1.5 MA  

NASA Astrophysics Data System (ADS)

Planar wire arrays Z pinches were carried out on Qiangguang generator (1.5 MA, 100 ns). Loads with varied row widths (6-24 mm) and wire numbers (10-34) were employed in the experiments. The implosion dynamics of planar wire arrays has been studied. Meanwhile, the changes of the implosion time, radiation yield and power with array mass, inter-wire gap, and array width were investigated. The images of a soft X-ray camera exhibit that the trailing mass, precursor column, and R-T instability exist during the implosion phase, and when m = 0 maybe accompanied with m = 1, instability will rapidly develop after stagnation. The implosion trajectories show that loads will implode by the snowplow mode and about 50% of total initial array mass will participate in the final implosion. The maximum total X-ray energy is 22 kJ with a power of 630 GW, while the maximum K-shell yield is 3.9 kJ with a power of 158 GW. Experiments with different planar wire arrays show that the value of mPD02 (the product of line mass and squared width) is the critical factor which affects the implosion time and the X-ray products of the wire arrays. The optimum value of mPD02 should be in the range of 200-400 ?gcm and the inter-wire gap should be less than 1 mm.

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

2012-12-01

18

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

19

Characteristics of implosion and radiation for aluminum planar wire array z-pinch at 1.5 MA  

SciTech Connect

Planar wire arrays Z pinches were carried out on Qiangguang generator (1.5 MA, 100 ns). Loads with varied row widths (6-24 mm) and wire numbers (10-34) were employed in the experiments. The implosion dynamics of planar wire arrays has been studied. Meanwhile, the changes of the implosion time, radiation yield and power with array mass, inter-wire gap, and array width were investigated. The images of a soft X-ray camera exhibit that the trailing mass, precursor column, and R-T instability exist during the implosion phase, and when m = 0 maybe accompanied with m = 1, instability will rapidly develop after stagnation. The implosion trajectories show that loads will implode by the snowplow mode and about 50% of total initial array mass will participate in the final implosion. The maximum total X-ray energy is 22 kJ with a power of 630 GW, while the maximum K-shell yield is 3.9 kJ with a power of 158 GW. Experiments with different planar wire arrays show that the value of m{sub P}D{sub 0}{sup 2} (the product of line mass and squared width) is the critical factor which affects the implosion time and the X-ray products of the wire arrays. The optimum value of m{sub P}D{sub 0}{sup 2} should be in the range of 200-400 {mu}gcm and the inter-wire gap should be less than 1 mm.

Wang Liangping; Wu Jian; Li Mo; Han Juanjuan; Guo Ning; Wu Gang; Qiu Aici [Northwest Institute of Nuclear Technology, Xi'an 710024 (China)

2012-12-15

20

UCI staged Z-pinch  

Microsoft Academic Search

Summary form only given, as follows. The UCI Staged Z-Pinch experiment is being assembled to study laboratory-scale thermonuclear fusion. The load configuration consists of an imploding-liner plasma that collapses onto a coaxial, hydrogenic-fiber target. The pulsed-power driver is a low-inductance, capacitor bank with the following design characteristics: 50 microFd, 50 kV, 50 kJ, 1.9 microsec risetime, and 2 MA into

A. Van Drie; V. Bystritskii; B. Moosman; H. U. Rahman; N. Rostoker; F. J. Wessel; G. Yur

1995-01-01

21

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

22

Modeling of Z-pinch-driven hohlraums  

Microsoft Academic Search

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

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

1999-01-01

23

Z and Z-Pinch IFE  

NASA Astrophysics Data System (ADS)

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

Olson, Craig

2002-04-01

24

The physics of fast Z pinches  

SciTech Connect

The spectacular progress made during the last few years in reaching high energy densities in fast implosions of annular current sheaths (fast Z pinches) opens new possibilities for a broad spectrum of experiments, from x-ray generation to controlled thermonuclear fusion and astrophysics. At present Z pinches are the most intense laboratory x-ray sources (1.8 MJ in 5 ns from a volume 2 mm in diameter and 2 cm tall). Powers in excess of 200 TW have been obtained. This warrants summarizing the present knowledge of physics that governs the behavior of radiating, current-carrying plasma in fast Z pinches. This survey covers essentially all aspects of the physics of fast Z pinches: initiation, instabilities of the early stage, magnetic Rayleigh-Taylor instability in the implosion phase, formation of a transient quasiequilibrium near the stagnation point, and rebound. Considerable attention is paid to the analysis of hydrodynamic instabilities governing the implosion symmetry. Possible ways of mitigating these instabilities are discussed. Nonmagnetohydrodynamic effects (anomalous resistivity, generation of particle beams, etc.) are summarized. Various applications of fast Z pinches are briefly described. Scaling laws governing development of more powerful Z pinches are presented. (c) 2000 The American Physical Society.

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

2000-01-01

25

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

26

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

27

The neo-Z-pinch concept in magnetic fusion  

Microsoft Academic Search

It is explained that the closed magnetic configuration is generated in the Z-pinch in a conductive casing provided that the axial current is over a critical value. By the formation of the closed configuration in the Z-pinch, the free-streaming end loss is automatically plugged. This type of Z-pinch is called the 'neo-Z-pinch'. The electrode problem of the neo-Z-pinch with respect

Kazunari Ikuta

1980-01-01

28

Progress on Z-pinch Inertial Fusion Energy  

Microsoft Academic Search

The long-range goal of the Z-pinch IFE program is to produce an economically-attractive power plant using high-yield Z-pinch-driven targets (?3 GJ) with low rep-rate per chamber (?0.1 Hz). He present mainline choice for a Z-pinch IFE power plant uses an LTD (Linear Transformer Driver) repetitive pulsed power driver, a Recyclable Transmission Line (RTL), a dynamic hohlraum Z-pinch-driven target, and a

C. L. Olson; G. Rochau; S. Slutz; C. Morrow; R. Olson; A. Parker; M. Cuneo; D. Hanson; G. Bennett; T. Sanford; J. Bailey; W. Stygar; R. Vesey; T. Mehlhorn; K. Struve; M. Mazarakis; M. Savage; A. Owen; T. Pointon; M. Kiefer; S. Rosenthal; L. Schneider; S. Glover; K. Reed; G. Benevides; D. Schroen; W. Krych; C. Farnum; M. Modesto; D. Oscar; L. Chhabildas; J. Boyes; V. Vigil; R. Keith; M. Turgeon; B. Smith; B. Cipiti; E. Lindgren; D. Smith; K. Peterson; V. Dandini; D. McDaniel; J. Quintenz; M. Matzen; J. P. VanDevender; W. Gauster; L. Shephard; M. Walck; T. Renk; T. Tanaka; M. Ulrickson; P. Peterson; J. De Groot; N. Jensen; R. Peterson; G. Pollock; P. Ottinger; J. Schumer; D. Kammer; I. Golovkin; G. Kulcinski; L. El-Guebaly; G. Moses; E. Mogahed; I. Sviatoslavsky; M. Sawan; M. Anderson; R. Gallix; N. Alexander; W. Rickman; H. Tran; P. Panchuk; W. Meier; J. Latkowski; R. Moir; R. Schmitt; R. Abbot; M. Abdou; A. Ying; P. Calderoni; N. Morley; S. Abdel-Khalik; D. Welch; D. Rose; W. Szaroletta; R. Curry; K. McDonald; D. Louie; S. Dean; A. Kim; S. Nedoseev; E. Grabovsky; A. Kingsep; V. Smirnov

2004-01-01

29

Analysis of Z Pinch Shock Wave Experiments  

Microsoft Academic Search

In this paper, we report detals of our computational study of two shock wave physics experiments performed on the Sandia Z machine in early 1998. The novelty of these particular experiments is that they represent the first successful application of VISAR interferometry to diagnose shock waves generated in experimental payloads by the primary X-ray pulse of this fast Z-pinch machine.

Timothy Trucano; Jeffrey Lawrence; Gordon Chandler; Kevin Fleming; Clint Hall; Kathleen Holland; Carl Konrad; Jeffery Lawrence; Wayne Trott

1999-01-01

30

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

Microsoft Academic Search

It is known that a thermonuclear target can be ignited by an implosion accomplished with X-radiation generated by means of laser radiation conversion or by a Z pinch formed by a high-power current pulse. For these purposes laser facility NIF has been constructed in the USA, 'Megajoule' is being constructed in France and there is a project of laser facility

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

2011-01-01

31

Use of an Electron Beam for Preionization in the Z-Pinch Experiment.  

National Technical Information Service (NTIS)

In the Z-pinch experiment a discharge of several mega-amps is initiated along a preionized filament in high density hydrogen gas. As presently proposed the preionized filament will be created by a high power laser focused in the gas. In the note the autho...

E. Ott R. Lee

1973-01-01

32

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

SciTech Connect

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

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

1998-01-01

33

Z-Pinch Power Plant Shock Mitigation Experiments, Modeling, and Code Assessment  

Microsoft Academic Search

We are investigating attenuation techniques to mitigate the powerful shock that occurs inside the Z-Pinch Power Plant. For this purpose, we conducted a series of experiments at the University of Wisconsin. These experiments consisted of shock waves traveling at greater than Ma 1 that impacted aluminum foam under various configurations. In turn, ABAQUS, ALEGRA, CTH, and DYNA3D were used to

Sal B. Rodriguez; Vincent J. Dandini; Virginia L. Vigil; Matt Turgeon; Dave Louie

2005-01-01

34

Z-Pinch Driven Isentropic Compression for Inertial Fusion  

SciTech Connect

The achievement of high gain with inertial fusion requires the compression of hydrogen isotopes to high density and temperatures. High densities can be achieved most efficiently by isentropic compression. This requires relatively slow pressure pulses on the order of 10-20 nanoseconds; however, the pressure profile must have the appropriate time. We present 1-D numerical simulations that indicate such a pressure profile can be generated by using pulsed power driven z pinches. Although high compression is calculated, the initial temperature is too low for ignition. Ignition could be achieved by heating a small portion of this compressed fuel with a short (-10 ps) high power laser pulse as previously described. Our 1-D calculations indicate that the existing Z-accelerator could provide the driving current (-20 MA) necessary to compress fuel to roughly 1500 times solid density. At this density the required laser energy is approximately 10 kJ. Multidimensional effects such as the Rayleigh-Taylor were not addressed in this brief numerical study. These effects will undoubtedly lower fuel compression for a given chive current. Therefore it is necessary to perform z-pinch driven compression experiments. Finally, we present preliminary experimental data from the Z-accelerator indicating that current can be efficiently delivered to appropriately small loads (- 5 mm radius) and that VISAR can be used measure high pressure during isentropic compression.

Asay, J.R.; Hall, C.A.; Holland, K.G.; Slutz, S.A.; Spielman, R.B.; Stygar, W.A.

1999-02-01

35

Positive polarity effect on 8-wire cylindrical z-pinches  

NASA Astrophysics Data System (ADS)

The Cornell University COBRA pulser is a nominal 1MA, 1MV machine, capableof driving up to 8 wire cylindrical Z-pinches. COBRA operates normally in negative polarity. A bolt-on convolute at the load was designed to allow both positive and negative polarity drives for the array. In positive polarity the electric field lines originate on the array wires while in negative polarity the field lines terminate on the wires Data were collected on 8-wire 12.5?m Aluminum Z-pinches in both polarities. Time dependent x-ray signals were measured using diodes and diamond detectors. A 6 ns pulsed laser was used as a backlighter to obtain images that were time-stepped through the evolution of the pinch. Pinches in positive polarity showed an increase in the power and total energy of the soft X-rays, and a decrease in the power and total energy of the emitted hard X-rays as compared to negative polarity pinches. Initial observations indicated that the pinch column in positive polarity began to form earlier than in negative polarity, and the structure of the imploding material was shown to be drastically different for the two polarity configurations. This research was supported by DOE grant DE-FG03-98ER54496, by Sandia National Laboratories contract AO258, and by the NNSA Stockpile Stewardship Academic Alliances program under DOE Cooperative Agreement DE-FC03-02NA00057.

Chalenski, David; Greenly, John; Schrafel, Peter; Kusse, Bruce

2006-10-01

36

High-density Z-pinch research  

SciTech Connect

The linear Z pinch is a plasma configuration which in its simplest form requires no auxiliary magnetic field; an axial current carried by the plasma produces an azimuthal confining field and provides ohmic (resistive) or implosion heating. The Lawson criterion (n tau > 10/sup 20/ m/sup -3/s) and high temperatures (T > 10 keV) must be simultaneously satisfied in any reactor scheme. Early Z-pinch experiments concentrated on the sub-atmospheric fill pressure regime, with 10/sup 19/ m/sup -3/ < n < 10/sup 23/ m/sup -3/ and a corresponding confinement time constraint of 10/sup 1/ s > tau > 10/sup -4/ s. In addition, these studies involved plasmas formed at the surface of an insulating wall; the plasmas were subsequently pinched inward by the radial j x B force. Following the implosion phase, gross MHD instabilities were invariably observed on a time scale short compared to the required confinement time.

Shlachter, J.S.

1983-01-01

37

ZAPP: Z-pinch atomic physics program  

SciTech Connect

High-density and high-temperature plasmas have been produced in a z-pinch with a hollow gas puff. A number of interesting atomic-physics phenomena occur in these plasmas and some of these phenomena provide important diagnostic information for characterizing the plasmas. We have been interested in collisions of high-energy electrons with highly stripped ions in these plasmas. Such collisions may produce a population inversion which could result in stimulated emission in the x-ray regime.

Reed, K.

1983-01-07

38

Z pinches: the past, present, and future  

NASA Astrophysics Data System (ADS)

Intense electron and light ion beam and z pinch research is based on pulsed power capabilities developed at the Atomic Weapons Establishment in the early 1960s to test the resistance of weapon components to radiation bursts by using short-duration bremsstrahlung sources. Research at Sandia and at the Kurchatov Institute in the 1970s led to an electron beam approach to inertial confinement fusion (ICF). The electron approach ended in 1979 when it was realized that the bremsstrahlung could significantly degrade the fuel compression. ICF research on a more promising approach, light ions, began in the late 1970s with the discovery, at Cornell, Sandia, and the Naval Research Laboratory, of efficient ways to produce intense beams of light ions. At the same time as emergence of the ion approach, z pinches that had produced copious keV x rays since the early 1970s were examined as a way to generate lower-voltage x rays to drive an ICF capsule. In this poster we review the research paths that led to these changes and predict what the future may hold for the z-pinch technology being pursued at Sandia.

Sweeney, M. A.; Yonas, G.

1998-11-01

39

Staged Z-pinch for Controlled Fusion  

NASA Astrophysics Data System (ADS)

A staged Z-pinch is considered in which an annular shell made of high Z material implodes onto a coaxial plasma target made of DT-mixture. The target plasma could be made either by exploding a cryogenically extruded fiber or by filling the annular shell with a plasma puff. An axial magnetic field is required to shear stabilize the most dangerous Rayleigh Taylor type instabilities. Modeling is performed with a 2D radiation-MHD code. A parameter study is made to detremine the sensitivity of this configuration to initial conditions of the shell and the target plasma. The axial magnetic field is essential for not only stable implosion but also efficient coupling of energy to the centeral load. Thermonuclear neutron yield is optimized by adjusting the initial strength of axial magnetic field and initial parameters of target plasma. The calculations are based on the parameters of presently operating UCI Z-pinch facility and PBFAZ facility at Sandia . The possibility of using this concept for a holraum type experiment where the X-ray radiation of Z-pinch is coupled to a spherical load is also considered.

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

1999-11-01

40

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

41

Radiation Losses In Z-pinch Plasma  

SciTech Connect

We have estimated the rate of total radiation losses from argon Z-pinches. Radiation losses due to excitation, dielectronic recombination, bremsstrahlung, radiative recombination and also ionization are considered. Ions in each ionization stage are analyzed, and the effects of finite density is taken into account. Our pinch dynamics includes Joule heating, anomalous plasma resistance, plasma outflow in the z-direction, electron beam generation, magnetic field pressure and radiation losses. For discharge current 1MA, the main radiation losses are associated with excitation. The effect of turbulent magnetic field is found essential in the later stage of the pinch.

Baronova, E. O.; Vikhrev, V. V.; Fujimoto, T. [RRC Kurchatov Institute, Moscow (Russian Federation); Kyoto University (Japan)

2006-01-15

42

Recent results on the dense Z-pinch  

SciTech Connect

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

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

1982-01-01

43

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

44

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

45

Polarization spectroscopy of x- and z-pinch plasmas  

Microsoft Academic Search

Further development of K- and L-shell spectroscopic monitoring of high-temperature x- and z-pinch plasmas demands taking account of the non-maxwellian electron distribution function and polarization properties of x-ray lines. Polarization spectroscopy is a powerful new tool for investigating the anisotropy of high-temperature x- and z-pinch plasmas. It is sensitive to the energetic electron distribution function and magnetic field, which, in

A. S. Shlyaptseva; V. L. Kantsyrev; B. S. Bauer; D. A. Fedin; S. B. Hansen; N. D. Ouart; S. A. Kazantsev; A. G. Petrashen; U. I. Safronova

2000-01-01

46

Z-Pinch Drivers for Shock Physics Research  

Microsoft Academic Search

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

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

1998-01-01

47

Azimuthal wire motion and ablation dynamics in z-pinches  

Microsoft Academic Search

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

Trevor S. Strickler

2006-01-01

48

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

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

49

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

50

Progress on 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.

Olson, Craig Lee

2004-09-01

51

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

52

Weldability of aluminum alloy with high power direct diode laser  

NASA Astrophysics Data System (ADS)

Characterized by high conversion efficiency, small size, light weight and a long lifetime, high power diode lasers are currently being developed for application to various types of metal fabrication, such as welding. In this report, a 4kW high power direct diode laser was used to weld aluminum alloys, which are the focus of increasing attention from the automobile industry because of their light weight, high formability and easy recyclability. The applicability of a direct diode laser to aluminum alloy bead-on plate, butt and lap-fillet welding was studied under various welding conditions. A sound bead without cracks was successfully obtained when 1 mm thick aluminum alloy was welded by bead-on welding at a speed of 12m/min. Moreover, the bead cross section was heat conduction welding type rather than the keyhole welding type of conventional laser welding. Investigation of the welding phenomena with a high-speed video camera showed no spattering or laser plasma, so there was no problem with laser plasma damaging the focusing lens despite the diode laser's short focusing distance.

Abe, Nobuyuki; Morikawa, Atsuhito; Tsukamoto, Masahiro; Maeda, Koichi; Namba, Keizo

2003-06-01

53

Thermonuclear fusion in a staged Z-Pinch  

NASA Astrophysics Data System (ADS)

The Staged Z-Pinch idea was born out of trying to understand the enhanced X-ray yield from shell onto target Z-Pinches I performed in the late 1980s as an undergraduate student at UCI [1]. The idea was further matured through later successes of multi-shell implosions demonstrated at UCI, the Ecole Polytechnique in France, and the Kurchatov Institute in Russia. The Staged Z-Pinch is based upon a hybrid of a Z-Z and Z- ? Pinch, i.e., an outer Z-Pinch drives Z and ? currents on a separate coaxial inner target, through compression of axial and azimuthal magnetic fields trapped between the two. These fields provide magnetic shear stabilization. The load configurations tested were: 4 cm dia. Kr hollow gas shell liner with a 1.7 cm dia. D2 hollow gas shell and solid D2 gas jet targets. It is experimentally and computationally observed, that the Kr liner achieves a spectrum of high charge states, which peels off and accelerates ahead of the bulk of the liner. As this Kr implodes onto the deuterium core, it compresses the axial and azimuthal magnetic fields trapped in the liner-target gap, driving the target as a Staged Z-Pinch. In addition, axial current is constantly transferring from the liner to the deuterium target, and eventually dominates over the staged z-pinching of the target and instead drives it as a Z-Pinch. Even without any initial axial Bz field both the peeling and implosion of the target appear RT stable. I call this type of load configuration a Peeled Pinch. For our Staged Z-Pinch experiments, I designed and assembled a mega-ampere, ? s-class pulsed-power driver [2]. This would drive the Kr liner at current levels of 1.2 MA with implosion times of about 150 ns. To study the pinch I developed and installed neutron, optical, and x-ray diagnostics. For neutrons this includes: Ag activation, bubble and TOF detectors. For optical this includes: a N2 laser schlieren and a streak camera diagnostics. For x-rays this includes: a pinhole camera, XRDS and PINs.

van Drie, Alan David

2001-05-01

54

Measurements of D-D neutrons in Z-pinches  

NASA Astrophysics Data System (ADS)

Fusion neutron measurements have been carried out on a small Z-pinch device (Z-150, CTU in Prague, 100 kA, 800 ns) as well as on a large Z-pinch generator (S-300, Kurchatov Institute in Moscow, 3 MA, 100 ns). The main goal of this research was to give an insight into the acceleration of fast ions and electrons, i.e. the most energetic processes in Z-pinches. For that purpose we used various deuterated Z-pinch loads and we studied the production of D-D neutrons together with the emission of soft and hard X-rays. The emphasis was put on the finding of (i) the evolution of Z-pinch plasmas, (ii) the time and duration of neutron production, (iii) the time and duration of X-ray generation, (iv) the region of X-ray emission, (v) neutron yields, (vii) X-ray energies, (viii) the neutron energy distribution function, (ix) the anisotropy of neutron emission, (x) the plasma current and voltage. Having obtained these pieces of information, the acceleration mechanism could be discussed.

Klir, D.; Kravarik, J.; Kubes, P.; Rezac, K.; Bakshaev, Yu. L.; Blinov, P. I.; Chernenko, A. S.; Danko, S. A.; Korolev, V. D.; Kravchenko, E. V.; Shaskov, A. Yu.; Ustroev, G. I.; Ivanov, M. I.

2006-10-01

55

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

56

Quantitative Measurements of Ablation in Wire Array Z-Pinches  

NASA Astrophysics Data System (ADS)

The long-time scale ablation of the wires in a wire array z-pinch is crucial in determining its subsequent implosion and X-ray emission. Using a combination of interferometry and Faraday probing, we report on direct measurements of the current and mass density profiles in cylindrical, radial and inverse wire array z-pinches leading up to and during implosion. The results are compared and contracted to the rocket ablation model and to both 2 and 3-D MHD simulations. This research was sponsored by Sandia National Labs and the NNSA under DOE Cooperative Agreement DE-F03-02NA00057.

Harvey-Thompson, A.; Lebedev, S. V.; Bland, S. N.; Chittenden, J. P.; Hall, G. N.; Palmer, J. B. A.; Suzuki-Vidal, F.; Bott, S. C.

2007-11-01

57

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

58

Equation-of-State Measurements with Z-Pinch Sources  

SciTech Connect

Validation of material models in a variety of scientific and technological applications requires accurate data regarding the high-pressure thermodynamic and mechanical properties. Traditional laboratory techniques for striking these measurements involve light gas guns to generate the required thermodynamic states, and the use of high-resolution time-resolved diagnostics to measure the desired material properties. EOS and constitutive material properties of importance to modeling needs include high-pressure Hugoniot curves and off-Hugoniot properties, such as. material strength and isentropic compression and decompression [1]. Conventional light gas guns are limited to impact pressures of about 7 Mbar in high-impedance materials. Pulsed radiation sources, such as high-intensity lasers, and pulsed power techniques significantly extend the accessible pressures and are becoming accepted methods for meeting the needs of material models in regimes inaccessible by gas guns. A present limitation of these new approaches is that samples must necessarily be small, typically a few tens of microns in thickness, which severely limits the accuracy of EOS measurements that can be made and also the ability to perform a variety of off-Hugoniot measurements. However, recent advances in z-pinch techniques for high-pressure material response studies provide potential opportunities for achieving accuracies comparable with gas guns because of the significantly larger samples that can be studied. Sample thicknesses approaching 1 mm may be possible with advances presently being made. These sample dimensions are comparable with gas gun sample dimensions so that accuracies should be comparable. The Sandia Z accelerator [2] is a recently developed facility that generates x-ray energies of about 2 MJ over time scales of 5-10 ns with resulting temperatures of 100-150 eV in containment fixtures, referred to as hohlraums, that are a few cubic centimeters in volume. This intense radiation source can be used to ablatively drive shock waves to about pressures of about 10 Mbar in a variety of materials. Because of the large source. In this paper, we discuss recent developments in the use of the Sandia Z accelerator for Hugoniot and off-Hugoniot measurements. Preliminary data on high-pressure dynamic response include Hugoniot EOS data on aluminum to about 5 Mbar using the z-pinch technique and isentropic compression data on iron and copper to about 300 and 130 kbar, respectively, using the direct current mode on Z. The isentropic compression experiments are performed on sample thicknesses to 0.8 mm and allow determination of the cx-s phase transition and the kinetic properties of this transition. Specifically, isentropic compression data on iron have been analyzed with a two-phase rate dependent model of the bcc-hcp phase transition, which shows that the relatively slow rates of pressure application achieved with this technique result in observable kinetic effects that can be easily analyzed. Other work in progress with the Z Accelerator includes EOS studies of liquid deutenum and the development of uniform, constant pressure drives that will provide higher accuracy in EOS measurements.

Asay, J.R.; Hall, C.; Bailey, J.E.; Knudson, M.D.; Holland, K.G.; Hanson, D.L.; Johnston, R.; Bernard, M.A.; Trott, W.M.; Spielman, R.E.; Stygar, W.A.; McDaniel, D.H.

1999-07-22

59

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

SciTech Connect

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 MgF{sub 2} 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 {yields} 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 1{sigma} to the best-fit conditions. This agreement indicates that both the driving radiation spectrum and the heating of the Al and MgF{sub 2} samples is understood within the accuracy of the spectroscopic method.

MacFarlane, Joseph John (Prism Computational Sciences, Madison, WI); Rochau, Gregory Alan; Bailey, James E.

2005-06-01

60

MHD simulation studies of z-pinch shear flow stabilization  

NASA Astrophysics Data System (ADS)

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

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

2003-10-01

61

Z-pinch experiments on Saturn at 30 TW  

NASA Astrophysics Data System (ADS)

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

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

1989-12-01

62

Z-pinch experiments on Saturn at 30 TW  

NASA Astrophysics Data System (ADS)

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

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

63

X-ray absorption spectroscopy measurements of thin foil heating by Z-pinch radiation.  

PubMed

Absorption spectroscopy measurements of the time-dependent heating of thin foils exposed to intense z-pinch radiation sources are presented. These measurements and their analysis provide valuable benchmarks for, and insights into, the radiative heating of matter by x-ray sources. Z-pinch radiation sources with peak powers of up to 160 TW radiatively heated thin plastic-tamped aluminum foils to temperatures approximately 60 eV. The foils were located in open slots at the boundary of z-pinch hohlraums surrounding the pinch. Time-resolved Kalpha satellite absorption spectroscopy was used to measure the evolution of the Al ionization distribution, using a geometry in which the pinch served as the backlighter. The time-dependent pinch radius and x-ray power were monitored using framing camera, x-ray diode array, and bolometer measurements. A three-dimensional view factor code, within which one-dimensional (1D) radiation-hydrodynamics calculations were performed for each surface element in the view factor grid, was used to compute the incident and reemitted radiation flux distribution throughout the hohlraum and across the foil surface. Simulated absorption spectra were then generated by postprocessing radiation-hydrodynamics results for the foil heating using a 1D collisional-radiative code. Our simulated results were found to be in good general agreement with experimental x-ray spectra, indicating that the spectral measurements are consistent with independent measurements of the pinch power. We also discuss the sensitivity of our results to the spectrum of the radiation field incident on the foil, and the role of nonlocal thermodynamic equilibrium atomic kinetics in affecting the spectra. PMID:12443339

MacFarlane, J J; Bailey, J E; Chandler, G A; Deeney, C; Douglas, M R; Jobe, D; Lake, P; Nash, T J; Nielsen, D S; Spielman, R B; Wang, P; Woodruff, P

2002-10-28

64

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

65

High performance capsule implosions driven by the Z-pinch dynamic hohlraum  

NASA Astrophysics Data System (ADS)

The Z-pinch dynamic hohlraum (ZPDH) is a high-power x-ray source that has been used in a variety of high energy-density experiments including inertial confinement fusion (ICF) studies. The system consists of a tungsten wire-array Z pinch that implodes onto a low-density CH2 foam converter launching a radiating shock that heats the hohlraum to radiation temperatures >200 eV. Through time-gated pinhole camera measurements, the mean shock speed is measured from 28 experiments to be 326 4 m ns-1 with a shot-to-shot standard deviation of 7%. Broad-band x-ray measurements indicate that the shot-to-shot reproducibility in the power emission and pulse-shape of the source shock is <15% and ~5%, respectively. Calculations have shown that an ICF capsule placed at the center of the foam in the ZPDH can absorb >40 kJ of x-ray energy, within a factor of 4 of the energy believed sufficient for ICF ignition. The capsule types imploded by the ZPDH have evolved over four years culminating in a design that produces record indirect-drive DD thermonuclear neutron yields of up to 3.5E11.

Rochau, G. A.; Bailey, J. E.; Chandler, G. A.; Cooper, G.; Dunham, G. S.; Lake, P. W.; Leeper, R. J.; Lemke, R. W.; Mehlhorn, T. A.; Nikroo, A.; Peterson, K. J.; Ruiz, C. L.; Schroen, D. G.; Slutz, S. A.; Steinman, D.; Stygar, W. A.; Varnum, W.

2007-12-01

66

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

NASA Astrophysics Data System (ADS)

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

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

2007-11-01

67

Optimization of Capsule Symmetry in Z-Pinch Driven Hohlraums  

NASA Astrophysics Data System (ADS)

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

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

1999-11-01

68

Observation on two parallel wires Z-pinch  

Microsoft Academic Search

We report on two parallel wires Z-pinch experiments, driven by a current up to 160kA, with a rise time (10-90%) of 65ns. Aluminium and tungsten wires of diameter 15 and 7.5 microns, separated by distance of 0.3, 0.6 and 1.5mm were used. The plasma dynamics was studied by schlieren probing, a four frame gated optical intensifier (GOI) and optical streak

J. Ruiz-Camacho; F. N. Beg; A. E. Dangor; I. Ross

1998-01-01

69

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

70

Measurement of Radiation Symmetry in Z-Pinch Driven Hohlraums  

NASA Astrophysics Data System (ADS)

The z-pinch driven hohlraum (ZPDH) is a promising approach to high yield inertial confinement fusion currently being characterized in experiments on the Sandia Z accelerator [1]. In this concept [2], x rays are produced by an axial z-pinch in a primary hohlraum at each end of a secondary hohlraum. A fusion capsule in the secondary is imploded by a symmetric x-ray flux distribution, effectively smoothed by wall reemission during transport to the capsule position. Capsule radiation symmetry, a critical issue in the design of such a system, is influenced by hohlraum geometry, wall motion and time-dependent albedo, as well as power balance and pinch timing between the two z-pinch x-ray sources. In initial symmetry studies on Z, we used solid low density burnthrough spheres to diagnose highly asymmetric, single-sided-drive hohlraum geometries. We then applied this technique to the more symmetric double z-pinch geometry [3]. As a result of design improvements, radiation flux symmetry in Z double-pinch wire array experiments now exceeds the measurement sensitivity of this self-backlit foam ball symmetry diagnostic (15% max-min flux asymmetry). To diagnose radiation symmetry at the 2 - 5% level attainable with our present ZPDH designs, we are using high-energy x rays produced by the recently-completed Z-Beamlet laser backlighter for point-projection imaging of thin-wall implosion and symmetry capsules. We will present the results of polar flux symmetry measuremets on Z for several ZPDH capsule geometries together with radiosity and radiation-hydrodynamics simulations for comparison. [1] M. E. Cuneo et al., Phys. Plasmas 8,2257(2001); [2] J. H. Hammer et al., Phys. Plasmas 6,2129(1999); [3] D. L. Hanson et al., Bull. Am. Phys. Soc. 45,360(2000).

Hanson, David L.

2001-10-01

71

Ideal Z-Pinch Instabilities Across Fluid Plasma Regimes  

NASA Astrophysics Data System (ADS)

In this paper we model instabilities in high density Z-pinches across fluid plasma regimes. The theory of MHD instabilities in a Z-pinch plasma is well understood, in this paper we look at numerical predictions that extend well beyond MHD to a variety of high energy density fluid models. Currently, researchers at Tech-X are investigating Hall MHD, Two-Fluid and Gyroviscous models of plasma to properly model fast fluid plasma processes that are high density, but where the plasma size approaches the ion magnetization scale length. It is in this regime that electron drift velocities are high relative to the ion acoustic speed and a number of new instabilities begin to emerge that cannot be modeled with traditional MHD theory and where numerical methods are highly desirable for modeling the non-linear effects. Results are presented for Z- pinch simulations using ideal fluid models with comparison to MHD. In time, we hope to model other key effects such as radiation and ionization in addition to developing algorithms for better modeling the vacuum region.

Loverich, John; Hakim, Ammar

2008-04-01

72

Architecture of petawatt-class z-pinch accelerators  

NASA Astrophysics Data System (ADS)

We have developed an accelerator architecture that can serve as the basis of the design of petawatt-class z-pinch drivers. The architecture has been applied to the design of two z-pinch accelerators, each of which can be contained within a 104-m-diameter cylindrical tank. One accelerator is driven by slow (1?s) Marx generators, which are a mature technology but which necessitate significant pulse compression to achieve the short pulses (?1?s) required to drive z pinches. The other is powered by linear transformer drivers (LTDs), which are less mature but produce much shorter pulses than conventional Marxes. Consequently, an LTD-driven accelerator promises to be (at a given pinch current and implosion time) more efficient and reliable. The Marx-driven accelerator produces a peak electrical power of 500 TW and includes the following components: (i) 300 Marx generators that comprise a total of 1.8104 capacitors, store 98 MJ, and erect to 5 MV; (ii) 600 water-dielectric triplate intermediate-store transmission lines, which also serve as pulse-forming lines; (iii) 600 5-MV laser-triggered gas switches; (iv) three monolithic radial-transmission-line impedance transformers, with triplate geometries and exponential impedance profiles; (v) a 6-level 5.5-m-diameter 15-MV vacuum insulator stack; (vi) six magnetically insulated vacuum transmission lines (MITLs); and (vii) a triple-post-hole vacuum convolute that adds the output currents of the six MITLs, and delivers the combined current to a z-pinch load. The accelerator delivers an effective peak current of 52 MA to a 10-mm-length z pinch that implodes in 95 ns, and 57 MA to a pinch that implodes in 120 ns. The LTD-driven accelerator includes monolithic radial transformers and a MITL system similar to those described above, but does not include intermediate-store transmission lines, multimegavolt gas switches, or a laser trigger system. Instead, this accelerator is driven by 210 LTD modules that include a total of 1106 capacitors and 5105 200-kV electrically triggered gas switches. The LTD accelerator stores 182 MJ and produces a peak electrical power of 1000 TW. The accelerator delivers an effective peak current of 68 MA to a pinch that implodes in 95 ns, and 75 MA to a pinch that implodes in 120 ns. Conceptually straightforward upgrades to these designs would deliver even higher pinch currents and faster implosions.

Stygar, W. A.; Cuneo, M. E.; Headley, D. I.; Ives, H. C.; Leeper, R. J.; Mazarakis, M. G.; Olson, C. L.; Porter, J. L.; Wagoner, T. C.; Woodworth, J. R.

2007-03-01

73

Implosion dynamics and X-ray production in wire array z-pinches  

NASA Astrophysics Data System (ADS)

Wire array z-pinches offer an efficient source of high power, high yield X-ray pulses, yet the mechanisms underlying X-ray production remain relatively undiagnosed. Detailed measurements of the implosion and stagnation of wire arrays were made on the 1MA MAGPIE generator. A variety of diagnostics, including XUV imaging and a spatially resolved spherical crystal spectrometer identified 4 stages of on axis pinch behavior: the snowplough implosion striking the on-axis precursor; compression of the stagnated plasma; the development of m=1 instabilities whilst the plasma was compressed; and finally breaks occurring in the stagnated plasma, destroying the pinch. X-ray emission is compared to pinch behavior and the relationship with between mass and current distribution is explored. This research was sponsored by Sandia National Laboratories, Albuquerque, and the SSAA program of NNSA under DOE Cooperative Agreement DE-FC03-02NA00057.

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

2004-11-01

74

Enhanced energy coupling and x-ray emission in Z-pinch plasma implosions  

NASA Astrophysics Data System (ADS)

Recent experiments conducted on the Saturn pulsed-power generator at Sandia National Laboratories [R. B. Spielman et al., in Proceedings of the Second International Conference on Dense Z Pinches, Laguna Beach, CA, 1989, edited by N. R. Pereira, J. Davis, and N. Rostoker (American Institute of Physics, New York, 1989), p. 3] have produced large amounts of x-ray output, which cannot be accounted for in conventional magnetohydrodynamic (MHD) calculations. In these experiments, the Saturn current had a rise time of ~180 ns in contrast to a rise time of ~60 ns in Saturn's earlier mode of operation. In both aluminum and tungsten wire-array Z-pinch implosions, 2-4 times more x-ray output was generated than could be supplied according to one-dimensional (1D) magnetohydrodynamic calculations by the combined action of the jB acceleration forces and ohmic heating (as described by a classical Braginskii resistivity). In this paper, we reexamine the problem of coupling transmission line circuits to plasma fluid equations and derive expressions for the Z-pinch load circuit resistance and inductance that relate these quantities in a 1D analysis to the surface resistivity of the fluid, and to the magnetic field energy that is stored in the vacuum diode, respectively. Enhanced energy coupling in this analysis, therefore, comes from enhancements to the surface resistivity, and we show that plasma resistivities approximately three orders of magnitude larger than classical are needed in order to achieve energy inputs that are comparable to the Saturn experiment x-ray outputs. Large enhancements of the plasma resistivity increase the rate of magnetic field and current diffusion, significantly modify the qualitative features of the MHD, and raise important questions as to how the plasma fluid dynamics converts enhanced energy inputs into enhanced x-ray outputs. One-dimensional MHD calculations in which resistivity values are adjusted phenomenologically are used to illustrate how various dynamical assumptions influence the way enhanced energy inputs are channeled by the fluid dynamics. Variations in the parameters of the phenomenological model are made in order to determine how sensitively they influence the dynamics and the degree to which the calculated x-ray outputs can be made to replicate the kinds of large variations in the experimental x-ray power data that were observed in three nominally identical aluminum wire shots on Saturn.

Whitney, K. G.; Thornhill, J. W.; Apruzese, J. P.; Davis, J.; Deeney, C.; Coverdale, C. A.

2004-08-01

75

Z-Pinch Power Plant Shock Mitigation Experiments, Modeling, and Code Assessment  

SciTech Connect

We are investigating attenuation techniques to mitigate the powerful shock that occurs inside the Z-Pinch Power Plant. For this purpose, we conducted a series of experiments at the University of Wisconsin. These experiments consisted of shock waves traveling at greater than Ma 1 that impacted aluminum foam under various configurations. In turn, ABAQUS, ALEGRA, CTH, and DYNA3D were used to simulate one of the experiments in order to validate the codes. Although the behavior of foamed solid and liquid metal is fundamentally different, we considered foamed metal because some disposable components of the ZP-3 (i.e. the RTL) may be designed with metal foam. In addition, the relatively simple experiments should help us determine which codes can better simulate shock waves. In the near future, we will conduct shock experiments using foamed materials such as water, oils, and other metals.

Rodriguez, Sal B. [Sandia National Laboratories (United States); Dandini, Vincent J. [Sandia National Laboratories (United States); Vigil, Virginia L. [Sandia National Laboratories (United States); Turgeon, Matt [Sandia National Laboratories (United States); Louie, Dave [Omicron (United States)

2005-04-15

76

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

Microsoft Academic Search

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 40 cm\\/μs. Design constraints resulted in an accelerator with a 0.12-Ω impedance, a

R. B. Spielman; S. F. Breeze; C. Deeney

1996-01-01

77

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

Microsoft Academic Search

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

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

2000-01-01

78

High yield inertial confinement fusion target design for a z-pinch-driven hohlraum  

Microsoft Academic Search

Calculations are presented for a high yield inertial fusion design, employing indirect drive with a double-ended z-pinch-driven hohlraum radiation source. A high current (?60 MA) accelerator implodes z pinches within an enclosing hohlraum. Radial spoke arrays and shine shields isolate the capsule from the pinch plasma, magnetic field, and direct x-ray shine. Our approach places minimal requirements on z-pinch uniformity

James H. Hammer; Max Tabak; Scott C. Wilks; John D. Lindl; David S. Bailey; Peter W. Rambo; Arthur Toor; George B. Zimmerman; John L. Porter

1999-01-01

79

High yield inertial confinement fusion target design for a z-pinch-driven hohlraum  

Microsoft Academic Search

Calculations are presented for a high yield inertial fusion design, employing indirect drive with a double-ended z-pinch-driven hohlraum radiation source. A high current (~60 MA) accelerator implodes z pinches within an enclosing hohlraum. Radial spoke arrays and shine shields isolate the capsule from the pinch plasma, magnetic field, and direct x-ray shine. Our approach places minimal requirements on z-pinch uniformity

James H. Hammer; Max Tabak; Scott C. Wilks; John D. Lindl; David S. Bailey; Peter W. Rambo; Arthur Toor; George B. Zimmerman; John L. Porter

1999-01-01

80

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

81

Fast Z - Pinch Study in Russia and Related Problems  

NASA Astrophysics Data System (ADS)

The fast Z pinches are considered as a perspective source of powerful soft x-ray emission for the ICF pellet ignition. The physical phenomena which take place in process fast of Z-pinch implosion are under investigation in the TRINITI (Troisk), in the RSC Kurchatov Institute (KI, Moscow) and the HCEI (Tomsk). In the KI the possibility of terawatt electrical power transfer in small volume hohlraum during nanosecond time duration is studied. In the TRINITI the physics of multi wire arrays implosion, the rate of plasma production in current-driven wire arrays, the conversion of pulsed power energy into x-ray emission are studied. In the HCEI (Tomsk) the stability of double gas puff implosion and the influence of gas puff regime and current pulse duration on the implosion and emitted x-ray spectrum are under investigation. The HCEI develops the new components of pulse power multi spark switches and the generators of impulse currents (LTD) with duration of an energy supply less than 100 ns. As available way to get the pulsed power generator with multi tens megaampere current the joint team of scientists from the laboratories of the TRINITI, the Efremov Institute, RFNC VNIITF (Snezinsk) have developed the concept of the Baikal facility. The KI designs, creates and tests the plasma erosion switches for the module of the Baikal facility. The inductive storage, the systems of magnetic field compression and the explosive open switches are developed in the TRINITI and the Efremov Institute. The development of new design of the pulse power generators and physics of fast Z-pinch implosion aims to create next advanced generation of powerful driver for ICF.

Grabovskii, E. V.

2002-12-01

82

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

83

Radiating Shock Measurements in the Z-Pinch Dynamic Hohlraum  

SciTech Connect

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 >200 eV. The time-dependent 300-400 eV electron temperature and 15-35 mg/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 exceed 50 TW, delivering >180 kJ to the hohlraum.

Rochau, G. A.; Bailey, J. E.; Chandler, G. A.; Lemke, R. W.; Peterson, K. J.; Slutz, S. A. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Maron, Y.; Fisher, D. V.; Fisher, V. I.; Stambulchik, E. [Weizmann Institute, Rehovot (Israel); Dunham, G. S. [K-tech Corporation, Albuquerque, New Mexico 87185 (United States); MacFarlane, J. J. [Prism Computational Sciences, Madison, Wisconsin 53704 (United States); Schroen, D. G. [General Atomics, San Diego, California 92186 (United States)

2008-03-28

84

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

85

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

86

Rapid solidification of aluminum die cast alloys by high-power laser radiation  

Microsoft Academic Search

Rapid solidification of aluminum alloys during the remelting process using high power laser radiation results in refined effects of the solidified grain texture and improved wear resistance and material hardness. High temperature gradients can be achieved, and energy coupling into the aluminum alloy is locally restricted and can be precisely controlled. For the adjustment of defined grain textures, the dynamic

Heinz Haferkamp; Ferdinand von Alvensleben; Oliver Thuerk

1998-01-01

87

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

88

Exploring Ways to Improve Z-Pinch Calculations  

NASA Astrophysics Data System (ADS)

Recent two-dimensional radiation magnetohydrodynamic (2-D RMHD) calculations of radiating Z-pinches agree well with integral data (current waveform, yield and power). The agreement between these calculations and detailed data, such as time-resolved X-ray images, is generally not as good. Improved physics models of Z-pinches, which better match detailed data, are needed to have true predictive capability. Furthermore, a better understanding of small-scale features may be crucial in designing and evaluating application experiments that use central targets. To address these problems, we first determine which integral data are most sensitive to the details in the models. This information is then used to investigate aspects of the pinch to which the data is sensitive, using non-standard techniques. For example, the pinch is calculated in (x,y) coordinates to investigate how a non-symmetric implosion affects the simulated data and whether the simulated data can be made to match the X-ray images as well as the integral data.

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

2004-11-01

89

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

90

Deuterated fibre Z-pinch on the S-300 generator  

NASA Astrophysics Data System (ADS)

Dense Z-pinch experiments were carried out on the S-300 generator (3.5 MA, 100 ns, 0.15 ?) at the Kurchatov Institute in Moscow. The experiments were performed at a peak current of 2 MA with a rise time of about 100 ns. The Z-pinch was formed from a deuterated polyethylene fibre of 100 ?m diameter and 1 cm length. The optical emission began early in the discharge and the coronal plasma expanded with a radial velocity of about 2106 cm s-1. The optical and XUV emission continued for several hundreds of nanoseconds. The peak power of sub-keV radiation reached 30 GW near the maximum current. The total emitted energy exceeded 5 kJ. The neutron yield from the D-D reaction reached 2107 per shot. The mean energy of neutrons obtained from time-of-flight analysis in the axial (downstream) direction was near 2.45 MeV.

Klir, D.; Kravarik, J.; Kubes, P.; Bakshaev, Yu L.; Blinov, P. I.; Chernenko, A. S.; Danko, S. A.; Korolev, V. D.; Ustroev, G. I.; Ivanov, M. I.; Hongchun, Cai

2006-04-01

91

Thermal Analysis of the Z-Pinch Power Plant Concept  

SciTech Connect

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

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

2005-04-15

92

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

SciTech Connect

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

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

2006-01-05

93

Low Mass Transmission Lines for Z-Pinch Driven Inertial Fusion  

Microsoft Academic Search

Recyclable transmission lines (RTL) are studied as a means of repetitively driving z pinches. The lowest reprocessing costs should be obtained by minimizing the mass of the RTL. Low mass transmission lines (LMTL) could also help reduce the cost of a single shot facility such as the proposed X-1 accelerator and make z-pinch driven space propulsion feasible. We present calculations

STEPHEN A. SLUTZ; CRAIG L. OLSON; PER PETERSON

2002-01-01

94

Shrapnel Formation in a Z-Pinch Power Plant  

NASA Astrophysics Data System (ADS)

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

de Groot, John

2005-10-01

95

Resolving Microstructures in Z Pinches with Intensity Interferometry  

NASA Astrophysics Data System (ADS)

Nearly 60 years ago, Hanbury Brown and Twiss\\footnotetextR. Hanbury Brown and R. Twiss, Nature 178, 1046 (1956). succeeded in measuring the 30 nanoradian angular diameter of Sirius using a new type of interferometry that exploited the interference of different photons emitted from opposite sides of the stellar disk. Its basis was the measurement of intensity correlations as a function of detector spacing, with no beam splitting or direct collection of phase information needed. Applied to Z pinches, X pinches, or laser-produced plasmas, this method could potentially yield spatial resolution well under one micron, using photon energies ranging from visible to x-ray. We consider the advantages, disadvantages, and possible complications in applying intensity interferometry to the pinch environment. Preliminary experimental designs are considered.

Apruzese, J. P.; Giuliani, J. L.; Thornhill, J. W.; Maron, Y.; Kroupp, E.

2012-10-01

96

Jets from young stars and z-pinch machines  

NASA Astrophysics Data System (ADS)

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

Ciardi, A.

2012-02-01

97

Tungsten Z-Pinch Long Implosions on the Saturn Generator  

SciTech Connect

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

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

1999-11-05

98

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

99

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

100

Structures of plasma and current in dynamic Z pinches  

SciTech Connect

The dynamics of plasma layers and the structure of the current in a Z-pinch device is experimentally investigated. It is found that the formation of the principal current sheath ends with a disruptive expansion of the sheath, and the pinch breaks up after compression into separate current filaments. It is also shown that the filling of the region outside the pinch with plasma and with currents that alternate in direction is the result of the interaction of current loops (inductons) produced in the magnetic piston after it is compressed by the reflected shock wave. The observed phenomena take place when overheat instability develops and can be realized, e.g., in theta pinches, plasma foci, and tokamaks.

Butov, I.Y.; Matveev, Y.V.

1981-08-01

101

Z-Pinch Drivers for Shock Physics Research  

SciTech Connect

The recent development of Z pinch drivers for producing intense radiation envkomn~ enables study of physical and mechanical properties of condensed materials in regimes previously inaccessible in the Mm-am-y. With Z pinch radiation sources, it is possible fo subject mm-sized sampies to pianar compressions of a fe w Mbar. Tie-resolved velocity interferometry was used to perform the first shock loading and unloading profiles in Al and Be for ablatively driven shock$s to 3 Mbar and the first iseritropic loading of iron specimens to 300 War. A principai goai of our shock physics program is to establish a capability to make accurats eqwion of state measurements on the Z pulsed radiation source. The Z accelerator is a source of intense radntion, which can be used to drive ablative shocks for E(X$ studies. With this source, ablative muki-Mbar shocks can be produced to study materials over the range of interest to both weapons and ICF physics programs. In developing the capability to diagnose these types of studies on Z, techniques commonly used in conventional impact generated experiments were implemented. The primary diagnostic presently being used for this work is ve"!ocity interferoinetry, VL%4R, [2] which not only provides Hugoniot particle velocity measurements, but also measurements of non-shock EOS measummenu,, such as isentropic compression. In addition to VKSAR capability, methods for measuring shock velocity have also been developed for shock studies on Z. When used in conjunction with the Rankine-Hugoniot jump conditions, material response at high temperatures and pressures can be inferred. The next section discusses the basic approach for conducting EOS experiments on Z for both shock loading and istmtropic compression on the Z accelerator.

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

1998-10-13

102

Dual-focus technique for high-power Nd:YAG laser welding of aluminum alloys  

Microsoft Academic Search

In order to apply aluminum alloys to structural components, they should be joined with sufficient strength and quality as high welding speed as possible. High-power laser welding is expected to achieve much higher productivity than conventional joining techniques. Welding of aluminum alloys was performed using 2-kW and 3-kW continuous wave Nd:YAG lasers. Two beams were delivered by optical cables 0.6

Takakuni Iwase; Hiroki Sakamoto; Kimihiro Shibata; Bernd Hohenberger; Friedrich Dausinger

2000-01-01

103

Fusion propulsion with a sheared helical flow stabilized z-pinch  

NASA Astrophysics Data System (ADS)

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 stabilizing effect on z-pinch instabilities. A novel mechanism for producing sheared helical flow was first proposed in 1999. Here we present flow profiles that can provide the shear and also prevent the Kelvin-Helmholtz instability from growing at the plasma/ambient medium boundary.

Wanex, L. F.; Winterberg, F.

2009-09-01

104

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

105

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

106

Deuterium-fiber-initiated Z-pinches: Simulation compared to experiment.  

National Technical Information Service (NTIS)

Deuterium-fiber-initiated Z-pinch experiments have been simulated using a two-dimensional resistive magnetohydrodynamic model which includes many important experimental details, such as ''cold-start'' initial conditions, thermal conduction, radiation, act...

P. Sheehey I. R. Lindemuth R. H. Lovberg R. A. Riley

1992-01-01

107

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

SciTech Connect

Recent developments have demonstrated the use of pulsed power for producing intense radiation sources (z-pinches) that can drive planar shock waves in samples with spatial dimensions significantly larger than possible with other radiation sources. In this paper, we will discuss the use of z-pinch sources for shock wave studies at multi-Mbar pressures. Experimental plans to use the technique for absolute shock Hugoniot measurements and with accuracies comparable to that obtained with gun launchers are discussed.

Konrad, C. H.; Trott, W. M.; Hall, C. A.; Lash, J. S.; Dukart, R. J.; Clark, B.; Hanson, D. L.; Chandler, G. A.; Fleming, K. J.; Trucano, T. G.; Chhabildas, L. C.; Asay, J. R. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1181 (United States)

1998-07-10

108

Escape Methods Vs Diffusion for Radiation Transport in Z-Pinch Simulations  

Microsoft Academic Search

Summary form only given. In Z-pinch loads designed for X-ray production the imploding kinetic and some of the electromagnetic energy is converted into radiation. Hence radiation and atomic processes control the plasma conditions of such loads at the time of assembly on axis. Simulations of Z-pinch dynamics need to properly account for this microphysics to be a viable analysis tool

J. L. Giuliani; R. W. Clark; J. P. Apruzese; J. W. Thornhill; J. Davis; T. A. Haill; C. Deeney; T. A. Mehlhorn

2005-01-01

109

Electromagnetic Wave Propagation Through the ZR Z-Pinch Accelerator  

NASA Astrophysics Data System (ADS)

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

Rose, D. V.; Welch, D. R.; Madrid, E. A.; Miller, C. L.; Clark, R. E.; Stygar, W. A.; Struve, K.; Corcoran, P. A.; Whitney, B.

2009-01-01

110

Progress in Double-Shell Gas Puff Z-Pinches  

NASA Astrophysics Data System (ADS)

An experimental study of high current (3-15 MA), high fidelity (multiple atomic number) and long implosion time (100-200 ns) gas puff loads using the 1-2-3-4 cm double-shell gas puff is in progress at Titan/PSD. Results of experiments conducted on Double-EAGLE, Saturn, Decade Quad and the Z accelerators will be analyzed and presented. The principal observations are: (1) The overall pinch quality and radiative characteristics of all the argon double shell z-pinches are quite satisfactory. The Ar K-shell yields varies from the expected I4 scaling in the inefficient regime for 3 to 7 MA to I2 scaling in the efficient regime from 7 to 15 MA. (2) On all experiments from 3 - 15 MA, selective seeding of the shells demonstrates that the hottest mass of the pinch originates from the inner shell. This suggests that mixing between the two plasma shells during their collision and final implosion is limited. (3) On the 15 MA Sandia Z accelerator, with a load mass of 0.8 mg/cm, the K-shell x-ray output reached 275 kJ in a 15 TW peak power, 12 ns pulse. The analyzed ion and electron densities reach 5 1019 and 1.0 1021 /cc and the highest electron temperature observed is up to 2.2 keV with a 2.0 keV continuum.

Sze, H.; Banister, J.; Failor, B. H.; Fisher, A.; Levine, J. S.; Song, Y.; Apruzese, J. P.; Clark, R. W.; Davis, J.; Mosher, D.; Thornhill, J. W.; Velikovich, A. L.; Weber, B. V.; Coverdale, C. A.; Deeney, C.; Gilliland, T. L.; McGurn, J.; Spielman, R. B.; Struve, K. W.; Stygar, W. A.; Bell, D.; Coleman, P.; Babinea, M.; Enis, C.; Kenyon, V.; Worley, T.

2002-12-01

111

X-ray backlight imaging in Z-pinch  

NASA Astrophysics Data System (ADS)

A novel X-ray backlight imaging system has been developed to obtain diagnostic information about implosion targets, wire-array Z-pinch implosions and ablative Rayleigh-Taylor instability. The key component of the imaging system is the spherically bent quartz (1 0 1 0) crystal with a curvature radius of 143 mm. The imaging system is capable of the two-dimensional, spatially resolved, monochromatic backlight imaging. A monochromatic X-ray backlight imaging experiment using the imaging system was performed for the first time on the "Yang" accelerator at the Chinese Academy of Engineering Physics. The plasma from implosion of aluminium wire arrays was used as the backlighting source. The X-ray film obtained the two-dimensional backlight mesh imaging of He-like aluminium ions. The experimental results show that the X-ray backlight imaging system provides an approximate 75 ?m spatial resolution at a 9 mm20 mm field of view. The backlight imaging system is adequate for monochromatic X-ray backlighting imaging diagnosis on the "Yang" accelerator.

Liu, Lifeng; Xiao, Shali; Qian, Jiayu; Huang, Xianbin; Cai, Hongchun

2012-08-01

112

Implosion and stagnation dynamics of wire array z-pinches  

NASA Astrophysics Data System (ADS)

We present detailed measurements of the implosion and stagnation phases of wire array z-pinch experiments on the MAGPIE generator (1MA, 240ns). The implosion of the array, which consists of an accelerating snowplough of current traveling towards the axis, critically depends upon the redistribution of mass ablated from the wires prior to implosion. Array configurations that alter the ablation of plasma from the wires of the array (e.g. by varying B?, introducing Bz and Br and/or by reversing the direction of Er) are used to explore the dependence of implosion on this process. The initiation of the implosion phase and formation of the snowplough sheath is investigated. The width of the sheath colliding with a precursor plasma column on axis is consistent with the rise time of the X-ray pulse observed in the experiments; and whilst the level of emission increases, the stagnated body of plasma on axis compresses, and axial electron beams are observed. After peak emission, the stagnated plasma shows large scale instabilities that then cause discontinuities. This research was sponsored by Sandia National Laboratories Albuquerque, the SSAA program of NNSA under DOE Cooperative Agreement DE-FC03-02NA00057

Bland, S. N.; Hammer, D. A.; Mitchell, I. H.

2005-10-01

113

Radiative collapse of a Bennett-relaxed z-pinch  

SciTech Connect

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

Turner, L.

1989-01-01

114

Electromagnetic wave propagation through the ZR Z-pinch accelerator.  

SciTech Connect

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

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

2008-08-01

115

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

NASA Astrophysics Data System (ADS)

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

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

2003-10-01

116

Preliminary Results of a 10 kJ Z-Pinch  

SciTech Connect

Preliminary results obtained on 10 kJ Z-pinch device developed at the Plasma and Electrical Discharge Laboratory in the University of Castilla-La Mancha are presented. The device called ENERGU-1 is composed by 8 capacitors (0.5 {mu}F, 75 kV, 20 nH) connected in parallel to a discharge chamber by means of one high power plane transmission line by mean of 8 spark-gaps switches triggered by a 100 kV, 13 ns trigger pulse. The discharge chamber is a cylindrical Pyrex glass tube externally surrounded by a SF{sub 6} isolation atmosphere with the electrodes at the ends. Two different chambers have been studied by discharging the capacitor bank energy in deuterium for optimizing the D-D nuclear fusion reactions: one of 100 mm long by 100 mm inner diameter and the other of the same length and 70 mm inner diameter. Several sequences of ultrahigh speed converter camera photography (5 ns) are presented showing the implosion of plasma columns for different deuterium pressure and currents. Preliminary measurements of integrated 2.45 MeV neutron emissions by a silver activated neutron counter are analyzed as a function of electrical and constructive parameters. A yield of 10{sup 7}-10{sup 8} D-D fusion reactions by shot is reported when the optimum conditions are reached conducting currents of 400-600 kA with a plasma column lifetime above 100 ns.

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

2008-04-07

117

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.

Cortzar, O. D.; Piriz, A. R.; Prieto, G. Rodrguez; Hoffmann, D. H. H.; Tahir, N. A.

2008-04-01

118

Effects of precursor plasma bombardment on on-axis targets in wire array z-pinches  

NASA Astrophysics Data System (ADS)

Several holhraum configurations have been suggested to couple the high power X-ray emission from wire array z-pinches to ICF targets. Potentially the most efficient method, the dynamic holhraum, mounts the target on the arrays axis inside a low density foam: the implosion of the array acts as a moving holhraum, whilst the foam allows radiation to reach the target before plasma stagnates on axis. Long before the implosion occurs, however, coronal plasma streams from the wires will bombard the foam. Experiments on the 1MA MAGPIE generator examined the behaviour of on axis foams. Radiography indicated that the foams were compressed by the pressure of the coronal plasma, whilst laser probing showed the development of long wavelength periodic modulations in the plasma that ablates from the foam surface. The scaling of the results to high current experiments will be discussed. This research was partially sponsored by Sandia National Laboratories, and the SSAA program of NNSA under DOE Cooperative Agreement DE-FC03-02NA00057

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

2004-11-01

119

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

120

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

SciTech Connect

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

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

2009-01-21

121

Epitaxy and surface melting of aluminum alloys by high powered directed energy  

Microsoft Academic Search

Aluminum alloy surfaces were melted by beams from high powered directed energy sources. A variety of techniques were employed\\u000a to examine the resulting alloy structures and it was found that the melted regions resolidify epitaxially onto the unmelted\\u000a crystalline substrate. It is demonstrated that there is a region of strained material lying close to the maximum depth of\\u000a fusion. Resolidification

A. Munitz

1980-01-01

122

Radiative properties of high-power 808 nm aluminum-free laser diodes  

Microsoft Academic Search

High-power diode lasers based on aluminum-free InGaP\\/InGaAsP\\/GaAs heterostructures gain increasing importance as a more reliable and efficient replacement for currently used AlGaAs\\/GaAs lasers. One of the major applications of those laser diodes is for the optical pumps for solid-state laser systems, in particular Nd:YAG which require 808 nm pumping wavelength. The subject of this dissertation is experimental research aimed to

Ivan Eliashevich

1997-01-01

123

The implosion and stagnation of wire array z-pinches  

NASA Astrophysics Data System (ADS)

Experiments at all levels of current drive have demonstrated that the first 60-80 percent of the evolution of a wire array z- pinch is dominated by the gradual ablation of cold, dense wire cores into low density coronal plasma that is projected towards the axis of the array. Implosion of the array only begins when the wire cores start to break up, at which time a piston of current snowploughs up coronal plasma as it accelerates towards the axis. Here we present the detailed measurements of the snowplough process and the dynamics of the array during its stagnation on axis. The stability and width of the snowplough and the compression of the plasma at stagnation are related to X-ray emission, providing data on the mechanisms responsible for X-ray production.Several methods to alter the implosion of an array are explored. The interaction between the outer and inner of a nested array configuration is directly observed for the first time, highlighting how X-ray emission can be shaped. In a new type of array a ``coiled'' array the magnetic field topology is altered, resulting in large changes to the ablation dynamics and an implosion that snowploughs less mass to a higher velocity. With a relatively low number of wires, the use of coiled arrays can increase X-ray emission by 5x over that usually observed at stagnation. Using a radial array configuration, meanwhile, the scale of the stagnating plasma can be reduced without adversely affecting X-ray power. This may enable arrays to couple to far smaller hohlraums, significantly raising the available temperatures for HEDP experiments. This research was sponsored by Sandia National Labs and the NNSA under DOE Cooperative Agreement DE-F03-02NA00057.

Bland, Simon

2006-10-01

124

PBFA Z: A 20-MA Driver for Z-Pinch Radiation Sources*  

NASA Astrophysics Data System (ADS)

Sandia National Laboratories has completed a major modification to the existing PBFA-II Light Ion Beam Fusion facility. This new operational mode, known as PBFA-Z, is a driver capable of delivering up to 20 MA to a z-pinch load. PBFA-Z is designed to optimize the coupling of electrical energy to the implosion kinetic energy of z pinches. These design constraints resulted in an accelerator with an impedance of 0.125 Ohms, a total inductance of 10 nH, and an electrical pulse width of 120 ns. Current is delivered to the z-pinch load through four, self-magnetically-insulated vacuum transmission lines (MITLs) and a double post- hole convolute. We will present data showing the electrical energy coupled to z- pinch and short circuit loads and preliminary data of the x-ray output of tungsten wire-array z pinches. X-ray diagnostics include a time-resolved x-ray pinhole camera, resistive bolometry, photoconducting x-ray detectors, x-ray diodes, and a time-resolved convex curved-crystal spectrograph. *This work supported by the U.S. Department of Energy under Contract DE-AC04- 94AL85000.

Spielman, R. B.; Chandler, G. A.; Deeney, C.; Long, F.; Martin, T. H.; Matzen, M. K.; McDaniel, D. H.; Nash, T. J.; Porter, J. L.; Ruggles, L. E.; Sanford, T. W. L.; Seamen, J. F.; Stygar, W. A.; Breeze, S. P.; McGurn, J. S.; Torres, J. A.; Zagar, D. M.; Gilliland, T. L.; Jobe, D.; Struve, K. W.; Mostrom, M.; Corcoran, P.; Smith, I.; Shoup, R. W.

1996-11-01

125

A Gas Embedded Z-pinch Driven by SPEED2 Generator  

SciTech Connect

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

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

2006-12-04

126

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

127

History of Z-Pinch Research in the U.S.  

NASA Astrophysics Data System (ADS)

Over the years, the scientific community has been fascinated with z pinches. Z-pinch references include papers on the quest for fusion, on applications for radiation effects testing, lithography, x-ray microscopy, and pumping x-ray lasers, and on the production of intense magnetic fields. Because much of the research has been pursued elsewhere-in the USSR, Russia, England, Germany, and Chile, among other countries-we must place the U.S. work in an international context. We assert here that the z pinch is a valuable asset for its applications, chiefly those related to the production of x rays, but it is a tool that has sometimes deceived us with its seeming simplicity.

Sweeney, Mary Ann

2002-12-01

128

Los Alamos compact toroid, fast-liner, and high-density Z-pinch programs  

SciTech Connect

The Compact Toroid (CT) and High Density Z-Pinch (HDZP) are two of the plasma configurations presently being studied at Los Alamos. The purpose of these two programs, plus the recently terminated (May 1979) Fast Liner (FL) program, is summarized in this section along with a brief description of the experimental facilities. The remaining sections summarize the recent results and the experimental status.

Linford, R.K.; Sherwood, A.R.; Hammel, J.E.

1981-03-01

129

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

130

Design of Z-Pinch and Dense Plasma Focus Powered Vehicles.  

National Technical Information Service (NTIS)

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 ...

C. D. Maples G. N. Statham J. Cassibry J. Santarius J. N. Miermik L. Fabisinski M. Turner R. Cortez R. B. Adams S. Fincher T. Percy T. Polsgrove

2011-01-01

131

Deuteron Acceleration and Fusion Neutron Production in Z-pinch plasmas  

NASA Astrophysics Data System (ADS)

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 1010 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.; Ananeev, S. S.; Bakshaev, Yu. L.; Blinov, P. I.; Chernenko, A. S.; Kazakov, E. D.; Korolev, V. D.; Ustroev, G. I.

2009-01-01

132

Experiments With Radiatively Cooled Supersonic Plasma Jets Generated in Conical Wire Array Z-Pinches  

Microsoft Academic Search

We present results of astrophysically relevant experiments where highly supersonic plasma jets are generated via conically convergent plasma flows in a conical wire array Z-pinch. Stagnation of plasma flow on the axis of symmetry forms a standing conical shock effectively collimating the flow in the axial direction. This scenario is essentially similar to that discussed by Canto and collaborators [1

S. V. Lebedev; D. J. Ampleford; S. N. Bland; J. P. Chittenden; A. Ciardi; N. Naz; M. G. Haines; A. Frank; E. Blackman; T. Gardiner

2002-01-01

133

MHRDRing Z-Pinches and Related Geometries: Four Decades of Computational Modeling Using Still Unconventional Methods  

SciTech Connect

For approximately four decades, Z-pinches and related geometries have been computationally modeled using unique Alternating Direction Implicit (ADI) numerical methods. Computational results have provided illuminating and often provocative interpretations of experimental results. A number of past and continuing applications are reviewed and discussed.

Lindemuth, Irvin R. [University of Nevada Reno NV USA (United States)

2009-01-21

134

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

135

Insulator Modifications to Extend Plasma Lifetime on the ZaP Flow Z-Pinch  

NASA Astrophysics Data System (ADS)

The ZaP Flow Z-Pinch at the University of Washington is a basic plasma physics experiment that utilizes sheared axial flows to maintain gross plasma stability. The experiment uses an annular acceleration region followed by a cylindrical assembly region in which the plasma column is formed and maintained. Upon Z-pinch formation, flowing plasma from the accelerator maintains the plasma supply in the Z-pinch in a quasi-steady state fashion. Past run campaigns have used changes in the injector parameters or to the annular area to alter the characteristics of the bulk plasma. Previous results show that the lifetime of the plasma is limited by the current from the power supply and by the plasma source from the accelerator. The supplied power has previously been increased to extend the current waveform. The insulated volume will be increased by 300% to extend the plasma supply from the accelerator, the stability period of the Z-pinch, and thus the plasma lifetime. Preliminary results will be discussed relating velocity shear measurements and interferometric accelerator densities. The increased source duration will be compared with the quasi-steady state duration of the pinch to show an increased control of the plasma lifetime through prolonged flow shear.

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

2012-10-01

136

Flow-through Z-pinch study for radiation generation and fusion energy production.  

National Technical Information Service (NTIS)

We discuss a high-density fusion reactor which utilizes a flow-through Z pinch magnetic confinement configuration. Assessment of this reactor system is motivated by simplicity and small unit size (few hundred MWe) and immunity to plasma contamination made...

C. W. Hartman J. L. Eddleman R. Moir U. Shumlak

1994-01-01

137

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

138

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

139

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

140

Plasma channel and z-pinch dynamics for heavy ion transport  

NASA Astrophysics Data System (ADS)

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 mus from the main bank discharge initiation with a FWHM of ?2 cm. Results also show that typical main bank discharge plasma densities reach 1017 cm-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 Miguel

141

Radiative properties of high-power 808 nm aluminum-free laser diodes  

NASA Astrophysics Data System (ADS)

High-power diode lasers based on aluminum-free InGaP/InGaAsP/GaAs heterostructures gain increasing importance as a more reliable and efficient replacement for currently used AlGaAs/GaAs lasers. One of the major applications of those laser diodes is for the optical pumps for solid-state laser systems, in particular Nd:YAG which require 808 nm pumping wavelength. The subject of this dissertation is experimental research aimed to evaluate radiative efficiency of the InGaAsP laser diode material and structures, as well as high-power performance and reliability of the laser diodes. This work also reveals key physicial processes and structure parameters affecting radiative efficiency of those lasers. Broad-area single quantum well separate confinement heterostructure lasers with varying layer structures are investigated for this purpose. First major conclusion of the work supported by experimental evidence is that InGaAsP active region material emitting at 808nm with radiative efficiency close to 100% can be grown by metal-organic chemical vapor deposition. High growth uniformity is shown to be possible with this method. After investigating the effects of carrier leakage and optical confinement, active region and waveguide thickness and composition are optimized to achieve high differential efficiency and low threshold current density. Second important result is the demonstration of low internal loss in InGaP cladding layers. The lasers have narrow transverse beam divergence and allow wavelength tunability to match the absorption band of Nd:YAG crystal. Finally, high power operation up to 7W per facet and over 30,000 hours of operation at 60spC with output power of 1W are experimentally demonstrated for lasers without mirror coating. Direct comparison with AlGaAs lasers shows the superiority of aluminum-free lasers in such critical parameters as catastrophic optical damage limit, absence of rapid degradation, low thermal resistance and, most important, long-term reliability.

Eliashevich, Ivan

1997-11-01

142

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

143

Effect of soft metal gasket contacts on contact resistance, energy deposition, and plasma expansion profile in a wire array Z pinch  

SciTech Connect

Soft metal gaskets (indium and silver) were used to reduce contact resistance between the wire and the electrode in an aluminum wire Z pinch by more than an order of magnitude over the best weighted contact case. Clamping a gasket over a Z-pinch wire compresses the wire to the electrode with a greater normal force than possible with wire weights. Average contact resistance was reduced from the range of 100-3000 {omega} (depending on wire weight mass) to 1-10 {omega} with soft metal gaskets. Single wire experiments (13 {mu}m Al 5056) on a 16 kA, 100 kV Marx bank showed an increase in light emission (97%) and emission volume (100%) of the plasma for the reduced contact resistance cases. The measured increases in plasma volume and light emission indicate greater energy deposition in the ablated wire. Additionally, dual-wire experiments showed plasma edge effects were significantly decreased in the soft metal gasket contact case. The average height of the edge effects was reduced by 51% and the width of the edge effects was increased by 40%, thus the gasket contact case provided greater axial uniformity in the plasma expansion profile of an individual wire.

Gomez, M. R.; Zier, J. C.; Gilgenbach, R. M.; French, D. M.; Tang, W.; Lau, Y. Y. [Plasma, Pulsed Power, and Microwave Laboratory, Nuclear Engineering and Radiological Sciences Department, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States)

2008-09-15

144

Exploring Ways to Improve Predictive Capability of Z-Pinch Calculations  

SciTech Connect

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

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

1998-10-19

145

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

146

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

147

Some characteristics of fusion neutrons produced by deuterium in loads of Z-pinch devices  

NASA Astrophysics Data System (ADS)

The fusion neutrons from Z-pinch devices are observed and studied for last fifty years. Many experimental and theoretical papers were published in this field. Some problems are still under discussion, for example, a thermal or beam-target origin of neutrons, mechanism of acceleration of high-energy electrons and ions, correlation of hard x-rays with neutrons, a reason for asymmetry of emitted particles and radiation, development of diagnostic methods and interpretation of results. This paper presents an experimental results of neutrons produced at the implosion of an Al liner onto a CD2 fiber at the 3 MA fast Z-pinch S-300 in RRC Kurchatov Institute in Moscow. The velocity and energy of neutrons in the axial direction were estimated from the temporal position of the maximum of neutron signals at two different distances from the neutron source and the relationship between hard x-rays and neutrons is discussed.

Kubes, P.; Kravarik, J.; Klir, D.; Bakshaev, Yu. L.; Blinov, P. I.; Chernenko, A. S.; Korolev, V. D.; Ustroev, G. I.; Ivanov, M. I.; Hongchun, C.

2004-03-01

148

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

149

Spectroscopy of Z-pinch plasmas: how atomic and plasma physics merge and unfold new applications  

NASA Astrophysics Data System (ADS)

Recent advances in theoretical and experimental work on plasma spectroscopy of Z-pinches are presented. We have shown that the University-scale Z-pinch generators are able to produce plasmas within a broad range of temperatures, densities, opacity, and radiative properties depending on the type, geometry, size, and mass of wire array loads and wire material. The full x-ray and EUV diagnostic set for detailed spatial and temporal monitoring of such a plasma together with relativistic atomic and non-LTE kinetic codes create a very useful and productive environment for the study of atomic and plasma spectroscopy features and development of their applications. A variety of examples of K-shell low-Z (such as Mg and Al), L-shell mid-Z (such as Ni, Cu, and Ag), and M- and L-shell high-Z (W) will be considered and their specific features and applications to fusion and astrophysics will be highlighted.

Safronova, Alla

2012-06-01

150

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

SciTech Connect

The authors are developing a new shock wave diagnostic using Z pinch sources for high-pressure equation of state (EOS) measurements. Specifically, they are employing VISAR interferometry to measure the particle velocity of shocked materials and fiber optic probes to measure the shock speed. Combination of these measurements will allow absolute EOS data with Z accelerators. This report is a progress report on the development of this new approach to EOS measurements; however, preliminary data obtained with the diagnostics are encouraging. With further development of Z pinch sources, it is envisioned that a variety of EOS and constitutive property measurements can be made. Time-resolved wave profile measurements will then provide a variety of EOS and material property data, such as isentropic EOS, initial compressive strength and shock-induced compressive strength, dynamic tensile strength, kinetics of phase transitions, and surface stability studies.

Asay, J.R.; Konrad, C.H.; Hall, C.A.; Trott, W.M.; Chandler, G.A.; Fleming, K.J.; Trucano, T.G.

1998-08-01

151

Critical Layer Penetration in a Cold Z-Pinch Plasma by High-Intensity 10.6 Microns Laser Radiation.  

National Technical Information Service (NTIS)

The intensity dependence of transmission of high-intensity 10.6 micrometer laser radiation through an overdense cold Z-pinch plasma has been measured to determine a threshold for transmission. A holographic cinema of plasma evolution, obtained independent...

J. G. Ackenhusen

1977-01-01

152

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

Microsoft Academic Search

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

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

1997-01-01

153

Z-pinch wire-contact resistance reduction using clamped and soft metal contacts  

Microsoft Academic Search

The contact resistance in a wire array z-pinch has a significant affect on both the level and uniformity of energy deposition in the wires. Typically wires are held taut against the electrodes by wire weights (-1-10 g depending on wire material and diameter). This can lead to contact resistance values of -90-99% of the load resistance. Previous techniques to reduce

M. R. Gomez; J. Zier; D. M. French; R. M. Gilgenbach; W. Tang; Y. Y. Lau

2008-01-01

154

Plasma dynamics during the evolution of two wire Z-pinch  

Microsoft Academic Search

Experiments on a two parallel wire Z-pinch are reported. The pinch was driven by a 160 kA peak current, 65 ns 1090% rise time pulsed power source. Aluminium (15 m) and tungsten (7.5 m) wires with varying separations (0.3, 0.6 and 1.5 mm) were used. In addition to the plasma at each wire and its associated corona, a plasma column

F N Beg; J Ruiz-Camacho; M G Haines; A E Dangor

2004-01-01

155

Plasma dynamics during the evolution of two wire Z-pinch  

Microsoft Academic Search

Experiments on a two parallel wire Z-pinch are reported. The pinch was driven by a 160 kA peak current, 65 ns 10-90% rise time pulsed power source. Aluminium (15 m) and tungsten (7.5 m) wires with varying separations (0.3, 0.6 and 1.5 mm) were used. In addition to the plasma at each wire and its associated corona, a plasma column

F. N. Beg; J. Ruiz-Camacho; M. G. Haines; A. E. Dangor

2004-01-01

156

Microsecond Z-pinch as ultrasoft X-ray radiation source  

Microsoft Academic Search

Spectral characterictics of plasma radiation of a gas Z-pinch with a rise time of 1 s and current amplitude of 250 kA have been measured. The measurements were performed in the range of X-ray energy quanta from 30 eV to 600 eV. A spectrograph with a transmission grating and a polychromator on the basis of multilayer X-ray mirrors served as

G. S. Volkov; V. I. Zaitsev; A. V. Kartashov; N. I. Lahtushko; A. A. Rupasov; A. S. Shikanov

2004-01-01

157

Mixed element plasmas in a Z-pinch on Double-EAGLE: radiation tunability and reliability  

Microsoft Academic Search

Summary form only given, as follows. We have recently completed experiments on the Double-EAGLE generator at Physics International which have demonstrated that the radiation output from mixed-element, Z-pinch plasmas is wavelength tunable. Our tests used mixtures of argon and krypton gas, ranging from 50% to 98% Ar (balance Kr). Measurements of the resulting output portions showed that Kr L-shell emissions

P. D. LePell; C. A. Coverdale; B. H. Failor; J. C. Riordan; S. L. Wong; C. Deeney; J. P. Apruzese; J. W. Thornhill; J. Davis

1996-01-01

158

Angular distribution of x-ray radiation from optically thick z-pinch plasmas  

Microsoft Academic Search

A z-pinch plasma is an x-ray radiation source of small size concerning the z-direction radiation. However, the plasma is optically thick with respect to the resonance lines, which contain a large fraction of the total radiation. The influence of the opacity on efficiency and spatial radiation distribution has been examined. A computer simulation solving the radiation transport equation demonstrates that

H.-P. Stormberg; S. Murayama; Y. Watanabe

1987-01-01

159

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

160

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

161

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

Microsoft Academic Search

A model using the TEXAS-NCV computer code is presented for the transport of dust and debris in a z-pinch driven explosive propagation of gas into vacuum. First, TEXAS-NC was improved, updated, and benchmarked against several experiments for quasi-one-dimensional shock propagation applications involving multi-component, multi-phase systems. Second, a vacuum transport model was developed and incorporated into TEXAS and benchmarked for adiabatic

Tristan Thomas Utschig

2001-01-01

162

Mixed gas Z pinch experiments using a shell-on-shell nozzle on Double-EAGLE  

Microsoft Academic Search

A series of Z pinch experiments using argon and krypton was conducted on the Double-EAGLE pulse power driver at 3.5 to 4.0 MA peak current and 170-190 ns implosion time. A shell-on-shell nozzle provided the opportunity to separate the two gases and to control which was driven more strongly (by virtue of being in the inner plenum). With argon in

J. S. Levine; B. H. Failor; H. M. Sze; D. Bell

2002-01-01

163

A conceptual fusion reactor based on the high-plasma-density Z-pinch  

Microsoft Academic Search

Conceptual DT and DD fusion reactors are discussed based on magnetic confinement with the high-plasma-density Z-pinch. The reactor concepts have no 'first wall', the fusion neutrons and plasma energy being absorbed directly into a surrounding lithium vortex blanket. Efficient systems with low recirculated power are projected, based on a flow-through pinch cycle for which overall Q values can approach 10.

C. W. Hartman; G. Carlson; M. Hoffman; R. Werner; D. Y. Cheng

1977-01-01

164

A high impedance mega-ampere generator for fiber z-pinch experiments  

Microsoft Academic Search

At Imperial College a mega-ampere generator for plasma implosion experiments has been designed, built, and commissioned. With a final line impedance of 1.25 Ω this terawatt class generator has been designed primarily to drive a maximum current of 1.8 MA with a rise time of 150 ns into high inductance {ital z}-pinch loads of interest to radiative collapse studies. This

I. H. Mitchell; J. M. Bayley; J. P. Chittenden; J. F. Worley; A. E. Dangor; M. G. Haines; P. Choi

1996-01-01

165

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

166

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

167

Sheath broadening in imploding z-pinches due to large-bandwidth Rayleigh-Taylor instability  

SciTech Connect

The magnetic Rayleigh-Taylor (RT) instability has been predicted and observed to cause breakup of the plasma sheath in imploding Z-pinches. In this work we show that for the type of density profile encountered in strongly radiating pinches, instability at very short wavelengths grows to the non-linear stage and seeds progressively longer wavelengths. The result is a self-similar broadening of the sheath as found for mix layers in fluid RT unstable systems.

Hammer, J.H.; Eddleman, J.L.; Tabak, M.; Toor, A.; Zimmerman, G.B. [Lawrence Livermore National Lab., CA (United States); De Groot, J.S. [California Univ., Davis, CA (United States)

1996-06-04

168

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

Microsoft Academic Search

Z-pinch implosions driven by the SATURN device [D. D. Bloomquist etal., Proceedingsofthe 6thInstituteofElectricalandElectronicsEngineers (IEEE) PulsedPowerConference, Arlington, VA, edited by P. J. Turchi and B. H. Bernstein (IEEE, New York, 1987), p. 310] at Sandia National Laboratory are modeled with a two-dimensional radiation magnetohydrodynamic (MHD) code, showing strong growth of the magneto-RayleighTaylor (MRT) instability. Modeling of the linear and nonlinear development

James H. Hammer; James L. Eddleman; Paul T. Springer; Max Tabak; Arthur Toor; Keith L. Wong; George B. Zimmerman; Chris Deeney; Russ Humphreys; Thomas J. Nash; Thomas W. L. Sanford; Rick B. Spielman; John S. de Groot

1996-01-01

169

Stimulation of Hela cells by intense pulsed UV radiaion from Z-pinch discharge  

Microsoft Academic Search

In the recent decade, biological effects and application of pulsed power energy have attracted much attention and been widely investigated, especially pulsed electric fields and atmospheric pressure non-thermal plasma. In this paper, we describe the stimulation of HeLa cells through intense pulsed UV irradiation. Pulsed UV source is driven by a short pulse current (110ns) Z-pinch discharge, compared with the

P. Lul; T. Watanabe; K. Mitsutake; S. Katsuki; H. Akiyama

2011-01-01

170

Theoretical analysis of some contemporary issues on wire-array Z-pinch  

Microsoft Academic Search

This thesis describes two contemporary issues on wire-array Z-pinch: (1) Linear and nonlinear evolution of azimuthal clumping instabilities, and (2) the problem of electrical contact resistance. The thesis presents an analytic theory on the linear and nonlinear evolution of the most unstable azimuthal clumping mode (the pi-mode) in a discrete wire array. In the pi-mode, neighboring wires of the array

Wilkin Tang

2009-01-01

171

Characteristics for the occurrence of a high-current, Z-pinch aurora as recorded in antiquity  

Microsoft Academic Search

The discovery that objects from the Neolithic or Early Bronze Age carry patterns associated with high-current Z-pinches provides a possible insight into the origin and meaning of these ancient symbols produced by man. This paper directly compares the graphical and radiation data from high-current Z-pinches to these patterns. The paper focuses primarily, but not exclusively, on petroglyphs. It is found

Anthony L. Peratt

2003-01-01

172

Deuterium Gas-Puff Experiments on the S-300 Z-pinch  

NASA Astrophysics Data System (ADS)

The neutron production from a deuterium gas-puff Z-pinch has been studied on the S-300 Z-pinch (Kurchatov Institute, Moscow). Neutron time-of-flight diagnostics was used to give an insight into the acceleration of fast deuterons. The emphasis was put on the finding of (i) the energy distribution of deuterons which produced fusion neutrons, (ii) the anisotropy of neutron emission, and (iii) the time and duration of neutron production with respect to the general Z-pinch dynamics. The peak neutron yield above 10^10 was achieved on the current level of 2 MA. The fusion neutrons were generated for 30 ns during the stagnation and at the beginning of the expansion of a plasma column. The side-on neutron energy spectra peaked at 2.420.04 MeV with about 400 keV FWHM. In the downstream direction (i.e. the direction of the current flow from the anode towards the cathode), the peak neutron energy was 2.6 0.1 MeV. The average kinetic energy of reacting deuterons was about 100 keV. The broad width of radial neutron spectra implied a high radial component of deuteron velocity. On the basis of these experimental data, it is possible to discuss acceleration of deuterons and fusion neutron production.

Klir, Daniel; Kravarik, Jozef; Kubes, Pavel; Rezac, Karel

2009-11-01

173

High Resolution Shadowgraphy and Interferometry at 266nm for 1-MA Z-Pinches  

NASA Astrophysics Data System (ADS)

A UV laser probing channel at the wavelength of 266 nm was implemented for investigations of wire-array Z-pinches at the Zebra generator. The UV channel has provided images of the dense plasma inside the lower-density trailing plasma, allowing the observation of details and structures in the pinch. Kink instabilities, loops, areas of disruption and micro-pinching were observed in Z-pinches. A high spatial resolution UV shadowgraphy and interferometry channel allows for investigation of the micron-scale instabilities. Experiments with high resolution shadowgraphy and interferometry are presented. The fine structure of the stagnated Z-pinches in cylindrical and star wire arrays was unfolded, and new information about instabilities was obtained. A two-frame UV shadowgraphy was tested for investigation of plasma dynamics. Shadowgraphy results show a very inhomogeneous pinch with instabilities on the microscopic level, strong kink instabilitiy, and micro-pinches. Interferometery results show plasma gradients on the edge of the pinch and a density of the trailing mass.

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

2011-11-01

174

Use of Z-Pinch Sources for High-Pressure Equation-of-State Studies  

SciTech Connect

In this paper, we describe a new technique for using a pulsed power source (Z pinch) to produce planar shock waves for high-pressure equation of state (EOS) studies. Initial EOS experiments conducted with techniques indicate that these sources are effective for shock wave studies in samples with diameters of a few millimeters and thicknesses of a fraction of one millimeter, and thus provide the possibility for achieving accuracy in shock and particle velocity measurements of a few percent. We have used the Z pinch source to produce the first in-situ time-resolve particle velocity profiles obtained with pulsed radiation sources in the Mbar regime. Particle velocity profiles obtained with a VISAR interferometer are compared with I-D numerical simulations performed with a radiation-hydrodynamics code, ALEGRA. Good agreement with experimental results was achieved in the simulations and suggests that Z pinch source should be a valuable tool for high-pressure EOS studies in thermodynamic regimes important to hypervelocity impact.

Asay, J.R.; Cauble, R.; Chandler, G.A., Fleming, K.J.; Chhabildas, L.C.; Foord, M.; Hall, C.A.; Hauer, A.; Holland, K.G.; Konrad, C.H.; Mehlhorn, T.A., Vesey, R.; Trott, W.M.; Trucano, T.G.

1998-10-14

175

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

NASA Astrophysics Data System (ADS)

UV, 266-nm wavelength, laser probing diagnostics were developed for the investigation of the dense plasma on the 1-MA pulsed power generator, Zebra, located at the University of Nevada, Reno. These new diagnostics complemented the 532-nm laser probing diagnostics, which were not highly applicable for a z-pinch with an electron density higher than 1019 cm -3, due to strong absorption and refraction of the beam as it passes through the plasma. The UV laser diagnostics, shadowgraphy and interferometry, have been successfully tested at the ablation, implosion, stagnation, and dissipation phases of wire-array z-pinches. Probing simultaneously with 266-nm and 532-nm light has shown that the UV laser probes deeper into the z-pinch plasma, with higher resolution. The UV laser probe enjoys a significant advantage over the 532-nm laser probe, because the inverse bremsstrahlung absorption increment and refraction in the plasma column is proportional to the wavelength squared. For interferometry, the phase shift of the laser beam is proportional to the wavelength. UV interferometry was employed to measure the plasma density profile up to an electron density of 12x1020 cm -3. A high resolution laser probing channel was developed for further study of the dense z-pinch plasma. Specially designed anode and cathode plates allowed installation of the objective lens inside of the vacuum chamber. A spatial resolution of 4 microns was achieved with UV. Instabilities in the dense plasma pinch were directly observed. The micro-structure of the dense pinch was unfolded for the first time. Micro-pinches, small-scale and mid-scale instabilities, large kink and sausage instabilities, and breaks in the plasma column were studied with UV high resolution shadowgraphy and interferometry. To investigate the dynamics of the dense plasma, a second, time-delayed, frame was developed for the UV laser diagnostics. Large velocities, greater than 100 km/s, were measured. These demonstrate the generation of kinetic energy in the stagnation phase of the z-pinch.

Altemara, Sara D.

176

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

SciTech Connect

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

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

2004-04-05

177

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

178

Characterization of energy flow and instability development in two-dimensional simulations of hollow z pinches  

NASA Astrophysics Data System (ADS)

A two-dimensional (2-D) Eulerian Radiation-Magnetohydrodynamic (RMHD) code has been used to simulate imploding z pinches for three experiments fielded on the Los Alamos Pegasus II capacitor bank [J. C. Cochrane et al., Dense Z-Pinches, Third International Conference, London, United Kingdom 1993 (American Institute of Physics, New York, 1994), p. 381] and the Sandia Saturn accelerator [R. B. Spielman et al., Dense Z-Pinches, Second International Conference, Laguna Beach, 1989 (American Institute of Physics, New York, 1989), p. 3] and Z accelerator [R. B. Spielman et al., Phys. Plasmas 5, 2105 (1998)]. These simulations match the experimental results closely and illustrate how the code results may be used to track the flow of energy in the simulation and account for the amount of total radiated energy. The differences between the calculated radiated energy and power in 2-D simulations and those from zero-dimensional (0-D) and one-dimensional (1-D) Lagrangian simulations (which typically underpredict the total radiated energy and overpredict power) are due to the radially extended nature of the plasma shell, an effect which arises from the presence of magnetically driven Rayleigh-Taylor instabilities. The magnetic Rayleigh-Taylor instabilities differ substantially from hydrodynamically driven instabilities and typical measures of instability development such as e-folding times and mixing layer thickness are inapplicable or of limited value. A new measure of global instability development is introduced, tied to the imploding plasma mass, termed ``fractional involved mass.'' Examples of this quantity are shown for the three experiments along with a discussion of the applicability of this measure.

Peterson, D. L.; Bowers, R. L.; McLenithan, K. D.; Deeney, C.; Chandler, G. A.; Spielman, R. B.; Matzen, M. K.; Roderick, N. F.

1998-09-01

179

Recyclable transmission line concept for z-pinch driven inertial fusion energy.  

SciTech Connect

Recyclable transmission lines (RTL)s are being studied as a means to repetitively drive z pinches to generate fusion energy. We have shown previously that the RTL mass can be quite modest. Minimizing the RTL mass reduces recycling costs and the impulse delivered to the first wall of a fusion chamber. Despite this reduction in mass, a few seconds will be needed to reload an RTL after each subsequent shot. This is in comparison to other inertial fusion approaches that expect to fire up to ten capsules per second. Thus a larger fusion yield is needed to compensate for the slower repetition rate in a z-pinch driven fusion reactor. We present preliminary designs of z-pinch driven fusion capsules that provide an adequate yield of 1-4 GJ. We also present numerical simulations of the effect of these fairly large fusion yields on the RTL and the first wall of the reactor chamber. These simulations were performed with and without a neutron absorbing blanket surrounding the fusion explosion. We find that the RTL will be fully vaporized out to a radius of about 3 meters assuming normal incidence. However, at large enough radius the RTL will remain in either the liquid or solid state and this portion of the RTL could fragment and become shrapnel. We show that a dynamic fragmentation theory can be used to estimate the size of these fragmented particles. We discuss how proper design of the RTL can allow this shrapnel to be directed away from the sensitive mechanical parts of the reactor chamber.

De Groot, J. S. (University of California, Davis, CA); Olson, Craig Lee; Cochrane, Kyle Robert (Ktech Corporation, Albuquerque, NM); Slutz, Stephen A.; Vesey, Roger Alan; Peterson, Per F. (University of California, Berkeley, CA)

2003-12-01

180

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

SciTech Connect

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

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

1998-12-31

181

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

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

182

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

183

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

NASA Astrophysics Data System (ADS)

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

2006-01-01

184

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

185

High-density Z-pinch pulse-power supply system  

SciTech Connect

The design and operation of the high-density Z-pinch experiment pulse-power supply is discussed. A 600-kV, 1-MA, 75-nH Marx bank is designed to charge a 1-..cap omega.., 90-ns, water-insulated transmission line to approx. 0.6 to 1.0 MV. The water line is then discharged through a small laser-initiated current channel in 1 to 5 atm of hydrogen. The components of the Marx bank, the trigger system, the water line, and the gas load as well as the control system that uses fiber optics and air links for monitor and control are discussed.

Nunnally, W.C.; Jones, L.A.; Singer, S.

1979-01-01

186

Effect of Radial-Electric-Field Polarity on Wire-Array Z-Pinch Dynamics  

SciTech Connect

The formation of plasma in wire-array Z-pinch experiments was found to depend upon the polarity of the radial-electric field near the wires. Reversing the radial-electric field midway along the length of an array resulted in the ablation rate of one-half of the array being reduced by 50%, significantly delaying the start of its implosion and altering its acceleration towards the axis. The observed phenomena cannot be explained by the standard magnetohydrodynamic models of array behavior, suggesting that effects such as electron emission may be important, especially during wire initiation.

Bland, S.N.; Lebedev, S.V.; Chittenden, J.P.; Ampleford, D.J.; Bott, S.C.; Haines, M.G.; Hall, G.N.; Palmer, J.B.A. [Imperial College, Blackett Laboratory, Prince Consort Road, London SW7 2BZ (United Kingdom); Gomez, J.A.; Mitchell, I.H. [Pontificia Universidad Catolica de Chile, Avenida Vicuna Mackenna 4860, Santiago (Chile); Hammer, D.A. [Laboratory of Plasma Studies, Cornell University, Ithaca, New York (United States)

2005-09-23

187

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

188

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

SciTech Connect

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

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

1999-06-16

189

Suppression of Rayleigh-Taylor Instability in {ital Z}-Pinch Loads with Tailored Density Profiles  

SciTech Connect

A load structure with tailored density profile which delays the onset of the Rayleigh-Taylor instability development in imploding {ital Z} pinches by inverting acceleration of the magnetic field/plasma interface is proposed and studied numerically. This approach makes it possible to start gas-puff implosions from large radii (say, 8cm) and produce significant {ital K}-shell yield with current pulse duration of 250ns and longer. It could also be used to mitigate imprinting of initial perturbations into laser fusion targets. {copyright} {ital 1996 The American Physical Society.}

Velikovich, A.L. [Berkeley Scholars, Inc., Springfield, Virginia 22150 (United States); Cochran, F.L. [Berkeley Research Associates, Inc., Springfield, Virginia 22150 (United States); Davis, J. [Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States)

1996-07-01

190

Implosions, equilibria, and stability of rotating, radiating Z-pinch plasmas  

SciTech Connect

The effects of uniform rotation on the dynamics, equilibria and stability of cylindrically symmetric, radiating Z-pinch plasmas are studied. Rotation changes the Bennett and Pease--Braginskii equilibria qualitatively, eliminating radiative collapse for both quasisteady and dynamic plasmas. In particular, a steady rotating plasma column can support any current above the Pease--Braginskii value, with Ohmic heating balanced by radiative losses. Stabilizing effect of rotation on the {ital m}=0 mode of Rayleigh--Taylor instability of a hollow plasma shell was found for long perturbation wavelengths. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Velikovich, A.L. [Berkeley Scholars, Inc., Springfield, Virginia 22150 (United States); Davis, J. [Radiation Hydrodynamics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States)

1995-12-01

191

Mapping return currents in laser-generated Z-pinch plasmas using proton deflectometry  

NASA Astrophysics Data System (ADS)

Dynamic return currents and electromagnetic field structure in laser-generated Z-pinch plasmas have been measured using proton deflectometry. Experiments were modeled to accurately interpret deflections observed in proton radiographs. Current flow is shown to begin on axis and migrate outwards with the expanding coronal plasma. Magnetic field strengths of ~1 T are generated by currents that increase from ~2 kA to ~7 kA over the course of the laser pulse. Proton deflectometry has been demonstrated to be a practical alternative to other magnetic field diagnostics for these types of plasmas.

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

2012-05-01

192

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

PubMed

The observation of Doppler splitting in K-shell x-ray lines emitted from optically thin dopants is used to infer implosion velocities of up to 70 cm/?s in wire-array and gas-puff Z pinches at drive currents of 15-20 MA. These data can benchmark numerical implosion models, which produce reasonable agreement with the measured velocity in the emitting region. Doppler splitting is obscured in lines with strong opacity, but red-shifted absorption produced by the cooler halo of material backlit by the hot core assembling on axis can be used to diagnose velocity in the trailing mass. PMID:22181529

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

2011-11-28

193

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

194

Flow-through Z-pinch study for radiation generation and fusion energy production  

NASA Astrophysics Data System (ADS)

We discuss a high-density fusion reactor which utilizes a flow-through Z pinch magnetic confinement configuration. Assessment of this reactor system is motivated by simplicity and small unit size (few hundred MWe) and immunity to plasma contamination made possible at high density. The type reactor discussed here would employ a liquid Li vortex as the first wall/blanket to capture fusion neutrons with minimum induced radioactivity and to achieve high wall loading and a power density of 200 w/cm(exp 3).

Hartman, Charles W.; Eddleman, James L.; Moir, Ralph; Shumlak, U.

1994-06-01

195

Flow-through Z-pinch study for radiation generation and fusion energy production  

SciTech Connect

We discuss a high-density fusion reactor which utilizes a flow-through Z pinch magnetic confinement configuration. Assessment of this reactor system is motivated by simplicity and small unit size (few hundred MWe) and immunity to plasma contamination made possible at high density. The type reactor discussed here would employ a liquid Li vortex as the first wall/blanket to capture fusion neutrons with minimum induced radioactivity and to achieve high wall loading and a power density of 200 w/cm{sup 3}.

Hartman, C.W.; Eddleman, J.L.; Moir, R. [Lawrence Livermore National Lab., CA (United States); Shumlak, U. [Phillips Lab., Kirtland AFB, NM (United States)

1994-06-20

196

The flow-through Z-pinch for fusion energy production  

SciTech Connect

The authors discuss a high-density fusion reactor which utilizes a flow-through Z pinch magnetic confinement configuration. Assessment of this reactor system is motivated by simplicity and small unit size (few hundred MWe) and immunity to plasma contamination made possible at high density. The type reactor discussed here would employ a liquid Li vortex as the first wall/blanket to capture fusion neutrons with minimum induced radioactivity and to achieve high wall loading and a power density of 200 W/cm{sup 3}.

Hartman, C.W.; Eddleman, J.L.; Moir, R. [Lawrence Livermore National Lab., CA (United States); Shumlak, U. [Phillips Lab., Kirtland AFB, NM (United States)

1994-11-01

197

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

SciTech Connect

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, placed 2 cm below the cathode. The cavity in the center of the cathode was enlarged from 6-mm diameter to 36 mm. The design of the cathode and the anode showed a marked improvement of the pinch stability over the previous design. Both zirconium and carbon-carbon nozzle were used for the Kr and Ne {ital z} pinches. After a few tens of shots the Zr nozzle was melted at the edge and the pinch degraded, while the carbon-carbon nozzle did not sustain any damage for more than 300 shots. Some shots showed the {ital di}/{ital dt} at the implosion is {similar to}5 times higher than the {ital di}/{ital dt} at the beginning of the discharge, this has never been obtained at UCI before. This ratio of the initial {ital di}/{ital dt} to pinch {ital di}/{ital dt} is a measure of the pinch quality. By serendipity it was found that double gas puff {ital z} pinch increased the hard x-ray ({gt}1 keV) output by about an order of magnitude. The nozzle was then modified to allow double puff operation. A 3.4-mm-diam hole was opened at the center of the nozzle and a plunger was inserted from the top to control the mass of the gas entering the hole. The diagnostics include {ital di}/{ital dt} coil, soft, and hard x-ray diodes. Soft and hard x-ray emission are both enhanced by the double gas puff {ital z} pinch.

Chang, T.; Fisher, A.; Van Drie, A. (Department of Physics, University of California, Irvine, California 92717 (US))

1991-03-15

198

Experimental Study of Implosion Dynamics of Multi-Shell Z-Pinches at Microsecond Implosion Times  

SciTech Connect

A set of experiments has been conducted on the GIT-12 generator (4.7 MA, 1.7 {mu}s) operating at microsecond mode. The experiments were carried out with multi-shell gas puffs. Dynamics of current-carrying plasma was registered by a set of B-dots monitors placed at different radii inside a multi-shell gas puff. The experimental data obtained with the help of B-dots monitors are compared with 0D snow-plow simulations of implosion dynamics and discussed taking into consideration the data from other Z-pinch diagnostics.

Shishlov, Alexander V.; Chaikovsky, Stanislav A.; Fedunin, Anatoly V.; Fursov, Fedor I.; Kokshenev, Vladimir A.; Kurmaev, Nikolai E.; Labetsky, Aleksey Yu.; Oreshkin, Vladimir I.; Rousskikh, Alexander G.; Zhidkova, Natalia A. [Institute of High Current Electronics, Tomsk, 634055 (Russian Federation)

2006-01-05

199

Modeling nonlinear Rayleigh-Tayor 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 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, A R

2008-09-16

200

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

201

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

SciTech Connect

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

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

2006-12-04

202

Recombination-pumped XUV lasing in capillary discharges and dynamic z-pinches  

NASA Astrophysics Data System (ADS)

A fully time-dependent collisional - radiative model is employed to calculate relevant population densities in a recombining carbon/hydrogen z-pinch plasma. In particular, the dependence of the small signal gain G on the maximum electron temperature and cooling rate, as well as the influence of Lyman-0022-3727/29/8/005/img8 reabsorption, are studied. Although in conditions typical for dynamic z-pinches the maximum electron temperature and cooling rates would, in principle, be sufficiently high, gain on the Balmer-0022-3727/29/8/005/img8 transition is strongly reduced by Lyman-0022-3727/29/8/005/img8 reabsorption. In order to investigate vacuum spark capillary discharges, the system of rate equations is coupled with balance equations of the plasma energy and the total number of heavy particles. The resulting set of equations is solved self-consistently. Results are presented that show the systematic dependence of the small signal gain on electrical input power, wall material, and capillary geometry. High gain coefficients 0022-3727/29/8/005/img11 could be achieved by modelling high-voltage discharges with short ringing periods through capillaries containing boron or carbon. While the maximum achievable gain coefficient for lithium is rather poor 0022-3727/29/8/005/img12 the duration of population inversion would be long enough (a few tens of nanoseconds) to make multi-pass operation possible.

Pckl, M.; Hebenstreit, M.; Fertner, R.; Neger, T.; Aumayr, F.

1996-08-01

203

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

204

2D and 3D Modelling of Z-pinch Implosions and Laboratory Astrophysics Experiments  

NASA Astrophysics Data System (ADS)

Results are presented from simulations of a number of different Z-pinch based experiments. 1D and 2D simulations of wire arrays in cross-section are used to show how the flow region between the ablating wires and the axis converges to a set of equilibrium profiles which can be reproduced using analytic theory. 3D simulations of imploding wire arrays are used to highlight the importance of current transferred to the axis in determining the level of soft X-ray power obtained. Mechanisms for power improvements using increased wire number, different materials and nested arrays are inferred from the 3D results. Simulations of hypersonic jet formation in conical wire arrays and the impact of these jets with ablated plasma targets are described using 2D MHD and hydrodynamic simulations. The development of flux limited radiation transport algorithms for these 2D and 3D models is discussed. Preliminary data from 2D radiation MHD modelling of imploding Z-pinches and of radiative ablation of clumpy media are presented. This research was sponsored by the NNSA under DOE Cooperative Agreement DE-F03-02NA00057.

Jennings, C. A.; Chittenden, J. P.; Ciardi, A.; Lebedev, S. V.; Bland, S. N.

2003-10-01

205

Observation of Skeletal Filamentary Structures in Plasma of a Fast Z-Pinch  

NASA Astrophysics Data System (ADS)

The results are presented of analyzing the plasma images taken at facility C-300 under condition of 1-3 MA electric currents for current growth front of 100 ns duration [1]. The load was a tailored cylinder (8 mm long, 3-5 mm in diameter, with a neck of 1 mm diameter), made of agar-agar with various heavy-element filling. The analyzed images were taken with the help of electronic optical converters (exposure 3 ns, interframe interval 15 ns, spatial resolution 50-100 micrometers). Three successive images were taken in each discharge in the visible light and soft x-rays, with covering a part of vacuum ultraviolet spectral range. This enabled us to (i) observe skeletal structures (SSs) in plasma, (ii) reveal the continuity of SS in the core and periphery, (iii) roughly trace their dynamics during the entire discharge and thus show the longevity of SS, (iv) resolve the fine structure of SS. The analysis carried out allows to extend the formerly identified phenomenon of long-lived SSs in a straight Z-pinch plasma [2] of microsecond discharge duration to the case of a fast Z-pinch. [1] Proc. 29-th EPS PPCF, Montreux, 2002, P4_015 (http://elise.epfl.ch/pdf/P4_015.pdf). [2] Proc. 27-th EPS PPCF, Budapest, 2000, http://epsppd.epfl.ch/Buda/pdf/p2_051.pdf.

Blinov, Peter I.; Korolev, Valery D.; Rantsev-Kartinov, Valentin A.

2002-11-01

206

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

207

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

208

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

209

Soft X-ray Radiation from Nitrogen Z-pinch Plasma Produced by Capillary Discharge  

NASA Astrophysics Data System (ADS)

Characteristics of soft X-ray radiation from nitrogen filled Z-pinch plasma columns energized by capillary discharge are reported in order to evaluate optimum plasma parameters for an H-like N recombination pumped soft X-ray laser, wavelength of which is 13.4 nm emitted by quantum transition from n=3 to n=2. The discharge system used in this experiment consists of a 3-stage Marx generator, a step-up transformer and a 3-nF water capacitor. Soft X-ray radiation from Z-pinch nitrogen plasma was measured by using a transmission grating spectrometer with a CCD array detector. Multiply-ionized ions up to N VII were confirmed to exist, and existence of N VIII was anticipated. This suggests that a plasma temperature at the pinch time is the order of 100 eV and might reaches over 150 eV. From these experimental results, plasma parameters and the discharge current required for realizing an H-like N recombination soft X-ray laser were estimated.

Sakai, Yusuke; Komatsu, Takanori; Xiao, Yifan; Song, Inho; Niimi, Gota; Watanabe, Masato; Okino, Akitoshi; Hotta, Eiki

210

Subdiffusive radial transport in a gyrokinetic Z-pinch plasma with zonal flows  

NASA Astrophysics Data System (ADS)

We report on numerical gyrokinetic studies of a confined, magnetized plasma in a Z-pinch configuration. Building upon previous resultsfootnotetextRicci et al PRL 97 245001 2006 for the entropy mode in a gyrokinetic Z-pinch, we examine the details of particle transport as diagnosed by the displacements of an ensemble of tracer particles in simulationsfootnotetextBroemstrup, Thesis University of Maryland. The density-gradient driven entropy mode of instability leads to vertical zonal flow structures in the turbulence that impede particle transport in the radial direction. Tracer displacements in this study point to the existence of subdiffusive radial transport, such that the spreading of the tracers proceeds more slowly than predicted by a canonical turbulent diffusion equation. The relevance of this result to the usual predictions of confinement-time scaling for fusion machines is examined. We compare the effects of collisions and several values of the density gradient for significant periods of time, measured in vthermal/L. We use continuous-time random walk and fractional diffusion equation models to understand the transport process more generally. The importance of long-range velocity correlations and scale-free transport is considered.

Gustafson, Kyle; Dorland, William

2009-11-01

211

Ion Beam Driven Shock Device Using Accelerated High Density Plasmoid by Phased Z-Pinch  

NASA Astrophysics Data System (ADS)

Different from three methods to generate high shock pressure by acceleration of high density plasma or particles (intense ion beams, plasma gun and rail gun) having their intrinsic deficiencies, new frontier is proposed to propel the shock physics and chemistry by using the high density plasma. In the present paper, new scheduled Z-pinch method is developed as a new device to generate high shock pressure. In the present method, plasma density can be compressed to the order of 10^18 to 10^19 cm-3, and high density plasma can be accelerated by zippering together with axial shock pressure, resulting in high-velocity launching of flyer. In the present paper, systematic experimental works are performed to demonstrate that high energy plasma flow can be electro-magnetically driven by the scheduled capillary Z-pinch, and to characterize the ion velocity and its current density. The estimated value of ion speed from the plasma-measurement reaches to 7 x 10^7 cm/s corresponding to 70 to 100 KeV for Ar. Copper flyer can be shot with the velocity range from 1km/s to 3km/s in the standard condition.

Horioka, Kazuhiko; Aizawa, Tatsuhiko; Tsuchida, Minoru

1997-07-01

212

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

SciTech Connect

Experimental results are presented that characterize the implosion dynamics and radiation output of wire-array Z pinches on the 1-MA, 100-ns rise-time Cornell Beam Research Accelerator (COBRA) [J. B. Greenly et al., Rev. Sci. Instrum. 79, 073501 (2008)]. The load geometries investigated include 20-mm-tall cylindrical arrays ranging from 4 to 16 mm in diameter, and consisting of 8, 16, or 32 wires of either tungsten, aluminum, or Invar (64% iron, 36% nickel). Diagnostics fielded include an optical streak camera, a time-gated extreme-ultraviolet framing camera, a laser shadowgraph system, time-integrated pinhole cameras, an x-ray wide-band focusing spectrograph with spatial resolution, an x-ray streak camera, a load voltage monitor, a Faraday cup, a bolometer, silicon diodes, and diamond photoconducting detectors. The data produced by the entire suite of diagnostics are analyzed and presented to provide a detailed picture of the overall implosion process and resulting radiation output on COBRA. The highest x-ray peak powers (300-500 GW) and total energy yields (6-10 kJ) were obtained using 4-mm-diameter arrays that stagnated before peak current. Additional findings include a decrease in soft x-ray radiation prior to stagnation as the initial wire spacing was changed from 1.6 mm to 785 {mu}m, and a timing correlation between the onset of energetic electrons, hard x-ray generation, and the arrival of trailing current on axis - a correlation that is likely due to the formation of micropinches. The details of these and other findings are presented and discussed.

McBride, R. D.; Shelkovenko, T. A.; Pikuz, S. A.; Hammer, D. A.; Greenly, J. B.; Kusse, B. R.; Douglass, J. D.; Knapp, P. F.; Bell, K. S.; Blesener, I. C.; Chalenski, D. A. [Laboratory of Plasma Studies, Cornell University, 439 Rhodes Hall, Ithaca, New York 14853 (United States)

2009-01-15

213

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

SciTech Connect

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

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

1997-05-05

214

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

SciTech Connect

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

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

1997-05-01

215

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

216

Z-pinch structured by a standing lightwave as a noncoherent radiator and x-ray lasing undulator  

Microsoft Academic Search

As z-pinches are powerful sources of X-radiation, the present work treats the possibility of their stratification by a standing light wave with the purpose of regularizing the radiation process. The ponderomotive force push out the plasma from the antinodes of the standing wave. Once the pinch shell has decreased up to the transverse dimensions of the laser beam, further compression

Michael Y. Romanovsky; T. V. Vishnitskaya; Igor V. Klimov; Vladlen V. Korobkin

1994-01-01

217

Progress in current scaling and optimization of argon K-shell radiation in a Z-pinch  

Microsoft Academic Search

Summary form only given, as follows. In Z-pinch implosions, simple dynamic arguments show that for fixed initial radius of mass and fixed implosion time, imploded mass varies as I2 and yield should scale as I4 (inefficient regime). As the radiated yield becomes comparable to the available implosion energy, energy conservation limits the yield. Then yield is expected to increase as

H. Sze; J. Banister; S. Chantrenne; P. L. C. B. H. Failor; A. Fisher; J. S. Levine; Y. Song; E. M. Waisman; J. P. Apruzese; J. Davis; D. Mosher; J. W. Thornhill; A. L. Velikovich; B. V. Weber; C. A. Coverdale; C. Deeney; T. Gilliland; J. Mcgurn; R. Spielman; K. Struve; W. Stygar; D. Bell

2001-01-01

218

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

219

Plasma density measurements in tungsten wire-array Z-pinches  

NASA Astrophysics Data System (ADS)

Measurements of the plasma density profile near the exploding wires in 1 MA tungsten (W) wire-array Z-pinches have been made using calibrated x-ray absorption. As many as 5 x-ray images per pulse were obtained between 65 and 160 ns after the start of the 100 ns rise time current pulse. Measured W ion densities range from above 1019/cm3 close to the wire to ~1017/cm3 about 1 mm away from the wire in the plasma stream. After accurate geometrical registration of the individual wires in each successive image in a pulse using the Genetic Algorithm, the temporal evolution of the axial modulation wavelength distribution of the ablation rate from the wires in each array and the global mass-ablation rate as a function of time are presented.

Douglass, J. D.; Hammer, D. A.; Pikuz, S. A.; Shelkovenko, T. A.; Blesener, K. S.

2012-07-01

220

Progress Toward Development of an IFE Power Plant Using Z-Pinch Technology  

SciTech Connect

The Z-Pinch Power Plant uses the results from Sandia National Laboratories' Z accelerator in a power plant application to generate energy pulses using inertial confinement fusion. A collaborative project has been initiated by Sandia to investigate the scientific principles of a power generation system using this technology. Research is under way to develop an integrated concept that describes the operational issues of a 1000 MW electrical power plant. Issues under consideration include: 1-20 gigajoule fusion pulse containment, repetitive mechanical connection of heavy hardware, generation of terawatt pulses every 10 seconds, recycling of ten thousand tons of steel, and manufacturing of millions of hohlraums and capsules per year.Additionally, waste generation and disposal issues are being examined. This paper describes the current concept for the plant and also the objectives for future research.

Rochau, Gary E. [Sandia National Laboratories (United States)] (and others)

2005-04-15

221

Progress toward development of an IFE power plant using Z-Pinch technology.  

SciTech Connect

The Z-Pinch Power Plant uses the results from Sandia National Laboratories Z accelerator in a power plant application to generate energy pulses using inertial confinement fusion. A collaborative project has been initiated by Sandia to investigate the scientific principles of a power generation system using this technology. Research is under way to develop an integrated concept that describes the operational issues of a 1000 MW electrical power plant. Issues under consideration include: 1-20 gigajoule fusion pulse containment, repetitive mechanical connection of heavy hardware, generation of terawatt pulses every 10 seconds, recycling of ten thousand tons of steel, and manufacturing of millions of hohlraums and capsules per year. Additionally, waste generation and disposal issues are being examined. This paper describes the current concept for the plant and also the objectives for future research.

Rochau, Gary Eugene

2004-09-01

222

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

SciTech Connect

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

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

2007-10-01

223

Neutron Signatures of Non-Thermal Ion Distributions in Z-Pinch Driven ICF Plasmas  

NASA Astrophysics Data System (ADS)

In preparation for upcoming ICF experiments on the 26 MA Z machine (e.g., D2 gas puff, MagLIF [1]), we are studying the neutron energy spectra produced by magnetically-driven loads beyond the archetypal single temperature, uniform plasma. Z-pinch sources frequently exhibit evidence of unusual neutron spectra [2], which can be attributed to three-dimensional turbulent motion, high-energy beams, and other phenomena leading to non-Maxwellian ion distributions. Understanding the nature of our plasma neutron sources is critical for understanding how they scale with increasing current. We will show Monte Carlo and analytic calculations for plausible scenarios and discuss the corresponding signatures for the existing set of time-of-flight diagnostics on Z.[4pt] [1] S. A. Slutz et al. Phys. Plasmas 17, 056303 (2010)[0pt] [2] V.V. Vikhrev and V.D. Korolev, Plasma Dynamics, Vol. 33, No. 5 (2007)

Knapp, Patrick; Jennings, Christopher; Sinars, Daniel

2012-10-01

224

Preliminary Results of Cone Z-Pinch Device with 5 kJ  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

225

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

NASA Astrophysics Data System (ADS)

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

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

2009-01-01

226

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

227

Spectroscopic study of z-pinch K-shell x-ray sources  

NASA Astrophysics Data System (ADS)

Fast z-pinches provide intense 1-10 keV photon energy radiation sources. Analysis of time-integrated K-shell x-ray spectra indicates electron temperatures up to 5 keV and ion densities of order 10^20 cm-3 in the stagnated plasma created from wire array implosions on Sandia's Z machine pulsed power driver. Elliptical crystal spectrometers coupled to microchannel plate detectors, fielded previously on Z, have recently provided time-resolved spectral measurements for Al (2 keV), stainless steel (6.7 keV), and Cu (8.4 keV) sources. We discuss implosion and stagnation dynamics, plasma conditions, and spectral analysis in the presence of opacity and Doppler effects.

Jones, B.; Rochau, G. A.; Bailey, J. E.; Ampleford, D. J.; Coverdale, C. A.; Hansen, S. B.; Jennings, C. A.; Cuneo, M. E.; Maron, Y.; Fisher, V.; Bernshtam, V.; Starobinets, A.; Weingarten, L.; Apruzese, J. P.; Dasgupta, A.; Clark, R. W.; Thornhill, J. W.; Whitney, K. G.; Giuliani, J. L.; Davis, J.

2009-11-01

228

Kinetic simulation of neutron production in a deuterium z-pinch.  

SciTech Connect

We have found computationally that, at sufficiently high currents, half of the neutrons produced by a deuterium z pinch are thermonuclear in origin. Early experiments below 1-MA current found that essentially all of the neutrons produced by a deuterium pinch are not thermonuclear, but are initiated by an instability that creates beam-target neutrons. Many subsequent authors have supported this result while others have claimed that pinch neutrons are thermonuclear. To resolve this issue, we have conducted fully kinetic, collisional, and electromagnetic simulations of the complete time evolution of a deuterium pinch. We find that at 1-MA pinch currents, most of the neutrons are, indeed, beam-target in origin. At much higher current, half of the neutrons are thermonuclear and half are beam-target driven by instabilities that produce a power law fall off in the ion energy distribution function at large energy. The implications for fusion energy production with such pinches are discussed.

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)

2010-11-01

229

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

NASA Astrophysics Data System (ADS)

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

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

2005-03-01

230

Reconstruction of Neutron and Deuteron Energy Spectra in Z-pinch Experiments  

NASA Astrophysics Data System (ADS)

The neutron energy spectra were reconstructed in Z-pinch experiments where deuterium atoms were present in a load. The reconstruction was based on the time-of-flight method in which time-resolved neutron detectors were placed at various distances from the neutron source. There are several theoretical approaches to the development of reconstruction algorithms (Monte Carlo, etc.). The improved Monte Carlo reconstruction technique, which simultaneously used neutron detectors placed on two opposite sites from the source, was applied to process data from experiments on the S-300 generator (Kurchatov Institute, Moscow). Since these experiments contained a small number of neutron detectors in one direction, a specific reconstruction procedure was used. From the reconstructed neutron energy spectra, also the energy distribution function of deuterons producing fusion neutrons could be calculated. The characteristics of the neutron scintillation detector and the influence of scattered neutrons were taken into account to estimate the error in the reconstruction.

Rezac, Karel; Klir, Daniel; Kubes, Pavel; Kravarik, Josef

2007-11-01

231

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

SciTech Connect

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

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

2009-01-21

232

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 . 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 . 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

233

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

234

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

235

Plasma ablation and precursor formation in wire array z-pinches  

NASA Astrophysics Data System (ADS)

Experiments on the 1MA MAGPIE generator were used to study the formation and dynamics of plasma in wire array z-pinches, prior to implosion. High magnification laser probing and gated optical imaging allowed the breakdown of the wires to be examined, and the evolution of the wires into core-corona plasma systems observed. The development of axial perturbations in the coronal plasma streams from the wires was compared to array characteristics. On-axis accumulation of the streams resulted in the formation of a precursor plasma column, through a process strongly dependent on collisionality. The temperature, density, X-ray emission and apparent stability of the precursor are discussed, and several applications are suggested. This research was sponsored by Sandia National Laboratories, Albuquerque; and the SSAA program of NNSA under DOE Cooperative Agreement DE-FC03-02NA00057.

Bott, S. C.; Lebedev, S. V.; Ampleford, D. J.; Bland, S. N.; Chittenden, J. P.; Hall, G. N.; Jennings, C.

2004-11-01

236

2D radiation-magnetohydrodynamic simulations of SATURN imploding Z-pinches  

SciTech Connect

Z-pinch implosions driven by the SATURN device at Sandia National Laboratory are modeled with a 2D radiation magnetohydrodynamic (MHD) code, showing strong growth of magneto-Rayleigh Taylor (MRT) instability. Modeling of the linear and nonlinear development of MRT modes predicts growth of bubble-spike structures that increase the time span of stagnation and the resulting x-ray pulse width. Radiation is important in the pinch dynamics keeping the sheath relatively cool during the run-in and releasing most of the stagnation energy. The calculations give x-ray pulse widths and magnitudes in reasonable agreement with experiments, but predict a radiating region that is too dense and radially localized at stagnation. We also consider peaked initial density profiles with constant imploding sheath velocity that should reduce MRT instability and improve performance. 2D krypton simulations show an output x-ray power > 80 TW for the peaked profile.

Hammer, J.H.; Eddleman, J.L.; Springer, P.T. [and others

1995-11-06

237

Improvements in the EQ-10 electrodeless Z-pinch EUV source for metrology applications  

NASA Astrophysics Data System (ADS)

Now that EUV lithography systems are beginning to ship into the fabs for next generation chips it is more critical that the EUV infrastructure developments are keeping pace. Energetiq Technology has been shipping the EQ-10 Electrodeless Z-pinch light source since 2005. The source is currently being used for metrology, mask inspection, and resist development. These applications require especially stable performance in both power and source size. Over the last 5 years Energetiq has made many source modifications which have included better thermal management as well as high pulse rate operation6. Recently we have further increased the system power handling and electrical pulse reproducibility. The impact of these modifications on source performance will be reported.

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

2011-03-01

238

Progress on Liquid Cryogenic Capsule Development for Fast Ignition with Z-Pinch-Driven Fuel Assembly  

NASA Astrophysics Data System (ADS)

We are currently developing a pulsed-power-based approach to fast ignitor fuel assembly where intense thermal x-rays from a z-pinch implosion drive the compression of a hemispherical fuel capsule in a vacuum secondary hohlraum. This asymmetric drive configuration, with hemi-capsule motion constrained by a planar high density glide surface, opens up new design possibilities for indirect-drive cryogenic fuel capsules. As an alternative to foam-stabilized cryogenic solid fuel layers, we are investigating cryogenic fast ignition capsules with a liquid fuel layer confined between a thick outer ablator shell and a thin inner shell. Several approaches are being explored for fabrication of thin (3-5 ?m) inner shells. 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.; Russell, C.; Johnston, R. R.

2005-10-01

239

Time Evolution of the Magnetic Field Topology of Cylindrical Wire Array Z-Pinches  

NASA Astrophysics Data System (ADS)

We study the influence of the magnetic field topology and the global field penetration time on the ablation plasma dynamics of individual wires in wire array Z-pinches. Knowledge of the magnetic field configuration is necessary for understanding the ablation plasma acceleration process near the wires and the validity of constant ablation velocity approximation as applied to the 1 MA COBRA pulsed power generator. Three-dimensional resistive MHD simulation results suggest that a change in the global magnetic field topology is critical to initiating inward flow of the ablation plasmas. These simulation results are investigated experimentally by using B-dot probes to track the evolution of the field topology over time for small wire number cylindrical arrays on COBRA. This research was supported by the Stewardship Sciences Academic Alliances program of the National Nuclear Security Administration under DOE Cooperative agreement DE-FC03-02NA00057.

Martin, Matthew; Greenly, John; Seyler, Charles

2007-11-01

240

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

NASA Astrophysics Data System (ADS)

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 . 1018 cm-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.; Baksht, R. B.

2011-09-01

241

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

242

Time-resolved K-shell line spectra measurement of z-pinch plasmas  

NASA Astrophysics Data System (ADS)

A Johann-type crystal spectrometer integrated with x-ray PIN diodes has been developed for measuring the time-resolved K-shell line spectra of the imploding Al wire array. In this spectrometer, the PIN diodes are mounted on the Rowland circle of the cylindrical bent crystal with an appointed position to collect the line emissions from z-pinch plasmas. The spectrometer with four typical channels, which are keyed to the Al ion hydrogen-like (H?, 0.7171 nm and H?, 0.6052 nm) and helium-like (He?, 0.7757 nm and He?, 0.6634 nm) resonance lines is designed and fabricated. Example data from the experiment on the Yang accelerator are shown and the time-dependent electron temperature is determined from the signal ratios of Al ion H? line to He? line using the collisional and radiative model.

Yang, Qingguo; Zhou, Shaotong; Chen, Guanhua; Huang, Xianbin; Cai, Hongchun; Li, Zeren

2013-11-01

243

A five-channel, diamond photoconducting x-ray detector array for z- pinch experiments  

SciTech Connect

We have built a five-channel, x-ray detector array based on diamond photoconducting detectors (PCDs). The diamond elements have dimensions of 3 mm {times} 1 mm {times} 1 mm (or 0.5 mm). We use PCDs for their stability, flat spectral response, and low leakage currents. The good time response of diamond PCDs is due to the 100-ps electron/hole recombination time. Filters were designed to give information in the 1--10 keV spectral region. Calibration of the diamond PCDs showed sensitivities between 4--7{times}10{sup {minus}4} A/W for a bias of 100 V. We shall present data from z-pinch experiments on Saturn. 10 refs.

Spielman, R.B.

1992-05-01

244

A five-channel, diamond photoconducting x-ray detector array for z-pinch experiments  

SciTech Connect

We have built a five-channel, x-ray detector array based on diamond photoconducting detectors (PCDs). The diamond elements have dimensions of 3 mm {times} 1 mm {times} 1 mm (or 0.5 mm). We use diamond PCDs for their stability, flat spectral response, and low leakage currents. The good time response of diamond PCDs is due to the 100-ps electron/hole recombination time. Filters were designed to give information in the 1--10-keV spectral region. Calibration of the diamond PCDs showed sensitivities between 4 and 7 {times} 10{sup {minus}4} A/W for a bias of 100 V. We shall present data from {ital z}-pinch experiments on Saturn.

Spielman, R.B. (Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States))

1992-10-01

245

A five-channel, diamond photoconducting x ray detector array for z-pinch experiments  

NASA Astrophysics Data System (ADS)

We have built a five-channel, x-ray detector array based on diamond photoconducting detectors (PCD's). The diamond elements have dimensions of 3 mm x 1 mm x 1 mm (or 0.5 mm). We use PCD's for their stability, flat spectral response, and low leakage currents. The good time response of diamond PCD's is due to the 100-ps electron/hole recombination time. Filters were designed to give information in the 1-10 keV spectral region. Calibration of the diamond PCD's showed sensitivities between 4-7 x 10(exp -4) A/W for a bias of 100 V. We shall present data from z-pinch experiments on Saturn.

Spielman, R. B.

1992-05-01

246

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

NASA Astrophysics Data System (ADS)

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

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

2002-11-01

247

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

NASA Astrophysics Data System (ADS)

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

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

2000-10-01

248

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

NASA Astrophysics Data System (ADS)

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

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

2009-09-01

249

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

SciTech Connect

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

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

2006-12-04

250

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

NASA Astrophysics Data System (ADS)

In this paper we present the results obtained on the plasma focus PF-1000 in IPPLM Warsaw and on the z-pinch S-300 in RRC Kurchatov Institute in Moscow using a deuterium load. On the PF-1000 plasma-focus device with deuterium filling gas the energy of neutrons and time of their generation are determined by time-of-flight method from seven scintillation detectors positioned in the axial direction. The neutron signals (total yield ~1011 neutrons per shot) correlate with hard x-rays and their maximum occur ~150-200 ns after the pinch phase. The initial portion of neutron pulse has beam-target origin with downstream energies up to 2.8-3.2 MeV and the final portion of neutrons has isotropic distribution of energies in the range of 2.2-2.7 MeV. The z-pinch experiments were performed on the S-300 generator with the load formed from a deuterated CD2 fibre in the axis of a tungsten wire array. The energy of neutrons and time of their generation are determined by time-of-flight method from 5 scintillation detectors positioned in the axial and side-on direction. The neutrons with total yield up to 3109 per shot are produced in the energy range of 1.8-3.2 MeV at 10-30 ns after the pinch phase represented by dip in the current waveform, peak of the voltage and minimum of the pinch diameter. The distribution of neutron velocities is random within the total solid angle. The neutrons in both devices are produced by a non-thermal mechanism with deuterons accelerated to the energies above 100 keV partially in anode-cathode direction and partially with almost isotropic distribution of velocities at the time of the plasma expansion, i.e. after the pinch phase.

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

2006-12-01

251

Polarization effects of a high-power CO2 laser beam on aluminum alloy weldability  

Microsoft Academic Search

Linearly polarized CO2 laser beams have been used to investigate the effects of polarization on aluminum alloy weldability. Bead-on-plate welding tests have been performed on A5083 (AlMg4.5Mn0.7) alloy plates with quasi-TEM00-mode beams whose polarization direction is parallel or perpendicular to the welding direction, referred to as the parallel or the perpendicular polarization beam, respectively. Comparison of the fusion zone shapes

Shunichi Sato; Kunimitsu Takahashi; Blent Mehmetli

1996-01-01

252

Amplitude reduction of nonuniformities induced by magnetic Rayleigh-Taylor instabilities in Z-pinch dynamic hohlraums  

NASA Astrophysics Data System (ADS)

Z-pinch plasmas are susceptible to the magnetic Rayleigh-Taylor (MRT) instability. The Z-pinch dynamic hohlraum (ZPDH), as implemented on the Z machine at Sandia National Laboratories, is composed of an annular tungsten plasma that implodes onto a coaxial foam convertor. The collision between tungsten Z pinch and convertor launches a strong shock in the foam. Shock heating generates radiation that is trapped by the tungsten Z pinch. The radiation can be used to implode a fuel-filled, inertial confinement fusion capsule. Hence, it is important to understand the influence that the MRT instability has on shock generation. This paper presents results of an investigation to determine the affect that the MRT instability has on characteristics of the radiating shock in a ZPDH. Experiments on Z were conducted in which a 1.5 cm tall, nested array (two arrays with initial diameters of 2.0 and 4.0 cm), tungsten wire plasma implodes onto a 5 mg/cc, CH2 foam convertor to create a ~135 eV dynamic hohlraum. X-ray pinhole cameras viewing along the ZPDH axis recorded time and space resolved images of emission produced by the radiating shock. These measurements showed that the shock remained circular to within +/-30-60 ?m as it propagated towards the axis, and that it was highly uniform along its height. The measured emission intensities are compared with synthetic x-ray images obtained by postprocessing two-dimensional, radiation magnetohydrodynamic simulations in which the amplitude of MRT perturbations is varied. These simulations accurately reproduce the measured shock trajectory and spatial profiles of the dynamic hohlraum interior emission as a function of time, even for large MRT amplitudes. Furthermore, the radiating shock remains relatively uniform in the axial direction regardless of the MRT amplitude because nonuniformities are tamped by the interaction of the tungsten Z-pinch plasma with the foam. These results suggest that inertial confinement fusion implosions driven by a ZPDH should be relatively free from random radiation symmetry variations produced by Z-pinch instabilities.

Lemke, R. W.; Bailey, J. E.; Chandler, G. A.; Nash, T. J.; Slutz, S. A.; Mehlhorn, T. A.

2005-01-01

253

The high power pulsed ion beam mixing of a titanium layer with an aluminum substrate  

NASA Astrophysics Data System (ADS)

This paper describes the MPOS application as an ion beam source for Ti film/Al substrate mixing. Single layer 500nm films of titanium were deposited on aluminum 6061-T6 samples and then irradiated by an ion beam. The ion beam energy was between 200 and 250keV, the pulse length was 100ns and the ion current density was between 10 and 150A/cm2. Characterization of the treated samples was done using the SEM, EDAX and Auger spectroscopy. Numerical calculations of the phase transitions in this system have been done, to estimate the ion current density needed for effective melting and mixing of the films and substrate. According to Auger analysis, significant mixing of the Ti film and Al substrate occurs up to depths of 1.3?m. Corrosion tests have shown improved corrosion resistance for the mixed layer in comparison with the untreated film.

Bystritskii, V.; Garate, E.; Grigoriev, V.; Kharlov, A.; Lavernia, E.; Peng, X.

1999-01-01

254

Initial Z-Pinch Results With a 12 cm Diameter Nozzle Using Argon on the Decade Quad  

NASA Astrophysics Data System (ADS)

We will report on the initial tests of a large diameter double shell nozzle using the 300 ns rise-time current pulse (> 6 MA) of the DECADE QUAD (DQ) pulsed power machine. With a large 4 cm recess, the gas flow at the pinch location is well collimated and nearly a uniform fill, a flow condition that has been shown (Ref.1) to give better output than shell-like flows for gas z-pinches. Results from a limited set of shots on DQ will be presented. Ref 1. P. L. Coleman, et.al., "A review of recent z-pinch research at Maxwell Physics International", Laser and Particle Beams, 19, 2001, pp. 409-441.

Krishnan, Mahadevan; Coleman, Philip; Bixler, Alex; Gerhan, Andrew; Thompson, John; Wilson, Kristi

2003-10-01

255

Comments on the critical issues for a high-density gas-embedded z-pinch CTR reactor concept  

SciTech Connect

The issues considered critical for the realization of a CTR reactor are discussed for the high-density gas-embedded z-pinch concept. A simple model of the pinch reactor is presented that gives estimates for Q in substantial agreement with elaborate computer studies. An attempt is made to identify such critical points that are amenable to exploratory experiments. There appears to be no fatal flaw in the issues covered that would preclude a viable reactor based on this concept.

Ekdahl, C.A.

1981-02-01

256

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

Microsoft Academic Search

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

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

2004-01-01

257

Two-dimensional radiation MHD modeling of stainless steel and Cu wire array Z-pinch implosions  

Microsoft Academic Search

Summary form only given. A two-dimensional radiation MHD model was recently developed and employed to investigate large diameter wire array Z-pinch experiments performed on the refurbished Z generator. This model incorporates into the Mach2 MHD code a self-consistent calculation for non-local thermodynamic equilibrium kinetics and ray trace based radiation transport. This level of detail is necessary in order to model

J. W. Thornhill; J. L. Giuliani; J. P. Apruzese; Y. K. Chong; J. Davis; A. Dasgupta; B. Jones; D. J. Ampleford; C. A. Coverdale; M. E. Cuneo

2009-01-01

258

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

Microsoft Academic Search

A soft x-ray (0.11 keV) streak camera using a grazing-incidence mirror has been developed for the Sandia Z facility, a 20 MA, 100 ns rise-time accelerator that can generate >200 TW,2 MJ, x-ray pulses. The streak camera is used to measure with one dimension of spatial resolution the continuous time history of sub-kilo-electron-volts emission from z-pinch and radiation flow experiments.

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

2004-01-01

259

Energy Transformation in Z-Pinch and Plasma Focus Discharges with Wire and Wire-in-Liner Loads  

NASA Astrophysics Data System (ADS)

The results of the study of the Z-pinch and plasma-focus plasmas at presence of the axial C, Al, or Cu wires of sufficient high diameter are discused in this paper. The wire was positioned on the top of the inner electrode of the PF 1000 plasma focus (1.8 MA, IPPLM Warsaw), or at the axis with or without the tungsten or alumine wire array load at the S-300 facility (3 MA, RRC Kurchatov Institute, Moscow), and at the axis of the small Z-pinch Z-150 (50 kA, CTU Prague). The plasma corona around the wire was generated both by the current going through the wires and by the implosion of the wire array or of the current sheath. The experiments showed interesting results often observed in some shots of Z-pinch type discharges - existence of helical structures, two relatively long and stable pinch phases, oscillation of pinch diameter, and back return of the plasma exploding from the pinch. All these observed phenomena can be evolved by spontaneous self-generation and transformation of the axial magnetic field in the pinch during the plasma implosion and explosion. A configuration of axial and azimuthal magnetic field confines the plasma and later transforms or dissipates during a few tens or hundreds ns. A fast transformation of internal magnetic fields can induce a sufficiently high electric field for generation of keV particles and radiation. Study and usage of Z-pinch discharges is connected with solving of two principal problems, limitation of instability development and a way of generation of high energy particles and radiation. The first problem is partially solved by the faster increase of the current, by better cylindrical symmetry of the load and plasma, by higher density of the plasma or by the presence of a stronger magnetized plasma.

Kube, Pavel; Kravrik, Jozef; Klr, Daniel; Scholz, Marek; Paduch, Marian; Tomaszewski, Krzysztof; Karpinski, Leslaw; Bakshaev, Yury L.; Blinov, Peter I.; Chernenko, Andrey S.; Dan'ko, Sergey A.; Korolev, Valery D.; Shashkov, Andrey Y.; Tumanov, Victor I.

2002-12-01

260

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

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

261

Multi-Frame Point-Projection X-Ray Imaging of Tungsten Wire-Array Z-Pinches  

Microsoft Academic Search

Summary form only given. X-pinch radiography has been used routinely at Cornell for more than 10 years to produce high quality X-ray images with excellent spatial and temporal resolution. This imaging technique is presently being used on the COBRA accelerator at Cornell University to study the ablation stage of wire-array Z-pinches. Two of four return-current posts in the wire-array load

J. D. Douglass; S. A. Pikuz; T. A. Shelkovenko; D. A. Hammer; K. S. Bell; P. F. Knapp; R. D. McBride

2007-01-01

262

Valve and nozzle design for injecting a shell-on-shell gas puff load into a z pinch  

Microsoft Academic Search

We have developed a dual-plenum gas valve coupled to a double shell nozzle for the generation of ``shell-on-shell'' gas loads in z-pinch plasma radiation source experiments. The gas density profiles of the nozzles have been characterized with laser interferometry. This valve\\/nozzle combination has been successfully fielded on the Double-EAGLE and Saturn pulsed-power generators. The design and characterization of the shell-on-shell

Y. Song; P. Coleman; B. H. Failor; A. Fisher; R. Ingermanson; J. S. Levine; H. Sze; E. Waisman; R. J. Commisso; T. Cochran; J. Davis; B. Moosman; A. L. Velikovich; B. V. Weber; D. Bell; R. Schneider

2000-01-01

263

Critical layer penetration in a cold Z-pinch plasma by high-intensity 10.6 micron laser radiation  

Microsoft Academic Search

The intensity dependence of transmission of 0.2-4 hundred billion W\\/sq cm laser radiation through an overdense cold Z-pinch plasma was measured to determine a threshold for transmission. The 10.6 micron 0.2-4 hundred CO2 laser radiation was focused to a diffraction-limited spot of 125 micron diameter, radially incident on the plasma column of 1 mm critical radius. Holographic interferometry at 347.2

J. G. Ackenhusen

1977-01-01

264

Critical layer penetration in a cold Z-pinch plasma by high-intensity 10.6 microns laser radiation  

Microsoft Academic Search

The intensity dependence of transmission of high-intensity 10.6 microns laser radiation through an overdense cold Z-pinch plasma has been measured to determine a threshold for transmission. A holographic cinema of plasma evolution, obtained independently of the CO2 laser, provided initial information about the target plasma. An intensity threshold for transmission was measured to be about 2.5 x 10 to the

J. G. Ackenhusen

1977-01-01

265

Critical Layer Penetration in a Cold Z-Pinch Plasma by High-Intensity 10.6 Microns Laser Radiation  

Microsoft Academic Search

The intensity dependence of transmission of high-intensity 10.6 micrometer laser radiation through an overdense cold Z-pinch plasma has been measured to determine a threshold for transmission. A holographic cinema of plasma evolution, obtained independently of the CO2 laser, provided initial information about the target plasma. An intensity threshold for transmission was measured to be about 2.5 x 10 to the

John Goodyear Ackenhusen

1977-01-01

266

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

Microsoft Academic Search

Understanding the magnetic field topology in wire-array Z-pinches is of great significance for their ultimate application to stockpile stewardship and inertial confinement fusion. We have developed and tested several novel techniques involving material-based sensors to measure magnetic fields as a function of space and time in high energy density plasmas on pulsed power machines. We first briefly introduce a technique

Wasif Syed

2010-01-01

267

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

SciTech Connect

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

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

2006-09-19

268

Two-dimensional gas density and velocity distributions of a 12-cm-diameter, triple-nozzle argon Z-pinch load  

Microsoft Academic Search

We have developed a 12-cm-diameter Ar gas Z-pinch load, which produces two annular gas shells and a center gas jet. The two-dimensional (2-D) gas density profiles of the load, in r-? and r-z planes, were measured with submillimeter spatial resolutions using the planar-laser-induced fluorescence (PLIF) method, for conditions used in Z-pinch experiments. Due to interactions between the shells, the net

Niansheng Qi; Bruce H. Failor; Jeff Banister; Jerrold S. Levine; Henry M. Sze; David Lojewski

2005-01-01

269

Design of a digital holographic interferometer for the ZaP Flow Z-Pinch  

NASA Astrophysics Data System (ADS)

The ZaP Flow Z-Pinch experiment investigates how flow shear stabilizes MHD modes. An upgrade to a high energy-density plasma experiment would allow exploration of flow shear's effectiveness in this operating regime. The experiment's upgrade would include the addition of a digital holographic interferometer to measure electron density with fine spatial resolution. The design uses a pulsed Korad ruby laser with a consumer digital camera to generate and record holograms, which are then numerically reconstructed to obtain the phase shift caused by the interaction of the laser beam with the plasma. The numerical reconstruction provides a two-dimensional map of chord-integrated electron density without employing labor-intensive physical reconstruction techniques. The interferometer's accuracy has been validated with comparisons to measurements from an existing four-chord HeNe interferometer. The new diagnostic will allow the ZaP team to search for structures such as plasma shocks that were not previously resolvable. It would also be able to resolve the density profile of the smaller, high-energy pinch.

Ross, Michael; Shumlak, Uri; Nelson, Brian; Golingo, Raymond; Hughes, Michal; Knecht, Sean; Paliwoda, Matt

2012-10-01

270

Simulations of the Radiative Environment Produced by a Z-pinch  

NASA Astrophysics Data System (ADS)

We describe the results of calculations of the generation and transport of soft x-rays produced by the Z Machine at Sandia National Laboratories. Over 2 MJoules of radiation energy have been produced in the facility, with peak temperatures of around 230-250 eV. Experiments driven by the source can be fielded to study various phenomena in high energy-density regimes. The design and analysis of such experiments require that the x-ray source be well-characterized. The objective of the present effort is to develop a useful (and eventually predictive) model of the radiation source by simulating the z-pinch implosion and comparing the results to data. Two-dimensional Eulerian and Lagrangian codes are used for the calculations. The configuration modeled includes the imploding plasma and a central foam cylinder which is filled with radiation as the plasma stagnates around it. Calculations of the radiation generation and transport within the foam, including the effects of the radiation pre-pulse associated with the run-in of the load plasma are presented.

Aubrey, Joysree; Bowers, Richard; Peterson, Darrell; Chandler, Gordon; Derzon, Mark; Nash, Tom

1999-11-01

271

Cylindrical Radiation Driven Hydrodynamic Experiments in Z-Pinch Driven Dynamic Hohlraums*  

NASA Astrophysics Data System (ADS)

Dynamic hohlraums created by imploding cylindrical liners onto an inner structured foam cushion (converter) in a Z-pinch configuration have been proposed for driving Inertial Confinement Fusion systems and application experiments. Experiments have been performed using the 20 MA, 100 ns Z- accelerator as a first step to drive cylindrical ablators in order to study the energy coupling and drive symmetry.In these experiments a dynamic hohlraum is created using a 1 cm long nested tungsten-wire array. The 2 mg outer array was imploded from an initial radius of 1 cm onto a 1 mg inner tungsten wire array at an initial radius of 1 cm. The nested array stabilizes the pinch with respect to magnetic instability effects and effects associated with drive current asymmetries. The wire array implodes onto an 8 mm diameter, 9 mm long low density foam inner load or converter at 60 cm/s where the kinetic energy of the liner, 550 KJ, is converted into radiation in the central target which drives an inner cylindrical ablator. Experiments are planned using a 2 mm diameter ablator having walls of 10, 20 or 30 m thick made of germanium doped plastic or copper doped beryllium. Drive temperature of 160 eV are calculated. *Supported by U.S. DOE Contract DE-AC04-94AL85000.

Chandler, G.; Derzon, M.; Lash, J.; Nash, T.; Aubrey, J.; Bowers, R.; Peterson, D.

1998-11-01

272

Manufacturing Concepts for an IFE Power Plant Using Z-Pinch Technology  

SciTech Connect

The Z-Pinch Power Plant (ZP3) uses the results from Sandia National Laboratories' Z accelerator in a power plant application to generate energy pulses using inertial confinement fusion. A collaborative project has been initiated by Sandia to investigate the scientific principles of a power generation system. Research is underway to investigate the use of recyclable transmission lines to directly connect the wire array and the hohlraum to the pulsed power driver. The resulting power plant will require an intense on-site manufacturing system to rebuild the transmission lines, wire arrays and hohlraums at a rate of 0.1 Hz per power unit. By recycling virtually all of the materials, the system is expected to be economically competitive with other power generation technologies. Current research is investigating the available approaches to manufacturing and determining the cost effectiveness of the alternatives. This paper examines the various options available for manufacturing and development requirements leading to a Proof-of-Principle experiment to demonstrate the technology.

Cipiti, B.B.; Rochau, G.E. [Sandia National Laboratories (United States)

2005-04-15

273

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

SciTech Connect

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

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

2008-01-15

274

Development of the Axial Instability in Low Wire Number Wire Array Z-Pinches  

NASA Astrophysics Data System (ADS)

We are investigating the development of the axial instability that occurs on wires in wire-array Z-pinches, which manifests itself as a modulation of the size of the coronal plasma. The modulation is evidently a result of non-uniform ablation of material from the wire core. It is known that the wavelength of this modulation reaches a constant as the pinch develops that is a strong function of the material and little else, thus it is known as the fundamental mode. In these experiments we have been imaging individual wires with laser shadowgraphy primarily in low wire number, large wire diameter arrays made with Al, Cu, Ag and other wires. We document the development of this modulation from the beginning of plasma formation and show the wavelength and amplitude growth as a function of time. The magnetic field is also measured using B-dot probes inside the array. The change from a closed to an open field topology and its relation to the instability growth will be discussed.This research was supported by the Stewardship Sciences Academic Alliances program of the National Nuclear Security Administration under DOE Cooperative agreement DE-FC03-02NA00057 and by Sandia National Laboratories contract AO258.

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

2008-11-01

275

Kinetic simulation of thermonuclear-neutron production by a 10{sup 7}-A deuterium Z pinch  

SciTech Connect

Fully kinetic simulations have demonstrated that at sufficiently high currents, half of the neutrons produced by a deuterium Z-pinch are thermonuclear in origin. At 150-kA pinch current, O. A. Anderson et al. [Phys. Rev. 110, 1375 (1958)] clearly shows that essentially all of the neutrons produced by a deuterium pinch are not thermonuclear, but are initiated by an instability that creates beam-target neutrons. Since this paper, many subsequent authors have supported this result while others have claimed that pinch neutrons are, on the contrary, thermonuclear. To resolve this issue, fully kinetic, collisional, and electromagnetic simulations of the complete time evolution of a deuterium pinch have been performed. The simulations were performed with the implicit particle-in-cell code LSP, as described in D. R. Welch et al. [Phys. Rev. Lett. 103, 255002 (2009)]. At 10{sup 6} -A pinch currents, most of the neutrons are, indeed, beam-target in origin. At 15-MA current, half of the neutrons are thermonuclear and half are beam-target driven by instabilities that produce a power law fall off in the ion energy distribution function at large energy. Simulation results suggest that from 7- to 15-MA current, the fraction of thermonuclear neutrons is not sensitive to current and that the strong dependence of neutron yield on current will continue at currents greater than 15 MA.

Welch, D. R.; Rose, D. V.; Thoma, C.; Clark, R. E.; Mostrom, C. B. [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)

2010-07-15

276

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

NASA Astrophysics Data System (ADS)

The physics of accretion disks is of fundamental importance for understanding of a wide variety of astrophysical sources that includes protostars, X-ray binaries, and active galactic nuclei. The interplay between hydrodynamic flows and magnetic fields and the potential for turbulence-producing instabilities is a topic of active research that would benefit from the support of dedicated experimental studies. Such efforts are in their infancy, but in an effort to push the enterprise forward we propose an experimental configuration which employs a modified cylindrical wire array Z-pinch to produce a rotating plasma flow relevant to accretion disks. We present three-dimensional resistive magnetohydrodynamic simulations which show how this approach can be implemented. In the simulations, a rotating plasma cylinder or ring is formed, with typical rotation velocity ~30 km s1, Mach number ~4, and Reynolds number in excess of 107. The plasma is also differentially rotating. Implementation of different external magnetic field configurations is discussed. It is found that a modest uniform vertical field of 1 T can affect the dynamics of the system and could be used to study magnetic field entrainment and amplification through differential rotation. A dipolar field potentially relevant to the study of accretion columns is also considered.

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

2013-04-01

277

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

SciTech Connect

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

Nielsen, P.D.

1981-06-01

278

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

279

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

280

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

281

2D-RMHD Modeling of the Dynamics of a Ne Gas Puff Z Pinch  

NASA Astrophysics Data System (ADS)

Detailed spatially resolved spectroscopic analysis of a neon gas puff Z pinch on the Weizmann 1MA generator [1,2] indicates that the radius of the K-shell regions grows to a maximum and then decreases during the radiation pulse -- the opposite of that calculated by 1D-RMHD models. Here we compare Mach2 2D-RMHD [r-z, high resolution, moving grid, non-LTE atomic populations, 3D ray trace radiation transport] simulation results to the size of the K-shell emission region as inferred from the spectroscopic analysis. In addition 2D, 3-ns time gated visible light images recorded during the neon experiments give us the opportunity to compare with the evolution of the outer pinch radius, r(z,t), as calculated by the 2D-RMHD model. Comparisons with spectroscopically inferred results and simulation results will also be made for electron and ion temperatures as well as internal energy to study the weak ion and electron temperature equilibration observed in the data.[4pt] [1] E. Kroupp, et al., PRL, 98, 115001 (2007).[0pt] [2] D. Osin, Ph.D. Thesis (2008).

Thornhill, J.; Giuliani, J.; Dasgupta, A.; Velikovich, A.; Chong, Y.; Clark, R.; Kroupp, E.; Osin, D.; Maron, Y.; Starobinets, A.; Stambulchik, E.; Fisher, V.; Bernshtam, V.; Fisher, A.; Deeney, C.

2012-10-01

282

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

283

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

NASA Astrophysics Data System (ADS)

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 of the array displayed significantly different characteristics. Having E^r directed towards the wires resulted in the formation of very small wire cores, which ablated relatively slowly into coronal plasma compared to the section of the array with E^r directed away from the wires. The different ablation rates caused 2 separate implosions, introducing a 2nd X-ray pulse to the emission. Possible mechanisms responsible for the different characteristics are discussed. This research was sponsored by Sandia National Laboratories, Albuquerque, and the SSAA program of NNSA under DOE Cooperative Agreement DE-FC03-02NA00057.

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

2004-11-01

284

Model of enhanced energy deposition in a Z-pinch plasma  

NASA Astrophysics Data System (ADS)

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

Velikovich, A. L.; Davis, J.; Thornhill, J. W.; Giuliani, J. L.; Rudakov, L. I.; Deeney, C.

2000-08-01

285

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

286

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

SciTech Connect

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

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

1999-12-14

287

ZPMHD-a Rep-rated Z-Pinch Power Plant Direct Conversion Concept*  

NASA Astrophysics Data System (ADS)

We have performed a preliminary conceptual study of ZPMHD, a z-pinch driven IFE power plant with Compact Fusion Advanced Rankine (CFARII) MHD direct conversion [B. G. Logan, Fusion Eng. and Des. 22, 151 (1993)]. We find that a competitive power plant could be built that has a Cost of Electricity (CoE) 40 mills/kWh for a compact blanket of Lithium Hydride and a fusion yield of 1.6 GJ. This result is based on an assumed target-driver figure of merit, RTD = Fusion gain/Driver unit cost = 4 Yield (J)/Driver cost ($). This figure of merit results from an estimated rep-rated driver unit cost of 20 /J and a target gain G = 80. Advanced targets with higher gain and/or lower driver cost give competitive power plants at higher yields (CoE 40 mills/kWh for RTD= 15). We also find that a much higher target-driver figure of merit ( ~ 20 J/) is required for low electricity cost (44 mills/kWh) with a Flibe blanket. *Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the United States Department of Energy Under Contract DE-AC04-94AL85000.

de Groot, John S.; Houssein Alki, El

2001-10-01

288

The Production of Hypersonic, Radiatively Cooled Plasma Projectiles of Extremely High Energy Density in Imploding Z-pinches  

NASA Astrophysics Data System (ADS)

Experiments with conical wire array Z-pinches, have shown that a highly supersonic tungsten plasma jet can be formed, with the presence of strong radiative cooling resulting in a very small flow divergence. In this work, we explore the possibilities of exploiting a similar effect in imploding wire arrays to produce a high velocity, dense plasma projectile. 2D(r,z) MHD simulations of imploding Z-pinches on the `Z' generator, with a shaped mass per unit length, indicate the production of a projectile with velocity, density and diameter comparable to the final implosion velocity and stagnated plasma density and diameter in present wire array Z-pinch experiments. This represents an enormous (~100TW) kinetic power delivered out of the end of the pinch. 2D radiation hydrodynamic simulations of the projectile impacting a solid tungsten foil are used to estimate the potential for generating both compact radiation sources and target plasmas of extremely high energy density. Results indicate that pressures of 2 Gbar and radiation temperatures of ~660eV are produced in the target. 3D view factor simulations of a double ended hohlraum system with twin projectiles and converter foils are used to evaluate these radiation sources for use in indirect drive inertial confinement fusion research. Results suggest that a flux-equivalent peak temperature of ~225eV could be delivered to a NIF scale ICF capsule.

Chittenden, J. P.; Dunne, A. M.; Zepf, M.; Lebedev, S. V.; Ciardi, A.; Bland, S. N.

2002-12-01

289

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

SciTech Connect

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

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

1999-11-08

290

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

291

Use of Z-Pinch Techniques for Equation of State Applications  

SciTech Connect

A principal goal of the shock physics program at Sandia is to establish a capability to make accurate equation of state (EOS) measurements on the Z pulsed radiation source. The Z accelerator is a source of intense x-ray radiation, which can be used to drive ablative shocks for EOS studies. With this source, ablative multi shocks can be produced to study materials over the range of interest to both weapons and ICF physics programs. In developing the capability to diagnose these types of studies on Z, techniques commonly used in conventional impact generated experimental were implemented. The primary diagnostic presently being used for this work is velocity interferometry, VISAR, which not only provides Hugoniot particle velocity measurements, but also measurements of non-shock EOS measurements, such as isentropic compression. In addition to VISAR capability, methods for measuring shock velocity have also been developed for shock studies on Z. When used in conjunction with the Rankine- Hugoniot jump conditions, material response at high temperatures and pressures can be inferred. Radiation in the Z accelerator is produced when approximately 18 MA are passed through a cylindrical wire array typically 20 to 50 mm in diameter and 10 to 20 mm in height. 200-300 wires with initial diameters on the order of 8 to 20 micron form, upon application of the current, a plasma shell, which is magnetically imploded until it collapses and stagnates on axis, forming a dense plasma emitter in the shape of a column, referred to as a" z pinch". The initial wire array and subsequent plasma pinch are confined within a metallic can, referred to as a primary hohlraum, which serves as both a current return path and a reflective surface to contain the radiation. Attached to openings in the primary hohlraum wall are smaller tubes referred to as secondaries. Multiple secondaries can be fielded on most experiments, which are the typical location for mounting EOS samples. In this configuration, the secondary S1 contains two separate VISAR probes for making velocity measurements at different material thicknesses. By correlating the resulting velocity profiles in time, a measurement of shock velocity can be determined. In addition, the velocity profiles provide the Hugoniot particle velocity after the records were impedance-matched. Secondaries S2 and S3 provide measurements of shock velocity using laser light reflected from steps. As the shock arrives at each of these surfaces, the surface reflectivity significantly decreases, which causes a sharp drop in return light. The shock velocity can be inferred from shock arrival at different steps The z-pinch technique is particularly useful for producing high amplitude shock waves for EOS applications. An alternative approach for using Z is to produce shockless loading directly with the magnetic pressure in the accelerator.

Asay, J.R.; Bernard, M.A.; Clark, B.; Fleming, K.J.; Hall, C.A.; Hauer, A.; McDaniel, D.H.; Slutz, S.A.; Spielman, R.B.; Stygar, W.A.; Trott, W.M.

1998-11-11

292

Initiation, ablation, precursor formation, and instability analysis of thin foil liner Z-pinches  

NASA Astrophysics Data System (ADS)

This dissertation presents the results of mostly experimental work studying the early-time behavior of thin foil liners as compared to wire-array Z-pinches. It involves three studies, covering initiation, ablation and precursor formation, and instability analysis. Initiation was studied by observing the optical emission of various thickness (0.6-23.5 ?m Cu) liners using a streak camera. It was found that thinner liners initiated sooner, more quickly, and more uniformly than thicker liners. This correlated well with both an increase in instantaneous dJ/dt at the time of first emission as well as the inductive voltage at the time of first emission. The threshold for uniform initiation was dJ/dt>3.51016Acm -2s-1. Uniform initiation is important for liners because nonuniformities could lead to enhanced instabilities and poor liner performance (compression, x-ray production, etc.). Ablation and precursor formation of wire-arrays (16x75 ?m Cu) and liners (6 ?m Cu) were studied using r-? density maps and radial mass profiles created by an axial X pinch radiography diagnostic. These images show very strong differences in this stage of the Z-pinch. Wire-arrays develop complex, azimuthally varying ablation structures that lead to dense precursors. Liners, however, show significantly reduced and azimuthally uniform ablation leading to an order of magnitude less dense precursor on axis. This is likely due to the discrete versus continuous nature of wire-arrays versus liners. With wire-arrays, plasma that is created on the outside of the wires can reach the array axis by being swept through the gaps between the stationary wire cores. In contrast, liners have no gaps for plasma to flow through. Therefore, any plasma that is created on the outside of the liner is trapped there until the bulk of the liner moves with the implosion. Consequently, only the plasma that is created on the inside of the liner is able to contribute to precursor formation. This is an important result because reduced precursor formation is important for fuel compression and heating in MagLIF. Less precursor can also lead to enhanced x-ray production because there is less mass on axis to cushion the conversion of kinetic energy into x-rays during the implosion and stagnation phases. Finally, in the instability studies, it was observed in laser shadow graph images that liners develop a much larger amplitude instability on their outside surface as compared to wire-arrays. This is an important discovery and could be detrimental to liner performance (compression, x-ray production, etc.) because it could lead to enhanced magnetic Rayleigh-Taylor (MRT) instability during the implosion phase. The reason for the larger instability in liners is again probably due to the fact that plasma builds up on the outside of the liners with no where to go. A possible source of the enhanced instability was found using 2D (xy) PERSEUS simulations comparing the results of MHD and Hall MHD simulations. The instability only developed in the Hall MHD case. The 2D nature of the simulation, along with all simulation parameters being equal between the two cases, rules out the possibility of MRT or m=0 for the cause of the instability (in the simulation). It was found that the Hall term was responsible for causing a shear-flow instability that developed later in time to resemble the experimental results.

Blesener, Isaac Curtis

293

Theoretical analysis of some contemporary issues on wire-array Z-pinch  

NASA Astrophysics Data System (ADS)

This thesis describes two contemporary issues on wire-array Z-pinch: (1) Linear and nonlinear evolution of azimuthal clumping instabilities, and (2) the problem of electrical contact resistance. The thesis presents an analytic theory on the linear and nonlinear evolution of the most unstable azimuthal clumping mode (the pi-mode) in a discrete wire array. In the pi-mode, neighboring wires of the array pair-up as a result of the mutual attraction of the wires which carry current in the same direction. The analytic solution displays two regimes, where the collective interactions of all wires dominate, versus where the interaction of the neighboring, single wire dominates. This solution was corroborated by numerical codes. All solutions show that azimuthal clumping of discrete wires occurs before appreciable radial motion of the wires. Thus, absence of azimuthal clumping of wires in comparison with the wires' radial motion may imply substantial lack of wire currents. Because of the surface roughness on a microscopic scale, true contact between two pieces of metal occurs only on the asperities of the two contacting surfaces. Current flows only through these asperities, which occupy a small fraction of the area of the nominal contacting surfaces, this gives rise to contact resistance. In the thesis, the electrical contact resistance is computed for a local constriction of finite length and finite transverse dimension in a conducting current channel. The connecting bridge, which models a local electrical contact, is assumed to be made of the same conducting material as the main current channel. Very simple analytic scaling laws for the contact resistance are constructed for a wide range of geometrical aspect ratios between the main current channel and its connecting bridge, which may assume rectangular shape, and cylindrical or funnel shape. These scaling laws have been confirmed by spot-checks with numerical code results. A statistical theory, together with an electrical lump circuit model for the microscopic electrical contacts are developed.

Tang, Wilkin

294

Characterization of energy flow and instability development in two-dimensional simulations of hollow {ital z} pinches  

SciTech Connect

A two-dimensional (2-D) Eulerian Radiation-Magnetohydrodynamic (RMHD) code has been used to simulate imploding {ital z} pinches for three experiments fielded on the Los Alamos Pegasus II capacitor bank [J. C. Cochrane {ital et al.}, {ital Dense Z-Pinches, Third International Conference, London, United Kingdom 1993} (American Institute of Physics, New York, 1994), p. 381] and the Sandia Saturn accelerator [R. B. Spielman {ital et al.}, {ital Dense Z-Pinches, Second International Conference, Laguna Beach, 1989} (American Institute of Physics, New York, 1989), p. 3] and {ital Z} accelerator [R. B. Spielman {ital et al.}, Phys. Plasmas {bold 5}, 2105 (1998)]. These simulations match the experimental results closely and illustrate how the code results may be used to track the flow of energy in the simulation and account for the amount of total radiated energy. The differences between the calculated radiated energy and power in 2-D simulations and those from zero-dimensional (0-D) and one-dimensional (1-D) Lagrangian simulations (which typically underpredict the total radiated energy and overpredict power) are due to the radially extended nature of the plasma shell, an effect which arises from the presence of magnetically driven Rayleigh{endash}Taylor instabilities. The magnetic Rayleigh{endash}Taylor instabilities differ substantially from hydrodynamically driven instabilities and typical measures of instability development such as {ital e}-folding times and mixing layer thickness are inapplicable or of limited value. A new measure of global instability development is introduced, tied to the imploding plasma mass, termed {open_quotes}fractional involved mass.{close_quotes} Examples of this quantity are shown for the three experiments along with a discussion of the applicability of this measure. {copyright} {ital 1998 American Institute of Physics.}

Peterson, D.L.; Bowers, R.L.; McLenithan, K.D. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Deeney, C.; Chandler, G.A.; Spielman, R.B.; Matzen, M.K. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Roderick, N.F. [University of New Mexico, Albuquerque, New Mexico 87131 (United States)

1998-09-01

295

Stability and radiative performance of structured Z-pinch loads imploded on high-current pulsed power generators  

SciTech Connect

The stability and radiative performance of structured Z-pinch plasma loads heated by high-current ({gt}20 MA) pulsed power generators are investigated. A limited mapping of parameter space is made for the regions of stability for loads configured as thin shells, uniform fills, and multiple shells. Although large diameter thin shell loads are shown to be the most efficient radiators of K-shell x rays, they are susceptible to disruption by the Rayleigh--Taylor instability. Large diameter uniform fill loads are shown to be more stable and very good radiators. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Cochran, F.L. [Berkeley Research Associates, Inc., Springfield, Virginia 22150 (United States); Davis, J. [Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States); Velikovich, A.L. [Berkeley Scholars, Inc., Springfield, Virginia 22150 (United States)

1995-07-01

296

Production of Thermonuclear Neutrons from Deuterium-Filled Capsule Implosions Driven by Z-Pinch Dynamic Hohlraums  

NASA Astrophysics Data System (ADS)

Evidence for the first production of thermonuclear neutrons by Z-pinch dynamic hohlraum driven deuterium-filled capsules is presented. The average neutron energy and yield isotropy measured is consistent with thermonuclear fusion production. The addition of Xe gas to certain capsules suppressed the fusion neutron yields by an order of magnitude, consistent with a thermonuclear production process. The ion temperature deduced from the neutron energy distribution was 4.81.5 keV and typical yields were 1 51010.

Ruiz, C. L.; Cooper, G. W.; Slutz, S. A.; Bailey, J. E.; Chandler, G. A.; Nash, T. J.; Mehlhorn, T. A.; Leeper, R. J.; Fehl, D.; Nelson, A. J.; Franklin, J.; Ziegler, L.

2004-06-01

297

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

298

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

SciTech Connect

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 CH{sub 2} foam target. Stagnation of the inner array at the axis produces the third shock. Capsules optimized for several of these shapes produce 290-900 MJ fusion yields in 1D simulations.

Cuneo, M.E.; Vesey, R.A.; Sinars, D.B.; Waisman, E.M.; Lemke, R.W.; Bliss, D.E.; Stygar, W.A.; Porter, J.L.; Mazarakis, M.G.; Chandler, G.A.; Mehlhorn, T.A. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1193 (United States); Chittenden, J.P.; Lebedev, S.V. [Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom); Schroen, D.G. [Schafer Corporation, Livermore, California 94550 (United States)

2005-10-28

299

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

SciTech Connect

Results are presented from experimental studies of the plasma formation dynamics in a Z-pinch produced from a cylindrical microporous agar-agar load. The experiments were performed on the S-300 facility at a current of 2 MA and current rise time of 100 ns. To enhance the energy concentration, a deuterated polyethylene neck with a mass density of 50-75 {mu}g/cm{sup 3} and diameter of 1-2 mm was made in the central part of the load. The spatiotemporal characteristics of the Z-pinch were studied using an optical streak camera and fast frame photography in the optical and soft X-ray spectral ranges. X-ray emission was detected using semiconductor and vacuum diodes, and neutron emission was studied by means of the time-of-flight method. It is found that, in the course of continuous plasma production, hot spots with a diameter of 100 {mu}m form in the pinch plasma. The hot spots emit short soft X-ray pulses with a duration of 2-4 ns, as well as neutron pulses with an average neutron energy of about 2.45 MeV. The maximum neutron yield was found to be 4.5 x 10{sup 9} neutrons per shot. The scenario of hot spot formation is adequately described by two-dimensional MHD simulations.

Akunets, A. A. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Anan'ev, S. S.; Bakshaev, Yu. L.; Blinov, P. I.; Bryzgunov, V. A.; Vikhrev, V. V.; Volobuev, I. V.; Dan'ko, S. A.; Zelenin, A. A.; Kazakov, E. D.; Korolev, V. D.; Meshcherov, B. R.; Nedoseev, S. L. [Russian Research Centre Kurchatov Institute (Russian Federation); Pimenov, V. G. [Russian Academy of Sciences, Zelinsky Institute of Organic Chemistry (Russian Federation); Smirnova, E. A.; Ustroev, G. I.; Chernenko, A. S.; Shchagin, V. A. [Russian Research Centre Kurchatov Institute (Russian Federation)

2010-08-15

300

FLUIDS, PLASMAS AND ELECTRIC DISCHARGES: Stability analysis of viscous Z-pinch plasma with a sheared axial flow  

NASA Astrophysics Data System (ADS)

Within the magnetohydrodynamics (MHD) frame, we analyse the effect of viscosity on magneto-Rayleigh-Taylor (MRT) instability in a Z-pinch configuration by using an exact method and an approximate method separately. It is demonstrated that the plasma viscosity indeed has a stabilization effect on the MRT mode in the whole wavenumber region, and its influence increases with the perturbation wavenumber increasing. After the characteristics and feasibility of the approximate method have been investigated, we apply it to the stability analysis of viscous plasma where a sheared axial flow (SAF) is involved, and we attain an analytical dispersion relation. It is suggested that the viscosity and the SAF are complemental with each other, and a wide wavenumber range of perturbation is possible to be restrained if the SAF and the viscosity are large enough. Finally, we calculate the possible value of viscosity parameter according to the current experimental conditions, and the results show that since the value of viscosity is much less than the threshold value, its mitigation effect is small enough to be neglected. The role of the viscosity in the stabilization becomes considerable only if special techniques are so developed that the Z-pinch plasma viscosity can be increased greatly.

Zhang, Yang; Ding, Ning

2008-08-01

301

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

NASA Astrophysics Data System (ADS)

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

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

2004-05-01

302

The effect of sheared axial flow on the interchange mode in a hard-core Z pinch  

SciTech Connect

It is well known that a static (i.e., v=0) closed field line configuration, such as a levitated dipole, or a hard-core Z pinch, can be stabilized against ideal magnetohydrodynamic (MHD) interchange modes when the edge pressure gradient is sufficiently weak. The stabilizing effect is provided by plasma compressibility. However, many laboratory plasmas exhibit a sheared velocity flow (i.e., n{center_dot}{nabla}v{ne}0), and this flow may affect the marginal stability boundary. The present work addresses this issue by an analysis of the effect of axially sheared flow on interchange stability in a hard-core Z pinch, a cylindrical model for the levitated dipole configuration. Specifically, the goal is to learn whether sheared flow is favorable, unfavorable, or neutral with respect to MHD stability. Analytic calculations of marginal stability for several idealistic velocity profiles show that all three options are possible depending on the shape of the shear profile. This variability reflects the competition between the destabilizing Kelvin-Helmholtz effect and the fact that shear makes it more difficult for interchange perturbations to form. Numerical calculation are also presented for more realistic experimental profiles and compared with the results for the idealized analytic profiles.

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

2007-01-15

303

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 . 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 . 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

304

Richtmyer-Meshkov-like instabilities and early-time perturbation growth in laser targets and Z-pinch loads  

SciTech Connect

The classical Richtmyer-Meshkov (RM) instability develops when a planar shock wave interacts with a corrugated interface between two different fluids. A larger family of so-called RM-like hydrodynamic interfacial instabilities is discussed. All of these feature a perturbation growth at an interface, which is driven mainly by vorticity, either initially deposited at the interface or supplied by external sources. The inertial confinement fusion relevant physical conditions that give rise to the RM-like instabilities range from the early-time phase of conventional ablative laser acceleration to collisions of plasma shells (like components of nested-wire-arrays, double-gas-puff Z-pinch loads, supernovae ejecta and interstellar gas). In the laser ablation case, numerous additional factors are involved: the mass flow through the front, thermal conduction in the corona, and an external perturbation drive (laser imprint), which leads to a full stabilization of perturbation growth. In contrast with the classical RM case, mass perturbations can exhibit decaying oscillations rather than a linear growth. It is shown how the early-time perturbation behavior could be controlled by tailoring the density profile of a laser target or a Z-pinch load, to diminish the total mass perturbation seed for the Rayleigh-Taylor instability development. (c) 2000 American Institute of Physics.

Velikovich, A. L. [Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States); Dahlburg, J. P. [Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States); Schmitt, A. J. [Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States); Gardner, J. H. [Laboratory for Computational Physics and Fluid Dynamics, Naval Research Laboratory, Washington, D.C. 20375 (United States); Phillips, L. [Laboratory for Computational Physics and Fluid Dynamics, Naval Research Laboratory, Washington, D.C. 20375 (United States); Cochran, F. L. [Berkeley Research Associates, Incorporated, Springfield, Virginia 22150 (United States); Chong, Y. K. [Berkeley Research Associates, Incorporated, Springfield, Virginia 22150 (United States); Dimonte, G. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Metzler, N. [Physics Department, Nuclear Research Center Negev, P. O. Box 9001, Beer Sheva, Israel, (Israel); Science Applications International Corporation, McLean, Virginia 22150 (United States)

2000-05-01

305

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

SciTech Connect

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. [Applied Science and Technology Program, University of California, Berkeley, California 94720 (United States); Shumlak, U. [Aerospace and Energetics Research Program, University of Washington, Seattle, Washington 98195-2250 (United States)

2011-10-15

306

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

NASA Astrophysics Data System (ADS)

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

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

2000-10-01

307

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

NASA Astrophysics Data System (ADS)

We are currently exploring symmetry requirements of the z-pinch-driven hohlraum concept [1] for high-yield inertial confinement fusion. In experiments on the Z accelerator, the burnthrough of a low-density self-backlit foam ball has been used to diagnose the large time-dependent flux asymmetry of several single-sided-drive hohlraum geometries [2]. We are currently applying this technique to study polar radiation flux symmetry in a symmetric double z-pinch geometry. Wire arrays on opposite ends of the hohlraum, connected in series to a single current drive of 18 MA, implode and stagnate on axis, efficiently radiating about 100 TW of x rays which heat the secondary to 75 eV. Comparisons with 3-D radiosity and 2-D rad-hydro models of hohlraum symmetry performance will be presented. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000. 1 J. H. Hammer et al., Phys. Plasmas 6, 2129 (1999). 2 D. L. Hanson et al., Bull. Am. Phys. Soc. 44, 40 (1999).

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

2000-10-01

308

Aximuthal Structure Observed and Modeled in Annular Wire-Array Z-Pinches Having a Solid Current-Return Anode  

NASA Astrophysics Data System (ADS)

Periodic structure associated with the periodic slots in the anode current-return (typically used for pinch viewing) is both expected and observed in x-ray images of a z-pinch. This paper discusses the azimuthal structure observed and modeled, for the first time, in high-wire number z-pinches where the current return is essentially a solid annular shell with no azimuthal structure. The geometry is that of Fig. 2 in Ref. 1, where a nested array of tungsten wires is imploded with either no target or a low-density foam target on axis. In either configuration, a quasi-periodic azimuthal structure, with mode number 62, is observed in x-ray images of the pinch, when viewed from above through a small radiation-exit-hole. Similar mode structures are generated near stagnation in numerical simulations, which assume in the outer array either (1) a fixed initial azimuthal density variation with mode number 6 or (2) simply an initial random density variation. In the full paper, the measured and modeled simulations with the solid current return anode are contrasted with those measured and modeled with the anode slots. [1] T. W. L. Sanford, R. E. Olson, R. C. Mock, et al, Phys.Plasmas 7, 4669 (2000). *Sandia is a multiprogram laboratory operated by the Sandia Corporation, a Lockheed Martin Company, for the U.S. Department of Energy under Contract No. DE-AC04-94AL85000.

Sanford, T. W. L.; Mock, R. C.; Struve, K. W.; Roderick, N. F.

2001-10-01

309

Magneto-Inertia Confinement Approach (MICA) to Fusion in Dynamic Z-Pinch Formed from a Frozen Deuterium-Tritium Tube  

NASA Astrophysics Data System (ADS)

This paper reconsiders the magneto-inertia confinement approach to fusion in dynamic z-pinch with a new method of generating a hot plasma using a frozen deuterium-tritium (D-T) tube as an initial condition. If modern pulsed power technology can induce the high current of the order of 10 MA along the tube, the dense z-pinch plasma formed from the electro-magnetical implosion of thin tubular D-T ice with a radius of about 1 mm can satisfy the Lawson criterion for its 1 cm length.

Ikuta, Kazunari

1988-02-01

310

Magneto-Inertia Confinement Approach (MICA) to fusion in dynamic Z-pinch formed from a frozen deuterium-tritium tube  

NASA Astrophysics Data System (ADS)

The magneto-inertial confinement approach to fusion in a dynamic z-pinch regime is reconsidered using a new method of generating a hot plasma using a frozen deuterium tube as an initial condition. It will be seen that the technology of fabricating deuterium ice tube is possible if available pulse power technology could induce a current on the order of 10 MA along the tube. The dense z-pinch plasma formed from the electromagnetic implosion of this tubular deuterium-tritium ice with a radius of approximately 1 mm can satisfy the Lawson criterion, provided that its length is 1 cm.

Ikuta, Kazunari

1987-11-01

311

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

Microsoft Academic Search

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

F. Winterberg

2000-01-01

312

Long-Living Filamentation of Electric Current and Formation of a Large-Scale "Stocking" in Dense Z-Pinch Plasmas  

NASA Astrophysics Data System (ADS)

The results of a high-resolution processing, based on techniques of fractal dimension analysis, of experimental data from earlier experiments in Kurchatov Institute on linear Z-pinches are presented which suggest the electric current-carrying plasmas to be a dynamical percolating network. The networking is based on the long-living filamentation of electric current. A special role of an almost-closed helical filamentary magnetoplasma configuration (called heteromac) is analysed. The results extend recently identified phenomenon of the 3-D large-scale (up to several centimeter size) helical filamentary plasma structures in plasma focus gaseous discharges to the case of Z-pinch gaseous discharges. The results suggest a networking-based view into the following phenomena: (1) formation of the large-scale filament-made stocking(s); (2) formation of electric current precursors on the axis, in advance of major current sheath's convergence on the axis; (3) fine structure of Z-pinch's main body and halo at stagnation stage; (4) development and saturation of the magnetically-driven Rayleigh- Taylor instability in the filamentary current sheath; (5) disruption of the necks in the filamentary Z-pinch; (6) fine structure of hot spots.

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

1998-11-01

313

Radiation transport for R-Z modeling of Z-pinches: Validating and optimizing ray tracing methods with Monte Carlo solutions  

Microsoft Academic Search

Summary form only given. Radiation, mostly soft X-rays, plays a critical role in the dynamical evolution as well as in the diagnosis of Z-pinches. Detailed MHD modeling is an important tool in gaining basic physical insight into their behavior and in guiding experiments and load design. With radiation dominating the energy budget, it is therefore important to employ the most

J. P. Apruzese; J. L. Giuliani

2009-01-01

314

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

SciTech Connect

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

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

2012-01-15

315

A novel extreme ultraviolet four channels normal incidence imaging system for plasma diagnostics of Z-pinch facility  

NASA Astrophysics Data System (ADS)

A novel EUV four channels normal incidence imaging system for plasma diagnostics of Z-pinch facility was presented in this paper, which consists of four concave mirrors and one convex mirror used for focusing an object onto four different positions with about 30 ?m resolution on the same image plane. In addition, this imaging system can work at the energies of 50 eV, 95 eV, 150 eV, and broadband of 50-100 eV by using different multilayer films deposited on the concave and convex mirrors. This instrument, combined with framing camera, can achieve the power of two-dimensional spatial and temporal resolution, as well as the ability to imaging the plasma at the specific temperature. In the paper, the four channels microscope centering at multi-energies was developed.

Wang, Xin; Mu, Baozhong; Zhu, Jingtao; Wang, Ling; Yi, Shengzhen; Li, Wenbin; Wang, Zhanshan; Qin, Yi; Xu, Zeping; Xu, Rongkun; Li, Zhenghong

2013-07-01

316

A novel extreme ultraviolet four channels normal incidence imaging system for plasma diagnostics of Z-pinch facility.  

PubMed

A novel EUV four channels normal incidence imaging system for plasma diagnostics of Z-pinch facility was presented in this paper, which consists of four concave mirrors and one convex mirror used for focusing an object onto four different positions with about 30 ?m resolution on the same image plane. In addition, this imaging system can work at the energies of 50 eV, 95 eV, 150 eV, and broadband of 50-100 eV by using different multilayer films deposited on the concave and convex mirrors. This instrument, combined with framing camera, can achieve the power of two-dimensional spatial and temporal resolution, as well as the ability to imaging the plasma at the specific temperature. In the paper, the four channels microscope centering at multi-energies was developed. PMID:23902074

Wang, Xin; Mu, Baozhong; Zhu, Jingtao; Wang, Ling; Yi, Shengzhen; Li, Wenbin; Wang, Zhanshan; Qin, Yi; Xu, Zeping; Xu, Rongkun; Li, Zhenghong

2013-07-01

317

Comparative calculations of plasma ionization balance, collisionality and resistivity using various models in application to z-pinch physics  

NASA Astrophysics Data System (ADS)

High energy density plasmas produced by the imploding wire array loads, including single- and multi-planar wire arrays, has been extensively studied for the past few years at the University of Nevada, Reno at 1.7 MA Zebra facility. Various modeling tools such as the magnetohydrodynamic (MHD) codes and non-LTE atomic kinetic models have been applied to analyze plasma dynamics and radiation features. In this work the results of the aforementioned models are compared with the average atom model (Thomas--Fermi and Ziman approximations). The analysis is accomplished for low (Al) and moderate (Cu) atomic number elements in broad ranges of Te and ne. The advantage of application of such approach to the analysis of z-pinch experiments is discussed.

Esaulov, Andrey; Johnson, Walter; Safronova, Alla; Safronova, Ulyana; Ouart, Nick; Weller, Mike; Kantsyrev, Victor

2010-11-01

318

Abel inversion of a holographic interferogram for determination of the density profile of a sheared-flow Z pinch  

SciTech Connect

A holographic interferometer is used to determine the radial electron number density profile of a sheared-flow Z pinch. Chord-integrated density information is recorded during a plasma pulse using the expanded beam of a pulsed ruby laser and holographic techniques. An Interactive Data Language (IDL) computer routine that requires only minimal user interaction is used to measure the resulting fringe shift in the reconstructed interferogram. This chord-integrated density information is inverted using an Abel inversion to determine the radial electron density profile. The density profiles obtained show a radially symmetric plasma column with an electron density of 10{sup 16}-10{sup 17} cm{sup -3} above the background plasma density. Holographic measurements are made at different times on separate plasma pulses to track the evolution of the density profile over time. These measurements are corroborated by time-dependent measurements made using a He-Ne interferometer.

Jackson, S. L.; Shumlak, U. [Aerospace and Energetics Research Program, University of Washington, Seattle, Washington 98195-2250 (United States)

2006-08-15

319

Experiments and Simulations on the Plasma Dynamics in Vacuum Transporting Lines Aimed at the Z-Pinch IFE Reactor  

SciTech Connect

A series of experiments has been carried out on the S-300 pulsed power machine (3 MA, 0.15 Ohm, 100 ns), devoted to the study of a section of magnetically insulated vacuum transporting line (MITL), by the current flow density up to 500 MA/cm{sup 2}, by the linear current flow density being up to 6 MA/cm. These parameters fairly correspond to those of the Sandia Laboratories' conceptual project of IFE reactor based on the fast Z-pinch. The goals of experiments were as follows: 1) study of the near-electrode plasma and its effect on the energy transfer; 2) testing the 2-temperature MHD code NPINCH modeling the behavior of near-electrode plasmas. As a result, the conditions of plasma formation and reconnection of the MITL gap have been determined.

Kalinin, Yu.; Bakshaev, Yu.; Bartov, A.; Blinov, P.; Chernenko, A.; Danko, S.; Kingsep, A.; Korolev, V.; Mizhititsky, V.; Shashkov, A.; Smirnov, V. [Russian Research Centre 'Kurchatov Institute', 1 Kurchatov Sq., 123182, Moscow (Russian Federation); Olson, C.L. [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Sasorov, P. [Institute for Theoretical and Experimental Physics, 25 B.Cheremushkinskaya, 117259, Moscow (Russian Federation)

2006-01-05

320

Wire array Z-pinch length variations for K-shell x-ray generation on Z.  

SciTech Connect

Large diameter (50-70 mm) wire array z pinches are fielded on the refurbished Z machine to generate 1-10 keV K-shell x-ray radiation. Imploding with velocities approaching 100 cm/{micro}s, these loads create large dL/dt which generates a high voltage, stresses the convolute, and leads to current loss. High velocities are required to reach the few-keV electron temperatures required to strip moderate-atomic-number plasmas to the K shell, thus there is an inherent trade-off between achieving high velocity and stressing the pulsed power driver via the large dL/dt.Here, we present experiments in which the length of stagnated Cu and stainless steel z pinches was varied from 12-24 mm. The motivation in reducing the pinch height is to lower the final inductance and improve coupling to the generator. Shortening a Cu pinch from 20 to 12 mm by angling the anode glide plane reduced the final L and dL/dt, enhancing the feed current by 1.4 MA, nearly doubling the K-shell power per unit length, and increasing the net K-shell yield by 20%. X-ray spectroscopy is employed to assess differences in plasma conditions between the loads. Lengthening the pinch could lead to yield enhancements by increasing the mass participating in the implosion, provided the increased inductance is not overly detrimental to the current coupling. In addition to the experimental results, these scenarios are studied via thin-shell 0D and also magneto-hydrodynamic modeling with a coupled driver circuit model.

Giuliani, J. L. (Naval Research Laboratory); Davis, J. (Naval Research Laboratory); Waisman, Eduardo Mario; DasGupta, A. (Naval Research Laboratory); Apruzese, John P. (Naval Research Laboratory); Jennings, Christopher A.; Clark, R. W. (Naval Research Laboratory); Ampleford, David J.; Thornhill, Joseph W. (Naval Research Laboratory); Cuneo, Michael Edward; Coverdale, Christine Anne; Jones, Brent Manley; Hansen, Stephanie B.

2010-06-01

321

Trends in plasma conditions inferred from an analysis of x-ray data from high wire-number, Z-pinch load implosions  

SciTech Connect

An analysis of x-ray data from two series of Z-pinch shots taken on the short current-risetime Saturn accelerator at Sandia National Laboratories [Proceedings of 6th International IEEE Pulsed Power Conference, Arlington, VA, edited by P. J. Turchi and B. H. Bernstein (IEEE, New York, 1987), p. 310] is presented. In one series, the array radius was held constant and the array mass was varied; in the other series, the array mass was held constant and its radius varied. In both sets of experiments, large wire-number loads (N{>=}93) of aluminum were used in contrast to earlier small wire-number aluminum array experiments on Saturn where N{<=}42. Average electron temperatures and ion densities were inferred from the data. In addition, from the measured size of the emission region of K-shell x rays and from the inferred ion density, a fraction of the total array mass that participated in the K-shell emission was inferred and found to be directly correlated to the K-shell yields that were measured. This paper also demonstrates that the yields varied as a function of array mass and radius in much closer agreement with predictions [J. Appl. Phys. 67, 1725 (1990)] than had been observed in the earlier small wire-number experiments. Thus, a serious misperception that the reason for the early disagreement was in the calculations and not in the experiments is corrected. These predictions were made using one-dimensional (1D) magnetohydrodynamics calculations. The density and temperature trends inferred from the data analysis are well-behaved and consistent with the 1D calculations. This data analysis confirms the importance of achieving uniform plasma initial conditions and implosion symmetry when comparing computer code calculations with experiment. When the wire number of an array load is increased, a more uniform shell of plasma is calculated initially as the wires explode and, as the plasma stagnates on axis, the x-ray powers and yields are found experimentally to approach the powers and yields predicted by 1D calculations.

Whitney, K. G.; Pulsifer, P. E.; Apruzese, J. P.; Thornhill, J. W.; Davis, J.; Chong, Y. K.; Sanford, T. W. L.; Mock, R. C.; Nash, T. J.

2001-08-01

322

Duty cycle and modulation effects in aluminum alloy welding with high-power Nd:YAG laser  

Microsoft Academic Search

The modulation and duty cycle effects on Al-alloy welding with high power Nd-YAG laser are investigated. Micro- structural characterization of the low and high duty welds with wave modulation identified the differences in the weld morphology. Welding depth, undercut and strength of fusion zone are discussed as a function of the processing parameters.

Y. P. Kathuria; Akihiko Tsuboi

1996-01-01

323

Duty cycle and modulation effects in aluminum alloy welding with high-power Nd:YAG laser  

NASA Astrophysics Data System (ADS)

The modulation and duty cycle effects on Al-alloy welding with high power Nd-YAG laser are investigated. Micro- structural characterization of the low and high duty welds with wave modulation identified the differences in the weld morphology. Welding depth, undercut and strength of fusion zone are discussed as a function of the processing parameters.

Kathuria, Y. P.; Tsuboi, Akihiko

1996-09-01

324

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

NASA Astrophysics Data System (ADS)

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

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

2007-06-01

325

A kinetic model of the plasma flow at the magnetic z-pinch and the plasmoid structure. Part 2 (in English)  

NASA Astrophysics Data System (ADS)

In this article we will follow the approach developed in articles N.~N.~Bogoliubov, V.~Hr.~Samoilenko, Ukr. Fiz. Zh., 37, 147 (1992); J.~Gibbon, Physica D, 3, 503 (1981) using modern Lie--algebraic and symplectic geometry methods. It is devoted to the description of Boltzman--Vlasov type kinetic equations and some two--dimensional hydrodynamic Benney type flows associated with them. In our case of the cylindrical symmetry taking place at the interrupted magnetic z--pinch in plasma we used intensively the corresponding two--dimensionality of the plasma flow under consideration which made it possible to build a kinetic model of the plasmoid vortex structure with a conserved number of linkages of vortex lines. The latter can be used to explain the observed earlier stability of the plasmoid structure at the magnetic z--pinch.

Kubes, P.; Prykarpatsky, A. K.; Zagrodzinski, J.; Prykarpatsky, Y. A.

326

Numerical Magnetohydrodynamic Simulation of Z-pinch Experiment Shot 51 on Z-machine using 2D Eulerian Code FLUX-RZ  

Microsoft Academic Search

Summary form only given. The paper presents simulation results of a Z-pinch experiment shot 51 using numerical code FLUX-rz, developed in STCP RFNC-VNIIEF. Calculations of an implosion process of a tungsten liner load were carried out with stationary uniform Eulerian grid in frameworks of a two-dimensional (in r-z plane) radiation magnetic hydrodynamics at self-consistent consideration of equations of the Z-machine

A. P. Orlov; P. B. Repin; E. V. Sukhanov

2007-01-01

327

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  

Microsoft Academic Search

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

Y. K. Chong; J. W. Thornhill Giuliani Jr.; J. P. Apruzese; R. E. Terry; J. Davis

2001-01-01

328

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

329

Advanced x-ray\\/EUV diagnostics for spectroscopy, imaging, and polarimetry at the Nevada Terawatt Facility z-pinch plasma source  

Microsoft Academic Search

A wide variety of x-ray and extreme ultraviolet (EUV) diagnostics are being developed to study z-pinch plasmas at the Nevada Terawatt Facility (NTF) at the University of Nevada, Reno. Time-resolved x-ray\\/EUV imaging and spectroscopy, polarization spectroscopy, and backlighting will be employed to measure profiles of plasma temperature, density, flow, and charge state and to investigate electron distribution functions and magnetic

Victor L. Kantsyrev; Bruno S. Bauer; Alla S. Shlyaptseva; Dmitry A. Fedin; Stephanie Hansen; Radu Presura; David Chamberlain; Nick Ouart; Alex Jones; Hank LeBeau

2000-01-01

330

Z-Pinch (LiF)2-BeF2 (flibe) Preliminary Vaporization Estimation Using the BUCKY 1-D Radiation Hydrodynamics Code  

Microsoft Academic Search

The post-explosion material vaporization characteristics of the proposed Z-pinch reactor design were simulated using the BUCKY 1-D radiation hydrodynamics code. To model the 3-D variations in the reactor chamber design, three separate BUCKY simulations were performed - one in each of the cylindrical coordinate geometries: +z, -z, and r. The simulations were run to a time of 80 mus and

T. A. Heltemesa; E. P. Marriotta; G. A. Moses; R. R. Peterson

2005-01-01

331

One- and two-dimensional density and temperature measurements of an argon-neon Z-pinch plasma at stagnation  

SciTech Connect

In order to benchmark and improve current 2D radiation magnetohydrodynamic (MHD) models of Z-pinch plasmas, we have performed experiments which characterize the plasma -conditions at stagnation. In the experiments the SATURN pulsed power facility at Sandia National Laboratory was used to create an imploding -Ar-Ne plasma. An absolutely calibrated, high resolution space- and time- resolving Johann crystal spectrometer was used to infer the electron temperature Te from the slope of the hydrogenlike Ne free-bound continuum, and the ion density ni from the Stark broadening of the Ar heliunlike Rydberg series. 2D electron temperature profiles of the plasma are obtained from a set of imaging crystals also focused on the Ne free-bound continuum. We shot two types of gas nozzles in the experiment, annular and uniform fill which varies the amount of mass in the plasma. 2D local thermodynamic equilibrium (LTE) and non-LTE MM models predict a radiating region denser and cooler than measured.

Wong, K.L.; Springer, P.T.; Hammer, J.H.; Iglesias, C.A.; Osterheld, A.L.; Foord, M.E.; Bruns, H.C.; Emig, J.A.; Deeney, C.

1996-10-01

332

Z-Beamlet Point Projection X-Ray Imaging of ICF Implosions in Z Accelerator Z-Pinch-Driven Hohlraums  

NASA Astrophysics Data System (ADS)

The Z-Beamlet laser backlighter system, a recent addition to Sandia's 20-MA Z accelerator, will be used to point project x-ray image a variety of Z-driven targets (Rev. Sci. Instrum. 72, 657 (2001). and references therein). This laser is a 2-TW, 2-kJ system and when fully commissioned it will have a <50-?m-diam spot size and a four-post picket fence pulse for high-spatial-resolution four-frame imaging. Although the point projection imaging mode forces the image plane detector to view through a large aperture, making it therefore sensitive to both the Bremsstrahlung background and debris characteristic of Z, recent data shows success in overcoming both these problems. In particular, as part of the z-pinch-driven hohlraum high-yield ICF assessment study (Phys. Plasmas. 8, 2257 (2001). and references therein) initial Z-Beamlet-backlit images of imploding ICF capsules have been captured, and will be presented. Sandia is a multiprogram laboratory operated by Sandia Corp., a Lockheed Martin Company, for the USDOE under Contract DE-AC04-94AL85000.

Bennett, G. R.; Adams, R. G.; Cuneo, M. E.; Dropinski, S. C.; Green, R. M.; Hurst, M. J.; Porter, J. L.; Rambo, P.; Rovang, D. C.; Ruggles, L. E.; Seamen, H.; Simpson, W. W.; Tanner, D. L.; Vesey, R. A.; Wenger, D. F.; Smith, I. C.

2001-10-01

333

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

NASA Astrophysics Data System (ADS)

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

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

2006-06-01

334

Mass accretion and nested array dynamics from Ni-Clad Ti-Al wire array Z pinches.  

SciTech Connect

Analysis of 50 mm diameter wire arrays at the Z Accelerator has shown experimentally the accretion of mass in a stagnating z pinch and provided insight into details of the radiating plasma species and plasma conditions. This analysis focused on nested wire arrays with a 2:1 (outeninner) mass, radius, and wire number ratio where Al wires were fielded on the outer array and Ni-clad Ti wires were fielded on the inner array.In this presentation, we will present analysis of data from other mixed Al/Ni-clad Ti configurations to further evaluate nested wire array dynamics and mass accretion. These additional configurations include the opposite configuration to that described above (Ni-clad Ti wires on the outer array, with Al wires on the inner array) as well as higher wire number Al configurations fielded to vary the interaction of the two arrays. These same variations were also assessed for a smaller diameter nested array configuration (40 mm). Variations in the emitted radiation and plasma conditions will be presented, along with a discussion of what the results indicate about the nested array dynamics. Additional evidence for mass accretion will also be presented.

Jones, Brent Manley; Jennings, Christopher A.; Coverdale, Christine Anne; Cuneo, Michael Edward; Maron, Yitzhak (Weizmann Institute, Israel); LePell, Paul David (Ktech Corporation, Albuquerque, NM); Deeney, Christopher

2010-07-01

335

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

SciTech Connect

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

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

2012-06-15

336

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

SciTech Connect

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, Ryan D.; Martin, Matthew Ryan; Vesey, Roger Alan; Lemke, Raymond William; Sinars, Daniel Brian; Herrmann, Mark C.; Jennings, Christopher A.; Cuneo, Michael Edward; Slutz, Stephen A.

2010-12-01

337

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

338

What can spectroscopy and imaging of multi-planar wire arrays reveal about Z-pinch radiation physics?  

SciTech Connect

The planar wire array research on Zebra at UNR that started in 2005 continues experiments with new types of planar loads with results for consideration and comprehensive analysis [see, for example, Kantsyrev et al, HEDP 5, 115 (2009)]. The detailed studies of radiative properties of such loads are important and spectroscopy and imaging constitute a very valuable and informative diagnostic tool. The set of theoretical codes is implemented which provides non-LTE kinetics, wire ablation dynamic, and MHD modeling. This talk is based on the results of new recent experiments with planar wire arrays on Zebra at UNR. We start with results on radiative properties of a uniform single planar wire array (SPWA) from alloyed Al wires and move to combined triple planar wire arrays (TPWA) made from two materials, Cu and Al. Such combined TPWA includes three planar wire rows that are parallel to each other and made of either Cu or Al alloyed wires. Three different configurations (Al/Cu/Al, Cu/Al/Cu, and Cu/Cu/Al) are considered and compared with each other, and with the results from SPWA of the same materials. X-ray time-gated and time integrated pinhole images and spectra are analyzed together with bolometer, PCD, and XRD measurements, and optical images. Emphasis is made on the radiative properties and temporal and spatial evolution of plasma parameters of such two-component plasmas. The opacity effects are considered and the important question of what causes K-shell Al lines to be optically thin in combined TPWAs is addressed. In conclusion, the new findings from studying multi-planar wire array implosions are summarized and their input to Z-pinch radiation physics is discussed.

Osborne, Glenn C. (University of Nevada, Reno, NV); Esaulov, Andrey A. (University of Nevada, Reno, NV); Apruzese, John P. (Naval Research Laboratory, Washington DC); Shrestha, I. (University of Nevada, Reno, NV); Kantsyrev, Victor Leonidovich (University of Nevada, Reno, NV); Shlyaptseva, V. (University of Nevada, Reno, NV); Coverdale, Christine Anne; Rudakov, Leonid I. (Icarus Res. Inc., Bethesda, MD); Williamson, K. M. (University of Nevada, Reno, NV); Deeney, Christopher (NNSA, DOE, Headquarters, Washington DC); Ouart, Nicholas D. (University of Nevada, Reno, NV); Weller, M. E. (University of Nevada, Reno, NV); Safronova, Alla S. (University of Nevada, Reno, NV)

2010-07-01

339

The wire array Z-pinch: an efficient x-ray source for ICF and a new ion heating mechanism  

NASA Astrophysics Data System (ADS)

The Z-pinch provides an efficient x-ray source for driving a hohlraum for inertial confinement fusion. The basic physics of wire-array implosions is reviewed. It can be understood in several sequential stages. Firstly, the wires heat and form a surrounding vapour which ionizes, causing the current to transfer to this lower resistance. The JB global force leads to ejection of this plasma towards the axis to form a precursor plasma. The wire cores continue to ablate due to the heat flux from the Joule-heated nearby plasma. The cooling of this plasma by the wire-cores leads to a low magnetic Reynolds number so that the precursor plasma carries little or no current. When gaps appear in the liquid/vapour cores the plasma temperature and Reynolds number rise and this plasma accelerates in towards the axis carrying the current. This is the main implosion, and it sweeps up earlier ablated plasma, which acts to reduce Rayleigh-Taylor growth. At stagnation, the ion kinetic energy is thermalized and equipartition heats the electrons, which then radiate in a 5 ns pulse. In some conditions the energy radiated by soft x-rays exceeds the ion kinetic energy by a factor of 3 or 4. A theory has been developed to explain this in which fine-scale, fast growing m= 0 MHD instabilities grow to saturation, viscous dissipation of which leads to ion heating, followed by equipartition. World record ion temperatures of 2-3 billion Kelvin were predicted, and measured at Sandia National Laboratory. Lastly, progress in capsule implosions and in application to inertial fusion energy is reported.

Haines, M. G.

2008-10-01

340

The Wire Array Z-Pinch AN Efficient X-Ray Source for Icf and a New Ion Heating Mechanism  

NASA Astrophysics Data System (ADS)

The Z-pinch provides an efficient x-ray source for driving a hohlraum for inertial confinement fusion. The basic physics of wire-array implosions is reviewed. It can be understood in several sequential stages. First, the wires heat and form a surrounding vapor which ionizes, causing the current to transfer to this lower resistance. The JB global force leads to ejection of this plasma towards the axis to form a precursor plasma. The wire cores continue to ablate due to the heat flux from the Joule-heated nearby plasma. The cooling of this plasma by the wire-cores leads to a low magnetic Reynolds number so that the precursor plasma carries little or no current. When gaps appear in the liquid/vapor cores the plasma temperature and Reynolds' number rise and this plasma accelerates in towards the axis carrying the current. This is the main implosion, and it sweeps up earlier ablated plasma, which acts to reduce Rayleigh-Taylor growth. At stagnation the ion kinetic energy is thermalised and equipartition heats the electrons, which then radiate in a 5 ns pulse. In some conditions the energy radiated as soft x-rays exceeds the ion kinetic energy by a factor of 3 or 4. A theory has been developed to explain this in which fine-scale, fast growing m = 0 MHD instabilities grow to saturation, viscous dissipation of which leads to ion heating, followed by equipartition. World record ion temperatures of 2 to 3 billion Kelvin were predicted, and measured at Sandia National Laboratory. Lastly progress in capsule implosions and in application to inertial fusion energy is reported.

Haines, M. G.

2009-07-01

341

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

SciTech Connect

The dynamics of ablated plasmas of wire-array Z-pinches are studied numerically in (r,{theta}) 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,{theta}) plane. The dynamics of ablation streams determine the distribution of magnetic field and the current density J{sub z} inside the wire array. The precursor current can be approximately calculated by the integral of J{sub z} 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 Shunkai; Ding Ning; Ning Cheng; Xiao Delong; Zhang Yang; Xue Chuang [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China)

2011-04-15

342

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

343

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

SciTech Connect

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

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

1999-08-25

344

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

345

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

346

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

347

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

NASA Astrophysics Data System (ADS)

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

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

2010-04-01

348

Improving Agreement between the Neutron Yield Scaling Model of Fast Z-pinches with Experimental Data Using the Time Derivative of the Current  

NASA Astrophysics Data System (ADS)

The Z-pinch community has accepted a power law scaling of the DD neutron yield with current (Y=aI^d) for decades. While the exponent, d, in the power law has received much of the attention in literature (3.5Z-pinch machines with peak currents ranging from 60 kA to 18 MA. The improved correlation of measured yield on both I and dI/dt motivates an examination of microscopic dynamics in these pinches., The dI/dt term is related to the pinch voltage that in turn is the source term for the fast ion spectrum that drives beam-target fusion.

Bures, Brian; Krishnan, Mahadevan

2012-10-01

349

Characterization of the plasma parameters for PBFA-Z type wire array Z-pinches and the implications for radiation MHD.  

NASA Astrophysics Data System (ADS)

Detailed simulations of wire-array Z pinches with Radiation MHD codes require calculations which span a broad range of plasma parameters. Predictive capabilities will rely on the applicability of MHD physics to the various plasma regimes. A universal diagram of pinch stability regimes for equilibrium pinches (pinches which satisfy the Bennet condition NkTe ~= NkTi ? I^2) has previously been presented by Haines and Coppins (M.G. Haines and M. Coppins, Phys. Rev. Lett, 66), 1462 (1991). Here, a similar study of the various plasma regimes accessed by non-equilibrium Z-pinches of the type fielded on the PBFA-Z accelerator at Sandia National Laboratories is presented. Beginning with wire initiation and breakdown and continuing towards stagnation on axis, the operational phase-space (in terms of current I, mass density ?, charge state Z, and temperature T_e) is outlined. The conditions for ideal and non-ideal MHD dynamics are presented and a discussion of the relevance of the various plasma regimes to MHD simulations and modeling is given.

Oliver, Bryan

1999-11-01

350

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

351

Incident Wire Array Z-pinch Plasma Radiation Fluence Effects on the Filter Material Property & Implications on the Observed Radiation Parameters  

NASA Astrophysics Data System (ADS)

The wire array Z-pinches on the refurb. Z are marked by an intense bright emission of high energy non-LTE photons. In order to diagnose the radiation in such a hostile environment, a number of materials w/ varying composition are used to provide select optimized radiation filtering. Traditionally, the various radiation parameters are determined from the deconvolution of the actual observed values using an appropriate time invariant filter response function (FRF). Under exposure to the radiation, however, the materials may undergo significant changes. We examine the response of various filters to an intense radiation from the plasmas. A MHD+multifreq. rad. x-port code is employed to establish the time varying non-LTE radiation & to investigate the evolution of the materials subject to the field. A characterization of the material EOS/FRF is made & their effect on the radiation characteristics are quantified w/ a goal of optimized filter design/deployment.

Chong, Y. K.; Thornhill, J.; Velikovich, A.; Giuliani, J.; Davis, J.; Clark, R.; Ampleford, D.; Coverdale, C.; Jones, B.

2010-11-01

352

Development and use of a two-dimensional interferometer to measure mass flow from a multi-shell Z-pinch gas puff  

NASA Astrophysics Data System (ADS)

For gas puff Z-pinches, the K-shell x-ray yield is maximized with the use of a multi-shell nozzle. Optimization of the yield, verification of hydrodynamic models of the nozzle flows, and plausible MHD code modeling of the implosions require data on the radial and axial (R,Z) distribution of mass in the nozzle's flow field. Interferometry is a well-established technique for acquiring such data. We describe the development and use of a two-dimensional interferometer with emphasis on the required data reduction methods. We also show that the instrument can derive the flow from each individual nozzle in a multi-shell system.

Coleman, P. L.; Lamppa, D. C.; Madden, R. E.; Wilson-Elliott, K.; Jones, B.; Ampleford, D. J.; Bliss, D. E.; Jennings, C.; Bixler, A.; Krishnan, M.

2012-08-01

353

Advanced x-ray/EUV diagnostics for spectroscopy, imaging, and polarimetry at the Nevada Terawatt Facility z-pinch plasma source  

NASA Astrophysics Data System (ADS)

A wide variety of x-ray and extreme ultraviolet (EUV) diagnostics are being developed to study z-pinch plasmas at the Nevada Terawatt Facility (NTF) at the University of Nevada, Reno. Time-resolved x-ray/EUV imaging and spectroscopy, polarization spectroscopy, and backlighting will be employed to measure profiles of plasma temperature, density, flow, and charge state and to investigate electron distribution functions and magnetic fields. These diagnostics are used to study the NTF pinch as an x-ray/EUV source for plasma spectroscopy research and to examine the early-time evolution of a current-driven wire, the formation of a plasma sheet from the explosion and merging of wires, etc. The instruments are state-of-the-art applications of glass capillary converters (GCC), multilayer mirrors (MLM), and crystals. Devices include: a novel glass-capillary-based two- dimensional imaging spectrometer, a time-resolved x-ray spectrometer, a 5-channel crystal/MLM spectrometer ('Polychromator') with a transmission grating spectrometer, and two-channel x-ray/EUV polarimeters-spectrometers (to study simultaneously polarization of K- and L-shell radiation). An x-pinch backlighter, yielding point-projection microscopy with ns resolution is under development. X-ray convex-crystal survey spectrometers, and fast filtered x-ray diodes have observed single Ti-, Fe and W-wire z-pinches, and Ti and Fe x- pinches. The NTF x-ray yield and x-ray pulse duration depend sensitively on the wire load. There is evidence of a strong energetic electron beam with a complex spatial structure in x- pinch plasmas. This work is supported by DOE, DOD, SNL, and UNR.

Kantsyrev, Victor L.; Bauer, Bruno S.; Shlyaptseva, Alla S.; Fedin, Dmitry A.; Hansen, Stephanie; Presura, Radu; Chamberlain, David; Ouart, Nick; Jones, Alex; LeBeau, Hank

2000-11-01

354

Comparative analysis of time-resolved and time-integrated x-ray data from long pulse Z-pinch implosions on Saturn  

NASA Astrophysics Data System (ADS)

Two series of Al:Mg wire array Z-pinch implosions were performed on the Saturn pulsed-power generator [R. B. Spielman et al., in Proceedings of the 2nd International Conference on Dense Z-Pinches, Laguna Beach, CA, 1989, edited by N. R. Pereira, J. Davis, and N. Rostoker (American Institute of Physics, New York, 1989), p. 3]. In one series, the wire number was varied, in the other, the load mass was varied. In all cases an initial array diameter of 40 mm was maintained. Sufficient x-ray data were obtained in these experiments to allow the plasma conditions to be inferred by matching x-ray data to that calculated by a collisional-radiative equilibrium (CRE) model. In fitting the data, the plasma has been assumed to be either uniform [zero dimension (0D)] or to vary one-dimensionally (1D) with radius. On one shot, a comparison of these two methods of data analysis performed with both time-resolved and time-integrated data has been carried out. While the same trends in plasma conditions as a function of load mass and wire number are seen, the uniform plasma assumption yields higher electron temperatures, lower core densities, but higher K-shell radiating mass fractions than those obtained from the 1D assumption. When comparing time-resolved and time-integrated spectroscopic data, a pronounced difference is seen in a density-sensitive line ratio whose time-resolved values corroborate experimental evidence that much of the K-shell radiation is emitted from a high density core plasma of spatial extent less than about 300 ?m.

Apruzese, J. P.; Thornhill, J. W.; Whitney, K. G.; Davis, J.; Deeney, C.; Coverdale, C. A.

2001-08-01

355

Electrical Resistivity Measurements of Hot Dense Aluminum  

NASA Astrophysics Data System (ADS)

Electrical transport properties of dense aluminum are measured in the disordered liquidlike phase using a well-tamped, thermally equilibrated, exploding wire z pinch. Direct measurements of the electrical conductivity have been made using voltage and current measurements. Our measurements span the minimum conductivity regime, at higher densities than have been produced previously. We find that some Ziman-like theoretical predictions are in fair agreement with the data and one Ziman-like theoretical approach is in good agreement, in contrast to other experiments performed in similar regimes which indicate poor agreement with such theories.

Benage, J. F.; Shanahan, W. R.; Murillo, M. S.

1999-10-01

356

Technique for in situ calibration of an x-ray streak camera in the nanosecond regime using a high density Z-pinch  

SciTech Connect

A technique for calibrating an x-ray streak camera in situ has been developed. It has been applied to an x-ray streak camera installed on a collapsing gas shell Z-pinch. The calibration was done by simultaneously measuring the emitted x-rays using a pinhole camera, an InP:Fe photoconductive detector, and the streak camera. The spatial dimension of the streak image was calibrated by integrating the film density over time and fitting the resulting data to the corresponding information taken from an x-ray pinhole image. The temporal calibration was obtained by similarly fitting the film density from the x-ray streak image as a function of time integrated over the appropriate part of the spatial dimension with the signal from an InP:Fe photoconductive detector. By using this technique we have found a spatial magnification of the streak camera system consistent with the results derived from the geometrical optics to within 10%. A temporal dispersion of 2.5 +- 0.5 ns/mm was obtained, which is in agreement with the nominal speed of 2.5 ns/mm. This technique also yielded an absolute intensity calibration of the streak camera.

Jones, L.A.; Kallne, E.; Kania, D.R.; Maestas, M.; McGurn, J.S.; Shepherd, R.

1985-09-01

357

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

SciTech Connect

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

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

2007-01-01

358

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

SciTech Connect

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

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

2009-01-21

359

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

NASA Astrophysics Data System (ADS)

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

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

2009-01-01

360

Laboratory Astrophysics on High Power Lasers and Pulsed Power Facilities.  

National Technical Information Service (NTIS)

Over the past decade a new genre of laboratory astrophysics has emerged, made possible by the new high energy density (HED) experimental facilities, such as large lasers, z-pinch generators, and high current particle accelerators. (Remington, 1999; 2000; ...

B. A. Remington

2002-01-01

361

Plasma evolution and dynamics in high-power vacuum-transmission-line post-hole convolutes  

NASA Astrophysics Data System (ADS)

Vacuum-post-hole convolutes are used in pulsed high-power generators to join several magnetically insulated transmission lines (MITL) in parallel. Such convolutes add the output currents of the MITLs, and deliver the combined current to a single MITL that, in turn, delivers the current to a load. Magnetic insulation of electron flow, established upstream of the convolute region, is lost at the convolute due to symmetry breaking and the formation of magnetic nulls, resulting in some current losses. At very high-power operating levels and long pulse durations, the expansion of electrode plasmas into the MITL of such devices is considered likely. This work examines the evolution and dynamics of cathode plasmas in the double-post-hole convolutes used on the Z accelerator [R. B. Spielman , Phys. Plasmas 5, 2105 (1998)PHPAEN1070-664X10.1063/1.872881]. Three-dimensional particle-in-cell (PIC) simulations that model the entire radial extent of the Z accelerator convolutefrom the parallel-plate transmission-line power feeds to the z-pinch load regionare used to determine electron losses in the convolute. The results of the simulations demonstrate that significant current losses (1.5 MA out of a total system current of 18.5 MA), which are comparable to the losses observed experimentally, could be caused by the expansion of cathode plasmas in the convolute regions.

Rose, D. V.; Welch, D. R.; Hughes, T. P.; Clark, R. E.; Stygar, W. A.

2008-06-01

362

High-power klystrons  

NASA Astrophysics Data System (ADS)

Novel emerging applications in advanced linear collider accelerators, ionospheric and atmospheric sensing and modification and a wide spectrum of industrial processing applications, have resulted in microwave tube requirements that call for further development of high power klystrons in the range from S-band to X-band. In the present paper we review recent progress in high power klystron development and discuss some of the issues and scaling laws for successful design. We also discuss recent progress in electron guns with potential grading electrodes for high voltage with short and long pulse operation via computer simulations obtained from the code DEMEOS, as well as preliminary experimental results. We present designs for high power beam collectors.

Siambis, John G.; True, Richard B.; Symons, R. S.

1994-05-01

363

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

SciTech Connect

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

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

2011-09-15

364

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

365

High power microwave generator  

DOEpatents

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

Minich, R.W.

1986-05-15

366

High power microwave generator  

DOEpatents

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

Minich, Roger W. (Patterson, CA)

1988-01-01

367

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

SciTech Connect

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

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

2000-03-20

368

Estimating Z-Pinch computing resources.  

SciTech Connect

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

Brunner, Thomas A.

2007-04-01

369

Analysis of Z Pinch Shock Wave Experiments.  

National Technical Information Service (NTIS)

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 application of VISAR inter...

J. Asay K. G. Budge G. Chandler K. Fleming C. Hall

1999-01-01

370

High Power Ferrite Phase Shifter.  

National Technical Information Service (NTIS)

Theoretical and experimental investigations of the microwave properties of ferrites at magnetic fields above ferromagnetic resonance are described. The program goal is the development of high power reciprocal phase shifters for X-band and C-band operation...

1965-01-01

371

Single foreplane high power rectenna  

Microsoft Academic Search

A dual polarization rectenna capable of high power handling is described. It consists of contiguous dipoles and rectification units on a single substrate. High efficiencies comparable to previous linear and multiplane dual polarization devices have been achieved.

A. Alden; T. Ohno

1992-01-01

372

High Power Mercury Switch Study.  

National Technical Information Service (NTIS)

The effort was both a theoretical and experimental program leading to the development of high voltage, high power switching devices which utilize a liquid metal cathode. A series of mercury tubes with plasma injection triggering were built and tested culm...

R. W. Waniek

1967-01-01

373

High Power Density Fuel Cell.  

National Technical Information Service (NTIS)

An exploratory development program continuing the investigation of high power density hydrogen-oxygen fuel cell technology was conducted. An evaporatively cooled four-cell power section was designed, fabricated, and successfully tested at a steady-state p...

J. K. Stedman D. P. Bloomfield N. A. Hassett

1970-01-01

374

High-power hollow fibers  

Microsoft Academic Search

Hollow glass fibers for delivery of high-powered infrared lasers. The hollow fibers are consisted of a glass capillary tube and metal and polymer layer on the inside of the glass tube. As the dielectric layer, polymers that are transparent at the desired wavelength are utilized. The fibers are fabricated by a simple, liquid phase technique. Firstly, a silver film is

Yuji Matsuura; Mitsunobu Miyagi

1998-01-01

375

Electronically Tuned High Power Network.  

National Technical Information Service (NTIS)

The report summarizes the progress of a program to develop an efficient high-power antenna matching network capable of high speed electronic tuning and suitable for manpack or airborne application in the 30 to 76 MHz frequency range. Included is progress ...

J. R. Gruber G. K. Squire J. E. Brunner

1971-01-01

376

Characterization of high power thyristors  

Microsoft Academic Search

As commercial applications for compact, efficient high voltage pulsed power systems expand, the need for high power, fast turn-on maintenance-free switches also increases. To meet this combination of requirements, there is a trend toward utilizing more solid state switches in high voltage systems. Of all the solid state devices commercially available, gate-triggered thyristors handle the highest power levels by a

G. J. Rohwein; L. D. Roose; W. M. Portnoy

1995-01-01

377

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

378

High-Power VCSEL Arrays  

NASA Astrophysics Data System (ADS)

We review recent developments on high-power , high-efficiency two-dimensional vertical-cavity surface-emitting laser (VCSEL) arrays emitting around 808 and 980 nm. Selectively oxidized, bottom-emitting single VCSEL emitters with 50% power conversion efficiency were developed as the basic building block of these arrays . More than 230 W of continuous-wave (CW) power is demonstrated from a 5 mm {} 5 mm array chip. In quasi-CW mode, smaller array chips exhibit 100 W output power, corresponding to more than 3.5 kW/cm2 of power-density. High-brightness VCSEL pumps have been developed, delivering a fiber output power of 40 W, corresponding to a brightness close to 50 kW/(cm2 sr). High-energy VCSEL arrays in the milli-Joule range have also been developed. Many of the advantages of low-power single VCSEL devices such as reliability , wavelength stability, low-divergence circular beam, and low-cost manufacturing are preserved for these high-power arrays . VCSELs thus offer an attractive alternative to the dominant edge-emitter technology for many applications requiring compact high-power laser sources.

Seurin, Jean-Franois P.

379

High power excimer-laser  

NASA Astrophysics Data System (ADS)

High-power excimer lasers are of special interest for advanced industrial applications in the fields of materials processing, photochemistry, and especially laser isotope separation. A pulse-forming network (PFN) made up of a large number of parallel waterline capacitor arranged normal to the laser optical axis has been developed for exiciting high-power excimer lasers. An elongated X-ray gun employing a hollow cathode preionizes the 45 cm gain length laser. Up to 4 J, optical energy has been measured at 308 nm up to 4 J. Between 1 J and 2.5 J, the laser emits at other known rare gas-halide wavelengths for a lower stored energy in the PFN. Low divergence operation has been achieved with an injection-locked amplifier. Results of a 20-channel pseudospark switch are presented which show a current rise of 2.6 x 10 to the 12th A/s for 100 kA peak current.

Cirkel, H.-J.

380

High Power Pulse Energy System Concept.  

National Technical Information Service (NTIS)

New advances in capacitor technology create exciting opportunities in size and weight reduction for high-power, pulse energy systems having a broad range of applications. Characteristics of a proposed high power pulse energy system, formed by combining a ...

H. L. Lee G. Mason K. Kern

1988-01-01

381

High Power Linacs for ADS  

NASA Astrophysics Data System (ADS)

Accelerator Driven Sub-critical (ADS) fission systems are proposed for energy production and for burners of long-lived fission product wastes. Generally the ADS concepts involve using beams of 1 GeV protons with powers of 10 MW. An important requirement is high reliability, with minimal machine trip rates. Superconducting RF powered linear accelerators have been proposed as an accelerator choice, as an approach to high reliability, modest operating cost accelerator technology. The advantage in operational reliability arises from the possibility of providing additional standby accelerating cavities that can be rapidly brought online to compensate for accelerating components that may have equipment issues. Also, the recent demonstration of 1 MW, 1 GeV proton beam operation with a superconducting linac for over 5000 hours/year at the Spallation Neutron Source (SNS) offers confidence in the approach. A description of the technologies involved in high power proton linacs and a review of the SNS experience will be given. Also beam loss requirements and experience will be discussed.

Galambos, John

2012-03-01

382

High power microwave source development  

NASA Astrophysics Data System (ADS)

The requirements of this project have been to: (1) improve and expand the sources available in the facility for testing purposes and (2) perform specific tasks under direction of the Defense Nuclear Agency about the applications of high power microwaves (HPM). In this project the HPM application was power beaming. The requirements of this program were met in the following way: (1) We demonstrated that a compact linear induction accelerator can drive HPM sources at repetition rates in excess of 100 HZ at peak microwave powers of a GW. This was done for the relativistic magnetron. Since the conclusion of this contract such specifications have also been demonstrated for the relativistic klystron under Ballistic Missile Defense Organization funding. (2) We demonstrated an L band relativistic magnetron. This device has been used both on our single pulse machines, CAMEL and CAMEL X, and the repetitive system CLIA. (3) We demonstrated that phase locking of sources together in large numbers is a feasible technology and showed the generation of multigigawatt S-band radiation in an array of relativistic magnetrons.

Benford, James N.; Miller, Gabriel; Potter, Seth; Ashby, Steve; Smith, Richard R.

1995-05-01

383

Metal Pipe Joining with Aluminum Alloy by Ultrasonic Insert Casting  

Microsoft Academic Search

Insert casting of aluminum is widely used in industry. In order to realize better metallurgical bonding between metallic pipe and aluminum alloy castings, a new insert casting method with aided by high-power ultrasound has been developed. The bonding strength between the metal pipe and the cast aluminum alloy was evaluated by shear testing, EPMA analysis at the bonding interface was

J. Pan; M. Yoshida; G. Sasaki; H. Fukunaga

2000-01-01

384

Aluminum-air batteries for military applications  

Microsoft Academic Search

The authors review the basic characteristics of aluminum-air batteries, describe some of the recent advances involving aluminum anodes and air cathodes, aluminum-air batteries and demonstrate certain potential military applications. They can be transported as lightweight, collapsible batteries and can be filled with water at the site of operation. The alkaline Al\\/air battery is advantageous when a high power is desired.

B. M. L. Rao; R. Cook; W. Kobasz; G. D. Deuchars

1992-01-01

385

Laboratory Astrophysics on High Power Lasers and Pulsed Power Facilities  

SciTech Connect

Over the past decade a new genre of laboratory astrophysics has emerged, made possible by the new high energy density (HED) experimental facilities, such as large lasers, z-pinch generators, and high current particle accelerators. (Remington, 1999; 2000; Drake, 1998; Takabe, 2001) On these facilities, macroscopic collections of matter can be created in astrophysically relevant conditions, and its collective properties measured. Examples of processes and issues that can be experimentally addressed include compressible hydrodynamic mixing, strong shock phenomena, radiative shocks, radiation flow, high Mach-number jets, complex opacities, photoionized plasmas, equations of state of highly compressed matter, and relativistic plasmas. These processes are relevant to a wide range of astrophysical phenomena, such as supernovae and supernova remnants, astrophysical jets, radiatively driven molecular clouds, accreting black holes, planetary interiors, and gamma-ray bursts. These phenomena will be discussed in the context of laboratory astrophysics experiments possible on existing and future HED facilities.

Remington, B A

2002-02-05

386

Corporate Tax Avoidance and High Powered Incentives  

Microsoft Academic Search

This paper analyzes the links between corporate tax avoidance, the growth of high-powered incentives for managers, and the structure of corporate governance. We develop and test a simple model that highlights the role of complementarities between tax sheltering and managerial diversion in determining how high-powered incentives influence tax sheltering decisions. The model generates the testable hypothesis that firm governance characteristics

Mihir A. Desai; Dhammika Dharmapala

2004-01-01

387

A high power X-band Butler matrix  

NASA Astrophysics Data System (ADS)

Feasibility studies of waveguide high power Butler matrices of arbitrary complexity have been completed. Component imperfections were simulated using a specially developed computer analysis program. This is capable of analyzing Butler matrices of up to 64 elements, far in excess of the capacity of general purpose programs. Computer results indicated that good performance could be expected over a 10 percent frequency band using practical hybrids and phase shifters. This was confirmed from results taken on a prototype 8-element Butler matrix constructed in WR112. The maximum phase error between any pair of input and output ports is 6 deg, with an RMS error of less than 3 deg. The coupling to the output ports showed a variation of 0.45 dB, and the dissipation loss of the unplated aluminum unit is 0.4 dB.

Levy, R.

388

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 ...

389

High Power Picosecond Laser Pulse Recirculation.  

National Technical Information Service (NTIS)

We designed and constructed a nonlinear crystal-based short pulse recirculation cavity that traps the second harmonic of an incident high power laser. This scheme aims to increase the efficiency of Compton-scattering based light sources.

C. Brown D. Gibson F. Hartemann I. Jovanovic M. Y. Shverdin S. Anderson

2007-01-01

390

High Power, High Frequency Component Test Facility.  

National Technical Information Service (NTIS)

The NASA Lewis Research Center has available a high frequency, high power laboratory facility for testing various components of aerospace and/or terrestrial power systems. This facility is described here. All of its capabilities and potential applications...

M. E. Roth W. Krawczonek

1990-01-01

391

High power, high frequency lasertron rf sources.  

National Technical Information Service (NTIS)

High power rf sources have historically been limited to frequencies at which intense electron beams could be efficiently modulated. We have been exploring the power, frequency and efficiency limitations associated with the use of lasertrons for generating...

J. Norem E. Chojnacki R. Konecny

1990-01-01

392

Coupling output of multichannel high power microwaves  

SciTech Connect

The coupling output of multichannel high power microwaves is a promising technique for the development of high power microwave technologies, as it can enhance the output capacities of presently studied devices. According to the investigations on the spatial filtering method and waveguide filtering method, the hybrid filtering method is proposed for the coupling output of multichannel high power microwaves. As an example, a specific structure is designed for the coupling output of S/X/X band three-channel high power microwaves and investigated with the hybrid filtering method. In the experiments, a pulse of 4 GW X band beat waves and a pulse of 1.8 GW S band microwave are obtained.

Li Guolin; Shu Ting; Yuan Chengwei; Zhang Jun; Yang Jianhua; Jin Zhenxing; Yin Yi; Wu Dapeng; Zhu Jun; Ren Heming; Yang Jie [College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

2010-12-15

393

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 sources with one based on ultrafast laser techniques.

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

2002-10-01

394

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

395

High power CW RF probe measurements  

Microsoft Academic Search

A novel technique for accurately and efficiently acquiring high-power, CW (continuous wave) RF probe measurements while overcoming the challenges from bias-driven oscillations and thermal gradients has been developed. The ability to make on-wafer CW high-power measurements addresses the measurement of nonpulsed application devices and also permits traditional RLC transient suppressive circuitry to be implemented as part of the test system,

A. Lum; C. Dale; D. Ragle; M. Vernon

1992-01-01

396

Advances in high power semiconductor diode lasers  

NASA Astrophysics Data System (ADS)

High power semiconductor lasers have broad applications in the fields of military and industry. Recent advances in high power semiconductor lasers are reviewed mainly in two aspects: improvements of diode lasers performance and optimization of packaging architectures of diode laser bars. Factors which determine the performance of diode lasers, such as power conversion efficiency, temperature of operation, reliability, wavelength stabilization etc., result from a combination of new semiconductor materials, new diode structures, careful material processing of bars. The latest progress of today's high-power diode lasers at home and abroad is briefly discussed and typical data are presented. The packaging process is of decisive importance for the applicability of high-power diode laser bars, not only technically but also economically. The packaging techniques include the material choosing and the structure optimizing of heat-sinks, the bonding between the array and the heat-sink, the cooling and the fiber coupling, etc. The status of packaging techniques is stressed. There are basically three different diode package architectural options according to the integration grade. Since the package design is dominated by the cooling aspect, different effective cooling techniques are promoted by different package architectures and specific demands. The benefit and utility of each package are strongly dependent upon the fundamental optoelectronic properties of the individual diode laser bars. Factors which influence these properties are outlined and comparisons of packaging approaches for these materials are made. Modularity of package for special application requirements is an important developing tendency for high power diode lasers.

Ma, Xiaoyu; Zhong, Li

2008-03-01

397

Instability Control in a Staged Z-pinch  

SciTech Connect

A \\Staged Z-Pinch? is a fusion-energy concept in which stored-electric energy is first converted into plasma-liner-kinetic energy, and then transferred to a coaxialtarget plasma [H. U. Rahman, F. J. Wessel, and N. Rostoker, Phys. Rev. Lett. 74, p. 714(1996)]. Proper choice of the liner and target materials, and their initial radii and mass densities, leads to dynamic stabilization, current amplification, and shock heating of the target. Simulations suggest that this configuration has merit as a alternative inertial-confinement-fusion concept, and may provide an energy release exceeding thermonuclear break-even, if tested on one of many newer pulsed power systems, for example those located at Sandia National Laboratories.

Frank J. WESSEL

2011-04-22

398

Argon Z-pinch experiments on decade quad  

Microsoft Academic Search

Summary form only given, as follows. An argon double-shell gas puff source was fielded on Decade Quad, which was configured in the PRS mode with the four modules combined into a single pulse power driver. In a series of six shots, four of which were taken at reduced Marx charge (70 kV vs. 85 kV full charge), we demonstrated 29

J. S. Levine; B. H. Failor; H. M. Sze; M. A. Babineau; C. Enis; V. Kenyon; T. Worley; D. Bell

2002-01-01

399

Equation-of-State Measurements with Z-Pinch Sources  

Microsoft Academic Search

Validation of material models in a variety of scientific and technological applications requires accurate data regarding the high-pressure thermodynamic and mechanical properties. Traditional laboratory techniques for striking these measurements involve light gas guns to generate the required thermodynamic states, and the use of high-resolution time-resolved diagnostics to measure the desired material properties. EOS and constitutive material properties of importance to

J. R. Asay; C. Hall; J. E. Bailey; M. D. Knudson; K. G. Holland; D. L. Hanson; R. Johnston; M. A. Bernard; W. M. Trott; R. E. Spielman; W. A. Stygar; D. H. McDaniel

1999-01-01

400

A High Power Density Electric Machine Element  

Microsoft Academic Search

A direct current homopolar machine with liquid metal contacts can achieve high power density and efficiency. The analysis of a simple model of such a machine shows that a power density of several horsepower per pound at 90 percent efficiency is possible. The results of a design study of an experimental 280-pound 250- horsepower homopolar automotive transmission showed a 90

F. L. Zeisler

1967-01-01

401

Future trends in high power devices  

Microsoft Academic Search

Power devices for MW and GW power electronics are discussed. The most important device concepts of today are Phase Controlled Thyristor (PCT), Integrated Gate Commutated Thyristor (IGCT), Insulated Gate Bipolar Transistor (IGBT), and PIN diode. In spite of long-term intensive research of compound semiconductor materials and related devices, the world of high-power devices is dominated by silicon. In the light

J. Vobecky

2010-01-01

402

High Power Medium Voltage Electronic Load.  

National Technical Information Service (NTIS)

A Pulse Width Modulation (PWM) type, high power (2Kw) medium voltage (200V) electronic load suitable for operation as a stand alone instrument or as an integral part of a more complex test configuration is described. In stand alone operation, the load pow...

M. Martin H. J. N. Spruijt

1989-01-01

403

Dispenser cathode high power gridded klystron gun  

Microsoft Academic Search

This paper describes the design and performance of a new shadow gridded gun useful for high power radar klystrons. The gun features an M-type dispenser cathode having heater power identical to a larger diameter cathode oxide cathode gun used in one application. It is known that dispenser cathodes are more tolerant of arcs, poisoning, and other effects that can ruin

R. B. True; M. F. Kirshner; L. Turek; G. R. Good; R. J. Hansen; T. M. Bemis; R. J. Bartkowski

2004-01-01

404

High Power, Octave Bandwidth, SPDT Microwave Switches  

Microsoft Academic Search

Previously, broadband SPDT switches used, principally, diodes in series with the transmission line -- sacrificing high power performance because of the difficulty with removal of the diodes' heat and compromising switching performance due to the inconvenience in tuning to maximize the isolatian. Means for broadbanding the \\

J. F. White; K. E. Mortenson

1967-01-01

405

Lifetime investigation of high power IGBT modules  

Microsoft Academic Search

This article concerns lifetime investigation of high power IGBT modules. Other research investigating windturbine failures of modern wind turbines observed that the power converter counts for 15 % of all failures. A test bench capable of testing the IGBT power modules in an accelerated application specific working point was constructed. The working point was given with regards to voltage, current,

Jens Due; Stig Munk-Nielsen; Rasmus Nielsen

2011-01-01

406

High-power and superpower Cerenkov masers  

Microsoft Academic Search

The linear and nonlinear theory of the efficient operation of high-power (gigawatt) and superpower (50 GW) Cerenkov masers is presented. Issues such as breakdown, plasma production, and coupling to the output device are discussed. The relative merits of dielectric Cerenkov masers and plasma Cerenkov masers are considered. The principal design tool is a new particle simulation model that was developed

J. S. De Groot; R. A. Stone; K. Mizuno; J. H. Rogers; T. D. Pointon

1988-01-01

407

High power CW klystrons for fusion experiments  

Microsoft Academic Search

On TORE SUPRA (TS) located in Cadarache, the Lower Hybrid Current Drive (LHCD) 3.7 GHz system is being upgraded* in the frame of the CIMES project. Since the end of 2001, several technological components have been under manufacturing or have been installed. Particularly, a new high power CW klystron has been successfully developed and tested at Thales Electron Devices (TED)

A. Beunas; F. Kazarian

2008-01-01

408

Development of high power microwave source  

NASA Astrophysics Data System (ADS)

To achieve thermonuclear fusion it is inevitable to develop high power microwave and millimeter wave sources for plasma heating. In 1990, working group was organized as a collaboration study in National Institute for Fusion Science to review the present status of development on high microwave source. The review of development on high power klystron and gyrotron, FEL and microwave power source by REB is reported. Development of high power klystron is almost finished except for cooling of the window, cavity, and collector. As for the gyrotron oscillating with the whispering gallery mode, one must overcome the same problem for CW operation. In the quasi-optical gyrotron, there is no special progress for increasing the frequency and efficiency. Though the experimental evidence on autoresonance in the development of peniotron is performed, output power and frequency is much smaller than that of the gyrotron. It is difficult to increase in the pulse width of FEL having giant power of GW level with several ten ns and the utilization for plasma heating is limited. In addition, microwave and millimeter wave oscillators with high power which are running in the laboratories and the institutes are summarized.

Ono, Shoichi

1992-04-01

409

S-Band High Power Microwave Monitor.  

National Technical Information Service (NTIS)

A high power microwave monitor, designed and fabricated for use at the INS 15 MeV injector linac, is fed with 6 MW peak microwave power. The signals are picked up through a two-hall directional coupler composed of the main and the auxiliary rectangular wa...

T. Fukushima E. Tojyo K. Yoshida

1975-01-01

410

High Power Density Water Dielectric Switching  

Microsoft Academic Search

Pulse forming networks for high current particle beam fusion accelerators must produce fast rise time, low jitter, low prepulse, and high voltage power pulses. Conventional water dielectric switching can provide the required rise time and jitter, but has limitations on prepulse and output voltage. A high power density, low prepulse, pulse forming line (PFL) configuration with self-breakdown water dielectric switches

D. L. Johnson; J. P. Vandevender; T. H. Martin

1980-01-01

411

CHALLENGES FACING HIGH POWER PROTON ACCELERATORS  

SciTech Connect

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

Plum, Michael A [ORNL

2013-01-01

412

Cathode structure for a high power laser  

Microsoft Academic Search

A cathode structure for a high power laser is formed from a first sheet of a hard metallic material such as molybdenum, which is joined to a second sheet of the same material by brazing, these first two sheets being brazed to a support structure of the same material. The first two sheets have a plurality of side by side

V. W. Biricik; K. R. Chun; L. S. Gresko

1980-01-01

413

Doppler spectroscopy on high power neutral beams  

Microsoft Academic Search

The light emitted by a high power neutral hydrogen beam has been spectrally analysed by taking advantage of the Doppler effect. Both spatial profiles (at a given wavelength) and spectral profiles have been obtained, thus allowing the angular divergences of the different species as well as their relative amounts to be evaluated.

J. F. Bonnal; G. Bracco; C. Breton; C. de Michelis; J. Druaux; M. Mattioli; R. Oberson; J. Ramette

1982-01-01

414

Thermal Management of High Power Devices  

Microsoft Academic Search

We report in this paper the thermal effects onto the performances of high power microwave transistors. Also, thermal simulation results along with means to optimize the heat dissipation on a wafer level are discussed. Finally we present a novel active thermal management technique using micro-fluidic channels. The simple fabrication process is presented. I. INTRODUCTION Due to the tremendous evolution of

J. Laskar; S. Nuttinck; S. Pinel

415

Materials issues in high power accelerators  

Microsoft Academic Search

High power accelerators present a broad array of materials issues for scientists and design engineers. Some materials considerations are unique to accelerators per se, or to a particular accelerator. For example, high intensity stress waves and the resulting cavitation erosion in heavy liquid metal targets may occur where the sharpness of the beam pulse produces shock by thermal expansion. Other

Louis K. Mansur; Louis K

2006-01-01

416

A high power linear solid state pulser  

Microsoft Academic Search

Particle accelerators usually require high voltage and high power. Typically, the high voltage\\/power generation utilizes a topology with an energy store and switching mechanisms to extract that stored energy. The switches may be active or passive devices. Active switches are hard or soft vacuum tubes, or semiconductors. When required voltages exceed tens of kilovolts, numerous semiconductors are stacked to withstand

Boris Yen; Brent Davis; Rex Booth

1999-01-01

417

IGBT driver chipset for high power applications  

Microsoft Academic Search

Power electronics systems in the 600 V to 1700 V range are commonly used in motor drive, power supply and power conversion applications. An integrated chipset is presented for application in IGBT high power systems. It has flexible controller ICs on the primary side and strong driver ICs on the secondary side. The whole system is arranged so that pulse

R. Herzer; S. Pawel; J. Lehmann

2002-01-01

418

Laser surface alloying of silicon into aluminum casting alloys  

Microsoft Academic Search

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:yttrium-aluminum-garnet laser with fiber-optic beam delivery was used

Zhiyue Xu; Keng H. Leong; Paul G. Sanders

2000-01-01

419

Aluminum Wire Array Experiments on the Z Generator  

NASA Astrophysics Data System (ADS)

Wire array Z-pinches consisting of Al wires are a bright source of >1 keV emission. We discuss data from recent experiments with large diameter Al wire array Z-pinches on the Z generator. Wire arrays at 40mm, 50mm and 65mm were imploded on the Z generator. Soft x-ray self-emission imaging is used to study the implosion dynamics. Spectroscopy is used to diagnose plasma conditions as material stagnates on the axis. Data indicates significant free-bound continuum emission is present. We will discuss the variation in plasma conditions and emission characteristics as the initial wire array setup is varied.

Ampleford, D. J.; Hansen, S. B.; Jennings, C. A.; Jones, B.; Cuneo, M. E.; Clark, R. W.; Chong, Y. K.; Apruzese, J.; Giuliani, J. L.

2012-10-01

420

Aluminum Boats  

NSDL National Science Digital Library

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

Center, Reuben H.

1999-01-01

421

High-power and superpower Cerenkov masers  

SciTech Connect

The linear and nonlinear theory of the efficient operation of high-power (gigawatt) and superpower (50 GW) Cerenkov masers is developed and discussed. Important technology issues such as breakdown, plasma production, and coupling to the output device are discussed. The relative merits of dielectric Cerenkov masers (DCM's) and plasma Cerenkov masers (PCM's) are considered. The principal design tool is a new particle simulation model that has been developed to investigate Cerenkov masers. The novel aspects of this model are briefly described along with a comparison of calculated and experimental results. The agreement between calculations and measurements is generally good. Finally, designs for a high-power and superpower PCM are described. These generators are compact and efficient (10- to 20- percent conversion from beam energy to microwave energy).

De Groot, J.S.; Stone, R.A.; Mizuno, K.; Rogers, J.H.; Pointon, T.D.

1988-04-01

422

High Power Disk Loaded Guide Load  

SciTech Connect

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

Farkas, Z.D.; /SLAC

2006-02-22

423

New high power linacs and beam physics  

SciTech Connect

New high-power proton linacs must be designed to control beam loss, which can lead to radioactivation of the accelerator. The threat of beam loss is increased significantly by the formation of beam halo. Numerical simulation studies have identified the space-charge interactions, especially those that occur in rms mismatched beams, as a major concern for halo growth. The maximum-amplitude predictions of the simulation codes must be subjected to independent tests to confirm the validity of the results. Consequently, the authors compare predictions from the particle-core halo models with computer simulations to test their understanding of the halo mechanisms that are incorporated in the computer codes. They present and discuss scaling laws that provide guidance for high-power linac design.

Wangler, T.P.; Gray, E.R.; Nath, S. [Los Alamos National Lab., NM (United States); Crandall, K.R. [Amparo Corp., Santa Fe, NM (United States); Hasegawa, K. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan)

1997-08-01

424

Hollow fibers for high-power lasers  

Microsoft Academic Search

Hollow fibers for variety of IR lasers are introduced. FOr delivery of IR lasers represented by CO2, Er:YAG, and Nd:YAG lasers, hollow fibers having a dielectric and a silver film on the inside of glass tubing have been developed. It is shown that the fibers transmit high-powered laser light with low attenuation due to the interference effect of the internal

Yuji Matsuura; Mitsunobu Miyagi

1999-01-01

425

Space Applications of High-Power Microwaves  

Microsoft Academic Search

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

James Benford

2008-01-01

426

New high power linacs and beam physics  

Microsoft Academic Search

New high-power proton linacs must be designed to control beam loss, which can lead to radioactivation of the accelerator. The threat of beam loss is increased significantly by the formation of beam halo. Numerical simulation studies have identified the space-charge interactions, especially those that occur in rms mismatched beams, as a major concern for halo growth. The maximum-amplitude predictions of

T. P. Wangler; E. R. Gray; S. Nath; K. R. Crandall; K. Hasegawa

1997-01-01

427

Rotating target for high power neutral beams  

NASA Astrophysics Data System (ADS)

For the development of 160 keV neutral deuterium beams, needed for the plasma heating in JET, a test bed was constructed in our laboratory at FAR. An important element of the test bed is a rotating target which can handle high power beams (~ 5 MW) with power densities up to 20 kW/cm2 for long pulse operation (~ 10 s). Here we describe the rotating target and its long term operation.

Becherer, R.

1986-02-01

428

Adaptive optics and high power pulse lasers  

NASA Astrophysics Data System (ADS)

Some peculiarities of the use of adaptive optical elements and the whole system to correct for the aberrations of high power single pulse lasers are discussed in this paper. The examples of the use of adaptive system to correct for the aberrations of some lasers are presented. As a corrector we used bimorph multi electrode deformable mirror while as a sensor - Shack- Hartmann wavefront sensor.

Kudryashov, Alexis; Alexandrov, Alexander; Zavalova, Valentina; Rukosuev, Alexey; Samarkin, Vadim

2007-05-01

429

Industrial Applications of High Power Ultrasonics  

Microsoft Academic Search

\\u000a Since the change of the millennium, high-power ultrasound has become an alternative food processing technology applicable\\u000a to large-scale commercial applications such as emulsification, homogenization, extraction, crystallization, dewatering, low-temperature\\u000a pasteurization, degassing, defoaming, activation and inactivation of enzymes, particle size reduction, extrusion, and viscosity\\u000a alteration. This new focus can be attributed to significant improvements in equipment design and efficiency during the late

Alex Patist; Darren Bates

2011-01-01

430

Space applications of high power microwaves  

Microsoft Academic Search

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

James Benford

2007-01-01

431

High-power, high-efficiency FELs  

SciTech Connect

High power, high efficiency FELs require tapering, as the particles loose energy, so as to maintain resonance between the electromagnetic wave and the particles. They also require focusing of the particles (usually done with curved pole faces) and focusing of the electromagnetic wave (i.e. optical guiding). In addition, one must avoid transverse beam instabilities (primarily resistive wall) and longitudinal instabilities (i.e sidebands). 18 refs., 7 figs., 3 tabs.

Sessler, A.M.

1989-04-01

432

A high power gold vapor laser  

Microsoft Academic Search

A high-power gold vapor laser emitting 20 watts at the 627.8 nm line for an input power of 15.7 kW is described. The laser head can withstand a temperature of 1730 C. Fee expansion or shrinkage of the internal laser tube is allowed in order to prevent mechanical stress on the laser tube. The electrical circuit is a capacitor transfer

S. Gabay; I. Hen; M. Lando

1990-01-01

433

High-power ultrawideband radiation source  

Microsoft Academic Search

The article presents a source producing high-power ultrawideband electromagnetic pulses. The source includes a generator of monopolar pulses, a bipolar pulse former, and a combined ultrawideband transmitting antenna. Monopolar 150-kV, 4.5-ns pulses are transformed into bipolar 120-kV, 1-ns pulses, which are emitted by the antenna. The pulse repetition rate of the setup is up to 100 Hz. The peak power

Yu. A. Andreev; V. P. Gubanov; A. M. Efremov; V. I. Koshelev; S. D. Korovin; B. M. Kovalchuk; V. V. Kremnev; V. V. Plisko; A. S. Stepchenko; K. N. Sukhushin

2003-01-01

434

Advanced High Power Proton Linac for ATW  

Microsoft Academic Search

A high-efficiency high-power proton linac has been designed for driving an ATW (Accelerator Transmutation of Nuclear Waste) plant. The linac design is derived from the integrated Normal-Conducting\\/Superconducting machine architecture that has been developed for APT (Accelerator Production of Tritium), but there is an increased emphasis on high electric power efficiency and compact size. Nominal beam parameters are 40 mA CW

George Lawrence

1998-01-01

435

Silicon carbide high-power devices  

Microsoft Academic Search

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

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

1996-01-01

436

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

437

Cockpit Protection Analysis against High Power Microwave  

Microsoft Academic Search

A model of high power microwave (HPM) with multiple parameters is brought forward, a calculation method of electromagnetic transmission rate and reflectivity is proposed, a finite-difference time-domain (FDTD) film algorithm is set forth, a shielded cockpit glass construction is designed by a new flow, and protective effect analysis on military aircraft's cockpit against HPM is carried out on a 3D

Jun Huang; Yun-an Hu; Hao-ran Zhang; Yan Jin

2010-01-01

438

Advanced characterization techniques for high power VCSELs  

NASA Astrophysics Data System (ADS)

The performance of high power VCSELs in a specific application depends on the geometrical and thermal design as well as on the quality of the epitaxially grown material. Due to the relatively high heat load in densely packed high power arrays the temperature in the active zone and the DBR mirrors changes significantly with the applied current and the traditional characterization methods become less meaningful than for low power devices. This paper presents a method to measure temperature independent power curves with the help of short pulse techniques and data mapping at different heat sink temperatures. In addition the internal quantum efficiency, the transparency current and the gain coefficient are measured by a novel method which operates the VCSEL material as an edge emitter and applies a cut-back technique. The optical losses in the DBR mirrors are determined using external feedback. In summary all relevant parameters which determine the quality of an epitaxial design are measured independently and can be directly compared with modeling and help to optimize the high power VCSEL performance.

Moench, Holger; Baier, Johannes; Gronenborn, Stephan; Kolb, Johanna; Miller, Michael; Pekarski, Pavel; Schemmann, Marcel; Valster, Adriaan

2010-02-01