Preliminary experimental results of tungsten wire-array Z-pinches on primary test stand

Energy Technology Data Exchange (ETDEWEB)

Huang, Xian-Bin; Zhou, Shao-Tong; Dan, Jia-Kun; Ren, Xiao-Dong, E-mail: amosrxd@163.com; Wang, Kun-Lun; Zhang, Si-Qun; Li, Jing; Xu, Qiang; Cai, Hong-Chun; Duan, Shu-Chao; Ouyang, Kai; Chen, Guang-Hua; Ji, Ce; Wei, Bing; Feng, Shu-Ping; Wang, Meng; Xie, Wei-Ping; Deng, Jian-Jun [Key Laboratory of Pulsed Power, Institute of Fluid Physics, China Academy of Engineering Physics, P.O. Box 919-108, Mianyang, Sichuan 621999 (China); Zhou, Xiu-Wen; Yang, Yi [Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-987, Mianyang, Sichuan 621999 (China)

2015-07-15

The Primary Test Stand (PTS) developed at the China Academy of Engineering Physics is a 20 TW pulsed power driver, which can deliver a ∼10 MA, 70 ns rise-time (10%–90%) current to a short-circuit load and has important applications in Z-pinch driven inertial confinement fusion and high energy density physics. Preliminary results of tungsten wire-array Z-pinch experiments on PTS are presented. The load geometries investigated include 15-mm-tall cylindrical single and nested arrays with diameter ranging from 13 mm to 30 mm, consisting of 132–300 tungsten wires with 5–10 μm in diameter. Multiple diagnostics were fielded to characterize the x-ray radiation from wire-array Z pinches. The x-ray peak power (∼50 TW) and total radiated energy (∼500 kJ) were obtained from a single 20-mm-diam array with 80-ns stagnation time. The highest x-ray peak power up to 80 TW with 2.4 ns FWHM was achieved by using a nested array with 20-mm outer diameter, and the total x-ray energy from the nested array is comparable to that of single array. Implosion velocity estimated from the time-resolved image measurement exceeds 30 cm/μs. The detailed experimental results and other findings are presented and discussed.

A tentative opinion of modeling plasma formation in metallic wire Z pinch

International Nuclear Information System (INIS)

Ding Ning

2002-01-01

Numerous experiments in both single wire and in wire arrays have attracted much attention. For the wire array Z-pinch implosions the plasma formation in the metallic wire Z pinches is a key question. By means of analyzing a number of single-wire and multi-wire experiments, two models to describe the behavior of a wire array Z-pinch in initial phase are suggested. In this phase each wire carries a rising current and behaves independently in a way similar to that found in single wire Z-pinch experiments in which a comparable current in one wire is employed. Based on one- or/and two-dimensional magnetohydrodynamics (MHD) theory, one model is used to simulate the electrical explosion stage of the metallic wire, another is used to simulate the wire-plasma formation stage

Plasma dynamics in aluminium wire array Z-pinch implosions

International Nuclear Information System (INIS)

Bland, S.N.

2001-01-01

The wire array Z-pinch is the world's most powerful laboratory X-ray source. An achieved power of ∼280TW has generated great interest in the use of these devices as a source of hohlraum heating for inertial confinement fusion experiments. However, the physics underlying how wire array Z-pinches implode is not well understood. This thesis presents the first detailed measurements of plasma dynamics in wire array experiments. The MAGPIE generator, with currents of up to 1.4MA, 150ns 10-90% rise-time, was used to implode arrays of 16mm diameter typically containing between 8 and 64 15μm aluminium wires. Diagnostics included: end and side-on laser probing with interferometry, schlieren and shadowgraphy channels; radial and axial streak photography; gated X-ray imaging; XUV and hard X-ray spectrometry; filtered XRDs and diamond PCDs; and a novel X-ray backlighting system to probe high density plasma. It was found that the plasma formed from the wires consisted of cold, dense cores, which ablated producing hot, low density coronal plasma. After an initial acceleration around the cores, coronal plasma streams flowed force-free towards the axis, with an instability wavelength determined by the core size. At ∼50% of the implosion time, the streams collided on axis forming a precursor plasma which appeared to be uniform, stable, and inertially confined. The existence of core-corona structure significantly affected implosion dynamics. For arrays with <64 wires, the wire cores remained in their original positions until ∼80% of the implosion time before accelerating rapidly. At 64 wires a transition in implosion trajectories to 0-D like occurred indicating a possible merger of current carrying plasma close to the cores - the cores themselves did not merge. During implosion, the cores initially developed uncorrelated instabilities that then transformed into a longer wavelength global mode of instability. The study of nested arrays (2 concentric arrays, one inside the other

Fast commutation of high current in double wire array Z-pinch loads

International Nuclear Information System (INIS)

Davis, J.; Gondarenko, N.A.; Velikovich, A.L.

1997-01-01

A dynamic model of multi-MA current commutation in a double wire array Z-pinch load is proposed and studied theoretically. Initially, the load is configured as nested concentric wire arrays, with the current driven through the outer array and imploding it. Once the outer array or the annular plasma shell formed from it approaches the inner array, the imploded plasma might penetrate through the gaps between the wires, but the azimuthal magnetic field is trapped due to both the high conductivity of the inner wires and the inductive coupling between the two parts of the array, causing a rapid switching of the total current to the inner part of the array. copyright 1997 American Institute of Physics

3D MHD Simulations of Radial Wire Array Z-pinches

International Nuclear Information System (INIS)

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

2009-01-01

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

Effects of Mass Ablation on the Scaling of X-Ray Power with Current in Wire-Array Z Pinches

International Nuclear Information System (INIS)

Lemke, R. W.; Sinars, D. B.; Waisman, E. M.; Cuneo, M. E.; Yu, E. P.; Haill, T. A.; Hanshaw, H. L.; Brunner, T. A.; Jennings, C. A.; Stygar, W. A.; Desjarlais, M. P.; Mehlhorn, T. A.; Porter, J. L.

2009-01-01

X-ray production by imploding wire-array Z pinches is studied using radiation magnetohydrodynamics simulation. It is found that the density distribution created by ablating wire material influences both x-ray power production, and how the peak power scales with applied current. For a given array there is an optimum ablation rate that maximizes the peak x-ray power, and produces the strongest scaling of peak power with peak current. This work is consistent with trends in wire-array Z pinch x-ray power scaling experiments on the Z accelerator

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

International Nuclear Information System (INIS)

Jones, Brent Manley; Jennings, Christopher A.; Coverdale, Christine Anne; Cuneo, Michael Edward; Maron, Yitzhak; LePell, Paul David; Deeney, Christopher

2010-01-01

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.

Review of effects of dielectric coatings on electrical exploding wires and Z pinches

Science.gov (United States)

Wu, Jian; Li, Xingwen; Li, Mo; Li, Yang; Qiu, Aici

2017-10-01

As the most powerful x-ray source in the laboratories, the wire array Z pinches have been of great relevance to inertial confinement fusions, laboratory astrophysics, and other high-energy density applications. In order to produce x-ray with greater power and higher efficiency, the dynamics of wire array has been investigated extensively, and various methods have been proposed to improve the implosion quality of the wire array. This review focuses on the experimental and theoretical investigations regarding the effects of the dielectric coatings on electrical exploding wires and Z pinches. Since the early 2000, the electrical wire explosion related to the first stage of the wire array Z pinches has been studied extensively, and the results indicated that the dielectric coatings can significantly increase the joule energy deposition into a wire in the initial stage, and even the corona free explosion of tungsten wires can be achieved. Recently, there is an increasing interest in the dynamics of insulated wire array Z pinches. By applying dielectric coatings, the ablation process is suppressed, the x-ray start time is delayed, and the possibility of multi-peak radiation is decreased. This review is organized by the evolution dynamics of wire array Z pinches, and a broad introduction to relevant scientific concepts and various other applications are presented. According to the current research status, the challenges, opportunities and further developments of Z pinch loads using dielectric coatings are proposed to further promote the researches and their applications.

Review of effects of dielectric coatings on electrical exploding wires and Z pinches

International Nuclear Information System (INIS)

Wu, Jian; Li, Mo; Li, Yang; Li, Xingwen; Qiu, Aici

2017-01-01

As the most powerful x-ray source in the laboratories, the wire array Z pinches have been of great relevance to inertial confinement fusions, laboratory astrophysics, and other high-energy density applications. In order to produce x-ray with greater power and higher efficiency, the dynamics of wire array has been investigated extensively, and various methods have been proposed to improve the implosion quality of the wire array. This review focuses on the experimental and theoretical investigations regarding the effects of the dielectric coatings on electrical exploding wires and Z pinches. Since the early 2000, the electrical wire explosion related to the first stage of the wire array Z pinches has been studied extensively, and the results indicated that the dielectric coatings can significantly increase the joule energy deposition into a wire in the initial stage, and even the corona free explosion of tungsten wires can be achieved. Recently, there is an increasing interest in the dynamics of insulated wire array Z pinches. By applying dielectric coatings, the ablation process is suppressed, the x-ray start time is delayed, and the possibility of multi-peak radiation is decreased. This review is organized by the evolution dynamics of wire array Z pinches, and a broad introduction to relevant scientific concepts and various other applications are presented. According to the current research status, the challenges, opportunities and further developments of Z pinch loads using dielectric coatings are proposed to further promote the researches and their applications. (topical review)

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

International Nuclear Information System (INIS)

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

1997-12-01

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

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

Energy Technology Data Exchange (ETDEWEB)

SANFORD,THOMAS W. L.

2000-05-23

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.

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

International Nuclear Information System (INIS)

SANFORD, THOMAS W. L.

2000-01-01

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

Wire-array initiation and interwire-plasma merger concerns in PBFA-Z tungsten z-pinch implosions

Energy Technology Data Exchange (ETDEWEB)

Sanford, T.W.L.; Spielman, R.B.; Allshouse, G.O. [Sandia National Labs., Albuquerque, NM (United States)] [and others

1997-12-31

Experiments with annular wire-array loads to generate high quality, high-power, z-pinch implosions on Saturn have shown the importance of maintaining azimuthal symmetry and how the individual wire plasmas merge to form a plasma shell. Here the authors discuss the impact of current symmetry, current prepulse, interwire spacing, and wire size on generating high-quality, high-power, z-pinch implosions on PBFA-Z, with annular tungsten wire loads. B-dot monitors measured the current as a function of azimuth in the MITLs and 4.5 cm upstream of the load. Bolometers and filtered XRDs and PCDs, spanning the energy range {approximately} 0 eV to 6 keV, monitored the temporal characteristics of the radiation. Time-integrated and time-resolved, filtered, fast-framing, x-ray pinhole cameras, and a crystal spectrometer monitored the spatial and spectral structure of the radiation. The radial dynamics of single-wire plasmas from the solid-state, using the measured current, was calculated by 1D radiation magnetohydrodynamics code (RMHC) and used as input to an xy RMHC. These calculations together with 2D RMHC simulations in the rz plane are discussed and correlated with the measurements.

Wire-array initiation and interwire-plasma merger concerns in PBFA-Z tungsten z-pinch implosions

International Nuclear Information System (INIS)

Sanford, T.W.L.; Spielman, R.B.; Allshouse, G.O.

1997-01-01

Experiments with annular wire-array loads to generate high quality, high-power, z-pinch implosions on Saturn have shown the importance of maintaining azimuthal symmetry and how the individual wire plasmas merge to form a plasma shell. Here the authors discuss the impact of current symmetry, current prepulse, interwire spacing, and wire size on generating high-quality, high-power, z-pinch implosions on PBFA-Z, with annular tungsten wire loads. B-dot monitors measured the current as a function of azimuth in the MITLs and 4.5 cm upstream of the load. Bolometers and filtered XRDs and PCDs, spanning the energy range ∼ 0 eV to 6 keV, monitored the temporal characteristics of the radiation. Time-integrated and time-resolved, filtered, fast-framing, x-ray pinhole cameras, and a crystal spectrometer monitored the spatial and spectral structure of the radiation. The radial dynamics of single-wire plasmas from the solid-state, using the measured current, was calculated by 1D radiation magnetohydrodynamics code (RMHC) and used as input to an xy RMHC. These calculations together with 2D RMHC simulations in the rz plane are discussed and correlated with the measurements

Multi-Dimensional Radiation Transport in Dense Z-pinch Wire Array Plasmas

Science.gov (United States)

Jennings, C. A.; Chittenden, J. P.; Ciardi, A.; Sherlock, M.; Lebedev, S. V.

2004-11-01

Z-pinch wire arrays have proven to be an extremely efficient high yield, short pulse x-ray source with potential application to ICF. The characteristics of the x-ray pulse produced have been shown to be largely determined by non-uniform break up of the wires leading to a highly irregular distribution of mass which implodes towards the axis. Modelling the inherent 3D nature of these plasmas is already computationally very expensive, and so energy exchange through radiation is frequently neglected, assuming instead an optically thin radiation loss model. With a significant fraction of the total energy at late stages being radiated through a dense, optically thick plasma this approach is potentially inadequate in fully describing the implosion. We analyse the effects of radiative cooling and radiation transport on stagnation and precursor development in wire array z-pinch implosions. A three temperature multidimensional MHD code using a single group radiation diffusion model is used to study radiation trapping in the precursor, and the effects of preheating on the implosion dynamics. Energy exchange in the final stagnated plasma and its effects on the x-ray pulse shape is also discussed. This work was partially supported by the SSAA program of the NNSA through DoE cooperative agreement DE-F03-02NA00057.

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

International Nuclear Information System (INIS)

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

2009-01-01

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

Experimental study of surface insulated-standard hybrid tungsten planar wire array Z-pinches at “QiangGuang-I” facility

Energy Technology Data Exchange (ETDEWEB)

Sheng, Liang; Peng, Bodong; Yuan, Yuan; Zhang, Mei; Zhao, Chen; Zhao, Jizhen; Wang, Liangping [State Key Laboratory of Intense Pulsed Radiation Simulation and Effect (Northwest Institute of Nuclear Technology), Xi' an 710024 (China); Li, Yang, E-mail: liyang@nint.ac.cn; Li, Mo [State Key Laboratory of Intense Pulsed Radiation Simulation and Effect (Northwest Institute of Nuclear Technology), Xi' an 710024 (China); Xi' an Jiaotong University, Xi' an 710049 (China)

2016-01-15

The experimental results of the insulated-standard hybrid wire array Z pinches carried out on “QiangGuang-I” facility at Northwest Institute of Nuclear Technology were presented and discussed. The surface insulating can impose a significant influence on the dynamics and radiation characteristics of the hybrid wire array Z pinches, especially on the early stage (t/t{sub imp} < 0.6). The expansion of insulated wires at the ablation stage is suppressed, while the streams stripped from the insulated wires move faster than that from the standard wires. The foot radiation of X-ray is enhanced by increment of the number of insulated wires, 19.6 GW, 33.6 GW, and 68.6 GW for shots 14037S, 14028H, and 14039I, respectively. The surface insulation also introduces nonhomogeneity along the single wire—the streams move much faster near the electrodes. The colliding boundary of the hybrid wire array Z pinches is bias to the insulated side approximately 0.6 mm.

Wire array Z-pinch insights for enhanced x-ray production

Energy Technology Data Exchange (ETDEWEB)

Sanford, T.W.; Mock, R.C.; Spielman, R.B. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1196 (United States); Haines, M.G.; Chittenden, J.P. [The Blackett Laboratory, Imperial College, London, SW7 2BZ (United Kingdom); Whitney, K.G.; Apruzese, J.P. [Naval Research Laboratory, Radiation Hydrodynamics Branch, Washington, D.C. 20375 (United States); Peterson, D.L. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Greenly, J.B.; Sinars, D.B. [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States); Reisman, D.B. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Mosher, D. [Naval Research Laboratory, Pulsed Power Physics Branch, Washington, D.C. 20375 (United States)

1999-05-01

Comparisons of measured total radiated x-ray power from annular wire-array {ital z}-pinches with a variety of models as a function of wire number, array mass, and load radius are reviewed. The data, which are comprehensive, have provided important insights into the features of wire-array dynamics that are critical for high x-ray power generation. Collectively, the comparisons of the data with the model calculations suggest that a number of underlying dynamical mechanisms involving cylindrical asymmetries and plasma instabilities contribute to the measured characteristics. For example, under the general assumption that the measured risetime of the total-radiated-power pulse is related to the thickness of the plasma shell formed on axis, the Heuristic Model [IEEE Trans. Plasma Sci. {bold 26}, 1275 (1998)] agrees with the measured risetime under a number of specific assumptions about the way the breakdown of the wires, the wire-plasma expansion, and the Rayleigh{endash}Taylor instability in the r{endash}z plane, develop. Likewise, in the high wire-number regime (where the wires are calculated to form a plasma shell prior to significant radial motion of the shell) the comparisons show that the variation in the power of the radiation generated as a function of load mass and array radius can be simulated by the two-dimensional Eulerian-radiation- magnetohydrodynamics code (E-RMHC) [Phys. Plasmas {bold 3}, 368 (1996)], using a single random-density perturbation that seeds the Rayleigh{endash}Taylor instability in the r{endash}z plane. For a given pulse-power generator, the comparisons suggest that (1) the smallest interwire gaps compatible with practical load construction and (2) the minimum implosion time consistent with the optimum required energy coupling of the generator to the load should produce the highest total-radiated-power levels. {copyright} {ital 1999 American Institute of Physics.}

Wire array Z-pinch insights for enhanced x-ray production

Science.gov (United States)

Sanford, T. W. L.; Mock, R. C.; Spielman, R. B.; Haines, M. G.; Chittenden, J. P.; Whitney, K. G.; Apruzese, J. P.; Peterson, D. L.; Greenly, J. B.; Sinars, D. B.; Reisman, D. B.; Mosher, D.

1999-05-01

Comparisons of measured total radiated x-ray power from annular wire-array z-pinches with a variety of models as a function of wire number, array mass, and load radius are reviewed. The data, which are comprehensive, have provided important insights into the features of wire-array dynamics that are critical for high x-ray power generation. Collectively, the comparisons of the data with the model calculations suggest that a number of underlying dynamical mechanisms involving cylindrical asymmetries and plasma instabilities contribute to the measured characteristics. For example, under the general assumption that the measured risetime of the total-radiated-power pulse is related to the thickness of the plasma shell formed on axis, the Heuristic Model [IEEE Trans. Plasma Sci. 26, 1275 (1998)] agrees with the measured risetime under a number of specific assumptions about the way the breakdown of the wires, the wire-plasma expansion, and the Rayleigh-Taylor instability in the r-z plane, develop. Likewise, in the high wire-number regime (where the wires are calculated to form a plasma shell prior to significant radial motion of the shell) the comparisons show that the variation in the power of the radiation generated as a function of load mass and array radius can be simulated by the two-dimensional Eulerian-radiation- magnetohydrodynamics code (E-RMHC) [Phys. Plasmas 3, 368 (1996)], using a single random-density perturbation that seeds the Rayleigh-Taylor instability in the r-z plane. For a given pulse-power generator, the comparisons suggest that (1) the smallest interwire gaps compatible with practical load construction and (2) the minimum implosion time consistent with the optimum required energy coupling of the generator to the load should produce the highest total-radiated-power levels.

Wire Array Z-Pinch Insights for Enhanced X-Ray Production

Energy Technology Data Exchange (ETDEWEB)

Apruzese, J.P.; Chittenden, J.P.; Greenly, J.B.; Haines, M.G.; Mock, R.C.; Mosher, D.; Peterson, D.L.; Reisman, D.B.; Sanford, T.W.L.; Sinars, D.B.; Spielman, R.B.; Whitnery, K.G.

1999-01-04

Comparisons of measured total radiated x-ray power from annular wire-array z-pinches with a variety of models as a function of wire number, array mass, and load radius are reviewed. The data, which are comprehensive, have provided important insights into the features of wire-array dynamics that are critical for high x-ray power generation. Collectively, the comparisons of the data with the model calculations suggest that a number of underlying dynamical mechanisms involving cylindrical asymmetries and plasma instabilities contribute to the measured characteristics. For example, under the general assumption that the measured risetime of the total-radiated-power pulse is related to the thickness of the plasma shell formed on axis, the Heuristic Model [IEEE Trans. Plasma Sci., 26, 1275 (1998)] agrees with the measured risetime under a number of specific assumptions about the way the breakdown of the wires, the wire-plasma expansion, and the Rayleigh-Taylor instability in the r-z plane, interact. Likewise, in the high wire-number regime (where the wires are calculated to form a plasma shell prior to significant radial motion of the shell) the comparisons show that the variation in the power of the radiation generated as a function of load mass and array radius can be simulated by the 2-D Eulerian-radiation-magnetohydrodynamics code (E-RMHC) [Phys. Plasmas 3, 368 (1996)], using a single random-density perturbation that seeds the Rayleigh-Taylor instability in the r-z plane. For a given pulse-power generator, the comparisons suggest that (1) the smallest interwire gaps compatible with practical load construction and (2) the minimum implosion time consistent with the optimum required energy coupling of the generator to the load should produce the highest total-radiated-power levels.

Wire array Z-pinch insights for enhanced x-ray production

International Nuclear Information System (INIS)

Sanford, T.W.; Mock, R.C.; Spielman, R.B.; Haines, M.G.; Chittenden, J.P.; Whitney, K.G.; Apruzese, J.P.; Peterson, D.L.; Greenly, J.B.; Sinars, D.B.; Reisman, D.B.; Mosher, D.

1999-01-01

Comparisons of measured total radiated x-ray power from annular wire-array z-pinches with a variety of models as a function of wire number, array mass, and load radius are reviewed. The data, which are comprehensive, have provided important insights into the features of wire-array dynamics that are critical for high x-ray power generation. Collectively, the comparisons of the data with the model calculations suggest that a number of underlying dynamical mechanisms involving cylindrical asymmetries and plasma instabilities contribute to the measured characteristics. For example, under the general assumption that the measured risetime of the total-radiated-power pulse is related to the thickness of the plasma shell formed on axis, the Heuristic Model [IEEE Trans. Plasma Sci. 26, 1275 (1998)] agrees with the measured risetime under a number of specific assumptions about the way the breakdown of the wires, the wire-plasma expansion, and the Rayleigh - Taylor instability in the r - z plane, develop. Likewise, in the high wire-number regime (where the wires are calculated to form a plasma shell prior to significant radial motion of the shell) the comparisons show that the variation in the power of the radiation generated as a function of load mass and array radius can be simulated by the two-dimensional Eulerian-radiation- magnetohydrodynamics code (E-RMHC) [Phys. Plasmas 3, 368 (1996)], using a single random-density perturbation that seeds the Rayleigh - Taylor instability in the r - z plane. For a given pulse-power generator, the comparisons suggest that (1) the smallest interwire gaps compatible with practical load construction and (2) the minimum implosion time consistent with the optimum required energy coupling of the generator to the load should produce the highest total-radiated-power levels. copyright 1999 American Institute of Physics

Wire Array Z-Pinch Insights for Enhanced X-Ray Production

International Nuclear Information System (INIS)

Apruzese, J.P.; Chittenden, J.P.; Greenly, J.B.; Haines, M.G.; Mock, R.C.; Mosher, D.; Peterson, D.L.; Reisman, D.B.; Sanford, T.W.L.; Sinars, D.B.; Spielman, R.B.; Whitnery, K.G.

1999-01-01

Comparisons of measured total radiated x-ray power from annular wire-array z-pinches with a variety of models as a function of wire number, array mass, and load radius are reviewed. The data, which are comprehensive, have provided important insights into the features of wire-array dynamics that are critical for high x-ray power generation. Collectively, the comparisons of the data with the model calculations suggest that a number of underlying dynamical mechanisms involving cylindrical asymmetries and plasma instabilities contribute to the measured characteristics. For example, under the general assumption that the measured risetime of the total-radiated-power pulse is related to the thickness of the plasma shell formed on axis, the Heuristic Model [IEEE Trans. Plasma Sci., 26, 1275 (1998)] agrees with the measured risetime under a number of specific assumptions about the way the breakdown of the wires, the wire-plasma expansion, and the Rayleigh-Taylor instability in the r-z plane, interact. Likewise, in the high wire-number regime (where the wires are calculated to form a plasma shell prior to significant radial motion of the shell) the comparisons show that the variation in the power of the radiation generated as a function of load mass and array radius can be simulated by the 2-D Eulerian-radiation-magnetohydrodynamics code (E-RMHC) [Phys. Plasmas 3, 368 (1996)], using a single random-density perturbation that seeds the Rayleigh-Taylor instability in the r-z plane. For a given pulse-power generator, the comparisons suggest that (1) the smallest interwire gaps compatible with practical load construction and (2) the minimum implosion time consistent with the optimum required energy coupling of the generator to the load should produce the highest total-radiated-power levels

X-ray backlighting of two-wire Z-pinch plasma using X-pinch

International Nuclear Information System (INIS)

Tong, Zhao; Xiao-Bing, Zou; Ran, Zhang; Xin-Xin, Wang

2010-01-01

Two 50-μm Mo wires in parallel used as a Z-pinch load are electrically exploded with a pulsed current rising to 275 kA in 125 ns and their explosion processes are backlighted using an X-pinch as an x-ray source. The backlighting images show clearly the processes similar to those occurring in the initial stages of a cylindrical wire-array Z-pinch, including the electric explosion of single wires characterised by the dense wire cores surrounded by a low-density coronal plasma, the expansion of the exploding wire, the sausage instability (m = 0) in the coronal plasma around each wire, the motion of the coronal plasma as well as the wire core toward the current centroid, the formation of the precursor plasma column with a twist structure something like that of higher mode instability, especially the kink instability (m = 1). (fluids, plasmas and electric discharges)

Spatially resolved single crystal x-ray spectropolarimetry of wire array z-pinch plasmas.

Science.gov (United States)

Wallace, M S; Haque, S; Neill, P; Pereira, N R; Presura, R

2018-01-01

A recently developed single-crystal x-ray spectropolarimeter has been used to record paired sets of polarization-dependent and axially resolved x-ray spectra emitted by wire array z-pinches. In this measurement, two internal planes inside a suitable crystal diffract the x-rays into two perpendicular directions that are normal to each other, thereby separating incident x-rays into their linearly polarized components. This paper gives considerations for fielding the instrument on extended sources. Results from extended sources are difficult to interpret because generally the incident x-rays are not separated properly by the crystal. This difficulty is mitigated by using a series of collimating slits to select incident x-rays that propagate in a plane of symmetry between the polarization-splitting planes. The resulting instrument and some of the spatially resolved polarized x-ray spectra recorded for a 1-MA aluminum wire array z-pinch at the Nevada Terawatt Facility at the University of Nevada, Reno will be presented.

Symmetric aluminum-wire arrays generate high-quality Z pinches at large array radii

International Nuclear Information System (INIS)

Sanford, T.W.; Mock, R.C.; Spielman, R.B.; Peterson, D.L.; Mosher, D.; Roderick, N.F.

1998-01-01

A Saturn-accelerator study of annular, aluminum-wire array, Z-pinch implosions, in the calculated high-wire-number plasma-shell regime [Phys. Rev. Lett. 77, 5063 (1996)], shows that the radiated x-ray pulse width increases from about 4 nsec to about 7 nsec, when the radius of the array is increased from 8.75 to 20 mm at a fixed array mass of 0.6 mg. Eulerian radiation- magnetohydrodynamic code (E-RMHC) simulations in the r-z plane suggest that this pulse-width increase with radius is due to the faster growth of the shell thickness (that arises from a two-stage development in the magnetic Rayleigh - Taylor instability) relative to the increase in the shell implosion velocity. Over the array radii explored, the measured peak total x-ray power of ∼40 TW and energy of ∼325 kJ show little change outside of a ±15% shot-to-shot fluctuation and are consistent with the E-RMHC simulations. Similarly, the measured peak K-shell (lines plus continuum) power of ∼8 TW and energy of ∼70 kJ show little change with radius. The minimal change in K-shell yield is in agreement with simple K-shell radiation scaling models that assume a fixed radial compression for all initial array radii. These results suggest that the improved uniformity provided by the large number of wires in the initial array reduces the disruptive effects of the Rayleigh - Taylor instability observed in small-wire-number imploding loads. copyright 1998 American Institute of Physics

Symmetric aluminum-wire arrays generate high-quality Z pinches at large array radii

Science.gov (United States)

Sanford, T. W. L.; Mock, R. C.; Spielman, R. B.; Peterson, D. L.; Mosher, D.; Roderick, N. F.

1998-10-01

A Saturn-accelerator study of annular, aluminum-wire array, Z-pinch implosions, in the calculated high-wire-number plasma-shell regime [Phys. Rev. Lett. 77, 5063 (1996)], shows that the radiated x-ray pulse width increases from about 4 nsec to about 7 nsec, when the radius of the array is increased from 8.75 to 20 mm at a fixed array mass of 0.6 mg. Eulerian radiation- magnetohydrodynamic code (E-RMHC) simulations in the r-z plane suggest that this pulse-width increase with radius is due to the faster growth of the shell thickness (that arises from a two-stage development in the magnetic Rayleigh-Taylor instability) relative to the increase in the shell implosion velocity. Over the array radii explored, the measured peak total x-ray power of ˜40 TW and energy of ˜325 kJ show little change outside of a ±15% shot-to-shot fluctuation and are consistent with the E-RMHC simulations. Similarly, the measured peak K-shell (lines plus continuum) power of ˜8 TW and energy of ˜70 kJ show little change with radius. The minimal change in K-shell yield is in agreement with simple K-shell radiation scaling models that assume a fixed radial compression for all initial array radii. These results suggest that the improved uniformity provided by the large number of wires in the initial array reduces the disruptive effects of the Rayleigh-Taylor instability observed in small-wire-number imploding loads.

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

Science.gov (United States)

Calamy, H.; Hamann, F.; Lassalle, F.; Bayol, F.; Mangeant, C.; Morell, A.; Huet, D.; Bedoch, J. P.; Chittenden, J. P.; Lebedev, S. V.; Jennings, C. A.; Bland, S. N.

2006-01-01

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

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

International Nuclear Information System (INIS)

Calamy, H.; Hamann, F.; Lassalle, F.; Bayol, F.; Mangeant, C.; Morell, A.; Huet, D.; Bedoch, J.P.; Chittenden, J.P.; Lebedev, S.V.; Jennings, C.A.; Bland, S.N.

2006-01-01

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

3D modeling of instabilities in multi-wire Z pinches

International Nuclear Information System (INIS)

Haill, T.A.; Desjarlais, M.P.; Marder, B.M.; Robinson, A.C.

1998-01-01

Recent success in generating large x-ray energies and powers from large wire-number Z pinch arrays has revived a strong interest in MHD and magneto-Rayleigh-Taylor (RT) instabilities. Two-dimensional r-z simulations of Z pinches typically start calculations with a preformed plasma sheath and seed RT instabilities with a random density perturbation. The magnitude of the random density perturbation is tuned so that the calculated x-ray radiation pulse matches the amplitude and pulse-width of experimentally measured data. While these calculations have been extremely useful in understanding the effect of RT instabilities on experiments, they do not capture all of the three-dimension structure seen in experimental images and are not truly predictive in nature. To remedy this shortcoming Sandia is developing a 3D nature of Z pinch dynamics, namely the merger of arrays of wires into a plasma sheath

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-03-15

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

Symmetric aluminum-wire arrays generate high-quality Z pinches at large array radii

Energy Technology Data Exchange (ETDEWEB)

Sanford, T.W.; Mock, R.C.; Spielman, R.B. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States); Peterson, D.L. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545-0010 (United States); Mosher, D. [Naval Research Laboratory, Pulsed Power Physics Branch, Washington, DC 20375 (United States); Roderick, N.F. [University of New Mexico, Albuquerque, New Mexico 87131 (United States)

1998-10-01

A Saturn-accelerator study of annular, aluminum-wire array, Z-pinch implosions, in the calculated high-wire-number plasma-shell regime [Phys. Rev. Lett. {bold 77}, 5063 (1996)], shows that the radiated x-ray pulse width increases from about 4 nsec to about 7 nsec, when the radius of the array is increased from 8.75 to 20 mm at a fixed array mass of 0.6 mg. Eulerian radiation- magnetohydrodynamic code (E-RMHC) simulations in the r-z plane suggest that this pulse-width increase with radius is due to the faster growth of the shell thickness (that arises from a two-stage development in the magnetic Rayleigh{endash}Taylor instability) relative to the increase in the shell implosion velocity. Over the array radii explored, the measured peak total x-ray power of {approximately}40 TW and energy of {approximately}325 kJ show little change outside of a {plus_minus}15{percent} shot-to-shot fluctuation and are consistent with the E-RMHC simulations. Similarly, the measured peak {ital K}-shell (lines plus continuum) power of {approximately}8 TW and energy of {approximately}70 kJ show little change with radius. The minimal change in {ital K}-shell yield is in agreement with simple {ital K}-shell radiation scaling models that assume a fixed radial compression for all initial array radii. These results suggest that the improved uniformity provided by the large number of wires in the initial array reduces the disruptive effects of the Rayleigh{endash}Taylor instability observed in small-wire-number imploding loads. {copyright} {ital 1998 American Institute of Physics.}

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

Energy Technology Data Exchange (ETDEWEB)

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

1996-08-01

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

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

International Nuclear Information System (INIS)

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

1996-08-01

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

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

International Nuclear Information System (INIS)

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

2014-01-01

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

Energy transformation in Z-pinch and plasma focus discharges with wire and wire-in-liner loads

International Nuclear Information System (INIS)

Kubes, Pavel; Kravarik, Jozef; Klir, 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.

2002-01-01

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 discussed 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

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

International Nuclear Information System (INIS)

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

1996-01-01

A systematic experimental study of annular aluminum-wire z-pinches on the Saturn accelerator shows that, for the first time, the measured spatial characteristics and x-ray powers can approach those of two-dimensional, radiation-magneto-hydrodynamic simulations when large numbers of wires are used. Calculations show that the implosion begins to transition from that of individual plasma wires to that of a continuous plasma shell, when the circumferential gap between wires in the array is reduced below 1.4 +1.3/-0.7 mm. This calculated gap coincides with the measured transition of 1.4 ± 0.4 mm between the observed regimes of slow and rapid improvement in power output with decreasing gap. In the plasma-shell regime, x-ray powers in excess of a factor of three over that generated in the plasma-wire region are measured. (author). 5 figs., 16 refs

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

Energy Technology Data Exchange (ETDEWEB)

Sanford, T W.L.; Allshouse, G O; Marder, B M [Sandia Labs., Albuquerque, NM (United States); and others

1997-12-31

A systematic experimental study of annular aluminum-wire z-pinches on the Saturn accelerator shows that, for the first time, the measured spatial characteristics and x-ray powers can approach those of two-dimensional, radiation-magneto-hydrodynamic simulations when large numbers of wires are used. Calculations show that the implosion begins to transition from that of individual plasma wires to that of a continuous plasma shell, when the circumferential gap between wires in the array is reduced below 1.4 +1.3/-0.7 mm. This calculated gap coincides with the measured transition of 1.4 {+-} 0.4 mm between the observed regimes of slow and rapid improvement in power output with decreasing gap. In the plasma-shell regime, x-ray powers in excess of a factor of three over that generated in the plasma-wire region are measured. (author). 5 figs., 16 refs.

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

Energy Technology Data Exchange (ETDEWEB)

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

1997-12-01

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

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

International Nuclear Information System (INIS)

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

1997-01-01

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

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

Science.gov (United States)

Sanford, T. W. L.; Mock, R. C.; Marder, B. M.; Nash, T. J.; Spielman, R. B.; Peterson, D. L.; Roderick, N. F.; Hammer, J. H.; De Groot, J. S.; Mosher, D.; Whitney, K. G.; Apruzese, J. P.

1997-05-01

A systematic study of annular aluminum-wire z-pinches on the Saturn accelerator shows that the quality of the implosion, (as measured by the radial convergence, the radiated energy, pulse width, and power), increases with wire number. Radiation magnetohydrodynamic (RMHC) xy simulations suggest that the implosion transitions from that of individual wire plasmas to that of a continuous plasma shell when the interwire spacing is reduced below ˜1.4 mm. In this "plasma-shell regime," many of the global radiation and plasma characteristics are in agreement with those simulated by 2D-RMHC rz simulations. In this regime, measured changes in the radiation pulse width with variations in load mass and array radius are consistent with the simulations and are explained by the development of 2D fluid motion in the rz plane. Associated variations in the K-shell yield are qualitatively explained by simple radiation-scaling models.

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

International Nuclear Information System (INIS)

Sanford, T. W. L.; Mock, R. C.; Marder, B. M.; Nash, T. J.; Spielman, R. B.; Peterson, D. L.; Roderick, N. F.; Hammer, J. H.; De Groot, J. S.; Mosher, D.; Whitney, K. G.; Apruzese, J. P.

1997-01-01

A systematic study of annular aluminum-wire z-pinches on the Saturn accelerator shows that the quality of the implosion, (as measured by the radial convergence, the radiated energy, pulse width, and power), increases with wire number. Radiation magnetohydrodynamic (RMHC) xy simulations suggest that the implosion transitions from that of individual wire plasmas to that of a continuous plasma shell when the interwire spacing is reduced below ∼1.4 mm. In this ''plasma-shell regime,'' many of the global radiation and plasma characteristics are in agreement with those simulated by 2D-RMHC rz simulations. In this regime, measured changes in the radiation pulse width with variations in load mass and array radius are consistent with the simulations and are explained by the development of 2D fluid motion in the rz plane. Associated variations in the K-shell yield are qualitatively explained by simple radiation-scaling models

The effects of insulating coatings and current prepulse on tungsten planar wire array Z-pinches

Energy Technology Data Exchange (ETDEWEB)

Li, M., E-mail: limo@nint.ac.cn; Li, Y. [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Shaanxi 710049 (China); State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Sheng, L.; Wang, L. P.; Zhao, C.; Yuan, Y.; Zhang, X. J.; Zhang, M.; Peng, B. D.; Zhang, J. H.; Zhang, S. G.; Qiu, M. T. [State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Li, X. W. [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Shaanxi 710049 (China)

2015-12-15

This paper presents experimental results on the effects of insulating coatings and current prepulse on tungsten planar wire array Z-pinches on ∼100 ns main current facility. Optical framing images indicated that without a current prepulse the wire ablation process was asymmetrical and the implosion was zippered. The x-ray peak power was ∼320 GW. By using insulating coatings on the wire surface the asymmetry remained, and the processes of ablation and implosion were delayed by ∼30 ns. The x-ray burst was narrow and decreased to ∼200 GW. When current prepulses were used on both standard and insulated wire arrays, implosion symmetry was improved and the x-ray burst was improved (to ∼520 GW peak power). In addition, there was a strong emitting precursor column for insulated loads with the current prepulse.

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

Energy Technology Data Exchange (ETDEWEB)

Sanford, T.W.; Mock, R.C.; Marder, B.M.; Nash, T.J.; Spielman, R.B. [Sandia National Laboratories, Albuquerque, New Mexico87185 (United States); Peterson, D.L.; Roderick, N.F. [Los Alamos National Laboratory, Los Alamos, New Mexico87545 (United States); Hammer, J.H.; De Groot, J.S. [Lawrence Livermore National Laboratory, Livermore, California94550 (United States); Mosher, D. [Naval Research Laboratory, Pulsed Power Physics Branch, Washington, District of Columbia20375 (United States); Whitney, K.G.; Apruzese, J.P. [Naval Research Laboratory, Radiation Hydrodynamics Branch, Washington, District of Columbia20375 (United States)

1997-05-01

A systematic study of annular aluminum-wire z-pinches on the Saturn accelerator shows that the quality of the implosion, (as measured by the radial convergence, the radiated energy, pulse width, and power), increases with wire number. Radiation magnetohydrodynamic (RMHC) xy simulations suggest that the implosion transitions from that of individual wire plasmas to that of a continuous plasma shell when the interwire spacing is reduced below {approximately}1.4mm. In this {open_quotes}plasma-shell regime,{close_quotes} many of the global radiation and plasma characteristics are in agreement with those simulated by 2D-RMHC rz simulations. In this regime, measured changes in the radiation pulse width with variations in load mass and array radius are consistent with the simulations and are explained by the development of 2D fluid motion in the rz plane. Associated variations in the K-shell yield are qualitatively explained by simple radiation-scaling models. {copyright} {ital 1997 American Institute of Physics.}

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

International Nuclear Information System (INIS)

Sanford, T.W.; Mock, R.C.; Marder, B.M.; Nash, T.J.; Spielman, R.B.; Peterson, D.L.; Roderick, N.F.; Hammer, J.H.; De Groot, J.S.; Mosher, D.; Whitney, K.G.; Apruzese, J.P.

1997-01-01

A systematic study of annular aluminum-wire z-pinches on the Saturn accelerator shows that the quality of the implosion, (as measured by the radial convergence, the radiated energy, pulse width, and power), increases with wire number. Radiation magnetohydrodynamic (RMHC) xy simulations suggest that the implosion transitions from that of individual wire plasmas to that of a continuous plasma shell when the interwire spacing is reduced below ∼1.4mm. In this open-quotes plasma-shell regime,close quotes many of the global radiation and plasma characteristics are in agreement with those simulated by 2D-RMHC rz simulations. In this regime, measured changes in the radiation pulse width with variations in load mass and array radius are consistent with the simulations and are explained by the development of 2D fluid motion in the rz plane. Associated variations in the K-shell yield are qualitatively explained by simple radiation-scaling models. copyright 1997 American Institute of Physics

PBFA Z: A 60-TW/5-MJ Z-pinch driver

International Nuclear Information System (INIS)

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

1997-01-01

PBFA Z, a new 60-TW/5-MJ electrical accelerator located at Sandia National Laboratories, is now the world's most powerful z-pinch driver. PBFA Z stores 11.4 MJ in its 36 Marx generators, couples 5 MJ into a 60-TW/105-ns FWHM pulse to the 120-mΩ water transmission lines, and delivers 3.0 MJ and 50 TW of electrical energy to the z-pinch load. Depending on load parameters, we attain peak load currents of 16-20 MA with a current rise time of ∼105ns with wire-array z-pinch loads. We have extended the x-ray performance of tungsten wire-array z pinches from earlier Saturn experiments. Using a 2-cm-radius, 2-cm-long tungsten wire array with 240, 7.5-μm diameter wires (4.1-mg mass), we achieved an x-ray power of 210 TW and an x-ray energy of 1.9 MJ. Preliminary spectral measurements suggest a mostly optically-thick, Planckian-like radiator below 1000 eV. Data indicate ∼100kJ of x rays radiated above 1000 eV. An intense z-pinch x-ray source with an overall coupling efficiency greater than 15% has been demonstrated. copyright 1997 American Institute of Physics

Anisotropy of energy losses in high-current Z-pinches produced by the implosion of cylindrical tungsten wire arrays

Science.gov (United States)

Aleksandrov, V. V.; Volkov, G. S.; Grabovski, E. V.; Gritsuk, A. N.; Lakhtyushko, N. I.; Medovshchikov, S. F.; Oleinik, G. M.; Svetlov, E. V.

2014-02-01

Results are presented from measurements of the anisotropy of energy losses in high-current Z-pinches produced by the implosion of wire arrays at the ANGARA-5-1 facility at load currents of up to 4MA. The energy losses were measured in the radial direction and along the pinch axis from the anode side. The main diagnostics were time-integrated thermocouple calorimeters, nanosecond X-ray diodes (XRDs) with different filters, and a foil radiation calorimeter with a time resolution of 2 μs. The azimuthal anisotropy of energy losses was measured for different wire array configurations and different shapes of the high-voltage electrode. The presence of strong initial azimuthal inhomogeneity of the wire mass distribution (sectioned arrays), as well as the use of conical electrodes instead of plane ones, does not increase the azimuthal inhomogeneity of the total energy losses. For cylindrical wire arrays, energy losses in the radial direction are compared with those along the pinch axis. According to XRD and calorimetric measurements, the radiation yield per unit solid angle along the pinch axis is two to three times lower than that in the radial direction. In the axial direction, the energy flux density of the expanding plasma is two to three times lower than the radiation intensity. The measured radiation yield across the pinch is 2.5-5 kJ/sr, while that along the pinch axis is 1-2 kJ/sr. The results obtained by means of XRDs agree to within measurement errors with those obtained using the radiation calorimeter. It is found that the energy per unit solid angle carried by the expanding plasma in the radial direction does not exceed 10% of the soft X-ray yield. Analysis of the structure of time-integrated pinhole images and signals from the radial and axial XRDs shows that radiation emitted in the radial direction from the hot central region of the pinch is partially screened by the less dense surrounding plasma halo, whereas radiation emitted in the axial direction is a

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

Energy Technology Data Exchange (ETDEWEB)

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

1997-06-01

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

X-ray emission from a high-atomic-number z-pinch plasma created from compact wire arrays

International Nuclear Information System (INIS)

Sanford, T.W.L.; Mosher, D.; De Groot, J.S.

1996-01-01

Thermal and nonthermal x-ray emission from the implosion of compact tungsten wire arrays in 5-MA Saturn discharges is reported. The timing of multiple implosions and the thermal x-ray spectra (1 to 10 keV) agree with 2D radiation-hydrocode simulations. Nonthermal x-ray emission (10 to 100 keV) correlates with pinch spots distributed along the z-axis. The similarities of the measured nonthermal spectrum, yield, and pinch-spot emission with those of 0.8-MA, single-exploded-wire discharges on Gamble-II suggest a common nonthermal-production mechanism. Nonthermal x-ray yields are lower than expected from current scaling of Gamble II results, suggesting that implosion geometries are not as efficient as single-wire geometries for nonthermal x-ray production. The instabilities, azimuthal asymmetries, and inferred multiple implosions that accompany the implosion geometry lead to larger, more irregular pinch spots, a likely reason for reduced nonthermal efficiency. A model for nonthermal-electron acceleration across magnetic fields in highly-collisional, high-atomic-number plasmas combined with 1D hydrocode simulations of Saturn compact loads predicts weak nonthermal x-ray emission. (author). 3 figs., 10 refs

X-ray emission from a high-atomic-number z-pinch plasma created from compact wire arrays

International Nuclear Information System (INIS)

Sanford, T.W.L.; Mosher, D.; De Groot, J.S.

1996-01-01

Thermal and nonthermal x-ray emission from the implosion of compact tungsten wire arrays in 5-MA Saturn discharges is reported. The timing of multiple implosions and the thermal x-ray spectra (1 to 10 keV) agree with 2D radiation-hydrocode simulations. Nonthermal x-ray emission (10 to 100 keV) correlates with pinch spots distributed along the z-axis. The similarities of the measured nonthermal spectrum, yield, and pinch-spot emission with those of 0.8-MA, single- exploded-wire discharges on Gamble-II suggest a common nonthermal- production mechanism. Nonthermal x-ray yields are lower than expected from current scaling of Gamble II results, suggesting that implosion geometries are not as efficient as single-wire geometries for nonthermal x-ray production. The instabilities, azimuthal asymmetries, and inferred multiple implosions that accompany the implosion geometry lead to larger, more irregular pinch spots, a likely reason for reduced nonthermal efficiency. A model for nonthermal-electron acceleration across magnetic fields in highly- collisional, high-atomic-number plasmas combined with 1D hydrocode simulations of Saturn compact loads predicts weak nonthermal x-ray emission

Neutron and soft X-ray emission from wire array Z-pinch imploding onto deuterated fiber

International Nuclear Information System (INIS)

Klir, D.; Kravarik, J.; Kubes, P.

2005-01-01

The implosion of a wire array Z-pinch onto a deuterated fiber was studied. The peak power of soft X-rays exceeded 200 GW and the total emitted energy was 2-8 kJ. The radiation was close to the radiation of the blackbody with the temperature of 40 eV. The neutron yield from the D-D reaction reached 2x10 8 per shot. The mean energy of neutrons determined in the axial direction was shifted from 2.45 MeV towards higher energies [ru

Design of a 5-MA 100-ns linear-transformer-driver accelerator for wire array Z-pinch experiments

Science.gov (United States)

Zhou, Lin; Li, Zhenghong; Wang, Zhen; Liang, Chuan; Li, Mingjia; Qi, Jianmin; Chu, Yanyun

2016-03-01

The linear-transformer-driver (LTD) is a recently developed pulsed-power technology that shows great promise for a number of applications. These include a Z -pinch-driven fission-fusion-hybrid reactor that is being developed by the Chinese Academy of Engineering Physics. In support of the reactor development effort, we are planning to build an LTD-based accelerator that is optimized for driving wire-array Z -pinch loads. The accelerator comprises six modules in parallel, each of which has eight series 0.8-MA LTD cavities in a voltage-adder configuration. Vacuum transmission lines are used from the interior of the adder to the central vacuum chamber where the load is placed. Thus the traditional stack-flashover problem is eliminated. The machine is 3.2 m tall and 12 m in outer diameter including supports. A prototype cavity was built and tested for more than 6000 shots intermittently at a repetition rate of 0.1 Hz. A novel trigger, in which only one input trigger pulse is needed by utilizing an internal trigger brick, was developed and successfully verified in these shots. A full circuit modeling was conducted for the accelerator. The simulation result shows that a current pulse rising to 5.2 MA in 91 ns (10%-90%) can be delivered to the wire-array load, which is 1.5 cm in height, 1.2 cm in initial radius, and 1 mg in mass. The maximum implosion velocity of the load is 32 cm /μ s when compressed to 0.1 of the initial radius. The maximum kinetic energy is 78 kJ, which is 11.7% of the electric energy stored in the capacitors. This accelerator is supposed to enable a radiation energy efficiency of 20%-30%, providing a high efficient facility for research on the fast Z pinch and technologies for repetition-rate-operated accelerators.

Improved Symmetry Greatly Increases X-Ray Power from Wire-Array Z-Pinches

International Nuclear Information System (INIS)

Sanford, T.W.; Allshouse, G.O.; Marder, B.M.; Nash, T.J.; Mock, R.C.; Spielman, R.B.; Seamen, J.F.; McGurn, J.S.; Jobe, D.; Gilliland, T.L.; Vargas, M.; Struve, K.W.; Stygar, W.A.; Douglas, M.R.; Matzen, M.K.; Hammer, J.H.; De Groot, J.S.; Eddleman, J.L.; Peterson, D.L.; Mosher, D.; Whitney, K.G.; Thornhill, J.W.; Pulsifer, P.E.; Apruzese, J.P.; Maron, Y.

1996-01-01

A systematic experimental study of annular aluminum-wire Z-pinches on a 20-TW electrical generator shows that the measured spatial characteristics and emitted x-ray power agree more closely with rad-hydro simulations when large numbers of wires are used. The measured x-ray power increases first slowly and then rapidly with decreasing interwire gap spacing. Simulations suggested that this increase reflects the transition from implosion of individual wire plasmas to one of an azimuthally symmetric plasma shell. In the plasma-shell regime, x-ray powers of 40TW are achieved. copyright 1996 The American Physical Society

A heuristic model of the wire array z-pinch

International Nuclear Information System (INIS)

Haines, M.G.

1998-01-01

Recent experimental results at the Sandia National Laboratory have shown that the X-ray power increases as the number of wires n employed is increased, with a sharper increase in power when the wire gap is below a critical value. This paper proposes a model that can not only explain these phenomena, but also shows how the initial perturbations that lead to the Rayleigh-Taylor instability scale as n -1/2 . The model predicts the shell thickness at merger of the expanding separate wires which will mainly determine the final pinch radius. The largest amplitude Rayleigh-Taylor mode at the pinch time is also found, in reasonable agreement with experiment

X-ray Power Increase from Symmetrized Wire-Array z-Pinch Implosions on Saturn.*

Science.gov (United States)

Sanford, T. W. L.; Allshouse, G. O.; Marder, B. M.; Nash, T. J.; Mock, R. C.; Douglas, M. R.; Spielman, R. B.; Seaman, J. F.; McGurn, J. S.; Jobe, D.; Gilliland, T. L.; Vargas, M.; Struve, K. W.; Stygar, W. A.; Hammer, J. H.; Degroot, J. S.; Eddleman, J. L.; Peterson, D. L.; Whitney, K. G.; Thornhill, J. W.; Pulsifer, P. E.; Apruzese, J. P.; Mosher, D.; Maron, Y.

1996-11-01

A systematic experimental study of annular aluminum wire z-pinches on the Saturn accelerator at Sandia National Laboratories shows that, for the first time, many of the measured spatial characteristics and x-ray powers can be correlated to 1D and 2D, radiation-magneto-hydrodynamic code (RMHC) simulations when large numbers of wires are used. Calculations show that the implosion begins to transition from that of individual wire plasmas to that of a continuous plasma shell when the circumferential gap between wires in the array is reduced below 1.4 +1.3/-0.7 mm. This calculated gap coincides with the measured transition of 1.4±0.4 mm between the observed regimes of slow and rapid improvement in power output with decreasing gap. In the plasma-shell regime, x-ray power has been more than tripled over that generated in the wire-plasma regime. In the full paper, measured characteristics in the plasma-shell regime are compared with 2D, 1- and 20-mm axial length simulations of the implosion using a multi-photon-group Lagrangian RMHC^1 and a three-temperature Eulerian RMHC,^2 respectively. ^1J.H. Hammer, et al., Phys. Plasmas 3, 2063 (1996). ^2D.L. Peterson, et al., Phys. Plasmas 3, 368 (1996). Work supported by U.S. DOE Contract No. DE-AC04-94AL85000.

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

Science.gov (United States)

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

2013-07-01

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

Design of a 5-MA 100-ns linear-transformer-driver accelerator for wire array Z-pinch experiments

Directory of Open Access Journals (Sweden)

Zhou Lin

2016-03-01

Full Text Available The linear-transformer-driver (LTD is a recently developed pulsed-power technology that shows great promise for a number of applications. These include a Z-pinch-driven fission-fusion-hybrid reactor that is being developed by the Chinese Academy of Engineering Physics. In support of the reactor development effort, we are planning to build an LTD-based accelerator that is optimized for driving wire-array Z-pinch loads. The accelerator comprises six modules in parallel, each of which has eight series 0.8-MA LTD cavities in a voltage-adder configuration. Vacuum transmission lines are used from the interior of the adder to the central vacuum chamber where the load is placed. Thus the traditional stack-flashover problem is eliminated. The machine is 3.2 m tall and 12 m in outer diameter including supports. A prototype cavity was built and tested for more than 6000 shots intermittently at a repetition rate of 0.1 Hz. A novel trigger, in which only one input trigger pulse is needed by utilizing an internal trigger brick, was developed and successfully verified in these shots. A full circuit modeling was conducted for the accelerator. The simulation result shows that a current pulse rising to 5.2 MA in 91 ns (10%–90% can be delivered to the wire-array load, which is 1.5 cm in height, 1.2 cm in initial radius, and 1 mg in mass. The maximum implosion velocity of the load is 32  cm/μs when compressed to 0.1 of the initial radius. The maximum kinetic energy is 78 kJ, which is 11.7% of the electric energy stored in the capacitors. This accelerator is supposed to enable a radiation energy efficiency of 20%–30%, providing a high efficient facility for research on the fast Z pinch and technologies for repetition-rate-operated accelerators.

Analysis of X-ray iron and nickel radiation and jets from planar wire arrays and X-pinches

International Nuclear Information System (INIS)

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

2010-01-01

University-scale Z-pinch devices are able to produce plasmas with a broad range of sizes, temperatures, densities, their gradients, and opacity properties. Radiative properties of such plasmas depend on material, mass, and configuration of the wire array loads. Experiments with two different types of loads, double planar wire arrays (DPWA) and X-pinches, performed on the 1 MA Zebra generator at UNR are analyzed. X-pinches are made from Stainless Steel (69% Fe, 20% Cr, and 9% Ni) wires. Combined DPWAs consist of one plane from SS wires and another plane from Alumel (95% Ni, 2% Al, 2% Si) wires. The main focus of this work is on the analysis of plasma jets at the early phase of plasma formation and the K-and L-shell radiation generation at the implosion and stagnation phases in experiments with the two aforementioned wire loads. The relevant theoretical tools that guide the data analysis include non-LTE collisional-radiative and wire ablation dynamics models. The astrophysical relevance of the plasma jets as well as of spectroscopic and imaging studies are demonstrated.

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

International Nuclear Information System (INIS)

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

2008-01-01

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 ∼10 kA and 50 μs. 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

Effect of wire shape on wire array discharge

International Nuclear Information System (INIS)

Shimomura, N.; Tanaka, Y.; Yushita, Y.; Nagata, M.; Teramoto, Y.; Katsuki, S.; Akiyama, H.

2001-01-01

Although considerable investigations have been reported on z-pinches to achieve nuclear fusion, little attention has been given from the point of view of how a wire array consisting of many parallel wires explodes. Instability existing in the wire array discharge has been shown. In this paper, the effect of wire shape in the wire array on unstable behavior of the wire array discharge is represented by numerical analysis. The claws on the wire formed in installation of wire may cause uniform current distribution on wire array. The effect of error of wire diameter in production is computed by Monte Carlo Method. (author)

Effect of wire shape on wire array discharge

Energy Technology Data Exchange (ETDEWEB)

Shimomura, N.; Tanaka, Y.; Yushita, Y.; Nagata, M. [University of Tokushima, Department of Electrical and Electronic Engineering, Tokushima (Japan); Teramoto, Y.; Katsuki, S.; Akiyama, H. [Kumamoto University, Department of Electrical and Computer Engineering, Kumamoto (Japan)

2001-09-01

Although considerable investigations have been reported on z-pinches to achieve nuclear fusion, little attention has been given from the point of view of how a wire array consisting of many parallel wires explodes. Instability existing in the wire array discharge has been shown. In this paper, the effect of wire shape in the wire array on unstable behavior of the wire array discharge is represented by numerical analysis. The claws on the wire formed in installation of wire may cause uniform current distribution on wire array. The effect of error of wire diameter in production is computed by Monte Carlo Method. (author)

Wire number dependence of the implosion dynamics, stagnation, and radiation output of tungsten wire arrays at Z driver

Energy Technology Data Exchange (ETDEWEB)

Mazarakis, Michael G.; Stygar, William A.; Sinars, Daniel B.; Cuneo, Michael E.; Nash, Thomas J.; Chandler, Gordon A.; Keith Matzen, M.; Porter, John L.; Struve, Kenneth W.; McDaniel, Dillon H. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States); Deeney, Christopher E. [National Nuclear Security Administration, Washington, D.C. 20585 (United States); Douglas, Melissa R. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Chittenden, Jerry [Imperial College, London, SW and 2BW (United Kingdom)

2011-11-15

We report results of the experimental campaign, which studied the initiation, implosion dynamics, and radiation yield of tungsten wire arrays as a function of the wire number. The wire array dimensions and mass were those of interest for the Z-pinch driven Inertial Confinement Fusion (ICF) program. An optimization study of the x-ray emitted peak power, rise time, and full width at half maximum was effectuated by varying the wire number while keeping the total array mass constant and equal to {approx}5.8 mg. The driver utilized was the {approx}20-MA Z accelerator before refurbishment in its usual short pulse mode of 100 ns. We studied single arrays of 20-mm diameter and 1-cm height. The smaller wire number studied was 30 and the largest 600. It appears that 600 is the highest achievable wire number with present day's technology. Radial and axial diagnostics were utilized including crystal monochromatic x-ray backlighter. An optimum wire number of {approx}375 was observed which was very close to the routinely utilized 300 for the ICF program in Sandia.

Wire number dependence of the implosion dynamics, stagnation, and radiation output of tungsten wire arrays at Z driver

International Nuclear Information System (INIS)

Mazarakis, Michael G.; Stygar, William A.; Sinars, Daniel B.; Cuneo, Michael E.; Nash, Thomas J.; Chandler, Gordon A.; Keith Matzen, M.; Porter, John L.; Struve, Kenneth W.; McDaniel, Dillon H.; Deeney, Christopher E.; Douglas, Melissa R.; Chittenden, Jerry

2011-01-01

We report results of the experimental campaign, which studied the initiation, implosion dynamics, and radiation yield of tungsten wire arrays as a function of the wire number. The wire array dimensions and mass were those of interest for the Z-pinch driven Inertial Confinement Fusion (ICF) program. An optimization study of the x-ray emitted peak power, rise time, and full width at half maximum was effectuated by varying the wire number while keeping the total array mass constant and equal to ∼5.8 mg. The driver utilized was the ∼20-MA Z accelerator before refurbishment in its usual short pulse mode of 100 ns. We studied single arrays of 20-mm diameter and 1-cm height. The smaller wire number studied was 30 and the largest 600. It appears that 600 is the highest achievable wire number with present day's technology. Radial and axial diagnostics were utilized including crystal monochromatic x-ray backlighter. An optimum wire number of ∼375 was observed which was very close to the routinely utilized 300 for the ICF program in Sandia.

Radius scaling of titanium wire arrays on the Z accelerator

International Nuclear Information System (INIS)

Coverdale, C.A.; Denney, C.; Spielman, R.B.

1999-01-01

The 20 MA Z accelerator has made possible the generation of substantial radiation (> 100 kJ) at higher photon energies (4.8 keV) through the use of titanium wire arrays. In this paper, the results of experiments designed to study the effects of initial load radius variations of nickel-clad titanium wire arrays will be presented. The load radius was varied from 17.5 mm to 25 mm and titanium K-shell (4.8 keV) yields of greater than 100 kJ were measured. The inclusion of the nickel cladding on the titanium wires allows for higher wire number loads and increases the spectral broadness of the source; kilovolt emissions (nickel plus titanium L-shell) of 400 kJ were measured in these experiments. Comparisons of the data to calculations will be made to estimate pinched plasma parameters such as temperature and participating mass fraction. These results will also be compared with previous pure titanium wire array results

Metal Wire-array Load for Z-pinch Used as X-ray Source

Institute of Scientific and Technical Information of China (English)

1999-01-01

<正> The inertial confinement fusion （ICF） has evident minatory applications becasuse ICF ignites the fusion fuel with high energy media. As a method of ICF, Z-pinch has obtained evidently increased X-ray power PX-ray and energy EX-ray. The scientists have noticed this promising achievement. The Z-accelerator which is an operating Z-pinch device in Sandia national laboratory （SNL） in USA achieved 290 TW Px-ray in 1997 and the energy and defense departments of USA will finance SNL for a larger Z-pinch device. The early Z-pinch aimed to obtain high tempera

X-ray sources by Z-pinch for inertial confinement fusion

International Nuclear Information System (INIS)

Akiyama, Hidenori; Katsuki, Sunao; Lisitsyn, Igor

1999-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2012-10-15

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

Two-dimensional integrated Z-pinch ICF design simulations

International Nuclear Information System (INIS)

Lash, J.S.

1999-01-01

The dynamic hohlraum ICF concept for a Z-pinch driver utilizes the imploding wire array collision with a target to produce a radiation history suitable for driving an embedded inertial confinement fusion (ICF) capsule. This target may consist of various shaped layers of low-density foams or solid-density materials. The use of detailed radiation magneto-hydrodynamic (RMHD) modeling is required for understanding and designing these complex systems. Critical to producing credible simulations and designs is inclusion of the Rayleigh-Taylor unstable wire-array dynamics; the bubble and spike structure of the collapsing sheath may yield regions of low-opacity enhancing radiation loss as well as introduce non-uniformities in the capsule's radiation drive. Recent improvements in LASNEX have allowed significant progress to be made in the modeling of unstable z-pinch implosions. Combining this with the proven ICF capsule design capabilities of LASNEX, the authors now have the modeling tools to produce credible, fully-integrated ICF dynamic hohlraum simulations. They present detailed two-dimensional RMHD simulations of recent ICF dynamic hohlraum experiments on the Sandia Z-machine as well as design simulations for the next-generation Z-pinch facility and future high-yield facility

Two-dimensional integrated Z-pinch ICF design simulations

Energy Technology Data Exchange (ETDEWEB)

Lash, J.S.

1999-07-01

The dynamic hohlraum ICF concept for a Z-pinch driver utilizes the imploding wire array collision with a target to produce a radiation history suitable for driving an embedded inertial confinement fusion (ICF) capsule. This target may consist of various shaped layers of low-density foams or solid-density materials. The use of detailed radiation magneto-hydrodynamic (RMHD) modeling is required for understanding and designing these complex systems. Critical to producing credible simulations and designs is inclusion of the Rayleigh-Taylor unstable wire-array dynamics; the bubble and spike structure of the collapsing sheath may yield regions of low-opacity enhancing radiation loss as well as introduce non-uniformities in the capsule's radiation drive. Recent improvements in LASNEX have allowed significant progress to be made in the modeling of unstable z-pinch implosions. Combining this with the proven ICF capsule design capabilities of LASNEX, the authors now have the modeling tools to produce credible, fully-integrated ICF dynamic hohlraum simulations. They present detailed two-dimensional RMHD simulations of recent ICF dynamic hohlraum experiments on the Sandia Z-machine as well as design simulations for the next-generation Z-pinch facility and future high-yield facility.

Implosion dynamics of a megampere wire-array Z-pinch with an inner low-density foam shell at the Angara-5-1 facility

International Nuclear Information System (INIS)

Aleksandrov, V. V.; Bolkhovitinov, E. A.; Volkov, G. S.; Grabovski, E. V.; Gritsuk, A. N.; Medovshchikov, S. F.; Oleinik, G. M.; Rupasov, A. A.; Frolov, I. N.

2016-01-01

The implosion dynamics of a pinch with a highly inhomogeneous initial axial distribution of the load mass was studied experimentally. A cascade array consisting of a double nested tungsten wire array and a coaxial inner cylindrical shell located symmetrically with respect to the high-voltage electrodes was used as a load of the Angara-5-1 high-current generator. The cylindrical foam shell was half as long as the cathode− anode gap, and its diameter was equal to the diameter of the inner wire array. It is shown experimentally that two stages are typical of the implosion dynamics of such a load: the formation of two separate pinches formed as a result of implosion of the wire array near the cathode and anode and the subsequent implosion of the central part of the load containing the cylindrical foam shell. The conditions are determined at which the implosion of the central part of the pinch with the foam cylinder is preceded by intense irradiation of the foam with the soft X-ray (SXR) emission generated by the near-electrode pinches and converting it into the plasma state. Using such a load, which models the main elements of the scheme of a dynamic hohlraum for inertial confinement fusion, it is possible to increase the efficiency of interaction between the outer accelerated plasma sheath and the inner foam shell by preionizing the foam with the SXR emission of the near-electrode pinches.

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

International Nuclear Information System (INIS)

Pavez, Cristian; Soto, Leopoldo; Moreno, Jose; Sylvester, Gustavo; Tarifeno, Ariel

2008-01-01

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 μF equivalent Marx generator capacity, 300 kV, 4 MA in short circuit, 187 kJ, 400 ns rise time, dI/dt∼10 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.

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

International Nuclear Information System (INIS)

Pavez, Cristian; Soto, Leopoldo; Moreno, Jose; Tarifeno, Ariel; Sylvester, Gustavo

2008-01-01

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 μF equivalent Marx generator capacity, 300 kV, 4 MA in short circuit, 187 kJ, 400 ns rise time, dI/dt∼10 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

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

International Nuclear Information System (INIS)

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

1996-01-01

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 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

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

International Nuclear Information System (INIS)

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

1998-01-01

Recent developments in pulsed power technology demonstrate use of intense radiation sources (Z pinches) for driving planar shock waves in samples with spatial dimensions larger than possible with other radiation sources. Initial indications are that the use of Z pinch sources can be used to produce planar shock waves in samples with diameters of a few millimeters and thicknesses approaching one half millimeter. These dimensions allow increased accuracy of both shock velocity and particle velocity measurements. The Z pinch radiation source uses imploding metal plasma induced by self-magnetic fields applied to wire arrays to produce high temperature x-ray environments in vacuum hohlraum enclosures. Previous experiments have demonstrated that planar shock waves can be produced with this approach. A photograph of a wire array located inside the vacuum hohlraum is shown here. Typically, a few hundred individual wires are used to produce the Z pinch source. For the shock wave experiments being designed, arrays of 120 to 240 tungsten wires with a diameter of 40 mm and with individual diameters of about 10 microm are used. Preliminary experiments have been performed on the Z pulsed radiation source to demonstrate the ability to obtain VISAR measurements in the Z accelerator environment. Analysis of these results indicate that another effect, not initially anticipated, is an apparent change in refractive index that occurs in the various optical components used in the system. This effect results in an apparent shift in the frequency of reflected laser light, and causes an error in the measured particle velocity. Experiments are in progress to understand and minimize this effect

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-04-15

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

Radiation hydrodynamics of z-pinch plasmas

International Nuclear Information System (INIS)

Davis, J.

1993-01-01

Over the years there has been a sustained interest in and fascination with Z-pinch plasmas. Whether the interest is in radiation source development, fusion plasmas, or basic research there exits an extensive bibliography of literature promulgating and perpetuating a variety of claims regarding the performance of Z-pinch plasmas. In this paper an attempt will be made to present a coherent picture of the documented and commonly held views for a class of Z-pinch plasmas concerned primarily with soft x-ray radiation source development. Many of the issues and findings are common to Z-pinch plasmas in general but the attention here will be focused on gas puffs and multiple wire arrays. The role and importance of radiation on the dynamics and the interplay between the radiation and the dynamics will also be presented and discussed. A number of comparisons with experimental results will be made with 0-, 1-, and 2-D numerical simulations for several pulsed power drivers ranging in current from several mega-amps to 10's of mega-amps for a variety of risetimes and load materials

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

International Nuclear Information System (INIS)

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

1996-01-01

Sandia National Laboratories is completing a major modification to the PBFA-II facility. PBFA Z will be 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 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. Calculations are presented showing MJ x-ray outputs from tungsten wire-array z pinches. (author). 4 figs., 14 refs

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

Energy Technology Data Exchange (ETDEWEB)

Spielman, R B; Breeze, S F; Deeney, C [Sandia Labs., Albuquerque, NM (United States); and others

1997-12-31

Sandia National Laboratories is completing a major modification to the PBFA-II facility. PBFA Z will be 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 {approx} 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. Calculations are presented showing MJ x-ray outputs from tungsten wire-array z pinches. (author). 4 figs., 14 refs.

Diagnosing x-ray power and energy of tungsten wire array z-pinch with a flat spectral response x-ray diode

International Nuclear Information System (INIS)

Wang, Kun-lun; Ren, Xiao-dong; Huang, Xian-bin; Zhang, Si-qun; Zhou, Shao-tong; Dan, Jia-kun; Li, Jing; Xu, Qiang; Ouyang, Kai; Cai, Hong-chun; Wei, Bing; Ji, Ce; Feng, Shu-ping; Wang, Meng; Xie, Wei-ping; Deng, Jian-jun

2015-01-01

Fast z-pinch is a very efficient way of converting electromagnetic energy to radiation. With an 8-10 MA current on primary test stand facility, about 1 MJ electromagnetic energy is delivered to vacuum chamber, which heats z-pinch plasma to radiate soft x-ray. To develop a pulsed high power x-ray source, we studied the applicability of diagnosing x-ray power from tungsten wire array z-pinch with a flat spectral response x-ray diode (FSR-XRD). The detector was originally developed to diagnose radiation of a hohlraum in SG-III prototype laser facility. It utilized a gold cathode XRD and a specially configured compound gold filter to yield a nearly flat spectral response in photon energy range of 0.1-4 keV. In practice, it was critical to avoid surface contamination of gold cathode. It is illustrated that an exposure of an XRD to multiple shots caused a significant change of response. Thus, in diagnosing x-ray power and energy, we used each XRD in only one shot after calibration. In a shot serial, output of FSR-XRD was compared with output of a nickel bolometer. In these shots, the outputs agreed with each other within their uncertainties which were about 12% for FSR-XRD and about 15% for bolometer. Moreover, the ratios between the FSR-XRD and the bolometer among different shots were explored. In 8 shots, the standard deviation of the ratio was 6%. It is comparable to XRD response change of 7%

Measurements for the radiation spectra of fast Z-pinches produced at compression of multi-wire arrays on the 'Angara-5-1' facility

International Nuclear Information System (INIS)

Bolkhovitinov, E.A.; Rupasov, A.A.; Shikanov, A.S.; Fedulov, M.V.; Grabovsky, E.V.; Gritsuk, A.N.; Oleinik, G.M.; Volkov, G.S.

2010-01-01

Complete text of publication follows. The measurements results on the radiation spectra of fast z-pinches produced at compression of cylindrical multi-wire tungsten and aluminum arrays in the experiments on a high-current 'Angara-5-1' facility are presented. Cylindrical multi-wire arrays has linear mass 200-400 μg/cm and the initial diameter 12-20 mm. The pinch current was about 3 MA with pulse duration of 140 ns and peak power 3 TW. The radiation spectra are measured within the range of 50-900 eV quanta by a spectrometer with transmission diffraction grating, where the radiation is recorded on the UF-4 X-ray film. An electromagnetic curtain shutter was used to protect the transmission grating from fast microparticles produced by the erosion of high-voltage electrodes. The radiation spectrum of 1-3 keV quanta was recorded by a convex crystal wide-range spectrometer. Total yield of the radiation was measured by a thermocouple calorimeter. The main part of the tungsten plasma radiative energy proves to correspond to the quasi-continuous spectrum within the range of 80-300 eV quanta. Measurements of the tungsten plasma radiation spectrum with spatial resolution by a pinch radius have shown that the effective transversal size (diameter) of the pinch as not higher than 1 mm. In the case of aluminum plasma an intensive linear radiation of the [H]- and [He]-like ions have been recorded along with a continuous and linear radiation of the [Li]- and [Be]-like ions with the range of 100-300 eV quanta. Spectral measurements of the aluminum plasma radiation with spatial resolution by the pinch radius have shown that the effective transversal size (diameter) of the pinch is around the value of 1.5 mm. Within the framework of the stationary collisional-radiative model, in respect of the [H]- and [He]-like ion spectral lines relative intensities, the parameters of the aluminum plasma pinch, namely, the electron temperature T e ∼ 550 eV and electron density n e ∼ 3 x 10 20 cm

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

Science.gov (United States)

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

2009-01-01

The Sphinx machine[1] is a 6 MA, 1 μS 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 η 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.

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

International Nuclear Information System (INIS)

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

2009-01-01

The Sphinx machine [1] is a 6 MA, 1 μS 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 η 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.

Wire number doubling in plasma-shell regime increases z-accelerator x-ray power

International Nuclear Information System (INIS)

Sanford, T.W.L.; Spielman, R.B.; Chandler, G.A.

1997-11-01

Doubling the number of tungsten wires from 120 to 240, keeping the mass fixed, increased the radiated x-ray power relative to the electrical power at the insulator stack of the z accelerator by (40±20)% for 8.75- and 20-mm-radii z-pinch wire arrays. Radiation-magneto-hydrodynamic calculations suggest that the arrays were operating in the 'plasma shell' regime, where the plasmas generated by the individual wires merge prior to the inward implosion of the entire array

Wire number doubling in plasma-shell regime increases Z-accelerator X-ray power

International Nuclear Information System (INIS)

Sanford, T.W.L.; Spielman, R.B.; Chandler, G.A.

1997-01-01

Doubling the number of tungsten wires from 120 to 240, keeping the mass fixed, increased the radiated x-ray power relative to the electrical power at the insulator stack of the z accelerator by (40 ± 20)% for 8.75- and 20-mm-radii z-pinch wire arrays. Radiation-magneto-hydrodynamic calculations suggest that the arrays were operating in the plasma shell regime, where the plasma generated by the individual wires merge prior to the inward implosion of the entire array

Wire number doubling in plasma-shell regime increases Z-accelerator X-ray power

Energy Technology Data Exchange (ETDEWEB)

Sanford, T.W.L.; Spielman, R.B.; Chandler, G.A. [and others

1997-12-01

Doubling the number of tungsten wires from 120 to 240, keeping the mass fixed, increased the radiated x-ray power relative to the electrical power at the insulator stack of the z accelerator by (40 {+-} 20)% for 8.75- and 20-mm-radii z-pinch wire arrays. Radiation-magneto-hydrodynamic calculations suggest that the arrays were operating in the plasma shell regime, where the plasma generated by the individual wires merge prior to the inward implosion of the entire array.

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

International Nuclear Information System (INIS)

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

1997-01-01

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

Wire number doubling in plasma-shell regime increases z-accelerator x-ray power

Energy Technology Data Exchange (ETDEWEB)

Sanford, T.W.L.; Spielman, R.B.; Chandler, G.A. [and others

1997-11-01

Doubling the number of tungsten wires from 120 to 240, keeping the mass fixed, increased the radiated x-ray power relative to the electrical power at the insulator stack of the z accelerator by (40{+-}20)% for 8.75- and 20-mm-radii z-pinch wire arrays. Radiation-magneto-hydrodynamic calculations suggest that the arrays were operating in the {open_quotes}plasma shell{close_quotes} regime, where the plasmas generated by the individual wires merge prior to the inward implosion of the entire array.

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

International Nuclear Information System (INIS)

Altemara, S. D.; Ivanov, V. V.; Astanovitskiy, A. L.; Haboub, A.

2009-01-01

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

Compact wire array sources: power scaling and implosion physics.

Energy Technology Data Exchange (ETDEWEB)

Serrano, Jason Dimitri; Chuvatin, Alexander S. (Laboratoire du Centre National de la Recherche Scientifique Ecole Polytechnique, Palaiseau, France); Jones, M. C.; Vesey, Roger Alan; Waisman, Eduardo M.; Ivanov, V. V. (University of Nevada - Reno, Reno, NV); Esaulov, Andrey A. (University of Nevada - Reno, Reno, NV); Ampleford, David J.; Cuneo, Michael Edward; Kantsyrev, Victor Leonidovich (University of Nevada - Reno, Reno, NV); Coverdale, Christine Anne; Rudakov, L. I. (Icarus Research, Bethesda, MD); Jones, Brent Manley; Safronova, Alla S. (University of Nevada - Reno, Reno, NV); Vigil, Marcelino Patricio

2008-09-01

A series of ten shots were performed on the Saturn generator in short pulse mode in order to study planar and small-diameter cylindrical tungsten wire arrays at {approx}5 MA current levels and 50-60 ns implosion times as candidates for compact z-pinch radiation sources. A new vacuum hohlraum configuration has been proposed in which multiple z pinches are driven in parallel by a pulsed power generator. Each pinch resides in a separate return current cage, serving also as a primary hohlraum. A collection of such radiation sources surround a compact secondary hohlraum, which may potentially provide an attractive Planckian radiation source or house an inertial confinement fusion fuel capsule. Prior to studying this concept experimentally or numerically, advanced compact wire array loads must be developed and their scaling behavior understood. The 2008 Saturn planar array experiments extend the data set presented in Ref. [1], which studied planar arrays at {approx}3 MA, 100 ns in Saturn long pulse mode. Planar wire array power and yield scaling studies now include current levels directly applicable to multi-pinch experiments that could be performed on the 25 MA Z machine. A maximum total x-ray power of 15 TW (250 kJ in the main pulse, 330 kJ total yield) was observed with a 12-mm-wide planar array at 5.3 MA, 52 ns. The full data set indicates power scaling that is sub-quadratic with load current, while total and main pulse yields are closer to quadratic; these trends are similar to observations of compact cylindrical tungsten arrays on Z. We continue the investigation of energy coupling in these short pulse Saturn experiments using zero-dimensional-type implosion modeling and pinhole imaging, indicating 16 cm/?s implosion velocity in a 12-mm-wide array. The same phenomena of significant trailing mass and evidence for resistive heating are observed at 5 MA as at 3 MA. 17 kJ of Al K-shell radiation was obtained in one Al planar array fielded at 5.5 MA, 57 ns and we

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

International Nuclear Information System (INIS)

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

2000-01-01

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, ge1 MJ in 7 ns), large characteristic hohlraum volumes (0.5 to >10 cm 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

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

International Nuclear Information System (INIS)

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.

1999-01-01

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

Diagnostics for Z-pinch implosion experiments on PTS

Energy Technology Data Exchange (ETDEWEB)

Ren, X. D., E-mail: amosrxd@163.com; Huang, X. B., E-mail: amosrxd@163.com; Zhou, S. T., E-mail: amosrxd@163.com; Zhang, S. Q., E-mail: amosrxd@163.com; Dan, J. K., E-mail: amosrxd@163.com; Li, J., E-mail: amosrxd@163.com; Cai, H. C., E-mail: amosrxd@163.com; Wang, K. L., E-mail: amosrxd@163.com; Ouyang, K., E-mail: amosrxd@163.com; Xu, Q., E-mail: amosrxd@163.com; Duan, S. C., E-mail: amosrxd@163.com; Chen, G. H., E-mail: amosrxd@163.com; Wang, M., E-mail: amosrxd@163.com; Feng, S. P., E-mail: amosrxd@163.com; Yang, L. B., E-mail: amosrxd@163.com; Xie, W. P., E-mail: amosrxd@163.com; Deng, J. J., E-mail: amosrxd@163.com [Key Lab of Pulsed Power, Institute of Fluid Physics, CAEP, P.O. Box 919-108, Mianyang, Sichuan 621999 (China)

2014-12-15

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

A short-pulse mode for the SPHINX LTD Z-pinch driver

Science.gov (United States)

D'Almeida, Thierry; Lassalle, Francis; Zucchini, Frederic; Loyen, Arnaud; Morell, Alain; Chuvatin, Alexander

2015-11-01

The SPHINX machine is a 6MA, 1 μs, LTD Z-pinch driver at CEA Gramat (France) and primarily used for studying radiation effects. Different power amplification concepts were examined in order to reduce the current rise time without modifying the generator discharge scheme, including the Dynamic Load Current Multiplier (DLCM) proposed by Chuvatin. A DLCM device, capable of shaping the current pulse without reducing the rise time, was developed at CEA. This device proved valuable for isentropic compression experiments in cylindrical geometry. Recently, we achieved a short pulse operation mode by inserting a vacuum closing switch between the DLCM and the load. The current rise time was reduced to ~300 ns. We explored the use of a reduced-height wire array for the Dynamic Flux Extruder in order to improve the wire array compression rate and increase the efficiency of the current transfer to the load. These developments are presented. Potential benefits of these developments for future Z pinch experiments are discussed.

Neutron emission generated during wire array Z-pinch implosion onto deuterated fiber

Czech Academy of Sciences Publication Activity Database

Klir, D.; Kravarik, J.; Kubes, P.; Rezac, K.; Ananev, S.S.; Bakshaev, Yu. L.; Blinov, P. I.; Chernenko, A. S.; Kazakov, E.D.; Korolev, V. D.; Meshcherov, B.R.; Ustroev, G. I.; Juha, Libor; Krása, Josef; Velyhan, Andriy

2008-01-01

Roč. 15, č. 3 (2008), 32701/1-32701/13 ISSN 1070-664X R&D Projects: GA MŠk(CZ) LC528; GA MŠk LA08024 Institutional research plan: CEZ:AV0Z10100523 Keywords : fusion plasmas * d-d reaction * neutron yield * Z pinch * high-current discharges Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.427, year: 2008

Soft X-Ray Measurements of Z-Pinch-Driven Vacuum Hohlraums

International Nuclear Information System (INIS)

Baker, K.L.; Porter, J.L.; Ruggles, L.E.; Chandler, G.A.; Deeney, Chris; Varas, M.; Moats, Ann; Struve, Ken; Torres, J.; McGurn, J.; Simpson, W.W.; Fehl, D.L.; Chrien, R.E.; Matuska, W.; Idzorek, G.C.

1999-01-01

This article reports the experimental characterization of a z-pinch driven-vacuum hohlraum. The authors have measured soft x-ray fluxes of 5 x 10 12 W/cm 2 radiating from the walls of hohlraums which are 2.4--2.5 cm in diameter by 1 cm tall. The x-ray source used to drive these hohlraums was a z-pinch consisting of a 300 wire tungsten array driven by a 2 MA, 100 ns current pulse. In this hohlraum geometry, the z-pinch x-ray source can produce energies in excess of 800 kJ and powers in excess of 100 TW to drive these hohlraums. The x-rays released in these hohlraums represent greater than a factor of 25 in energy and more than a factor of three in x-ray power over previous laboratory-driven hohlraums

X-ray emission from a high-atomic-number z-pinch plasma created from compact wire arrays

International Nuclear Information System (INIS)

Sanford, T.W.L.; Nash, T.J.; Marder, B.M.

1996-03-01

Thermal and nonthermal x-ray emission from the implosion of compact tungsten wire arrays, driven by 5 MA from the Saturn accelerator, are measured and compared with LLNL Radiation-Hydro-Code (RHC) and SNL Hydro-Code (HC) numerical models. Multiple implosions, due to sequential compressions and expansions of the plasma, are inferred from the measured multiple x-radiation bursts. Timing of the multiple implosions and the thermal x-ray spectra measured between 1 and 10 keV are consistent with the RHC simulations. The magnitude of the nonthermal x-ray emission measured from 10 to 100 keV ranges from 0.02 to 0.08% of the total energy radiated and is correlated with bright-spot emission along the z-axis, as observed in earlier Gamble-11 single exploding-wire experiments. The similarities of the measured nonthermal spectrum and bright-spot emission with those measured at 0.8 MA on Gamble-II suggest a common production mechanism for this process. A model of electron acceleration across magnetic fields in highly-collisional, high-atomic-number plasmas is developed, which shows the existence of a critical electric field, E c , below which strong nonthermal electron creation (and the associated nonthermal x rays) do not occur. HC simulations show that significant nonthermal electrons are not expected in this experiment (as observed) because the calculated electric fields are at least one to two orders-of-magnitude below E c . These negative nonthermal results are confirmed by RHC simulations using a nonthermal model based on a Fokker-Plank analysis. Lastly, the lower production efficiency and the larger, more irregular pinch spots formed in this experiment relative to those measured on Gamble II suggest that implosion geometries are not as efficient as single exploding-wire geometries for warm x-ray production

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

Science.gov (United States)

Haines, M. G.

2008-10-01

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 J×B 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.

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

Science.gov (United States)

Yu, Edmund

2007-11-01

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

Computational modeling of z-pinch-driven hohlraum experiments on Z

International Nuclear Information System (INIS)

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

1999-01-01

The high-yield inertial confinement fusion concept based on a double-ended z-pinch driven hohlraum tolerates the degree of spatial inhomogeneity present in z-pinch plasma radiation sources by utilizing a relatively large hohlraum wall surface to provide spatial smoothing of the radiation delivered to the fusion capsule. The z-pinch radiation sources are separated from the capsule by radial spoke arrays. Key physics issues for this concept are the behavior of the spoke array (effect on the z-pinch performance, x-ray transmission) and the uniformity of the radiation flux incident on the surface of the capsule. Experiments are underway on the Z accelerator at Sandia National laboratories to gain understanding of these issues in a single-sided drive geometry. These experiments seek to measure the radiation coupling among the z-pinch, source hohlraum, and secondary hohlraum, as well as the uniformity of the radiation flux striking a foam witness ball diagnostic positioned in the secondary hohlraum. This paper will present the results of computational modeling of various aspects of these experiments

Sausage mode of a high density Z-pinch

International Nuclear Information System (INIS)

Pereira, N.; Rostoker, N.

1983-01-01

In Z-pinch experiments at Maxwell Laboratories, Inc., growth rates have been measured by observing optical emission along the pinch axis. Growth rates estimated by means of the usual model of a pinch involving an incompressible fluid and a surface current are too large by a factor of 2-4. X-ray pinhole photographs generally have the appearance of a series of beads that would be expected from instability of the sausage mode. In some cases, particularly the implosion of large diameter wire arrays with BLACKJACK 5, the beads disappear and only the kink instability is apparent. Generalizing the pinch model to include compressibility does not significantly alter the predictions. A further generalization to include distributed current has therefore been considered. It seems likely that the current can penetrate significantly during the lifetime of the pinch. We consider a model of the pinch that is initially an infinite cylinder. For the sausage mode, stability is determined by a simple second order differential equation together with the boundary condition that follows from the wave number and the frequency of the instability

The C-300 soft X-ray power measurement on Sino-Russian joint Z-pinch experiment

International Nuclear Information System (INIS)

Ning Jiamin; Jiang Shilun; Xu Rongkun; Guo Cun

2008-06-01

The measurement system for soft X-ray radiation power was introduced which applied in Sino-Russia joint Z-pinch experiments on C-300. The system measured the soft X-ray radiation power and energy, investigated relation between radiation power and time, and provided the time-relating signals. The type of experimental wire array loads were tungsten wire array single layer, aluminum wire array and nested wire array, and obtained the radiation wave, power and energy. Radiation peak of double wire array generally lower than that of single wire, radial radiation synchronization didn't obviously affected radiation front, fast pulse front may reflect better homogenous of plasma inner explosive which generally produced higher radiation power. There are no direct relationship between wide and power of radiation pulse. The micro-structures of wire array load were a very important factor for radiation power. Increasing the homogenous of wire array gap could optimize radiation synchronization and obviously increased the radiation power. (authors)

Increasing Z-pinch vacuum hohlraum capsule coupling efficiency

International Nuclear Information System (INIS)

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

2004-01-01

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

Studies of Hot Spots in Imploding Wire Arrays at 1 MA on COBRA

International Nuclear Information System (INIS)

Pikuz, Sergey A.; Shelkovenko, Tatiana A.; McBride, Ryan D.; Hammer, David A.

2009-01-01

We present recent results from hot spot investigations in imploding Al wire array z-pinches on the COBRA generator at Cornell University using x-ray diagnostics. Measurements of the temporal and spatial distribution of hot spots in stagnating plasmas by an x-ray streak-camera are included. Experiments show that hot spots have nanosecond lifetime and appear randomly along the array axis after plasma stagnation in secondary pinches in 8 mm diameter and during plasma stagnation in the arrays with 4 mm diameter.

Tungsten Z-Pinch Long Implosions on the Saturn Generator

International Nuclear Information System (INIS)

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

1999-01-01

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

Physical features of the wire-array Z-pinch plasmas imploding process

International Nuclear Information System (INIS)

Gao Chunming; Feng Kaiming

2001-01-01

In the process of research on controlled fusion reactors, scientists found that the Z-pinch plasma can produce very strong X-rays, comparing with other X-ray sources. In researching the process of imploding, the snowplow model and Haines model are introduced and proved. About amassing X-rays, several ways of discharging X-rays are carefully analyzed and the relative theories are proved. In doing simulations, the one dimension model is used in writing codes, the match relationships are calculated and the process of imploding is also simulated. Some useful and reasonable results are obtained

Detailed spectral simulations in support of PBFA-Z dynamic hohlraum Z-pinch experiments

International Nuclear Information System (INIS)

MacFarlane, J.J.; Wang, P.; Derzon, M.S.; Haill, A.; Nash, T.J.; Peterson, D.L.

1997-01-01

In PBFA-Z dynamic hohlraum Z-pinch experiments, 16--18 MA of current is delivered to a load comprises of a tungsten wire array surrounding a low-density cylindrical CH foam. The magnetic field accelerates the W plasma radially inward at velocities ∼ 40--60 cm/micros. The W plasma impacts into the foam, generating a high T R radiation field which diffuses into the foam. The authors are investigating several types of spectral diagnostics which can be used to characterize the time-dependent conditions in the foam. In addition, they are examining the potential ramifications of axial jetting on the interpretation of axial x-ray diagnostics. In the analysis, results from 2-D radiation-magnetohydrodynamics simulations are post-processed using a hybrid spectral analysis code in which low-Z material is treated using a detailed collisional-radiative atomic model, while high-Z material is modeled using LTE UTA (unresolved transition array) opacities. They will present results from recent simulations and discuss ramifications for x-ray diagnostics

Astrophysically relevant radiatively cooled hypersonic bow shocks in nested wire arrays

Science.gov (United States)

Ampleford, David

2009-11-01

We have performed laboratory experiments which introduce obstructions into hypersonic plasma flows to study the formation of shocks. Astrophysical observations have demonstrated many examples of equivalent radiatively cooled bow shocks, for example the head of protostellar jets or supernova remnants passing through the interstellar medium or between discrete clumps in jets. Wire array z-pinches allow us to study quasi-planar radiatively cooled flows in the laboratory. The early stage of a wire array z-pinch implosion consists of a steady flow of the wire material towards the axis. Given a high rate of radiative cooling, these flows reach high sonic- Mach numbers, typically up to 5. The 2D nature of this configuration allows the insertion of obstacles into the flow, such as a concentric ``inner'' wire array, as has previously been studied for ICF research. Here we study the application of such a nested array to laboratory astrophysics where the inner wires act as obstructions perpendicular to the flow, and induce bow shocks. By varying the wire array material (W/Al), the significance of radiative cooling on these shocks can be controlled, and is shown to change the shock opening angle. As multiple obstructions are present, the experiments show the interaction of multiple bow shocks. It is also possible to introduce a magnetic field around the static object, increasing the opening angle of the shocks. Further experiments can be designed to control the flow density, magnetic field structure and obstruction locations. In collaboration with: S.V. Lebedev, M.E. Cuneo, C.A. Jennings, S.N. Bland, J.P. Chittenden, A. Ciardi, G.N. Hall, S.C. Bott, M. Sherlock, A. Frank, E. Blackman

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

International Nuclear Information System (INIS)

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

1999-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1999-07-01

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

Titanium K-Shell X-Ray Production from High Velocity Wire Arrays Implosions on the 20-MA Z Accelerator

International Nuclear Information System (INIS)

Apruzese, J.P.; Beg, F.N.; Clark, R.C.; Coverdale, C.A.; Davis, J.; Deeney, C.; Douglas, M.R.; Nash, T.J.; Ruiz-Comacho, J.; Spielman, R.B.; Struve, K.W.; Thornhill, J.W.; Whitney, K.G.

1999-01-01

The advent of the 20-MA Z accelerator [R.B. Spielman, C. Deeney, G.A. Chandler, et al., Phys. Plasmas 5, 2105, (1997)] has enabled implosions of large diameter, high-wire-number arrays of titanium to begin testing Z-pinch K-shell scaling theories. The 2-cm long titanium arrays, which were mounted on a 40-mm diameter, produced between 75±15 to 125±20 kJ of K-shell x-rays. Mass scans indicate that, as predicted, higher velocity implosions in the series produced higher x-ray yields. Spectroscopic analyses indicate that these high velocity implosions achieved peak electron temperatures from 2.7±0.1 to 3.2±0.2 keV and obtained a K-shell emission mass participation of up to 12%

Single and nested tungsten-wire-array dynamics and applications to inertial confinement fusion

Science.gov (United States)

Cuneo, Michael

2005-10-01

Wire array z-pinches show great promise as x-ray sources for indirect-drive inertial confinement fusion (ICF). The double z-pinch hohlraum, for example, has produced capsule radiation drive symmetric to within 3%. This ICF concept will require that each of two 20-mm-diam arrays scale to x-ray powers ˜1 PW, to drive high-yield (>0.2 GJ) capsules to ignition. High-yield fusion will also require a temporally shaped radiation pulse to drive a low-entropy capsule implosion. Recently, improved understanding of high current (11-19 MA) single and nested wire-array dynamics has enabled significant progress towards these goals. As at lower currents, a single wire array (and both the outer and inner arrays of a nested system) shows a wire ablation phase, axial modulation of the ablation rate, a larger ablation rate for larger diameter wires, trailing mass and trailing current. These processes and others produce a broad mass profile that may impact the optimization of x-ray output for single and nested arrays. Our new insights into wire array physics have led to 20-mm-diam single and nested arrays with peak powers of 150-190 TW at implosion times of 55-90 ns, increased from 60-120 TW at 95-110 ns, improving power scaling. Radiation pulse shapes required for 3-shock isentropic compression of high-yield ICF capsules have also been demonstrated with nested wire arrays operating in current-transfer mode. In collaboration with: D.B. Sinars, R.A. Vesey, E.M. Waisman, W.A. Stygar, D.E. Bliss, S.V. Lebedev, J.P. Chittenden, P.V. Sasorov, R.W. Lemke, E.P. Yu, B.B. Afeyan, G.R. Bennett, M.G. Mazarakis, M.R. Lopez, M.E. Savage, J.L. Porter, T.A. Mehlhorn.

Current scaling of radiated power for 40-mm diameter single wire arrays on Z

Science.gov (United States)

Nash, T. J.; Cuneo, M. E.; Spielman, R. B.; Chandler, G. A.; Leeper, R. J.; Seaman, J. F.; McGurn, J.; Lazier, S.; Torres, J.; Jobe, D.; Gilliland, T.; Nielsen, D.; Hawn, R.; Bailey, J. E.; Lake, P.; Carlson, A. L.; Seamen, H.; Moore, T.; Smelser, R.; Pyle, J.; Wagoner, T. C.; LePell, P. D.; Deeney, C.; Douglas, M. R.; McDaniel, D.; Struve, K.; Mazarakis, M.; Stygar, W. A.

2004-11-01

In order to estimate the radiated power that can be expected from the next-generation Z-pinch driver such as ZR at 28 MA, current-scaling experiments have been conducted on the 20 MA driver Z. We report on the current scaling of single 40 mm diameter tungsten 240 wire arrays with a fixed 110 ns implosion time. The wire diameter is decreased in proportion to the load current. Reducing the charge voltage on the Marx banks reduces the load current. On one shot, firing only three of the four levels of the Z machine further reduced the load current. The radiated energy scaled as the current squared as expected but the radiated power scaled as the current to the 3.52±0.42 power due to increased x-ray pulse width at lower current. As the current is reduced, the rise time of the x-ray pulse increases and at the lowest current value of 10.4 MA, a shoulder appears on the leading edge of the x-ray pulse. In order to determine the nature of the plasma producing the leading edge of the x-ray pulse at low currents further shots were taken with an on-axis aperture to view on-axis precursor plasma. This aperture appeared to perturb the pinch in a favorable manner such that with the aperture in place there was no leading edge to the x-ray pulses at lower currents and the radiated power scaled as the current squared ±0.75. For a full-current shot we will present x-ray images that show precursor plasma emitting on-axis 77 ns before the main x-ray burst.

Dense sheet Z-pinches

International Nuclear Information System (INIS)

Tetsu, Miyamoto

1999-01-01

The steady state and quasi-steady processes of infinite- and finite-width sheet z-pinches are studied. The relations corresponding to the Bennett relation and Pease-Braginskii current of cylindrical fiber z-pinches depend on a geometrical factor in the sheet z-pinches. The finite-width sheet z-pinch is approximated by a segment of infinite-width sheet z-pinch, if it is wide enough, and corresponds to a number of (width/thickness) times fiber z-pinch plasmas of the diameter that equals the sheet thickness. If the sheet current equals this number times the fiber current, the plasma created in the sheet z-pinches is as dense as in the fiber z-pinches. The total energy of plasma and magnetic field per unit mass is approximately equal in both pinches. Quasi-static transient processes are different in several aspects from the fiber z-pinch. No radiation collapse occurs in the sheet z-pinch. The stability is improved in the sheet z-pinches. The fusion criterions and the experimental arrangements to produce the sheet z-pinches are also discussed. (author)

Experimental study of parallel multi-tungsten wire Z-pinch

International Nuclear Information System (INIS)

Huang Xianbin; China Academy of Engineering Physics, Mianyang; Lin Libin; Yang Libing; Deng Jianjun; Gu Yuanchao; Ye Shican; Yue Zhengpu; Zhou Shaotong; Li Fengping; Zhang Siqun

2005-01-01

The study of three parallel tungsten wire loads and five parallel tungsten wire loads implosion experiment on accelerator 'Yang' are reported. Tungsten wires (φ17 μm) with separation of 1 mm were used. The pinch was driven by a 350 kA peak current, 80 ns 10%-90% rise time. By means of pinhole camera and X-ray diagnostics technology, a non-uniform plasma column is formed among the wires and soft X-ray pulse are observed. the change of load current are analyzed, the development of sausage instability and kink instability, 'hot spot' effect and dispersion spot for plasma column are also discussed. (authors)

Prepulse suppression and allowable prepulse voltage in Z-pinch experiments

International Nuclear Information System (INIS)

Xia Minghe; Xie Weiping; Li Hongtao

2004-01-01

The causes of prepulse origin in pulse power machine especially in Blumlein pulser are analyzed in this paper. A method that can reduce the prepulse by an inductance between Marx and zero voltage node has been presented while a calculation example used Pspice is provided. The prepulse switches can be used to reduce the prepulse effects in many fields. The prepulse requests for wire arrays in Z-pinch experiments are analyzed and explained by means of specific reaction quantity and vaporization heat, the results of the calculations are similar. In fact, the results of experiments indicate that the energy deposited in the wires is sufficient to bring the aluminium wires to partial or total vaporization. Because the value of prepulse current is larger than that of calculation, this indicates the calculation method is right

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

International Nuclear Information System (INIS)

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

2006-01-01

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

Measurements of high-current electron beams from X pinches and wire array Z pinches

International Nuclear Information System (INIS)

Shelkovenko, T. A.; Pikuz, S. A.; Blesener, I. C.; McBride, R. D.; Bell, K. S.; Hammer, D. A.; Agafonov, A. V.; Romanova, V. M.; Mingaleev, A. R.

2008-01-01

Some issues concerning high-current electron beam transport from the X pinch cross point to the diagnostic system and measurements of the beam current by Faraday cups are discussed. Results of computer simulation of electron beam propagation from the pinch to the Faraday cup give limits for the measured current for beams having different energy spreads. The beam is partially neutralized as it propagates from the X pinch to a diagnostic system, but within a Faraday cup diagnostic, space charge effects can be very important. Experimental results show evidence of such effects.

Study of X-ray emission in aluminium z-pinches

International Nuclear Information System (INIS)

Rosch, R.

1999-01-01

Previous experiments, at 0.1. TX level, have shown that stability and x-ray emission of fast Z-pinches, could be strongly increased by imploding an aluminium vapor jet onto a very thin coaxial wire. We present here first results of an aluminium Z-pinch, using a similar liner, but at mega-ampere level. The pinch is driven by AMBIORIX high-power facility, a 2 TW, 0.5 Ω, 2 MA, 50 ns pulse-line generator. We study the effect of an aluminium wire and its diameter (20-50 μm) on the implosion dynamics, on x-ray yield on MHD stability of the column at stagnation. Analysis of A1 jet on A1 wire shots demonstrates that x-ray yield due to emission processes in the H- and He- like ionization stages (i.e. the K-shell) is significantly enhanced, relative to that of A1 jet only ones. The wire also leads to better symmetry of the implosion, and to better reproducibility of shots. X-ray signals exhibit two similar pulses, 10 ns in width, 15 ns spaced. To discern spectral origin of both pulses, experiments are realized with stainless steel wire (25 μm in diameter). Results show that liner and wire radial simultaneously and contribute to both pulses. Analysis of a typical A1 jet on A1 wire shot, using detailed collisional-radiative equilibrium (CRE) model is also given in this thesis. View o the pinch at stagnation as a cola-dense core surrounded by a hot-low density corona reproduces all features of the X-ray data. (author)

Study of X-ray emission in aluminium z-pinches; Etude de l'emission X dans les plasmas d'aluminium de type Z-pinch

Energy Technology Data Exchange (ETDEWEB)

Rosch, R [CEA/DAM-Ile de France, Dept. de Conception et Realisation des Experimentations (DCRE), 91 - Bruyeres-le-Chatel (France); [Paris-11 Univ., 91 - Orsay (France)

1999-07-01

Previous experiments, at 0.1. TX level, have shown that stability and x-ray emission of fast Z-pinches, could be strongly increased by imploding an aluminium vapor jet onto a very thin coaxial wire. We present here first results of an aluminium Z-pinch, using a similar liner, but at mega-ampere level. The pinch is driven by AMBIORIX high-power facility, a 2 TW,0.5 {omega}, 2 MA, 50 ns pulse-line generator. We study the effect of an aluminium wire and its diameter (20-50 {mu}m) on the implosion dynamics, on x-ray yield on MHD stability of the column at stagnation. Analysis of A1 jet on A1 wire shots demonstrates that x-ray yield due to emission processes in the H- and He- like ionization stages (i.e. the K-shell) is significantly enhanced, relative to that of A1 jet only ones. The wire also leads to better symmetry of the implosion, and to better reproducibility of shots. X-ray signals exhibit two similar pulses, 10 ns in width, 15 ns spaced. To discern spectral origin of both pulses, experiments are realized with stainless steel wire (25 {mu}m in diameter). Results show that liner and wire radial simultaneously and contribute to both pulses. Analysis of a typical A1 jet on A1 wire shot, using detailed collisional-radiative equilibrium (CRE) model is also given in this thesis. View o the pinch at stagnation as a cola-dense core surrounded by a hot-low density corona reproduces all features of the X-ray data. (author)

Dense Z-pinch plasmas

International Nuclear Information System (INIS)

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

1985-01-01

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

Demonstration of radiation pulse shaping with nested-tungsten-wire-array pinches for high-yield inertial confinement fusion.

Science.gov (United States)

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

2005-10-28

Nested wire-array 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 CH2 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.

Experiments with a Gas-Puff-On-Wire-Array Load on the GIT-12 Generator for Al K-shell Radiation Production at Microsecond Implosion Times

International Nuclear Information System (INIS)

Shishlov, Alexander V.; Baksht, Rina B.; Chaikovsky, Stanislav A.; Fedunin, Anatoly V.; Fursov, Fedor I.; Kovalchuk, Boris M.; Kokshenev, Vladimir A.; Kurmaev, Nikolai E.; Labetsky, Aleksey Yu.; Oreshkin, Vladimir I.; Rousskikh, Alexander G.; Lassalle, Francis; Bayol, Frederic

2006-01-01

Results of the experiments carried out on the GIT-12 generator at the current level of 3.5 MA and the Z-pinch implosion times from 700 ns to 1.1 μs are presented. A multi-shell (triple-shell) load configuration with the outer gas puffs (neon) and the inner wire array (aluminum) was used in the experiments. In the course of the research, implosion dynamics of the triple-shell z-pinch was studied, and the radiation yield in the spectral range of neon and aluminum K-lines have been measured. Optimization of the inner wire array parameters aimed at obtaining the maximum aluminum K-shell radiation yield has been carried out. As a result of optimization of the gas-puff-on-wire-array Z-pinch load, the aluminum K-shell radiation yield (hv> 1.55 keV) up to 4 kJ/cm in the radiation pulse with FWHM less than 30 ns has been obtained. Comparison of the experimental results with the results of preliminary 1D RMHD simulations allows a conclusion that at least 2/3 of the generator current is switched from a gas puff to an aluminum wire array. The radiation yield in the spectral range of neon K-lines (0.92-1.55 keV) increases considerably in the shots with the inner wire array in comparison with the shots carried out with the outer gas puffs only. The radiation yield in the spectral range above 1 keV registered in the experiments reached 10 kJ/cm. The presence of a high portion of the neon plasma inside an inner wire array can limit the radiation yield in the spectral range above 1.55 keV

Nonthermal x-ray emission from a tungsten z-pinch at 5 MA

International Nuclear Information System (INIS)

Sanford, T.W.L.; Nash, T.J.; Marder, B.M.

1995-01-01

The generation of intense bursts of warm x rays with power in the 1-TW regime are of interest for the study of in-depth nuclear radiation effects. Results from high-atomic-number single-wire experiments carried out at 0.8 MA on Gamble II in the 1970s showed 0.25% efficient production of nonthermal, bremsstrahlung-like lines and continuum in the 5- to 100-keV regime. This high efficiency in combination with suggested Z 2 and I 2 scaling of the nonthermal radiation motivated the present experiment to measure and model the radiation from the z pinch formed from compact high-Z wire arrays at high current. In the experiment, tungsten wire arrays of length 20 mm on a mounting radius of 2 mm were imploded over the mass range 1 to 16 mg on the Saturn accelerator operating with a peak discharge current of 5 MA. As in the Gamble-II experiments, bright spots were observed to form at ∼1-mm intervals along the z axis at the time of a first implosion and to be the source of the hard radiation measured. Maximum radiation occurred for masses less than or approximately equal to 4 mg. The experiment was simulated using the LASNEX and TIP numerical codes with a nonthermal model. The timing of the multiple implosions, owing to compression and expansion of the resulting plasma are observed to be in agreement with predictions from both codes and analytic modeling

Z-pinches

International Nuclear Information System (INIS)

Yan'kov, V.V.

1991-01-01

Although pinches, unlike tokamaks, have not occupied a central position in fusion research, their structural simplicity and the wealth of physical processes associated with plasma foci have maintained a steady interest. The development of Z-pinches, including plasma foci, micropinches, and dense Z-pinches, is reviewed. Attention is focused on theoretical as opposed to experimental questions, and on recent work rather than the basic results now found in textbooks. Finally, Soviet work is discussed more fully than work done abroad, and applications to controlled fusion are emphasized

Fusion with Z-pinches

International Nuclear Information System (INIS)

Cook, D.

1998-06-01

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

History of HERMES III diode to z-pinch breakthrough and beyond :

Energy Technology Data Exchange (ETDEWEB)

Sanford, Thomas Williamlou.

2013-04-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Rochau, G A [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Bailey, J E [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Chandler, G A [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Cooper, G [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Dunham, G S [K-tech Corporation, 10800 Gibson S E, Albuquerque, NM 87123 (United States); Lake, P W [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Leeper, R J [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Lemke, R W [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Mehlhorn, T A [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Nikroo, A [General Atomics, PO Box 85608, San Diego, CA 92186 (United States); Peterson, K J [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Ruiz, C L [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Schroen, D G [General Atomics, PO Box 85608, San Diego, CA 92186 (United States); Slutz, S A [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Steinman, D [General Atomics, PO Box 85608, San Diego, CA 92186 (United States); Stygar, W A [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Varnum, W [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States)

2007-12-15

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 CH{sub 2} 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 {mu}m ns{sup -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 {approx}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.

A Pb-TLD spectrometer to measure high energy photons in z-pinch experiments on the primary test stand

International Nuclear Information System (INIS)

Si, Fenni; Yang, Jianlun; Xu, Rongkun; Yuan, Xi; Huang, Zhanchang; Ye, Fan; Wang, Dong; Zhang, Chuanfei

2017-01-01

Highlights: • A Pb-TLD spectrometer has been developed to measure spectra of high energy photons in wire-array z pinches on PTS. • Energy spectra of high energy photons on PTS has been firstly obtained by unfolding programs developed with MATLAB code. • The energy of high energy x-ray on PTS is obtained to be mainly within the region of 100 keV to 1.3 MeV. - Abstract: A Pb-TLD spectrometer has been developed based on attenuation techniques to measure high energy photons in wire-array z-pinch experiments on the primary test stand (PTS). It is composed of a stack of 18 lead filters interspersed with 19 thermoluminescent dosimeters (TLD). A shield is constructed for the spectrometer and scattered radiation is reduced to less than 5% by the shield. Response functions of the spectrometer are calculated by MCNP5 for 0–2 MeV photons. Based on response functions and 19 dose data measured in experiments, energy spectra of high energy photons on PTS has been firstly obtained by unfolding programs developed with MATLAB code using iterative least square fit. Results show that energy peak locates within 200 keV and 300 keV, and the fluence decreases to background level at energy higher than 1.3 MeV.

A Pb-TLD spectrometer to measure high energy photons in z-pinch experiments on the primary test stand

Energy Technology Data Exchange (ETDEWEB)

Si, Fenni; Yang, Jianlun; Xu, Rongkun; Yuan, Xi; Huang, Zhanchang; Ye, Fan; Wang, Dong; Zhang, Chuanfei, E-mail: sifenni@163.com

2017-05-15

Highlights: • A Pb-TLD spectrometer has been developed to measure spectra of high energy photons in wire-array z pinches on PTS. • Energy spectra of high energy photons on PTS has been firstly obtained by unfolding programs developed with MATLAB code. • The energy of high energy x-ray on PTS is obtained to be mainly within the region of 100 keV to 1.3 MeV. - Abstract: A Pb-TLD spectrometer has been developed based on attenuation techniques to measure high energy photons in wire-array z-pinch experiments on the primary test stand (PTS). It is composed of a stack of 18 lead filters interspersed with 19 thermoluminescent dosimeters (TLD). A shield is constructed for the spectrometer and scattered radiation is reduced to less than 5% by the shield. Response functions of the spectrometer are calculated by MCNP5 for 0–2 MeV photons. Based on response functions and 19 dose data measured in experiments, energy spectra of high energy photons on PTS has been firstly obtained by unfolding programs developed with MATLAB code using iterative least square fit. Results show that energy peak locates within 200 keV and 300 keV, and the fluence decreases to background level at energy higher than 1.3 MeV.

Z-pinches

International Nuclear Information System (INIS)

Yan'kov, V.V.

1991-01-01

The development of Z-pinches, including plasma foci, micropinches and dense Z-pinches are reviewed. A special attention is paid to the physics of sausage instability development. Theoretical questions are discussed in more detail that the experimental ones, recent works - to a fuller extent than the fundamental pioneer ones which are included in the textbooks. The Soviet works are given a greater coverage as compared to the foreign ones. An emphasis is made on the problem of controlled thermonuclear fusion

Generation of a subgigagauss magnetic field by pinching the plasma channel of exploded-wire

International Nuclear Information System (INIS)

Bogolyubsky, S.L.

1990-01-01

An interest in the dense pinches produced in the explosion of thin wires in the diodes of high current-nanosecond-REB-generators is provided by an opportunity to obtain high temperature-dense plasma configurations as an object of fusion studies and that in the spectroscopy of multi-charged ions. One needs to have a micrometer size of the Z-pinch neck to ignite the fusion reaction. The plasma channel pinching of the wires exploded by a megaampere current to a micrometer size of its neck can provide gigagauss magnetic fields. An important aspect of a given study is verification of an opportunity to obtain the radiation collapse of the plasma channel due to an exploded wire along its whole length up to the kA because of a line radiation cut-off due to the Braginsky-Pease current reduction to 150-200 from the plasma with left-angle Z right-angle much-gt 1. This paper presents experimental studies in this field, with the currents 0.2 MA, 0.5 MA, 1.2 MA

Numerical simulation of wire array load implosion on Yang accelerator

International Nuclear Information System (INIS)

Zhao Hailong; Deng Jianjun; Wang Qiang; Zou Wenkang; Wang Ganghua

2012-01-01

Based on the ZORK model describing the Saturn facility, a zero dimensional load model of the wire array Z-pinch on Yang accelerator is designed using Pspice to simulate the implosion process. Comparisons between the calculated results and experimental data prove the load model to be correct. The applicability and shortcomings of the load model are presented. One-dimensional magnetohydrodynamic calculations are performed by using the current curve obtained from calculated results of experiment Yang 1050#. and the parameters such as implosion time and radiation X-ray power are obtained. (authors)

Phenomenological modeling of turbulence in Z-pinch implosions

International Nuclear Information System (INIS)

Thornhill, J.W.; Whitney, K.G.; Deeney, C.; LePell, P.D.

1994-01-01

A phenomenological investigation into the effects of magnetohydrodynamic (MHD) turbulence on the initial stagnation dynamics of aluminum wire array and argon gas puff Z-pinch implosions is performed. The increases that turbulence produces in the plasma viscosity, heat conductivity, and electrical resistivity are modeled by using multipliers for these quantities in one-dimensional (1-D) MHD calculations. The major effect of these increases is to soften the 1-D implosions by decreasing the densities that are achieved on axis at stagnation. As a consequence, a set of multipliers can be found that reasonably duplicates the average electron temperatures, ion densities, and mass of the K-shell emission region that were measured at stagnation for a variety of Physics International aluminum wire array and argon gas puff experiments. It is determined that the dependence of these measured quantities on the multipliers is weak once a level of enhancement is reached, where agreement between calculations and experiments is attained. The scaling of K-shell yield with load mass for a fixed implosion velocity is then reexamined, and the minimum load mass needed to efficiently produce K-shell emission by thermalization of kinetic energy is calculated for aluminum and argon using this phenomenological soft implosion modeling. The results show an upward shift in the minimum mass by a factor of 6 when compared to the original nonturbulent hard implosion calculations

Experimental study on imploding characteristics of wire-array Z pinches on Qiangguang-1 facility

Institute of Scientific and Technical Information of China (English)

Wang Zhen; Xu Rong-Kun; Yang Jian-Lun; Hua Xin-Sheng; Li Lin-Bo; Xu Ze-Ping; Ning Jia-Min; Song Feng-Jun

2007-01-01

To investigate the imploding characteristics of cylindrical wire array,experiments with load current varying from 1.5MA to 1.7MA were carried out on the Qiangguang-1 facility.The complicated temporal-spatial distribution of x-ray radiation was measured by the one-dimensional (1D) x-ray imaging system.Other diagnostic equipments including the x-ray power meter(XRPM) and the time-integrated pinhole camera were used to record time-resolved x-ray power pulse and pinhole x-ray images.Analysis shows that the fast leading edge of the local x-ray radiation pulse is of primary importance in sharpening x-ray power pulse rather than the temporal synchrony and the spatial uniformity of implosion.Experimental results indicated that the better axial imploding synchrony,the faster the increase of X-ray power for an array consisting of 32 tungsten wires of 5μm diameter than for the others,and the higher the x-ray radiation power with maximal convergence ratio (r0/r1) of 10.5.A 'zipper-like' effect of x-ray radiation extending from the cathode Was also observed.

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

International Nuclear Information System (INIS)

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

1998-01-01

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

Observation of >400-eV precursor plasmas from low-wire-number copper arrays at the 1-MA zebra facility.

Science.gov (United States)

Coverdale, C A; Safronova, A S; Kantsyrev, V L; Ouart, N D; Esaulov, A A; Deeney, C; Williamson, K M; Osborne, G C; Shrestha, I; Ampleford, D J; Jones, B

2009-04-17

Experiments with cylindrical copper wire arrays at the 1-MA Zebra facility show that high temperatures exist in the precursor plasmas formed when ablated wire array material accretes on the axis prior to the stagnation of a z pinch. In these experiments, the precursor radiated approximately 20% of the >1000 eV x-ray output, and time-resolved spectra show substantial emission from Cu L-shell lines. Modeling of the spectra shows an increase in temperature as the precursor forms, up to approximately 450 eV, after which the temperature decreases to approximately 220-320 eV until the main implosion.

Investigation of dynamics of soft X-ray radiation of mixed-material wire-arrays on S-300 pulsed power generator

NARCIS (Netherlands)

Cai, HC; Chernenko, AC; Korolev, VD; Ustroev, GI; Ivanov, MI

2004-01-01

The dynamics of radiation spectra of fast Z-pinch plasmas was studied. The experiments were carried out on the S-300 pulsed power machine (4 MA, 0.15 Omega, 100 ns). By means of the polychromator, X-ray spectra of imploding wire arrays were measured in the range of 60 divided by 1500 eV, where the

Study of the internal structure, instabilities, and magnetic fields in the dense Z-pinch

Energy Technology Data Exchange (ETDEWEB)

Ivanov, Vladimir V. [Univ. of Nevada, Reno, NV (United States)

2016-08-17

Z-pinches are sources of hot dense plasma which generates powerful x-ray bursts and can been applied to various areas of high-energy-density physics (HEDP). The 26-MA Z machine is at the forefront of many of these applications, but important aspects of HEDP have been studied on generators at the 1 MA current level. Recent development of laser diagnostics and upgrade of the Leopard laser at Nevada Terawatt Facility (NTF) give new opportunities for the dense Z-pinch study. The goal of this project is the investigation of the internal structure of the stagnated Z pinch including sub-mm and micron-scale instabilities, plasma dynamics, magnetic fields, and hot spots formation and initiation. New plasma diagnostics will be developed for this project. A 3D structure and instabilities of the pinch will be compared with 3D MHD and spectroscopic modeling and theoretical analysis. The structure and dynamics of stagnated Z pinches has been studied with x-ray self-radiation diagnostics which derive a temperature map of the pinch with a spatial resolution of 70-150 µm. The regular laser diagnostics at 532 nm does not penetrate in the dense pinch due to strong absorption and refraction in trailing plasma. Recent experiments at NTF showed that shadowgraphy at the UV wavelength of 266 nm unfolds a fine structure of the stagnated Z-pinch with unprecedented detail. We propose to develop laser UV diagnostics for Z pinches with a spatial resolution <5 μm to study the small-scale plasma structures, implement two-frame shadowgraphy/interferometry, and develop methods for investigation of strong magnetic fields. New diagnostics will help to understand better basic physical processes in Z pinches. A 3D internal structure of the pinch and characteristic instabilities will be studied in wire arrays with different configurations and compared with 3D MHD simulations and analytical models. Mechanisms of “enhanced heating” of Z-pinch plasma will be studied. Fast dynamics of stagnated

Measurements of high energy photons in Z-pinch experiments on primary test stand

International Nuclear Information System (INIS)

Si, Fenni; Zhang, Chuanfei; Xu, Rongkun; Yuan, Xi; Huang, Zhanchang; Xu, Zeping; Ye, Fan; Yang, Jianlun; Ning, Jiamin; Hu, Qingyuan; Zhu, Xuebin

2015-01-01

High energy photons are measured for the first time in wire-array Z-pinch experiments on the Primary Test Stand (PTS) which delivers a current up to 8 MA with a rise time of 70 ns. A special designed detecting system composed of three types of detectors is used to measure the average energy, intensity, and pulse waveform of high energy photons. Results from Pb-TLD (thermoluminescence dosimeter) detector indicate that the average energy is 480 keV (±15%). Pulse shape of high energy photons is measured by the photodiode detector consisted of scintillator coupled with a photodiode, and it is correlated with soft x-ray power by the same timing signal. Intensity is measured by both TLD and the photodiode detector, showing good accordance with each other, and it is 10 10 cm −2 (±20%) at 2 m in the horizontal direction. Measurement results show that high energy photons are mainly produced in pinch regions due to accelerated electrons. PTS itself also produces high energy photons due to power flow electrons, which is one order smaller in amplitude than those from pinch region

Progress on z-pinch inertial fusion energy

International Nuclear Information System (INIS)

Olson, C.; Rochau, G.; Matzen, M.K.

2005-01-01

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. (author)

Producing High-Performance, Stable, Sheared-Flow Z-Pinches in the FuZE project

Science.gov (United States)

Golingo, R. P.; Shumlak, U.,; Nelson, B. A.; Claveau, E. L.; Forbes, E. G.; Stepanov, A. D.; Weber, T. R.; Zhang, Y.; McLean, H. S.; Tummel, K. K.; Higginson, D. P.; Schmidt, A. E.; University of Washington (UW) Collaboration; Lawrence Livermore National Laboratory (LLNL) Collaboration

2017-10-01

The Fusion Z-Pinch Experiment (FuZE) has made significant strides towards generating high-performance, stable Z-pinch plasmas with goals of ne = 1018 cm-3 and T =1 keV. The Z-pinch plasmas are stabilized with a sheared axial flow that is driven by a coaxial accelerator. The new FuZE device has been constructed and reproduces the major scientific achievements the ZaP project at the University of Washington; ne = 1016 cm-3,T = 100 eV, r20 μs. These parameters are measured with an array of magnetic field probes, spectroscopy, and fast framing cameras. The plasma parameters are achieved using a small fraction of the maximum energy storage and gas injection capability of the FuZE device. Higher density, ne = 5×1017 cm-3, and temperature, T = 500 eV, Z-pinch plasmas are formed by increasing the pinch current. At the higher voltages and currents, the ionization rates in the accelerator increase. By modifying the neutral gas profile in the accelerator, the plasma flow from the accelerator is maintained, driving the flow shear. Formation and sustainment of the sheared-flow Z-pinch plasma will be discussed. Experimental data demonstrating high performance plasmas in a stable Z-pinches will be shown. This work is supported by an award from US ARPA-E.

The physics of fast Z pinches

International Nuclear Information System (INIS)

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

1998-07-01

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

The Physics of Fast Z Pinches

Energy Technology Data Exchange (ETDEWEB)

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

1999-10-25

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.

Z-Pinch Fusion for Energy Applications

Energy Technology Data Exchange (ETDEWEB)

SPIELMAN,RICK B.

2000-01-01

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.

Z-Pinch Fusion for Energy Applications

International Nuclear Information System (INIS)

SPIELMAN, RICK B.

2000-01-01

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

Dynamic hohlraum and ICF pellet implosion experiments on Z

International Nuclear Information System (INIS)

Nash, T.J.; Derzon, M.S.; Chandler, G.A.

1999-01-01

By stabilizing an imploding z-pinch on Z (20 MA, 100 ns) with a solid current return can and a nested wire array the authors have achieved dynamic hohlraum radiation temperatures over 200 eV at a diameter of approximately 1 mm. The pinch configuration yielding this temperature is a nested tungsten wire array of 240 and 120 wires at 4 and 2 cm diameters weighing 2 and 1 mg, 1 cm long, imploding onto a 5 mm diameter, 14 mg/cc cylindrical CH foam, weighing 3 mg. They have used a single 4 cm diameter tungsten wire array to drive a 1.6 mm diameter ICF capsule mounted in a 6 mg/cc foam inside a 3 mg copper annulus at 5 mm diameter, and measured x-ray emissions indicative of the pellet implosion. Mounting the pellet in foam may have caused the hohlraum to become equator-hot. They will present results from upcoming pellet experiments in which the pellet is mounted by thread and driven by a larger diameter, 6 or 7 mm, copper annulus to improve radiation drive symmetry. They will also discuss designs for tapered foam annular targets that distort a cylindrical pinch into a quasi-sphere that will wrap around an ICF pellet to further improve drive symmetry

The ZaP Flow Z-Pinch Project

International Nuclear Information System (INIS)

Shumlak, U.; Nelson, B. A.

2005-01-01

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 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

Increased kilo-electron-volt x-ray yields from Z-pinch plasmas by mixing elements of similar atomic numbers

International Nuclear Information System (INIS)

Deeney, C.; LePell, P.D.; Failor, B.H.; Wong, S.L.; Apruzese, J.P.; Whitney, K.G.; Thornhill, J.W.; Davis, J.; Yadlowsky, E.; Hazelton, R.C.; Moschella, J.J.; Nash, T.; Loter, N.

1995-01-01

Magnesium-coated aluminum wire array Z pinch plasmas have been tested on a 4-MA, 6-TW pulsed electrical generator. A mixture of 80% aluminum and 20% magnesium is observed to maximize the radiated kilovolt x-ray yield at ≥50 kJ, which is 50% higher than that obtained with pure aluminum. Spectroscopic analysis and collisional radiative equilbrium models with radiation transport are employed to show that the aluminum-magnesium mixture reduces the opacity of the strongest emission lines, thus increasing the yield by increasing the probability of photon escape. Furthermore, the spectroscopic data also point to the presence of a strong temperature gradient in the pinched plasma that results in the outer magnesium coating of the wires having a higher electron temperature in the pinch. This temperature difference also plays a role in enhancing the kilovolt x-ray yield. The observation of a higher magnesium electron temperature offers evidence that the magnesium reaches the axis first, forming a core that is compressed and heated by the imploding mass of aluminum. Since the emissions from the core are not absorbed by the outer aluminum, the yields are increased. By comparison, aluminum-magnesium alloys imploded on a different but similar generator do not show a temperature difference

Confined discharge plasma sources for Z-pinch experiments

International Nuclear Information System (INIS)

Hinshelwood, D.D.; Goodrich, P.J.; Mehlman, G.; Scherrer, V.E.; Stephanakis, S.J.; Young, F.C.

1989-01-01

The authors report their investigation Z-pinch implosions on the NRL Gamble II generator using metallic sources of sodium and aluminum, and non-metallic source of sodium (NaF), magnesium (MgF 2 ), and aluminum (Al 2 0 3 ). For 1 MA driving currents, peak Κ-shell radiated powers of about 100 GW and energies of about 1.5 kj have been obtained with both pure aluminum and NaF implosions. The aluminum results are comparable to those in previous Gamble II experiments with aluminum wire arrays. Confined discharge sources have been used to generate tens of GW in the Na Heα pump line and flourescence of the neon has been observed. The effects of nozzle shape and size, chamber diameter, amount of fuse material, and confined discharge current have been investigated in Gamble II implosion experiments. These studies indicate that confined discharge sources are capable of supplying significantly more material than required for implosions at the 1 MA level, so that this technique could be extended to higher current generators

Hybrid simulations of Z-Pinches in support of wire array implosion experiments at NTF

International Nuclear Information System (INIS)

Sotnikov, Vladimir Isaakovich; Oliver, Bryan Velten; Ivanov, Vladimir V.; LePell, Paul David; Fedin, Dmitry; Kantsyrev, Victor Leonidovich; Coverdale, Christine Anne; Travnicek, P.; Deeney, Christopher; Hellinger, P.; Jones, B.; Leboeuf, J.N.; Cowan, Thomas E.; Safronova, Alla S.

2005-01-01

Three-dimensional hybrid simulation of a plasma current-carrying column reveal two different regimes of sausage and kink instability development. In the first regime, with small Hall parameter, development of instabilities leads to the appearance of large-scale axial perturbations and eventually to bending of the plasma column. In the second regime, with a four-times-larger Hall parameter, small-scale perturbations dominate and no bending of the plasma column is observed. Simulation results are compared with laser probing experimental data obtained during wire array implosions on the Zebra pulse power generator at the Nevada Terawatt Facility.

Evidence of flow stabilization in the ZaP Z pinch experiment

International Nuclear Information System (INIS)

Shumlak, U.; Crawford, E.; Golingo, R.P.; Nelson, B.A.; Zyrmpas, A.; Den Hartog, D.J.; Holly, D.J.

2001-01-01

The stabilizing effect of an axial flow on the m = 1 kink instability in Z pinches has been studied numerically with a linearized ideal MHD model to reveal that a sheared axial flow stabilizes the kink mode when the shear exceeds a threshold. The sheared flow stabilizing effect is investigated with the flow-through Z pinch experiment, ZaP. An azimuthal array of surface mounted magnetic probes located at the midplane of the 50 cm long pinch plasma measures the fluctuation levels of the azimuthal modes m=1, 2, and 3. After pinch formation a quiescent period is found where the mode activity is reduced to a few percent of the average field. Optical images from a fast framing camera and a HeNe interferometer also indicate a stable pinch plasma during this time. Doppler shift measurements of a C-III line correspond to an axial flow velocity of 9.6x10 4 m/s internal to the pinch. During the time when the axial plasma flow is high, the plasma experiences a quiescent period which lasts approximately 800 exponential growth times predicted by linear theory for a static plasma. (author)

D-D fusion experiments using fast z pinches

International Nuclear Information System (INIS)

Spielman, R.B.; Baldwin, G.T.; Cooper, G.

1994-01-01

The development of high current (I > 10 MA) drivers provides us with a new tool for the study of neutron-producing plasmas in the thermal regime. The imploded deuterium mass (or collisionality) increases as I 2 and the ability of the driver to heat the plasma to relevant fusion temperatures improves as the power of the driver increases. Additionally, fast ( 2 fiber arrays were imploded in a fast z-pinch configuration on Sandia's Saturn facility generating up to 3 x 10 12 D-D neutrons. These experiments were designed to explore the physics of neutron-generating plasmas in a z-pinch geometry. Specifically, we intended to produce neutrons from a nearly thermal plasma where the electrons and ions have a nearly Maxwellian distribution. This is to be clearly differentiated from the more usual D-D beam-target neutrons generated in many dense plasma focus (DPF) devices

D-D fusion experiments using fast Z pinches

International Nuclear Information System (INIS)

Spielman, R.B.; Baldwin, G.T.; Cooper, G.

1998-03-01

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

The achievements of the Z-machine; Les exploits de la Z-machine

Energy Technology Data Exchange (ETDEWEB)

Larousserie, D

2008-03-15

The ZR-machine that represents the latest generation of Z-pinch machines has recently begun preliminary testing before its full commissioning in Albuquerque (Usa). During its test the machine has well operated with electrical currents whose intensities of 26 million Ampere are already 2 times as high as the intensity of the operating current of the previous Z-machine. In 2006 the Z-machine reached temperatures of 2 billions Kelvin while 100 million Kelvin would be sufficient to ignite thermonuclear fusion. In fact the concept of Z-pinch machines was imagined in the fifties but the technological breakthrough that has allowed this recent success and the reborn of Z-machine, was the replacement of gas by an array of metal wires through which the electrical current flows and vaporizes it creating an imploding plasma. It is not well understood why Z-pinch machines generate far more radiation than theoretically expected. (A.C.)

Plasma focus - dense Z pinch and their applications

International Nuclear Information System (INIS)

Ishii, Shozo

1986-02-01

''Workshop on the possibility of Z-pinch as a intense pulse light source'' in 1983 and ''Research meeting on plasma focus and Z-pinch'' in 1984 were held at Institute of Plasma Physics, Nagoya University under a collaborating research program. Research activities reported at the meetings on plasma focus, dense Z-pinch, and related phenomena are summerized. (author)

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

International Nuclear Information System (INIS)

Matuska, W.; Lee, H.

1997-01-01

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

Using 1D theory to understand 3D stagnation of a wire-array Z pinch in the absence of radiation

Science.gov (United States)

Yu, Edmund

2015-11-01

Many high-energy-density systems implode towards the axis of symmetry, where it collides on itself, forming a hot plasma. However, experiments show these imploding plasmas develop three-dimensional (3D) structures. As a result, the plasma cannot completely dissipate its kinetic energy at stagnation, instead retaining significant 3D flow. A useful tool for understanding the effects of this residual flow is 3D simulation, but the amount and complexity of information can be daunting. To address this problem, we explore the connection between 3D simulation and one-dimensional (1D) theory. Such a connection, if it exists, is mutually beneficial: 1D theory can provide a clear picture of the underlying dynamics of 3D stagnation. On the other hand, deviations between theory and simulation suggest how 1D theory must be modified to account for 3D effects. In this work, we focus on a 3D, magnetohydrodynamic simulation of a compact wire-array Z pinch. To provide a simpler background against which to test our ideas, we artificially turn off radiation during the stagnation phase. Examination of the initial accumulation of mass on axis reveals oblique collision between jets, shock accretion, and vortex formation. Despite evidence for shock-dominated stagnation, a 1D shockless stagnation solution is more appropriate for describing the global dynamics, in that it reproduces the increase of on-axis density with time. However, the 1D solution must be modified to account for 3D effects: the flows suggest enhanced thermal transport as well as centrifugal force. Upon reaching peak compression, the stagnation transitions to a second phase, in which the high-pressure core on axis expands outward into the remaining imploding plasma. During this phase, a 1D shock solution describes the growth of the shock accretion region, as well as the decrease of on-axis density with time. However, the effect of 3D flows is still present: the on-axis temperature does not cool during expansion, which

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

International Nuclear Information System (INIS)

Matzen, M.K.

1997-01-01

Fast z-pinch implosions can convert more than 10% of the stored electrical energy in a pulsed-power accelerator into x rays. These x rays are produced when an imploding cylindrical plasma, driven by the magnetic field pressure associated with very large axial currents, stagnates upon the cylindrical axis of symmetry. On the Saturn pulsed-power accelerator at Sandia National Laboratories, for example, currents of 6 to 8 MA with a risetime of less than 50 ns are driven through cylindrically-symmetric loads, producing implosions velocities as high as 100 cm/μs and x-ray energies as high as 500 kJ. The keV component of the resulting x-ray spectrum has been used for many years 8 a radiation source for material response studies. Alternatively, the x-ray output can be thermalized into a near-Planckian x-ray source by containing it within a large cylindrical radiation case. These large volume, long-lived radiation sources have recently been used for ICF-relevant ablator physics experiments as well as astrophysical opacity and radiation-material interaction experiments. Hydromagnetic Rayleigh-Taylor instabilities and cylindrical load symmetry are critical, limiting factors in determining the assembled plasma densities and temperatures, and thus in the x-ray pulse widths that can be produced on these accelerators. In recent experiments on the Saturn accelerator, these implosion nonuniformities have been minimized by using uniform-fill gas puff loads or by using wire arrays with as many a 192 wires. These techniques produced significant improvements in the pinched plasma quality, Zn reproducibility, and x-ray output power. X-ray pulse widths of less than 5 ns and peak powers of 75±10 TW have been achieved with arrays of 120 tungsten wires. These powers represent greater than a factor of three in power amplification over the electrical power of the Saturn n accelerator, and are a record for x-ray powers in the laboratory

History of the Z-pinch

International Nuclear Information System (INIS)

Lovberg, R.H.

1988-01-01

The plasma Z-Pinch occupies a unique position in the history of controlled fusion research as the first confinement and heating scheme to be tried experimentally. In contrast to the sophistication of programs being conducted today, in which extensive theoretical and experimental forces are in close collaboration, early pinch experiments were designed on quite elementary theoretical grounds. Indeed, these systems and the results from them provided the focus for much of the rapid development of theoretical plasma physics and magnetohydrodynamics during the 1950's. In comparison to present programs, these early experiments had the considerable advantage of small size and minimal managerial encumbrance. After nearly three decades of abandonment because of difficulties with MHD instabilities, the Z-pinch is arising once again in a new incarnation characterized by microscopic size and time scales, and very high density. Uniquely in the history of the pinch, the new experimental surprises seem encouraging, rather than discouraging, to the goal of thermonuclear fusion

High-density fusion and the Z-pinch

International Nuclear Information System (INIS)

Hartman, C.W.; Eddleman, J.L.; Munger, R.H.

1975-01-01

The formation of a Z-pinch in dense gas is investigated using numerical modeling in one and two dimensions. Hot, dense Z-pinches are calculated with n approximately 2 x 10 21 cm 3 and T = 10 keV. Relaxation by sausage instability of an unstable pinch profile to a marginally stable one is calculated along with end losses in 2 dimensions to show that, if plasma is confined for N = 50 to 200 sound transits across the radius a, pinches with length L = Na are of interest for fusion power. A conceptual, ''no-wall'' fusion reactor is discussed. (author)

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

International Nuclear Information System (INIS)

Rochau, Gregory A.; Derzon, Mark S.; Chandler, Gordon A.; Lazier, Steven Earl

2000-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Kantsyrev, V. L., E-mail: victor@unr.edu; Shrestha, I. K.; Esaulov, A. A.; Safronova, A. S.; Shlyaptseva, V. V.; Osborne, G. C.; Astanovitsky, A. L.; Weller, M. E.; Stafford, A.; Schultz, K. A.; Cooper, M. C. [Physics Department, University of Nevada, Reno, NV 89557 (United States); Chuvatin, A. S. [Laboratorie de Physique des Plasmas, Ecole Polytechnique, 91128 Palaiseau (France); Rudakov, L. I. [Icarus Research Inc., P.O. Box 30780, Bethesda, MD 20824-0780 (United States); Velikovich, A. L. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Cuneo, M. E.; Jones, B.; Vesey, R. A. [Sandia National Laboratories, Albuquerque, NM 87110 (United States)

2014-12-15

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

The achievements of the Z-machine

International Nuclear Information System (INIS)

Larousserie, D.

2008-01-01

The ZR-machine that represents the latest generation of Z-pinch machines has recently begun preliminary testing before its full commissioning in Albuquerque (Usa). During its test the machine has well operated with electrical currents whose intensities of 26 million Ampere are already 2 times as high as the intensity of the operating current of the previous Z-machine. In 2006 the Z-machine reached temperatures of 2 billions Kelvin while 100 million Kelvin would be sufficient to ignite thermonuclear fusion. In fact the concept of Z-pinch machines was imagined in the fifties but the technological breakthrough that has allowed this recent success and the reborn of Z-machine, was the replacement of gas by an array of metal wires through which the electrical current flows and vaporizes it creating an imploding plasma. It is not well understood why Z-pinch machines generate far more radiation than theoretically expected. (A.C.)

Overview of the Fusion Z-Pinch Experiment FuZE

Science.gov (United States)

Weber, T. R.; Shumlak, U.; Nelson, B. A.; Golingo, R. P.; Claveau, E. L.; McLean, H. S.; Tummel, K. K.; Higginson, D. P.; Schmidt, A. E.; UW/LLNL Team

2016-10-01

Previously, the ZaP device, at the University of Washington, demonstrated sheared flow stabilized (SFS) Z-pinch plasmas. Instabilities that have historically plagued Z-pinch plasma confinement were mitigated using sheared flows generated from a coaxial plasma gun of the Marshall type. Based on these results, a new SFS Z-pinch experiment, the Fusion Z-pinch Experiment (FuZE), has been constructed. FuZE is designed to investigate the scaling of SFS Z-pinch plasmas towards fusion conditions. The experiment will be supported by high fidelity physics modeling using kinetic and fluid simulations. Initial plans are in place for a pulsed fusion reactor following the results of FuZE. Notably, the design relies on proven commercial technologies, including a modest discharge current (1.5 MA) and voltage (40 kV), and liquid metal electrodes. Supported by DoE FES, NNSA, and ARPA-E ALPHA.

Aluminium K-shell radiation from 800 ns implosion time nested wire arrays. First results on the 1 MJ SPHINX generator

International Nuclear Information System (INIS)

Bayol, F.; Lassalle, F.; Mangeant, C.

2005-01-01

This paper discusses experiments to analyze the performances of plasma radiation sources for K-shell production with long implosion time increased up to 800 ns. SPHINX generator is used to implode single and nested aluminium wire arrays Z-pinches with maximum current 3.4 MA to 3.8 MA. Results show more than 10 kJ of energy radiated above 1 keV, with pulse widths of 30-50 ns for a total radiation yield around 100 kJ [ru

Experimental studies of an Extrap Z-Pinch

International Nuclear Information System (INIS)

Drake, J.R.

1983-01-01

Experimental studies of the formation, equilibrium and stability of a linear Extrap Z-pinch are reported on. The Z-pinch discharge is generated between electrodes along the Z-axis of a linear octupole field produced by currents in four Z-directed rods. The combined discharge current and rod currents produce a magnetic field having a separatrix with four null X-points which define the corners of a square shaped region where the high beta plasma discharge is contained. Bounding the pinch discharge with a separatrix produces equilibria which are stable against global kink modes for the 50-μsec duration of the discharge which corresponds to about 100 Alfven transit times. The equilibria, with line densities of about 3 x 10 18 m - 1 , are consistent in magnitude and scaling with the Bennet relation. (Author)

Development of an all-optical framing camera and its application on the Z-pinch.

Science.gov (United States)

Song, Yan; Peng, Bodong; Wang, Hong-Xing; Song, Guzhou; Li, Binkang; Yue, Zhiqin; Li, Yang; Sun, Tieping; Xu, Qing; Ma, Jiming; Sheng, Liang; Han, Changcai; Duan, Baojun; Yao, Zhiming; Yan, Weipeng

2017-12-11

An all-optical framing camera has been developed which measures the spatial profile of photons flux by utilizing a laser beam to probe the refractive index change in an indium phosphide semiconductor. This framing camera acquires two frames with the time resolution of about 1.5 ns and the inter frame separation time of about 13 ns by angularly multiplexing the probe beam on to the semiconductor. The spatial resolution of this camera has been estimated to be about 140 μm and the spectral response of this camera has also been theoretically investigated in 5 eV-100 KeV range. This camera has been applied in investigating the imploding dynamics of the molybdenum planar wire array Z-pinch on the 1-MA "QiangGuang-1" facility. This framing camera can provide an alternative scheme for high energy density physics experiments.

Pulsed power performance of PBFA Z

International Nuclear Information System (INIS)

Spielman, R.B.; Stygar, W.A.; Seamen, J.F.

1997-01-01

PBFA Z is a new 60-TW/5-MJ electrical driver located at Sandia National Laboratories. The authors use PBFA Z to drive z pinches. The pulsed power design of PBFA Z is based on conventional single-pulse Marx generator, water-line pulse-forming technology used on the earlier Saturn and PBFA II accelerators. PBFA Z stores 11.4 MJ in its 36 Marx generators, couples 5 MJ in a 60-TW/105-ns pulse to the output water transmission lines, and delivers 3.0 MJ and 50 TW of electrical energy to the z-pinch load. Depending on the initial load inductance and the implosion time, the authors attain peak currents of 16-20 MA with a rise time of 105 ns. Current is fed to the z-pinch load through self magnetically-insulated transmission lines (MITLs). Peak electric fields in the MITLs exceed 2 MV/cm. The current from the four independent conical-disk MITLs is combined together in a double post-hole vacuum convolute with an efficiency greater than 95%. The authors achieved x-ray powers of 200 TW and x-ray energies of 1.9 MJ from tungsten wire-array z-pinch loads

On the Heating of Ions in Noncylindrical Z-Pinches

Science.gov (United States)

Svirsky, E. B.

2018-01-01

The method proposed here for analyzing processes in a hot plasma of noncylindrical Z-pinches is based on separation of the group of high-energy ions into a special fraction. Such ions constitute an insignificant fraction ( 10%) of the total volume of the Z-pinch plasma, but these ions contribute the most to the formation of conditions in which the pinch becomes a source of nuclear fusion products and X-ray radiation. The method allows a quite correct approach to obtaining quantitative estimates of the plasma parameters, the nuclear fusion energy yield, and the features of neutron fluxes in experiments with Z-pinches.

Compression of an Applied Bz field by a z-pinch onto a Tamped DT Fiber for Inertial Confinement Fusion

Science.gov (United States)

Nash, Tom

2009-11-01

Simulations of a z-pinch compressing an applied 100 kG Bz field onto an on-axis DT fiber tamped with beryllium show the field reaching over 100 MG in the tamp, sufficient to confine DT alpha particles and to form a thermal barrier. The barrier allows the DT plasma to burn at a rho*r value as low as 0.045 g/cm^2, and at temperatures over 50 keV for a 63 MA drive current. Driving currents between 21 and 63 MA are considered with cryogenic DT fiber diameters between 600 μm and 1.6 mm. Pinch implosion times are 120 ns with a peak implosion velocity of 35 cm/μs. 1D simulations are of a foil pinch, but for improved stability we propose a nested wire-array. Simulated fusion yields with this system scale as the sixth power of the current, with burn fractions scaling as the fourth power of the current. At 63 MA the simulated yield is 521 MJ from 4.2 mg/cm of DT with a 37% burn fraction at a rho*r of only 0.18 g/cm^2.

Architecture of petawatt-class z-pinch accelerators

International Nuclear Information System (INIS)

Stygar, William A.; Mazarakis, Michael Gerrassimos; Cuneo, Michael Edward; Leeper, Ramon Joe; Ives, H.C.; Headley, D.I.; Wagoner, Tim C.; Porter, John Larry Jr.

2006-01-01

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 (micro)s) Marx generators, which are a mature technology but which necessitate significant pulse compression to achieve the short pulses ( 4 capacitors, store 98 MJ, and erect to 5 MV; (ii) 600 water-dielectric triplate intermediate-store transmission lines, which also serve as pulse-forming lines; (iii) 600 5-MV laser-triggered gas switches; (iv) three monolithic radial-transmission-line impedance transformers, with triplate geometries and exponential impedance profiles; (v) a 6-level 5.5-m-diameter 15-MV vacuum insulator stack; (vi) six magnetically insulated vacuum transmission lines (MITLs); and (vii) a triple-post-hole vacuum convolute that adds the output currents of the six MITLs, and delivers the combined current to a z-pinch load. The accelerator delivers an effective peak current of 52 MA to a 10-mm-length z pinch that implodes in 95 ns, and 57 MA to a pinch that implodes in 120 ns. The LTD-driven accelerator includes monolithic radial transformers and a MITL system similar to those described above, but does not include intermediate-store transmission lines, multimegavolt gas switches, or a laser trigger system. Instead, this accelerator is driven by 210 LTD modules that include a total of 1 x 10 6 capacitors and 5 x 10 5 200-kV electrically triggered gas switches. The LTD accelerator stores 182 MJ and produces a peak electrical power of 1000 TW. The accelerator delivers an effective peak current of 68 MA to a pinch that implodes in 95 ns, and 75 MA to a pinch that implodes in 120 ns. Conceptually straightforward upgrades to these designs would deliver even higher pinch currents and faster implosions

Experimental investigation of the hot point generation in the Z pinch plasma

International Nuclear Information System (INIS)

Afonin, V.I.; Podgornov, V.A.; Litvin, D.N.; Senik, A.V.

1999-01-01

Experiments to explode thin composite (W-Al-W, W-SiO 2 -W) wires in SIGNAL fast high-current generator diode under about 200 kA load current amplitude and about 50 ns rise duration were carried out to study the possibility to control generation of hot point in Z pinch plasma. The parameters of generated hot points were studied using X-ray techniques. Analysis of the experiment results shows the possibility to control this process [ru

Architecture of petawatt-class z-pinch accelerators

Directory of Open Access Journals (Sweden)

W. A. Stygar

2007-03-01

Full Text Available 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   μs Marx generators, which are a mature technology but which necessitate significant pulse compression to achieve the short pulses (≪1   μs required to drive z pinches. The other is powered by linear transformer drivers (LTDs, which are less mature but produce much shorter pulses than conventional Marxes. Consequently, an LTD-driven accelerator promises to be (at a given pinch current and implosion time more efficient and reliable. The Marx-driven accelerator produces a peak electrical power of 500 TW and includes the following components: (i 300 Marx generators that comprise a total of 1.8×10^{4} capacitors, store 98 MJ, and erect to 5 MV; (ii 600 water-dielectric triplate intermediate-store transmission lines, which also serve as pulse-forming lines; (iii 600 5-MV laser-triggered gas switches; (iv three monolithic radial-transmission-line impedance transformers, with triplate geometries and exponential impedance profiles; (v a 6-level 5.5-m-diameter 15-MV vacuum insulator stack; (vi six magnetically insulated vacuum transmission lines (MITLs; and (vii a triple-post-hole vacuum convolute that adds the output currents of the six MITLs, and delivers the combined current to a z-pinch load. The accelerator delivers an effective peak current of 52 MA to a 10-mm-length z pinch that implodes in 95 ns, and 57 MA to a pinch that implodes in 120 ns. The LTD-driven accelerator includes monolithic radial transformers and a MITL system similar to those described above, but does not include intermediate-store transmission lines, multimegavolt gas switches, or a laser trigger system. Instead, this accelerator is driven by 210

Compression dynamics of quasi-spherical wire arrays with different linear mass profiles

International Nuclear Information System (INIS)

Mitrofanov, K. N.; Aleksandrov, V. V.; Gritsuk, A. N.; Grabovski, E. V.; Frolov, I. N.; Laukhin, Ya. N.; Oleinik, G. M.; Ol’khovskaya, O. G.

2016-01-01

Results of experimental studies of the implosion of quasi-spherical wire (or metalized fiber) arrays are presented. The goal of the experiments was to achieve synchronous three-dimensional compression of the plasma produced in different regions of a quasi-spherical array into its geometrical center. To search for optimal synchronization conditions, quasi-spherical arrays with different initial profiles of the linear mass were used. The following dependences of the linear mass on the poloidal angle were used: m_l(θ) ∝ sin"–"1θ and m_l(θ) ∝ sin"–"2θ. The compression dynamics of such arrays was compared with that of quasi-spherical arrays without linear mass profiling, m_l(θ) = const. To verify the experimental data, the spatiotemporal dynamics of plasma compression in quasi-spherical arrays was studied using various diagnostics. The experiments on three-dimensional implosion of quasi-spherical arrays made it possible to study how the frozen-in magnetic field of the discharge current penetrates into the array. By measuring the magnetic field in the plasma of a quasi-spherical array, information is obtained on the processes of plasma production and formation of plasma flows from the wire/fiber regions with and without an additionally deposited mass. It is found that penetration of the magnetic flux depends on the initial linear mass profile m_l(θ) of the quasi-spherical array. From space-resolved spectral measurements and frame imaging of plasma X-ray emission, information is obtained on the dimensions and shape of the X-ray source formed during the implosion of a quasi-spherical array. The intensity of this source is estimated and compared with that of the Z-pinch formed during the implosion of a cylindrical array.

Investigation of magnetic field effects on the mitigation of the magnetohydrodynamic Rayleigh-Taylor instability in fast z-pinch implosions

International Nuclear Information System (INIS)

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

1999-01-01

Numerical simulations have been carried out to investigate the role that magnetic field diffusion and ohmic heating have on the magnetohydrodynamic Rayleigh-Taylor (RT) development in fast z-pinch implosions. Previous work has indicated these terms can strongly influence the evolution of RT growth, leading to a reduction in RT amplitude, and an improvement in pinch performance. Indeed, Roderick et al have suggested that magnetic smoothing is an important mechanism in linear RT growth. To examine this in more detail, simulations are presented for a 1.4 mg, 25.0 mm diameter tungsten wire array imploded in the Saturn long pulse mode. The 130 ns implosion time of this calculation should enhance any mitigating effects that may be attributed to nonideal MHD. Calculations were performed using the 2D MHD code Mach2. The wire array was approximated by a right cylindrical slab of 1.0 mm width. Both a random density perturbation and single mode density perturbations were incorporated to initiate the instability. In the former case, a 5% cell-to-cell random perturbation was used. This allowed a range of modes to be initially present. In the single mode case, a 1.25 mm wavelength, on the order of the shell thickness, was defined. To isolate the contributions due to field diffusion, joule heating, and equation of state, simulations were run with and without ohmic heating using both constant and material-dependent spitzer resistivities. This analysis was then extended to look at the effect of such parameters on the nested shell load configuration. Detailed analysis of the simulations will be presented

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

International Nuclear Information System (INIS)

Lazier, S.E.; Barber, T.L.; Derzon, M.S.; Kellogg, J.W.

1996-01-01

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

Energy balance in a Z pinch with suppressed Rayleigh-Taylor instability

Science.gov (United States)

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

2018-03-01

At present Z-pinch has evolved into a powerful plasma source of soft x-ray. This paper considers the energy balance in a radiating metallic gas-puff Z pinch. In this type of Z pinch, a power-law density distribution is realized, promoting suppression of Rayleigh-Taylor (RT) instabilities that occur in the pinch plasma during compression. The energy coupled into the pinch plasma, is determined as the difference between the total energy delivered to the load from the generator and the magnetic energy of the load inductance. A calibrated voltage divider and a Rogowski coil were used to determine the coupled energy and the load inductance. Time-gated optical imaging of the pinch plasma showed its stable compression up to the stagnation phase. The pinch implosion was simulated using a 1D two-temperature radiative magnetohydrodynamic code. Comparison of the experimental and simulation results has shown that the simulation adequately describes the pinch dynamics for conditions in which RT instability is suppressed. It has been found that the proportion of the Ohmic heating in the energy balance of a Z pinch with suppressed RT instability is determined by Spitzer resistance and makes no more than ten percent.

Signatures of hot electrons and fluorescence in Mo Kα emission on Z

Energy Technology Data Exchange (ETDEWEB)

Hansen, S. B.; Ampleford, D. J.; Cuneo, M. E.; Jones, B.; Jennings, C. A.; Coverdale, C. A.; Rochau, G. A.; Dunham, G. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Ouart, N.; Dasgupta, A.; Giuliani, J. L. [Naval Research Laboratory, Washington, DC 20375 (United States); Apruzese, J. P. [Consultant to NRL through Engility Corp., Chantilly, Virginia 20151 (United States)

2014-03-15

Recent experiments on the Z accelerator have produced high-energy (17 keV) inner-shell K-alpha emission from molybdenum wire array z-pinches. Extensive absolute power and spectroscopic diagnostics along with collisional-radiative modeling enable detailed investigation into the roles of thermal, hot electron, and fluorescence processes in the production of high-energy x-rays. We show that changing the dimensions of the arrays can impact the proportion of thermal and non-thermal K-shell x-rays.

The ZaP Flow Z-Pinch Project - Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Shumlak, Uri [Univ. of Washington, Seattle, WA (United States); Nelson, Brian A. [Univ. of Washington, Seattle, WA (United States)

2013-12-31

The ZaP Flow Z-Pinch Project is a project to extend the performance of the flow Z-pinch experiment at the University of Washington to investigate and isolate the relevant physics of the stabilizing effect of plasma flow. Experimental plasmas have exhibited an enhanced stability under certain operating parameters which generate a flow state (axial flows in Z-pinches and VH mode in tokamaks). Flow has also been suggested as the stabilizing mechanism in astrophysical jets.

Experimental studies of the argon-puff Z-pinch implosion process

International Nuclear Information System (INIS)

Huang Xianbin; Yang Libing; Gu Yuanchao; Deng Jianjun; Zhou Rongguo; Zou Jie; Zhou Shaotong; Zhang Siqun; Chen Guanghua; Chang Lihua; Li Fengping; Ouyang Kai; Li Jun; Yang Liang; Wang Xiong; Zhang Zhaohui

2006-01-01

A preliminary experiment for studying the argon-puff Z-pinch implosion process has been performed on the Yang accelerator. The ten-frame nanosecond temporal and spatial gated camera, visible high-speed scanning camera, differential laser interferometer, X-ray time integration pinhole camera and X-ray power system have been used to investigated the evolution of the argon-puff Z-pinch. Some typical results of argon-puff Z-pinch during implosion and pinch phase, including the 'zipper' effect, necking phenomenon, sausage instability, temperature changes and the effect of load current rise time, are given and analyzed as examples, and some relevant conclusions are drawn. (authors)

Mechanism of neutron generation in Z-pinches

International Nuclear Information System (INIS)

Vikhrev, V.V.

1986-01-01

The review of experimental and theoretical investigations in a mechanism of neutron generation in Z-pinches is presented. Special attention is paid to the thermonuclear mechanism of neutron generation occuring due to the formation of high-temperature plasma regions in Z-pinch sausage-type instabilities. This mechanism is shown to be predominant in charges with the neutron yield more than 10 9 per a charge. Experimental data, which are considered to be contradicting to thermonuclear nature of neutron radiation, are explained

Flow effects on the stability of z-pinches

International Nuclear Information System (INIS)

Shumlak, U.; Hartman, C.W.

1996-01-01

The effect of an axial flow on the m = 1 kink instability in z-pinches is studied numerically by reducing the linearized ideal MHD equations to a one-dimensional eigenvalue equation for the radial displacement. The derivation of the displacement equation for equilibria with axial flows will be presented. A diffuse z-pinch equilibrium is chosen that is made marginally stable to the m = 0 sausage mode by tailoring the pressure profile. The principle result reveals that a sheared axial flow does stabilize the kink mode when the shear exceeds a threshold value. Additionally, the m = 0 sausage mode is driven from marginal stability into the stable regime which suggests that the equilibrium pressure profile control can be relaxed. Fast z-pinches such as liner implosions are plagued by the Rayleigh-Taylor instability which destroys the liner and disrupts the current path before the liner arrives on axis. A sheared axial flow in a liner may quench the Rayleigh-Taylor instability in the same way that it quenches MHD instabilities in a diffuse z-pinch. Simulation results will be presented showing the effect of a sheared axial flow on the Rayleigh-Taylor instability in a fast liner implosion

Z-pinch driven hohlraums design for the 100 nanoseconds current time scale

International Nuclear Information System (INIS)

Hamann, F.

2003-12-01

This work estimates Z-pinch driven hohlraums capabilities to obtain high temperatures (>200 eV). Simple models are proposed to calculate the performances offered by currents of 5 to 100 MA in 100 ns. The one dimensional physics of the Z-pinch at the length scale of its thickness and the hydrodynamics instabilities are studied. Then the enhancement of hohlraums performances with double nested Z-pinches or the use of an axial magnetic field is analysed. Z-pinch direct drive approach for inertial confinement fusion is finally considered. All the presented results are based on theoretical and 2D numerical approach and on the analysis of experimental results which were obtained on the american 'Z' generator. Annexes recall radiation MHD equations and check their validity for Z-pinch implosion. (author)

Hybrid Z-Θ Pinches with fused capacitor banks

International Nuclear Information System (INIS)

Grandey, R.; Gersten, M.; Loter, N.; Rauch, J.; Rostoker, N.; Thompson, W.; Ware, K.

1987-01-01

The Hybrid Z-Θ Pinch circuit equations in the thin shell model were reexamined to see what advantages can be obtained by using a fused, high-energy (>--1MJ) bank driver. The DNA ACE facility at MLI utilizes a 36 μF capacitor band which can be charged to 120 kV to provide 250 kJ of stored energy. This configuration appears to be very appropriate to test the performance of a hybrid-stabilized fused-bank driven pinch. The circuit analyses suggest that the energy transfer efficiency from the bank to a pinched plasma can be increased from less than 1%, for a nonfused bank, to about 10% for a fused configuration. In the applicable region of parameter space, the Hybrid Pinch does not increase the efficiency of energy transfer into the plasma over that obtainable from a Z-pinch. The additional stability may allow larger initial radii to be used with concomitant improved coupling into radiation above 1 keV

Observation of fast expansion velocity with insulating tungsten wires on ∼80 kA facility

Energy Technology Data Exchange (ETDEWEB)

Li, M.; Li, Y. [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Zhang, J. H.; Sun, T. P.; Wang, L. P.; Sheng, L.; Qiu, M. T.; Mao, W. T. [State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Wu, J., E-mail: jxjawj@mail.xjtu.edu.cn; Li, X. W. [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China)

2016-07-15

This paper presents experimental results on the effects of insulating coatings on tungsten planar wire array Z-pinches on an 80 kA, 100 ns current facility. Expansion velocity is obviously increased from ∼0.25 km/s to ∼3.5 km/s by using the insulating coatings. It can be inferred that the wire cores are in gaseous state with this fast expansion velocity. An optical framing camera and laser probing images show that the standard wire arrays have typical ablation process which is similar to their behaviors on mega-ampere facilities. The ablation process and precursor plasma are suppressed for dielectric tungsten wires. The wire array implosion might be improved if these phenomena can be reproduced on Mega-ampere facilities.

PBFA Z: A 55 TW/4.5 MJ electrical generator

International Nuclear Information System (INIS)

Spielman, R.B.; Stygar, W.A.; Struve, K.W.; Seamen, J.F.

1997-01-01

PBFA Z is a new 55 TW/4.5 MJ short pulse electrical driver located at Sandia National Laboratories. The authors use PBFA Z to magnetically-implode plasma shells. These configurations are historically known as z pinches. The pulsed power design of PBFA Z is based on conventional single-pulse Marx generator, water-line pulse-forming technology used on the earlier Saturn and PBFA II accelerators. PBFA Z stores 11.4 MJ in a 55-TW/105-ns pulse to the output water transmission lines, and delivers up to 3.0 MJ and 40 TW of electrical energy to the z-pinch load. Depending on the initial load inductance and the implosion time, they attain peak currents of 16--20 MA with a rise time of 105 ns. Current is fed to the z-pinch load through self magnetically-insulated transmission lines (MITLs). Peak electric fields in the MITLs exceed 2 MV/cm. The current from the four independent conical disk MITLs is combined together in a double post-hole vacuum convolute with an efficiency greater than 95%. The measured system performance of the water transmission lines, the vacuum insulator stack, the MITLs, and the double post-hole vacuum convolute differed from preshot predictions by ∼ 5%. Using a 2-cm radius and a 2-cm length tungsten wire array with 240, 7.5-microm diameter wires (4.1-mg mass) as the z-pinch load, they achieved x-ray powers of 200 TW and x-ray energies of 1.85 MJ as measured by x-ray diodes and resistive bolometry

Experimental study of implosion dynamics of multi-material nested wire-arrays on S-300 pulsed power generator

International Nuclear Information System (INIS)

Chernenko, A.S.; Smirnov, V.P.; Kingsep, A.S.

2004-01-01

On 'S-300' generator (700 kV, 4 MA, 70 ns) at the Kurchatov Institute, the experimental studies with multi-material wire array units are carried on aimed at creating the powerful X-ray source. The development of new diagnostic methods would definitely contribute to attain new data, which could help in explanation of X-ray emission mechanism of imploding multi-wire arrays that has not well understood yet. The experimental study of soft X-ray emission of different wire sets, different in both mass and composition, has been carried on in the same geometry. One of the purposes of these experiments was investigation of the wire array chemical composition influence on the implosion dynamics and stability. Study of the nested (cascade) liner dynamics shows that the minimal liner radius at the stagnation moment of time (2r ∼ 3 - 3.5 mm) recorded in the visible range by the streak camera fairly coincides with the outer diameter of the inner tungsten array of 4 mm. The same size is shown by the integral pinhole pictures obtained in the SXR range, without a filter. Unlike all these pictures, images obtained in the range E > 2 keV demonstrate the resulting state of Z-pinch in the form of a thin (∼ 0.2 mm) twisting filament. In addition, small space scales are typical of the liner pictures taken in the range of He- and H-like aluminum ions by means of a spectrograph. Thus, one may conclude that Al plasma of the outer liner passes into the inner space of the almost immovable W array where becomes trapped and compressed by the magnetic field. (author)

Deuterated fibre Z-pinch on the S-300 generator

NARCIS (Netherlands)

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.; Cai, Hongchun

2006-01-01

Dense Z-pinch experiments were carried out on the S-300 generator (3.5 MA, 100 ns, 0.15 Omega) 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 mu m

Development of sausage-type instability in a Z-pinch plasma column

International Nuclear Information System (INIS)

Vikhrev, V.V.; Ivanov, V.V.; Rozanova, G.A.

1993-01-01

The development of sausage-type instabilities in an initially homogeneous Z-pinch plasma column has been investigated by means of numerical modelling. It is shown that in the presence of short-wave perturbations of a Z-pinch boundary and a rarefied plasma surrounding the pinch, cavities filled with a rarefied plasma and with a magnetic field are formed in the plasma column. As a result of this cavity growth, small columns of dense plasma form on the axis in the Z-pinch which have a temperature substantially higher than the average plasma temperature in the plasma column. When deuterium is present in the pinch, these dense high temperature bunches can become a source of intensive neutron radiation. (author). 24 refs, 7 figs

Wire-Array Precursor Plasma Interactions With On-Axis Foam Targets

Science.gov (United States)

Palmer, J. B. A.; Bland, S. N.

2005-10-01

The Dynamic Hohlraum (DH) Z-pinch on Z at Sandia National Laboratory (SNL) has been used to drive Inertial Confinement Fusion (ICF) and High Energy Density Physics (HEDP) relevant experiments. The power pulse from the DH cannot yet be reproduced using codes that can reproduce the performance of a Vacuum Hohlraum (VH) configuration on Z. Unlike the VH the DH has a low-density CH foam cylinder placed on the array axis. Production of precursor plasma, prior to the main implosion, is not included in the codes. This plasma is accelerated towards the array axis by the global J x B force and impacts onto the on-axis target. This bombardment alters the foam in various ways. Experiments have been performed on the 1 MA MAGPIE generator at Imperial College, London, to investigate the effect of this precursor bombardment. Diagnostics used were point-projection radiography with x-pinches, x-ray emission framing cameras, shadowgraphy and photoconduction diodes. Results show ablation of low-density plasma from the foam surface and compression of the foam by precursor pressure. Research sponsored by AWE, SNL, the SSAA program of NNSA under DOE Cooperative Agreement DE-FC03-02NA00057.

Experimental investigations of ablation stream interaction dynamics in tungsten wire arrays: Interpenetration, magnetic field advection, and ion deflection

Energy Technology Data Exchange (ETDEWEB)

Swadling, G. F.; Lebedev, S. V.; Hall, G. N.; Suzuki-Vidal, F.; Burdiak, G. C.; Pickworth, L.; De Grouchy, P.; Skidmore, J.; Khoory, E.; Suttle, L.; Bennett, M.; Hare, J. D.; Clayson, T.; Bland, S. N.; Smith, R. A.; Stuart, N. H.; Patankar, S.; Robinson, T. S. [Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom); Harvey-Thompson, A. J. [Sandia National Laboratories, PO Box 5800, Albuquerque, New Mexico 87185-1193 (United States); Rozmus, W. [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1 (Canada); and others

2016-05-15

Experiments have been carried out to investigate the collisional dynamics of ablation streams produced by cylindrical wire array z-pinches. A combination of laser interferometric imaging, Thomson scattering, and Faraday rotation imaging has been used to make a range of measurements of the temporal evolution of various plasma and flow parameters. This paper presents a summary of previously published data, drawing together a range of different measurements in order to give an overview of the key results. The paper focuses mainly on the results of experiments with tungsten wire arrays. Early interferometric imaging measurements are reviewed, then more recent Thomson scattering measurements are discussed; these measurements provided the first direct evidence of ablation stream interpenetration in a wire array experiment. Combining the data from these experiments gives a view of the temporal evolution of the tungsten stream collisional dynamics. In the final part of the paper, we present new experimental measurements made using an imaging Faraday rotation diagnostic. These experiments investigated the structure of magnetic fields near the array axis directly; the presence of a magnetic field has previously been inferred based on Thomson scattering measurements of ion deflection near the array axis. Although the Thomson and Faraday measurements are not in full quantitative agreement, the Faraday data do qualitatively supports the conjecture that the observed deflections are induced by a static toroidal magnetic field, which has been advected to the array axis by the ablation streams. It is likely that detailed modeling will be needed in order to fully understand the dynamics observed in the experiment.

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

International Nuclear Information System (INIS)

Sheehey, P.T.

1994-02-01

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

An overview of the main design and performance of PBFA Z machine

International Nuclear Information System (INIS)

Song Shengyi

2002-01-01

PBFA Z is a new 60 TW/5 MJ electrical driver located at Sandia National Laboratories (SNL). It has been used to drive Z-pinches. The pulsed power design of PBFA Z is based on conventional single-pulse Marx generator with water-line pulse-forming technology used on the earlier Saturn and PBFA II accelerators. PBFA Z stores 11.4 MJ in its 36 Marx generators, couples 5 MJ in a 60 TW/105 ns pulse to the output water transmission lines, and delivers 3.0 MJ and 50 TW of electrical energy to the Z-pinch load. Depending on the initial load inductance and the implosion time, PBFA Z has attained peak currents of 16-20 MA with a rise time of 105 ns. Current is fed to the Z-pinch load through self-magnetically insulated transmission lines (MITLs). Peak electrical fields in the MITLs exceed 2 MV/cm. The current from the four independent conical-disk MITLs is combined together in a double post-hole vacuum convolute with an efficiency greater than 95%. SNL has achieved X-ray powers of 200TW and X-ray energies of 1.9 MJ from tungsten wire-array Z-pinch loads

Finite-Larmor-radius effects on z-pinch stability

Science.gov (United States)

Scheffel, Jan; Faghihi, Mostafa

1989-06-01

The effect of finite Larmor radius (FLR) on the stability of m = 1 small-axial-wavelength kinks in a z-pinch with purely poloidal magnetic field is investigated. We use the incompressible FLR MHD model; a collisionless fluid model that consistently includes the relevant FLR terms due to ion gyroviscosity, Hall effect and electron diamagnetism. With FLR terms absent, the Kadomtsev criterion of ideal MHD, 2r dp/dr + m2B2/μ0 ≥ 0 predicts instability for internal modes unless the current density is singular at the centre of the pinch. The same result is obtained in the present model, with FLR terms absent. When the FLR terms are included, a normal-mode analysis of the linearized equations yields the following results. Marginally unstable (ideal) modes are stabilized by gyroviscosity. The Hall term has a damping (but not absolutely stabilizing) effect - in agreement with earlier work. On specifying a constant current and particle density equilibrium, the effect of electron diamagnetism vanishes. For a z-pinch with parameters relevant to the EXTRAP experiment, the m = 1 modes are then fully stabilized over the crosssection for wavelengths λ/a ≤ 1, where a denotes the pinch radius. As a general z-pinch result a critical line-density limit Nmax = 5 × 1018 m-1 is found, above which gyroviscous stabilization near the plasma boundary becomes insufficient. This limit corresponds to about five Larmor radii along the pinch radius. The result holds for wavelengths close to, or smaller than, the pinch radius and for realistic equilibrium profiles. This limit is far below the required limit for a reactor with contained alpha particles, which is in excess of 1020 m-1.

Finite-Larmor-radius effects on z-pinch stability

Energy Technology Data Exchange (ETDEWEB)

Scheffel, J.; Faghihi, M. (Royal Inst. of Tech., Stockholm (Sweden))

1989-06-01

The effect of finite Larmor radius (FLR) on the stability of m = 1 small-axial-wavelength kinks in a z-pinch with purely poloidal magnetic field is investigated. The incompressible FLR MHD model is used; a collisionless fluid model that consistently includes the relevant FLR terms due to ion gyroviscosity, Hall effect and electron diamagnetism. With FLR terms absent, the Kadomtsev criterion of ideal MHD, 2rdp/dr+m{sup 2}B{sup 2}/{mu}{sub 0}{ge}0 predicts instability for internal modes unless the current density is singular at the centre of the pinch. The same result is obtained in the present model, with FLR terms absent. When the LFR terms are included, a normal-mode analysis of the linearized equations yields the following results. Marginally unstable (ideal) modes are stabilized by gyroviscosity. The Hall term has a damping (but no absolutely stabilizing) effect - in agreement with earlier work. On specifying a constant current and particle density equilibrium, the effect of electron diamagnetism vanishes. For a z-pinch with parameters relevant to the EXTRAP experiment, the m = 1 modes are then fully stabilized over the cross-section for wavelengths {lambda}/{alpha}{le}1, where {alpha} denotes the pinch radius. As a general z-pinch result a critical line-density limit ''N''{sub max}=5x10{sup 18}m{sup -1} is found, above which gyroviscous stabilization near the plasma boundary becomes insufficient. This limit corresponds to about five Larmor radii along the pinch radius. The result holds for wavelengths close to, or smaller than, the pinch radius and for realistic equilibrium profiles. This limit is far below the required limit for a reactor with contained alpha particles, which is in excess of 10{sup 20} m{sup -1}. (author).

Finite-Larmor-radius effects on z-pinch stability

International Nuclear Information System (INIS)

Scheffel, J.; Faghihi, M.

1989-01-01

The effect of finite Larmor radius (FLR) on the stability of m = 1 small-axial-wavelength kinks in a z-pinch with purely poloidal magnetic field is investigated. The incompressible FLR MHD model is used; a collisionless fluid model that consistently includes the relevant FLR terms due to ion gyroviscosity, Hall effect and electron diamagnetism. With FLR terms absent, the Kadomtsev criterion of ideal MHD, 2rdp/dr+m 2 B 2 /μ 0 ≥0 predicts instability for internal modes unless the current density is singular at the centre of the pinch. The same result is obtained in the present model, with FLR terms absent. When the LFR terms are included, a normal-mode analysis of the linearized equations yields the following results. Marginally unstable (ideal) modes are stabilized by gyroviscosity. The Hall term has a damping (but no absolutely stabilizing) effect - in agreement with earlier work. On specifying a constant current and particle density equilibrium, the effect of electron diamagnetism vanishes. For a z-pinch with parameters relevant to the EXTRAP experiment, the m = 1 modes are then fully stabilized over the cross-section for wavelengths λ/α≤1, where α denotes the pinch radius. As a general z-pinch result a critical line-density limit ''N'' max =5x10 18 m -1 is found, above which gyroviscous stabilization near the plasma boundary becomes insufficient. This limit corresponds to about five Larmor radii along the pinch radius. The result holds for wavelengths close to, or smaller than, the pinch radius and for realistic equilibrium profiles. This limit is far below the required limit for a reactor with contained alpha particles, which is in excess of 10 20 m -1 . (author)

Wire Array Photovoltaics

Science.gov (United States)

Turner-Evans, Dan

Over the past five years, the cost of solar panels has dropped drastically and, in concert, the number of installed modules has risen exponentially. However, solar electricity is still more than twice as expensive as electricity from a natural gas plant. Fortunately, wire array solar cells have emerged as a promising technology for further lowering the cost of solar. Si wire array solar cells are formed with a unique, low cost growth method and use 100 times less material than conventional Si cells. The wires can be embedded in a transparent, flexible polymer to create a free-standing array that can be rolled up for easy installation in a variety of form factors. Furthermore, by incorporating multijunctions into the wire morphology, higher efficiencies can be achieved while taking advantage of the unique defect relaxation pathways afforded by the 3D wire geometry. The work in this thesis shepherded Si wires from undoped arrays to flexible, functional large area devices and laid the groundwork for multijunction wire array cells. Fabrication techniques were developed to turn intrinsic Si wires into full p-n junctions and the wires were passivated with a-Si:H and a-SiNx:H. Single wire devices yielded open circuit voltages of 600 mV and efficiencies of 9%. The arrays were then embedded in a polymer and contacted with a transparent, flexible, Ni nanoparticle and Ag nanowire top contact. The contact connected >99% of the wires in parallel and yielded flexible, substrate free solar cells featuring hundreds of thousands of wires. Building on the success of the Si wire arrays, GaP was epitaxially grown on the material to create heterostructures for photoelectrochemistry. These cells were limited by low absorption in the GaP due to its indirect bandgap, and poor current collection due to a diffusion length of only 80 nm. However, GaAsP on SiGe offers a superior combination of materials, and wire architectures based on these semiconductors were investigated for multijunction

Numerical investigations of Z-pinch plasma instabilities

International Nuclear Information System (INIS)

Duan Yaoyong; Guo Yonghui; Wang Wensheng; Qiu Aici

2004-01-01

A two-dimensional, radiation magneto-hydrodynamics model is applied to the simulation of Z-pinch plasma sausage instability. Different implosion mechanisms in the cases of the existence and the non-existence of instability are analyzed, and the effects of various initial density perturbation levels on the x-ray power and energy are investigated. Numerical results show that x-ray energy output is not susceptive to sausage instabilities in a certain extent but x-ray power versus time is evidently dependent on the instabilities. In addition, this paper also studies the effects of numerical treatment of extreme low density in Z-pinch simulations on numerical results

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

International Nuclear Information System (INIS)

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

1989-01-01

A gas-puff z-pinch plasma has been produced on the pulsed power generator LIMAY-I at IPP Nagoya University. The stored energy of the generator is 13 kJ, and it generates 600 kV-70 ns-3 Ω power pulse. Ar or He gas is puffed from a hollow nozzle with 18 mm diameter, and a z-pinch plasma is produced by a discharge between 3 mm gap electrodes

Nonlinear stage of a Z-pinch instability

International Nuclear Information System (INIS)

Garanin, S.F.; Chernyshev, Y.D.

1987-01-01

The nonlinear evolution of the sausage instability is analyzed for a Z-pinch with a fully developed skin effect in the current. Two-dimensional numerical calculations carried out on the sausage instability show that its occurrence leads to a stage describable by a self-similar solution when the length of the neck is fixed and the plasma compression is isentropic. At a perturbation wavelength small in comparison with the pinch radius, this stage is preceded by a stage which reduces to a nonlinear Rayleigh--Taylor instability. The dynamics of the motion of magnetic field ''bubbles'' and of plasma ''jets'' is analyzed in this case. The plasma jets emerging from the pinch do not block the pinch from the current source

Dense transient pinches and pulsed power technology: research and applications using medium and small devices

International Nuclear Information System (INIS)

Soto, Leopoldo; Pavez, Cristian; Moreno, Jose; Cardenas, Miguel; Zambra, Marcelo; Tarifeno, Ariel; Huerta, Luis; Tenreiro, Claudio; Giordano, Jose Luis; Lagos, Miguel; Escobar, Rodrigo; Ramos, Jorge; Altamirano, Luis; Retamal, Cesar; Silva, Patricio

2008-01-01

The Plasma Physics and Plasma Technology Group of the Chilean Nuclear Energy Commission (CCHEN) has, since about ten years ago, used plasma production devices to study dense hot plasmas, particularly Z-pinches and plasma foci (PFs). In the case of Z-pinches, the studies include studies on the dynamics and stability of gas-embedded Z-pinches at currents of thermonuclear interest, and preliminary studies on wire arrays. For PF research, the aim of the work has been to characterize the physics of these plasmas and also to carry out the design and construction of smaller devices-in terms of both input energy and size-capable of providing dense hot plasmas. In addition, taking advantage of the experience in pulsed power technology obtained from experimental researches in dense transient plasmas, an exploratory line of pulsed power applications is being developed. In this paper, a brief review listing the most important results achieved by the Plasma Physics and Plasma Technology Group of the CCHEN is presented, including the scaling studies, PF miniaturization and diagnostics and research on Z-pinches at currents of thermonuclear interest. Then, exploratory applications of pulsed power are presented, including nanoflashes of radiation for radiography and substances detection, high pulsed magnetic fields generation and rock fragmentation.

Linear Transformer Drivers for Z-pinch Based Propulsion

Science.gov (United States)

Adams, Robert; Seidler, William; Giddens, Patrick; Fabisinski, Leo; Cassibry, Jason

2017-01-01

The MSFC/UAH team has been developing of a novel power management and distribution system called a Linear Transformer Driver (LTD). LTD's hold the promise of dramatically reducing the required mass to drive a z-pinch by replacing the capacitor banks which constitute half the mass of the entire system. The MSFC?UAH tea, is developing this technology in hope of integrating it with the Pulsed Fission Fusion (PuFF) propulsion concept. High-Voltage pulsed power systems used for Z-Pinch experimentation have in the past largely been based on Marx Generators. Marx generators deliver the voltage and current required for the Z-Pinch, but suffer from two significant drawbacks when applied to a flight system: they are very massive, consisting of high-voltage capacitor banks insulated in oil-filled tanks and they do not lend themselves to rapid pulsing. The overall goal of Phase 2 is to demonstrate the construction of a higher voltage stack from a number of cavities each of the design proven in Phase 1 and to characterize and understand the techniques for designing the stack. The overall goal of Phase 3 is to demonstrate the feasibility of constructing a higher energy cavity from a number of smaller LTD stacks, to characterize and understand the way in which the constituent stacks combine, and to extend this demonstration LTD to serve as the basis for a 64 kJ pulse generator for Z-Pinch experiments.

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

International Nuclear Information System (INIS)

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

2003-01-01

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

Plasma channel and Z-pinch dynamics for heavy ion transport

Energy Technology Data Exchange (ETDEWEB)

Ponce-Marquez, David [Univ. of California, Berkeley, CA (United States)

2002-01-01

A self stabilized, free standing, z-pinch plasma channel has been proposed to deliver the high intensity heavy ion beam from the end of a driver to the fuel target in a heavy ion inertial fusion power plant. The z-pinch relaxes emittance and energy spread requirements requiring a lower cost driver. A z-pinch transport would reduce the number of beam entry port holes to the target chamber from over a hundred to four as compared to neutralized ballistic focusing thus reducing the driver hardware exposure to neutron flux. Experiments where a double pulse discharge technique is used, z-pinch plasma channels with enhanced stability are achieved. Typical parameters are 7 kV pre-pulse discharge and 30 kV main bank discharge with 50 kA of channel current in a 7 torr background gas atmosphere. This work is an experimental study of these plasma channels examining the relevant physics necessary to understand and model such plasmas. Laser diagnostics measured the dynamical properties of neutrals and plasma. Schlieren and phase contrast techniques probe the pre-pulse gas dynamics and infrared interferometry and faraday effect polarimetry are used on the z-pinch to study its electron density and current distribution. Stability and repeatability of the z-pinch depend on the initial conditions set by the pre-pulse. Results show that the z-pinch channel is wall stabilized by an on-axis gas density depression created by the pre-pulse through hydrodynamic expansion where the ratio of the initial gas density to the final gas density is > 10/1. The low on-axis density favors avalanching along the desired path for the main bank discharge. Pinch time is around 2 s from the main bank discharge initiation with a FWHM of ~ 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

Study of gas-puff Z-pinches on COBRA

Energy Technology Data Exchange (ETDEWEB)

Qi, N.; Rosenberg, E. W.; Gourdain, P. A.; Grouchy, P. W. L. de; Kusse, B. R.; Hammer, D. A.; Bell, K. S.; Shelkovenko, T. A.; Potter, W. M.; Atoyan, L.; Cahill, A. D.; Evans, M.; Greenly, J. B.; Hoyt, C. L.; Pikuz, S. A.; Schrafel, P. C. [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States); Kroupp, E.; Fisher, A.; Maron, Y. [Weizmann Institute of Science, Rehovot 76100 (Israel)

2014-11-15

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

Nonlinear development of the sausage instability in dense Z-pinches

International Nuclear Information System (INIS)

Colombant, D.; Mosher, D.

1989-01-01

In this paper, a 2d envelope model is described for the nonlinear development of the sausage instability in dense Z-pinches. Numerical solutions for various cases of interest are provided which lay the foundation for a quantitative model of nonthermal neutron emission in dense Z-pinches by determining the induced electric fields associated with the development of the instability

The Z-pinch as plasma lens for the focusing of heavy ion beams

International Nuclear Information System (INIS)

Elfers, M.

1992-04-01

In the present thesis the influence of a Z-pinch plasma on the shape of heavy-ion beams and the for the understanding of this interaction most important plasma parameters were studied. For this the Z-pinch at the heavy-ion accelerator UNILAC was operated. The magnet field gradients of up to (25 ± 3) T/m occuring in the Z-pinch lead to the plasma-lens effect - the focusing of a charged-particle beam traversing axially the Z-pinch. In this thesis for the first time the focusing of a heavy-ion beam by the azimutal magnetic field of a Z-pinch is described. Different beams with an original diameter of 10 mm were focused. The smallest measured beam diameter amounts to 1 mm half-width. The beam energy amounts to 11.4 MeV/u, which leads at gold as projectile matter to a beam energy of 2.25 GeV. (orig./HSI) [de

Numerical simulation of a Z-pinch compressed by imploding liner

International Nuclear Information System (INIS)

Bilbao, L.; Linhart, J.G.; Verri, G.; Bernal, L.

2001-01-01

The spark created in a neck of a dense Z-pinch can ignite a fusion detonation in the adjacent D-T plasma channel. Using an appropriate transition between the ignited D-T plasma and an inertially confined cylinder of highly compressed advanced fuel plasma it is possible to amplify the spark energy to a level adequate for the ignition of a detonation wave in the advanced fuel. An m=0 instability of a Z-pinch carrying a current of the order of 10 MA, with a rise time inferior to 10 ns can generate a spark capable of igniting a fusion detonation in the adjacent D-T plasma channel. Such μZ-pinch may be produced by a fast implosion of a cylindrical liner, while a conical channel properly chosen can amplify the spark energy. In order to derive some general rules for the parameters of the spark, the transition, the cylinder of advanced fuel and the liner different numerical models were used. We present here a review of these results and an outline of a possible experimental arrangement for obtaining such a Z-pinch compression

Effects of drive current rise-time and initial load density distribution on Z-pinch characteristics

Institute of Scientific and Technical Information of China (English)

Duan Yao-Yong; Guo Yong-Hui; Wang Wen-Sheng; Qiu Ai-Ci

2005-01-01

A two-dimensional, three-temperature radiation magneto-hydrodynamics model is applied to the investigation of evolutional trends in x-ray radiation power, energy, peak plasma temperature and density as functions of drive current rise-time and initial load density distribution by using the typical experimental parameters of tungsten wire-array Z-pinch on the Qiangguang-Ⅰ generator. The numerical results show that as the drive current rise-time is shortened, x-ray radiation peak power, energy, peak plasma density and peak ion temperature increase approximately linearly, but among them the x-ray radiation peak power increases more quickly. As the initial plasma density distribution in the radial direction becomes gradually flattened, the peak radiation power and the peak ion-temperature almost exponentially increase, while the radiation energy and the peak plasma density change only a little. The main effect of shortening drive current rise-time is to enhance compression of plasma, and the effect of flattening initial load density distribution in the radial direction is to raise the plasma temperature. Both of the approaches elevate the x-ray peak radiation power.

Expansion of plasma of electrically exploding single copper wire under 4.5 kA-9.5 kA/wire

International Nuclear Information System (INIS)

Li Yexun; Yang Libing; Sun Chengwei

2003-01-01

The experimental system for electrically exploding single metal wire has been designed and manufactured. Expansion of the dense plasma column formed from an electrically exploding Cu wire of diameter 30 μm has been studied with a high-speed photographer to obtain the time-dependent radius (R-t) curve. The experimental results demonstrate that the mean expansion rate of the dense plasma column is 1.94 μm/ns, 2.6 μm/ns and 3.75 μm/ns according to the peak pulse current 4.5 kA, 7 kA and 9.5 kA respectively. The results can be beneficial to giving a profound understanding of the early stage of wire-array Z-pinch physics and to improvement on their design

Wire array K-shell sources on the SPHINX generator

Science.gov (United States)

D'Almeida, Thierry; Lassalle, Francis; Grunenwald, Julien; Maury, Patrick; Zucchini, Frédéric; Niasse, Nicolas; Chittenden, Jeremy

2014-10-01

The SPHINX machine is a LTD based Z-pinch driver operated by the CEA Gramat (France) and primarily used for studying K-shell radiation effects. We present the results of experiments carried out with single and nested large diameter aluminium wire array loads driven by a current of ~5 MA in ~800 ns. The dynamic of the implosion is studied with filtered X-UV time-integrated pin-hole cameras. The plasma electron temperature and the characteristics of the sources are estimated with time and spatially dependent spectrographs and PCDs. It is shown that Al K-shell yields (>1 keV) up to 27 kJ are obtained for a total radiation of ~ 230 kJ. These results are compared with simulations performed using the latest implementation of the non-LTE DCA code Spk in the 3D Eulerian MHD framework Gorgon developed at Imperial College. Filtered synthetic bolometers and PCD signals, time-dependent spatially integrated spectra and X-UV images are produced and show a good agreement with the experimental data. The capabilities of a prospective SPHINX II machine (20 MA ~ 800 ns) are also assessed for a wider variety of sources (Ti, Cu and W).

Diffusion-driven steady states of the Z-pinch

International Nuclear Information System (INIS)

Lehnert, B.

1988-01-01

Steady states of a Z-pinch where no electric field is imposed along the pinch axis by external means are investigated. In this case, diffusion-driven states become possible when imposed volume sources of particles and heat drive a radial diffusion velocity that, in its turn, generates the electric plasma current. The particle sources can be from pellet injection or a neutral gas blanket, and the heat sources provided by thermonuclear reactions or auxiliary heating. The present analysis and associated kinetic considerations indicate that steady diffusion-driven operation should become possible for certain classes of plasma profiles, without running into singularity problems at the pinch axis. Such operation leads to higher axial currents in a Z-pinch without an axial magnetic field than in a tokamaklike case under similar plasma conditions. The technical difficulty in realizing a volume distribution of particle sinks introduces certain constraints on the plasma and current profiles. This fact has to be taken into account in a stability analysis. Neoclassical or anomalous diffusion will increase the diffusion velocity of the plasma but is not expected to affect the main physical features of the present results

Study of the internal structure, instabilities, and magnetic fields in the dense Z-pinch

International Nuclear Information System (INIS)

Ivanov, Vladimir V.

2016-01-01

Z-pinches are sources of hot dense plasma which generates powerful x-ray bursts and can been applied to various areas of high-energy-density physics (HEDP). The 26-MA Z machine is at the forefront of many of these applications, but important aspects of HEDP have been studied on generators at the 1 MA current level. Recent development of laser diagnostics and upgrade of the Leopard laser at Nevada Terawatt Facility (NTF) give new opportunities for the dense Z-pinch study. The goal of this project is the investigation of the internal structure of the stagnated Z pinch including sub-mm and micron-scale instabilities, plasma dynamics, magnetic fields, and hot spots formation and initiation. New plasma diagnostics will be developed for this project. A 3D structure and instabilities of the pinch will be compared with 3D MHD and spectroscopic modeling and theoretical analysis. The structure and dynamics of stagnated Z pinches has been studied with x-ray self-radiation diagnostics which derive a temperature map of the pinch with a spatial resolution of 70-150 µm. The regular laser diagnostics at 532 nm does not penetrate in the dense pinch due to strong absorption and refraction in trailing plasma. Recent experiments at NTF showed that shadowgraphy at the UV wavelength of 266 nm unfolds a fine structure of the stagnated Z-pinch with unprecedented detail. We propose to develop laser UV diagnostics for Z pinches with a spatial resolution 20 MG, suggested in micropinches, Cotton-Mouton and cutoff diagnostics will be applied. A picosecond optical Kerr shutter will be tested to increase a sensitivity of UV methods for application at multi-MA Z pinches. The proposal is based on the experimental capability of NTF. The Zebra generator produces 1-1.7 MA Z-pinches with electron plasma density of 10"2"0-10"2"1cm"-"3, electron temperature of 0.5-1 keV, and magnetic fields >10 MG. The Leopard laser was upgraded to energy of 90-J at 0.8 ns. This regime will be used for laser initiation

Kinetic theory of the sausage instability of a z-pinch

International Nuclear Information System (INIS)

Isichenko, M.B.; Kulyabin, K.L.; Yan'kov, V.V.

1989-01-01

A linear problem of z-pinch sausage development is considered taking into account the influence of kinetic effects for ideal scanning current. Plasma electrons are considered to be cold and ions - collisionless. It is also supposed that the magnetic field inside a pinch doesn't affect the motion of ions, which are reflected like in a mirror from a jump of an electric potential arising on the plasma boundary. In case of long-wave perturbations ka >1 the acount of kinetics leads to considerable decrease of the increment [(ka) 1/2 times] in comparison with the hydrodynamic description, that permits to explain the increased instability of z-pinches observed in experiments

Spatially and temporally resolved EUV emissions from SATURN z-pinches

International Nuclear Information System (INIS)

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

1995-01-01

EUV emissions can be used to measure several z-pinch parameters. The authors have measured implosion velocity from Doppler splitting of lines and estimated electron temperature during run-in from the mean ionization state of line emissions. In an argon pinch they measure an electron temperature of 100 eV before stagnation. To date Doppler split lines have measured implosion velocities less than 40 cm/microsecond. They are presently attempting to measure magnetic field or load current from Zeeman splitting and it may be possible to measure electron density from a Stark-broadened line. Opacity and ion thermal broadening may also contribute to line width information. The spectrometer utilizes a variable line space grating to give a flat focal field. Spectral resolution with a 60 micron detector resolution is up to 3,000 and generally increases with wavelength. This is sufficient to detect several plasma line broadening mechanisms. The spectrometer may detect lines above 100 angstrom and below 1,400 angstrom. Spectral range across a microchannel plate stripline detector decreases with increasing wavelength setting. The authors may gate two striplines with 1 to 12 nsec gates at any time during the pinch discharge. Each stripline spatially images the pinch diameter perpendicular to the direction of dispersion. Spatial resolution in the pinch diameter is 1 mm. Spatial acquisition along the z axis is also 1 mm. Data are presented from argon, krypton, and aluminum z-pinch discharges on the SATURN accelerator

On the dynamics of cylindrical z-pinch

International Nuclear Information System (INIS)

Solov'ev, L.S.

1984-01-01

The stationary configurations of cylindrical plasma flow in the framework of two-liquid relativistic electromagnetic gas dynamics (REMG)) and nonlinear radial oscillations of the plasma cylinder with longitudinal current in the framework of classical monoliquid MGD are considered. It is shown that at sufficiently high conductivity Z-pinch is stable relative to one-dimensional radial perturbations and its motion represents respectively nonlinear radial oscillations. In case of a rather low conductivity or low particle concentration there is in cross section a stability also in relation to the development of sausage type instability. The performed investigations of cylindrical equilibrium and radial oscillations give a qualitative representation on plasma behaviour in Z-pinch at the initial stage of it compression and expansion as well as on motion in an average plane of the developing sausage type instability

Determination of plasma Z-pinch effect by intrinsic stimulated emission

International Nuclear Information System (INIS)

Lue, J.T.; Liang, J.M.

1977-01-01

The plasma Z-pinch behavior has been observed in a relatively small-bore diameter tube and low bank voltage discharge system. The instant of the occurrence of the laser line at 4880 A coincides with the plasma pinch time calculated by using a one-fluid snow-plow model. A determination of plasma pinch parameters by measuring the intrinsic stimulated emission of the ions is described

Multipoint Thomson scattering system for the EXTRAP Z-pinch experiment

International Nuclear Information System (INIS)

Karlsson, P.

1986-03-01

A Thomson scattering system for simultaneous measurements of the electron temperature and density at three different positions at two different times during a single plasma shot has been developed for the EXTRAP-L1 Z-pinch. The plasma in the present version of EXTRAP-L1 is characterized by densities in the range from 10 21 to 10 22 m -3 , temperatures up to 50 eV and a pinch radius of the order of 1 cm. A spatial resolution down to 3 mm between positions is obtained by imaging the plasma onto an array of quartz optical fibres at the output slit of the spectrometer. Fifteen PM-tubes are used to detect the scattered radiation as well as the background radiation. Due to the relatively dense plasma prevailing in the present version of EXTRAP-L1 the number of scattered photons in large and the photon to electron conversion noise is small. The background radiation is the most important factor limiting the accuracy of the measurements. (author)

A simplified MHD model of capillary Z-Pinch compared with experiments

Energy Technology Data Exchange (ETDEWEB)

Shapolov, A.A.; Kiss, M.; Kukhlevsky, S.V. [Institute of Physics, University of Pecs (Hungary)

2016-11-15

The most accurate models of the capillary Z-pinches used for excitation of soft X-ray lasers and photolithography XUV sources currently are based on the magnetohydrodynamics theory (MHD). The output of MHD-based models greatly depends on details in the mathematical description, such as initial and boundary conditions, approximations of plasma parameters, etc. Small experimental groups who develop soft X-ray/XUV sources often use the simplest Z-pinch models for analysis of their experimental results, despite of these models are inconsistent with the MHD equations. In the present study, keeping only the essential terms in the MHD equations, we obtained a simplified MHD model of cylindrically symmetric capillary Z-pinch. The model gives accurate results compared to experiments with argon plasmas, and provides simple analysis of temporal evolution of main plasma parameters. The results clarify the influence of viscosity, heat flux and approximations of plasma conductivity on the dynamics of capillary Z-pinch plasmas. The model can be useful for researchers, especially experimentalists, who develop the soft X-ray/XUV sources. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Plasma-erosion-enhanced neutron emission in fiber-generated dense Z-pinches

International Nuclear Information System (INIS)

Mosher, D.; Colombant, D.

1990-01-01

Experiments in which dense z-pinches are created from high-current discharges through frozen deuterium fibers have reported neutron yields far in excess of those expected from thermal processes. A simple analysis based on pinch collapse due to the sausage instability has successfully predicted the relative variation of neutron yield with discharge current, but model assumptions precluded prediction of absolute values of the yield. A pinch-collapse model derived from a 2-dimensional, nonlinear treatment of the sausage instability, combined with space-charged-limited (SCL) ion orbital dynamic for the vacuum region above the pinches and between the expanding flares, leads to neutron yields four or more orders-of-magnitude below experimental values. Here, the same pinch-collapse model is used in conjunction with a low-density plasma background above the collapsing pinches. Ions are accelerated across the space-charge sheath separating the background plasma from the flares, which electron emission from the flares is strongly insulated by the z-discharge magnetic field. The sheath gap increases in time, i.e., the background plasma erodes, at a rate determined by its density and the SCL ion current density which, in turn, depends on the z-discharge dynamics and the associated induced electromagnetic fields. A model incorporating the above processes is used to determine the accelerated ion energy spectrum and associated neutron yield as functions of the discharge, instability, and background parameters

Measurements of hot spots and electron beams in Z-pinch devices

International Nuclear Information System (INIS)

Deeney, C.

1988-04-01

Hot spots and Electron Beams have been observed in different types of Z-pinches. There is, however, no conclusive evidence on how either are formed although there has been much theoretical interest in both these phenomena. In this thesis, nanosecond time resolved and time correlated, X-ray and optical diagnostics, are performed on two different types of Z-pinch: a 4 kJ, 30 kV Gas Puff Z-pinch and a 28 kJ, 60 kV Plasma Focus. The aim being to study hot spots and electron beams, as well as characterise the plasma, two different Z-pinch devices. Computer codes are developed to analyse the energy and time resolved data obtained in this work. These codes model both, X-ray emission from a plasma and X-ray emission due to electron beam bombardment of a metal surface. The hot spot and electron beam parameters are measured, from the time correlated X-ray data using these computer codes. The electron beams and the hot spots are also correlated to the plasma behaviour and to each other. The results from both devices are compared with each other and with the theoretical work on hot spot and electron beam formation. A previously unreported 3-5 keV electron temperature plasma is identified, in the gas puff Z-pinch plasma, prior to the formation of the hot spots. it is shown, therefore, that the hot spots are more dense but not hotter than the surrounding plasma. Two distinct periods of electron beam generation are identified in both devices. (author)

Investigation of layered Z-pinches on ANGARA-5-1

Energy Technology Data Exchange (ETDEWEB)

Branitskij, A V; Grabovskij, E V; Zakharov, S V; Zurin, M V; Nedoseev, S L; Olejnik, G M; Smirnov, V P; Frolov, I N [Troitsk Inst. of Innovative and Fusion Research (Russian Federation)

1997-12-31

Experimental results of layered Z-pinch investigations on Angara-5-1 are presented. The level of current was 3-4 MA through a load with a 70-90 ns rise time. The initial-to-final radius ratio increased from 10-15 for a conventional single pinch, up to 30-50 for the double layered design. A power flux of about 8-12 TW/cm{sup 2} was achieved with front rise time about 3 ns. The final pinch diameter was down to 0.5-1 mm. (author). 4 figs., 1 ref.

Numerical studies of neon gas-puff Z-pinch dynamic processes

International Nuclear Information System (INIS)

Ning Cheng; Yang Zhenhua; Ding Ning

2003-01-01

Dynamic processes of neon gas-puff Z-pinch are studied numerically in this paper. A high temperature plasma with a high density can be generated in the process. Based on some physical analysis and assumption, a set of equations of one-dimensional Lagrangian radiation magneto-hydrodynamic (MHD) and its code are developed to solve the problem. Spatio-temporal distributions of plasma parameters in the processes are obtained, and their dynamic variations show that the major results are self-consistent. The duration for the plasma pinched to centre, as well as the width and the total energy of the x-ray pulse caused by the Z-pinch are in reasonable agreement with experimental results of GAMBLE-II. A zipping effect is also clearly shown in the simulation

PBFA Z: A 50 TW/5 MJ Electrical Generator

Science.gov (United States)

Spielman, R. B.

1997-05-01

PBFA Z is a new 50 TW/5 MJ short electrical driver located at Sandia National Laboratories. We use PBFA Z to magnetically-implode solid or plasma shells. These configurations are historically known as z pinches. The pulsed power design of PBFA Z(R. B. Spielman, et al., Proc. of the Ninth IEEE Pulsed Power Conf., Albuquerque, NM 1995) is based on conventional single-pulse Marx generator, water-line pulse-forming technology used on the earlier Saturn (D. D. Bloomquist, et al., Proc. of the Sixth IEEE Pulsed Power Conf., Arlington, VA edited by P. J. Turchi and B. H. Bernstein (IEEE, New York, 1987), p. 310) and PBFA II(B. N. Turman, et al., Proc. of the Fifth IEEE Pulsed Power Conf., Arlington, VA 1985, pp. 155) accelerators. PBFA Z stores 11.4 MJ in its 36 Marx generators, couples 5 MJ in a 50 TW/100 ns pulse to the output water transmission lines, and delivers 3.4 MJ and 40 TW of electrical energy to the z-pinch load. Depending on the initial load inductance and the implosion time, we attain a peak current of 16-20 MA with a rise time of 105 ns. Current is fed to the z-pinch load through self magnetically-insulated transmission lines (MITLs). Peak electric fields in the MITLs exceed 2 MV /cm. The current from the four independent conical disk MITLs is combined together in a double post-hole vacuum convolute with an efficiency greater than 95%. The measured system performance of the water transmission lines, the vacuum insulator stack, the MITLs, and the double post-hole vacuum convolute differed from preshot predictions by ~ 5%. Using a 2-cm radius and a 2-cm length tungsten wire array with 240, 7.5-=B5m diameter wires (4.1-mg mass) as the z-pinch load, we achieved x-ray powers of 160 TW and x-ray energies of 1.85 MJ as measured by x-ray diodes and resistive bolometry.

DT ignition in a Z pinch compressed by an imploding liner

International Nuclear Information System (INIS)

Bilbao, L.; Bernal, L.; Linhart, J.G.; Verri, G.

2001-01-01

It has been shown that an m=0 instability of a Z pinch carrying a current of the order of 10 MA with a rise time of less than 10 ns can generate a spark capable of igniting a fusion detonation in the adjacent DT plasma channel. A possible method for generating such currents, necessary for the implosion of an initial large radius, low temperature Z pinch, can be a radial implosion of a cylindrical fast liner. The problem has been addressed in previous publications without considering the role played by an initially impressed m=0 perturbation, a mechanism indispensable for the generation of a spark. The liner-Z pinch dynamics can be solved at several levels of physical model completeness. The first corresponds to a zero dimensional model in which the liner has a given mass per unit length and a zero thickness, the plasma is compressed adiabatically and is isotropic, and there are no energy losses or Joule heating. The second level is one dimensional. The Z pinch plasma is described by the full set of MHD, two-fluid equations. The liner is treated first as thin and incompressible, and subsequently it is assumed that it has a finite thickness and is composed of a heavy ion plasma, having an artificial but realistic equation of state. Both plasma and liner are considered uniform in the Z direction and only DT reactions are considered. It is shown that, given sufficient energy and speed of the liner, the Z pinch can reach a volume ignition. The third level is two dimensional. Plasma and liner are treated as in the second level but either the Z pinch or the liner is perturbed by an m=0 non-uniformity. Provided the liner energy is high enough and the initial m=0 perturbation is correctly chosen, the final neck plasma can act as a spark for DT ignition. It is also shown that the liner energy required for generating a spark and the subsequent detonation propagation are considerably less than in the case of volume ignition. (author)

Investigation of energy and current concentration in composite Z-pinch through its soft X-ray emission on Angara-5-1

Energy Technology Data Exchange (ETDEWEB)

Branitskij, A V; Grabovskij, E V; Zakharov, S V; Zurin, M V; Olejnik, G M; Smirnov, V P; Frolov, I N [Troitsk Inst. of Innovative and Fusion Research (Russian Federation); Slavnov, Yu K; Usov, Yu K [Scientific Reseacrh Inst. of Impulse Technique, Moscow (Russian Federation)

1997-12-31

The Z-pinch of thin dense fiber with gas shell (composite pinch) was investigated at current levels of 2-3 MA on the ``Angara-5-1`` generator. High efficiency of generator power transfer into the pinch of 0.6-1 mm diameter was achieved when the masses of the gas and wire were comparable (20-40 {mu}g/cm). At the time of increase of a current {approx} 90 ns, powerful (0.5-1 TW) pulses of soft X-radiation with font rise times up to 1 ns were obtained. Up to a maximum of a pulse of radiation, the current from an external plasma shell penetrates mainly into the plasma corona of the fiber. The corona consists of a small part of fiber substance which is evaporated by radiation during compression of the external shell. (author). 3 figs., 11 refs.

Experimental study of the neck formation in an X pinch

International Nuclear Information System (INIS)

Artyomov, A P; Chaikovsky, S A; Fedunin, A V; Labetskaya, N A; Rousskikh, A G; Zhigalin, A S; Oreshkin, V I

2014-01-01

X-pinch experiments have been performed on a compact 250 kA, 180 ns pulsed power generator specially designed for this purpose at the Institute of High Current Electronics (Tomsk, Russia). The X pinches were composed of two molybdenum wires of diameter 25 μm making an angle of 36° with the z-axis. The X-pinch dynamics was recorded with a 3 ns exposure time using an HSFC Pro four-frame camera. Axial plasma jets propagating toward both the anode and the cathode were observed. The jets became noticeable within 10 ns after the onset of current flow, which approximately corresponded to the time at which the electrical explosion of the X-pinch wires occurred. The velocity of the anode-directed jet reached 10 7 cm/s, which was about 1.5 times the velocity of the cathode-directed jet. These high jet velocities are inconsistent with the plasma temperature resulting from the wire explosion. Hence, these jets seem to develop due to implosion of the light plasma layer stripped by magnetic forces from the wire surface, and the increase in their velocities is perhaps due to cumulative effects taking place at the X-pinch axis. The X-pinch neck formed as a rule above the initial wire cross point (closer to the anode). In this region, the plasma diameter gradually increased with time and then drastically decreased 10-15 ns prior to the x-ray pulse. Immediately before the x-ray pulse, in the (250-300 μm long) plasma neck, a lower scale constriction developed, forming a h ot spot . It has been confirmed that the anode-directed plasma jet could take some part of the X-pinch wire current because of the evident jet pinching in the anode region. This process seems to determine the neck length

High energy density Z-pinch plasmas using flow stabilization

Energy Technology Data Exchange (ETDEWEB)

Shumlak, U., E-mail: shumlak@uw.edu; Golingo, R. P., E-mail: shumlak@uw.edu; Nelson, B. A., E-mail: shumlak@uw.edu; Bowers, C. A., E-mail: shumlak@uw.edu; Doty, S. A., E-mail: shumlak@uw.edu; Forbes, E. G., E-mail: shumlak@uw.edu; Hughes, M. C., E-mail: shumlak@uw.edu; Kim, B., E-mail: shumlak@uw.edu; Knecht, S. D., E-mail: shumlak@uw.edu; Lambert, K. K., E-mail: shumlak@uw.edu; Lowrie, W., E-mail: shumlak@uw.edu; Ross, M. P., E-mail: shumlak@uw.edu; Weed, J. R., E-mail: shumlak@uw.edu [Aerospace and Energetics Research Program, University of Washington, Seattle, Washington, 98195-2250 (United States)

2014-12-15

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

Z-pinch driven fusion energy

International Nuclear Information System (INIS)

Slutz, Stephen A.; Olson, Craig L.; Rochau, Gary E.; Dezon, Mark S.; Peterson, P.F.; Degroot, J.S.; Jensen, N.; Miller, G.

2000-01-01

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

Development of fast pulsed power driver for radiography and Z-pinch

International Nuclear Information System (INIS)

Qiu Aici; Sun Fengju

2008-01-01

Z-pinch and flash X-ray radiography have an important application in inertial confine fusion (ICF) and nuclear radiation effects simulation and high performance hydrodynamic test, etc. Z-pinch ICF and multi-pulse multi-axis high energy X-ray radiography put forward a huge challenge for pulsed power driver, so the direct-driven-load fast pulsed power driver are developed actively in home and abroard. The paper summarized the recent advances and developing trends of the fast pulsed power driver based on fast Marx(FMG) and fast linear transformer driver (LTD), and analysized the advantages and disadvantages and restricting factors about FMG and FLTD and their key technologies, then introduced the state-of-arts on the investigation in Northwest Institute of Nuclear Technology. In the end, the paper presented some advices and views about studying fast pulsed power driver applied to Z-pinch and flash X-ray radiography in home. (authors)

Reconsideration of the m=0 Z-pinch stability

International Nuclear Information System (INIS)

Scheffel, J.; Coppins, M.

1993-01-01

Possible paths for obtaining linear stability against the m=0 mode in the Z-pinch are studied. Using a generalized energy principle, the necessary and sufficient Chew-Goldberger-Low (CGL) m=0 stability criterion is derived. This criterion is less restrictive than that of ideal MHD, although it also requires the boundary plasma pressure to be finite. It is shown that the edge pressure cannot be stably upheld by a surface current. By instead assuming a finite pressure external gas, it is found that an edge pressure to on-axis pressure ratio of 0.5 is required for stability of a constant current density profile. A parabolic current density profile lowers the limit to the value 0.17. The growth rates are shown to be monotonically decreasing as a function of the external gas pressure. Detailed derivations of the boundary conditions are also given. The results aid in clarifying the experimental stability of four major Z-pinch experiments. Finite Larmor radius stabilization is hence required to maintain stability in future fibre pinch experiments in vacuum, implying line densities less than 10 19 m -1 . (author). 28 refs, 10 figs

Energy Conversion in Imploding Z-Pinch Plasma

International Nuclear Information System (INIS)

Fisher, V.I.; Gregorian, L.; Davara, G.; Kroupp, E.; Bernshtam, V.A.; Ralchenko, Yu. V.; Starobinets, A.; Maron, Y.

2002-01-01

Due to important applications, Z-pinches became a subject of extensive studies. In these studies, main attention is directed towards improvement in efficiency of electric energy conversion into high-power radiation burst. At present, knowledge available on physics of Z-pinch operation, plasma motion, atomic kinetics, and energy conversion is mainly knowledge of numerical simulation results. We believe further progress require (i) experimental determination of spatial distribution and time history of thermodynamic parameters and magnetic field, as well as (ii) utilization of this data for experiment-based calculation of r,t-distribution of driving forces, mass and energy fluxes, and local energy deposition rates due to each of contributing mechanisms, what provides an insight into a process of conversion of stored electric energy into radiation burst. Moreover, experimentally determined r, t-distribution of parameters may serve for verification of computer programs developed for simulation of Z-pinch operation and optimization of radiation output. Within this research program we performed detailed spectroscopic study of plasmas imploding in modest-size (25 kV, 5 kJ, 1.2 μs quaterperiod) gas-puff Z-pinch. This facility has reasonably high repetition rate and provides good reproducibility of results. Consistent with plasma ionization degree in the implosion period, measurements are performed in UV-visible spectral range. Observation of spectral lines emitted at various azimuthal angles f showed no dependence on f. Dependence on axial coordinate z is found to be weak in near-anode half of the anode-cathode gap. Based on these observations and restricting the measurements to near-anode half of the gap, an evolution of parameters is studied in time and radial coordinate r only. In present talk we report on determination of radial component of plasma hydrodynamic velocity u r (r,t), magnetic field B ζ (r,t), electron density n e (r,t), density of ions in various

Proposal for the ZT-40 reversed-field Z-pinch experiment

International Nuclear Information System (INIS)

Baker, D.A.; Machalek, M.D.

1977-08-01

A next-generation, toroidal, reversed-field Z-pinch experiment to be constructed at LASL is proposed. On the basis of encouraging ZT-I and ZT-S experimental results, a larger device with a 40-cm bore and a 114-cm major radius is proposed, to extend the confinement time by about an order of magnitude. The new experiment will explore the physics of programming reversed-field pinches in a size range unexplored by previous reversed-field pinch experiments. Model reversed-field pinch reactor calculations show that, if stability is assumed, small fusion reactors are possible if the pinch current density is high. A basic aim will be to delineate the plasma and current density ranges in which stable reversed-field pinches can be produced. Improved vacuum techniques will be used to overcome the radiation losses that probably kept electron temperatures low in the earlier, smaller experiments

Si Wire-Array Solar Cells

Science.gov (United States)

Boettcher, Shannon

2010-03-01

Micron-scale Si wire arrays are three-dimensional photovoltaic absorbers that enable orthogonalization of light absorption and carrier collection and hence allow for the utilization of relatively impure Si in efficient solar cell designs. The wire arrays are grown by a vapor-liquid-solid-catalyzed process on a crystalline (111) Si wafer lithographically patterned with an array of metal catalyst particles. Following growth, such arrays can be embedded in polymethyldisiloxane (PDMS) and then peeled from the template growth substrate. The result is an unusual photovoltaic material: a flexible, bendable, wafer-thickness crystalline Si absorber. In this paper I will describe: 1. the growth of high-quality Si wires with controllable doping and the evaluation of their photovoltaic energy-conversion performance using a test electrolyte that forms a rectifying conformal semiconductor-liquid contact 2. the observation of enhanced absorption in wire arrays exceeding the conventional light trapping limits for planar Si cells of equivalent material thickness and 3. single-wire and large-area solid-state Si wire-array solar cell results obtained to date with directions for future cell designs based on optical and device physics. In collaboration with Michael Kelzenberg, Morgan Putnam, Joshua Spurgeon, Daniel Turner-Evans, Emily Warren, Nathan Lewis, and Harry Atwater, California Institute of Technology.

Fiber Z-pinch experiments and calculations in the finite Larmor radius regime

International Nuclear Information System (INIS)

Haines, M.G.; Dangor, A.E.; Coppins, M.

1996-01-01

The dense Z-pinch project at Imperial College is aimed at achieving radiative collapse to high density in a hydrogen plasma, and also to study plasmas close to controlled fusion conditions. To this end, the MAGPIE generator (2.4 MV, 1.25 Ω, and 200 ns) has been built and tested, and is now giving preliminary experimental data at 60% of full voltage for carbon and CD 2 fibers. These discharges are characterized by an initial radial expansion followed by the occurrence of m = 0 structures with transient X-ray emission from bright spots. Late in the discharge a disruption can occur, accompanied by hard X-ray emission from the anode due to an energetic electron beam and, in the case of CD 2 fibers, a neutron burst. Concomitant theoretical studies have solved the linear stability problem for a Z-pinch with large ion Larmor radii, showing that a reduction in growth rate of m = 0 and m = 1 modes to about 20% of the magnetohydrodynamic (MHD) value can occur for a parabolic density profile when the Larmor radius is optimally 20% of the pinch radius. Two-dimensional MHD simulations of Z-pinches in two extremes of focussed short-pulse laser-plasma interactions and of galactic jets reveal a nonlinear stabilizing effect in the presence of sheared flow. One-dimensional simulations show that at low line density the lower hybrid drift instability can lead to coronal radial expansion of a Z-pinch plasma. (Author)

Classical transport in a non-circular z-pinch

International Nuclear Information System (INIS)

Eriksson, G.

1987-05-01

A method is devised, in which particle and heat fluxes are found by solving the heat balance equation self-consistently for specified profiles. The procedure is applied to an equilibrium which corresponds to a non-circular z-pinch. (author)

Pinch Related Research At Institute For Plasma Research, India

International Nuclear Information System (INIS)

Shyam, Anurag

2006-01-01

Several pinch related experiment, their drivers and related diagnostics are being developed in our laboratory. The first set of experiments is to investigate various aspects of magnetized target fusion (MTF/MAGO). To drive the liner, in Z or theta pinch configuration, a 1.2 MJ, 3.6 MA capacitor bank is developed. For liner diagnostics flash radiography, VISAR and pyrometery are being developed. To produce magnetized (target) plasma a 120 kJ, 3 MA and several other banks are developed. Hot magnetized Plasma will be diagnosed by optical schlieren, interferometery and X-Ray spectrometry. A terra-watt system consisting of a Marx bank and water line delivering 800 kA at 1.6 MV will be commissioned, soon. The device will be used to study different pinch (wire array) configurations for production of electro-magnetic radiations. Smaller pulsed power systems, consisting of 1MV/500 kV Marx bank/tesla transformer and than water or solid state (cables) pulse forming network (coax) are also being developed for capillary discharge and other experiments. Two plasma foci experiments are also being conducted. The effort is produce a repetitively operating compact plasma focus

Stabilization of long wavelength sausage and kink modes of a Z-pinch by nonlinear radial oscillations

International Nuclear Information System (INIS)

Bud'ko, A.B.; Karlson, E.T.; Liberman, M.A.

1992-01-01

A number of experiments with fiber-initiated dense Z-pinches, with compressional and gas-embedded Z-pinches, with imploding gas-puff Z-pinches and the straight Extrap configuration performed in the last decade demonstrated sufficiently improved stability of Z-pinch configurations. The striking stability with respect to the sausage modes can be explained, in principle, by ideal MHD theory as well as by finite plasma conductivity effects. The global kink mode can not be stabilized by the appropriate choice of the unperturbed profiles neither within the scope of the ideal MHD nor taking into account finite ion Larmor radius and viscous damping effects. In this report we shall demonstrate that stabilization of the global kink modes can be explained by the assumption that pinch is not in a stationary but in a dynamic equilibrium. (author) 12 refs., 2 figs

A study of Z-pinch in capillary filled by boron vapours

Czech Academy of Sciences Publication Activity Database

Vrba, Pavel; Vrbová, M.; Bobrova, N. A.; Sasorov, P. V.

2009-01-01

Roč. 51, č. 2 (2009), s. 481-486 ISSN 1434-6079. [Symposium on Plasma Physics and Technology/23rd./. Praha, 16.06.2008-19.06.2008] R&D Projects: GA ČR GA102/07/0275; GA MŠk LA08024 Institutional research plan: CEZ:AV0Z20430508 Keywords : Z-pinches * plasma focus and other pinch devices * Plasma devices for generation of coherent radiation * Magnetohydrodynamics and fluid equation Subject RIV: BH - Optics, Masers, Lasers www.edpsciences.org/epjd nebo www.epj.org

Kinetic simulation of neutron production in a deuterium z-pinch

International Nuclear Information System (INIS)

Mostrom, C.; Stygar, William A.; Thoma, Carsten; Welch, Dale Robert; Clark, R.E.; Leeper, Ramon Joe; Rose, David V.

2010-01-01

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.

Solid fiber Z-pinches

International Nuclear Information System (INIS)

Lindemuth, I.R.

1989-01-01

One- and two-dimensional magnetohydrodynamic computations have been performed to study the behavior of solid deuterium fiber Z-pinch experiments performed at Los Alamos and the Naval Research Laboratory. The computations use a tabulated atomic data base and ''cold-start'' initial conditions. The computations predict that the solid fiber persists longer in existing experiments than previously expected and that the discharge actually consists of a relatively low-density, hot plasma which has been ablated from the fiber. The computations exhibit m = 0 behavior in the hot, exterior plasma prior to complete ablation of the solid fiber. The m = 0 behavior enhances the fiber ablation rate. 10 refs., 5 figs

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

International Nuclear Information System (INIS)

Baker, K. L.; Porter, J. L.; Ruggles, L. E.; Chandler, G. A.; Deeney, Chris; Vargas, M.; Moats, Ann; Struve, Ken; Torres, J.; McGurn, J. S.

2000-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2000-02-01

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

Analysis of staged Z-pinch implosion trajectories from experiments on Zebra

Science.gov (United States)

Ross, Mike P.; Conti, F.; Darling, T. W.; Ruskov, E.; Valenzuela, J.; Wessel, F. J.; Beg, F.; Narkis, J.; Rahman, H. U.

2017-10-01

The Staged Z-pinch plasma confinement concept relies on compressing an annular liner of high-Z plasma onto a target plasma column of deuterium fuel. The interface between the liner and target is stable against the Magneto-Rayleigh-Taylor Instability, which leads to effective fuel compression and makes the concept interesting as a potential fusion reactor. The liner initiates as a neutral gas puff, while the target plasma is a partially ionized (Zeff coaxial plasma gun. The Zebra pulsed power generator (1 MA peak current, 100 ns rise time) provides the discharge that ionizes the liner and drives the Z-pinch implosion. Diverse diagnostics observe the 100-300 km/s implosions including silicon diodes, photo-conducting detectors (PCDs), laser shadowgraphy, an XUV framing camera, and a visible streak camera. The imaging diagnostics track instabilities smaller than 0.1 mm, and Z-pinch diameters below 2.5 mm are seen at peak compression. This poster correlates the data from these diagnostics to elucidate implosion behavior dependencies on liner gas, liner pressure, target pressure, and applied, axial-magnetic field. Funded by the Advanced Research Projects Agency - Energy, DE-AR0000569.

Scintillator power meter applied on Z-pinch plasma soft X-ray yield measurement

International Nuclear Information System (INIS)

Zhang Siqun; Huang Xianbin; Li Jing; Dan Jiakun; Li Jun; Yang Libing; Cui Mingqi; Zhao Yidong

2010-01-01

This paper presents the configuration and measuring parameters of scintillator power meter applied in Z-pinch plasma soft X-ray yield measurement on Yang accelerator. It also introduces the calibration experiment on BSRF, and analyzes the defect of the power meter from calibration results, the possible errors and feasible method for correcting the errors. The measuring results are revised according to spectrum acquired from Dante spectrometer. The revised discrepancy of two instruments is decreased from over 30% to subter-15%. Finally, the result of yield measurement of the puff Z-pinch X-ray radiation is reported as well, i.e., hundreds of Joule, multigigawatt levels of soft X ray radiation were produced by puff Z-pinch on Yang accelerator. (authors)

Finite Larmor radius effects on Z-pinch stability

International Nuclear Information System (INIS)

Scheffel, J.; Faghihi, M.

1987-10-01

The effect of finite Larmor radius (FLR) on the stability of m=1 small axial wavelength kinks in a z-pinch with purely poloidal magnetic field is investigated. We use the Incompressible FLR MHD model; a collisionless fluid model which consistently includes the relevant FLR terms due to ion gyroviscosity, Hall effect and electron diamagnetism. With FLR terms absent, the Kadomtsev criterion of ideal MHD 2rdp/dr+m 2 B 2 /μ 0 >=0 predicts instability for internal modes unless the current density becomes singular at the centre of the pinch. The same result is obtained in the present model, with FLR terms absent. When the FLR terms are included, a normal mode analysis of the linearized equations yields the following results. Marginally unstable (ideal) modes are stabilized by gyroviscosity. The Hall terms have a damping, however not stabilizing, effect, in agreement with earlier work. Specifying a constant current and particle density equilibrium, the effect of electron diamagnetism vanishes. For a z-pinch with parameters relevant to the EXTRAP experiment, the m=1 modes are then fully stabilized over the cross-section for wavelengths λ/a max =3-5x10 18 m -1 is found, above which gyroviscous stabilization near the plasma boundary becomes insufficient. The result holds for wavelengths close to, or smaller than, the pinch radius and for realistic equilibrium profiles. This limit is far below the required limit for a reactor with contained alpha particles, which is in excess of 10 20 m -1 . (authors)

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

International Nuclear Information System (INIS)

Vesey, R. A.; Herrmann, M. C.; Lemke, R. W.; Desjarlais, M. P.; Cuneo, M. E.; Stygar, W. A.; Bennett, G. R.; Campbell, R. B.; Christenson, P. J.; Mehlhorn, T. A.; Porter, J. L.; Slutz, S. A.

2007-01-01

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

Effects of boundary conditions on temperature and density in an EXTRAP Z-pinch

International Nuclear Information System (INIS)

Drake, J.R.; Karlsson, P.

1985-08-01

Using the fluid equations, we examine transport in an Extrap configuration by carrying out calculations incorporating model profiles for the density and temperature. The goal of this analysis is to examine the scaling of the pinch equilibrium plasma density, temperature and radius with parameters that are characteristic for Extrap Z-pinches. These parameters include the discharge current, the neutral hydrogen filling density, an oxygen impurity fractional concentration and the condition at the pinch boundary. An Extrap Z-pinch is a pinch discharge where the current channel has a characteristic non-circular cross-section achieved by bounding the discharge by a magnetic separatrix produced when a vacuum octupole magnetic field, generated by currents in external conductors, combines with the self-magnetic field produced by the discharge current. The pinch boundary is changed from a plasma-vacuum boundary to an interface between a high-beta pinch plasma and a low-beta plasma contained in the vacuum magnetic field. The energy that is lost from the pinch region sustains this boundary layer. The introduction of a separatrix boundary around the pinch with four X-point nulls deteriorates the containment of the pinch somewhat. However the presence of the warm, low-beta plasma scrape-off layer, which provides a boundary condition on the pinch, tends to counteract the negative effects of the poorer confinement. Thus the equilibrium parameters that characterize the pinch may not be severely deteriorated by the introduction of the separatrix when the entire configuration, including the scrape-off layer, is considered. (author)

The stability of Z-pinches with equilibrium flows

International Nuclear Information System (INIS)

Howell, D.F.

1999-01-01

According to Ideal Magnetohydrodynamic (MHD) theory the Z-pinch is an inherently unstable magnetic configuration. However it is possible that there exist regimes of operation whereby the predicted instabilities may be reduced or even eliminated. We must look to effects normally ignored in the Ideal MHD model in order to predict such regimes. In this thesis various non-ideal effects will be studied, namely the inclusion of equilibrium flow and finite Larmor radius effects. Astrophysical jets, for example those seen to be emitted from active galactic nuclei, are seen to persist for a greater time than suggested by Ideal MHD before the onset of instabilities. It is postulated that one of the contributing factors to this enhanced stability is the presence of a sheared axial flow. In this thesis we study the stability properties of the Z-pinch where flow is present in the equilibrium. It is found that a sheared axial flow generally has a stabilising effect, the degree of which is determined by the equilibrium and flow profiles, but that absolute stability cannot be achieved due to the onset of the Kelvin-Helmholtz instability. The effect of adding rotation has also been studied. It is found that adding rotation changes the equilibrium density profiles from the static case, and that it always has a destabilising effect. Another postulated method of stabilising the Z-pinch is by increasing the ratio of the ion Larmor radius to the pinch radius, and it is seen to have a stabilising effect for some equilibria in the collisionless regime. In this thesis we study the effects of increasing the Larmor radius in the collisional regime using the Hall fluid model. It is found that for free boundary modes the stability properties are unchanged for experimentally realistic values of the Larmor radius, but for fixed boundary modes a small stabilising effect is noted for some equilibria. (author)

Dynamics of low density coronal plasma in low current x-pinches

International Nuclear Information System (INIS)

Haas, D; Bott, S C; Vikhrev, V; Eshaq, Y; Ueda, U; Zhang, T; Baranova, E; Krasheninnikov, S I; Beg, F N

2007-01-01

Experiments were performed on an x-pinch using a pulsed power current generator capable of producing an 80 kA current with a rise time of 50 ns. Molybdenum wires with and without gold coating were employed to study the effect of high z coating on the low-density ( 18 cm -3 ) coronal plasma dynamics. A comparison of images from XUV frames and optical probing shows that the low density coronal plasma from the wires initially converges at the mid-plane immediately above and below the cross-point. A central jet is formed which moves with a velocity of 6 x 10 4 ms -1 towards both electrodes forming a z-pinch column before the current maximum. A marked change in the low density coronal plasma dynamics was observed when molybdenum wires coated with ∼ 0.09 μm of gold were used. The processes forming the jet structure were delayed relative to bare Mo x-pinches, and the time-resolved x-ray emission also showed differences. An m = 0 instability was observed in the coronal plasma along the x-pinch legs, which were consistent with x-ray PIN diode signals in which x-ray pulses were observed before x-ray spot formation. These early time x-ray pulses were not observed with pure molybdenum x-pinches. These observations indicate that a thin layer of gold coating significantly changes the coronal plasma behaviour. Two dimensional MHD simulations were performed and qualitatively agree with experimental observations of low density coronal plasma

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

International Nuclear Information System (INIS)

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

2001-01-01

Initial experiments to study the Z-pinch-driven hohlraum high-yield inertial confinement fusion (ICF) concept of Hammer, Tabak, and Porter [Hammer et al., Phys. Plasmas 6, 2129 (1999)] are described. The relationship between measured pinch power, hohlraum temperature, and secondary hohlraum coupling ('hohlraum energetics') is well understood from zero-dimensional semianalytic, and two-dimensional view factor and radiation magnetohydrodynamics models. These experiments have shown the highest x-ray powers coupled to any Z-pinch-driven secondary hohlraum (26±5 TW), indicating the concept could scale to fusion yields of >200 MJ. A novel, single-sided power feed, double-pinch driven secondary that meets the pinch simultaneity requirements for polar radiation symmetry has also been developed. This source will permit investigation of the pinch power balance and hohlraum geometry requirements for ICF relevant secondary radiation symmetry, leading to a capsule implosion capability on the Z accelerator [Spielman et al., Phys. Plasmas 5, 2105 (1998)

On finite larmor radius stabilization of Z-pinches

International Nuclear Information System (INIS)

Hellsten, T.

1982-12-01

Finite Larmor radius stabilization of Z-pinches is discussed. Stability criteria can be derived for a class of equilibria having constant mass and current density. The internal modes can be stabilized provided the line density not exceed a critical value of the order of 10 18 ions/m. (Author)

ZAPP: Z-pinch atomic physics program

International Nuclear Information System (INIS)

Reed, K.

1983-01-01

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

High-energy electron acceleration in the gas-puff Z-pinch plasma

Energy Technology Data Exchange (ETDEWEB)

Takasugi, Keiichi, E-mail: takasugi@phys.cst.nihon-u.ac.jp [Institute of Quantum Science, Nihon University, 1-8 Kanda-Surugadai, Chiyoda, Tokyo 101-8308 (Japan); Miyazaki, Takanori [Institute of Quantum Science, Nihon University, 1-8 Kanda-Surugadai, Chiyoda, Tokyo 101-8308, Japan and Dept. Innovation Systems Eng., Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585 (Japan); Nishio, Mineyuki [Anan National College of Technology, 265 Aoki, Minobayashi, Anan, Tokushima 774-0017 (Japan)

2014-12-15

The characteristics of hard x-ray generation were examined in the gas-puff z-pinch experiment. The experiment on reversing the voltage was conducted. In both of the positive and negative discharges, the x-ray was generated only from the anode surface, so it was considered that the electrons were accelerated by the induced electromagnetic force at the pinch time.

OSA (Optical Society of America) Proceedings on Short Wavelength Coherent Radiation: Generation and Applications Held in North Falmouth, Massachusetts on 26-29 September 1988. Volume 2

Science.gov (United States)

1988-09-01

in Nikel -like Ions",Phys. 16. Y. Ichikawa et al.,"Highly damage- Rev. Lett. 59, 2157-2160 (1987). resistant Mo mirror for high-power TEA CO 5. S...the current. This gain estimate assumes a neon ion density of 1018 Gas puff Z-pinches and imploding wire arrays are cm-3 . copious X-ray sources. When...brought to in Z-pinches, compared to ordinary metals that can be within 4 cm of each other. The advantage of this made into wires and imploded as arrays

Self-similar oscillations of a Z pinch

International Nuclear Information System (INIS)

Felber, F.S.

1982-01-01

A new analytic, self-similar solution of the equations of ideal magnetohydrodynamics describes cylindrically symmetric plasmas conducting constant current. The solution indicates that an adiabatic Z pinch oscillates radially with a period typically of the order of a few acoustic transit times. A stability analysis, which shows the growth rate of the sausage instability to be a saturating function of wavenumber, suggests that the oscillations are observable

Development of pulsed high current drivers for fast Z-pinch

International Nuclear Information System (INIS)

Sun Fengju; Qiu Aici; Zeng Zhengzhong; Zeng Jiangtao; Kuai Bin; Yang Hailiang

2006-01-01

It is required that the peak current of high power pulsed drive for fast Z-pinch reaches 60 MA to realize inertial confine fusion (ICF) and high yield (HY). With the conventional technological methods similar to the Z or Saturn apparatus, increasing driver current further is impractical and difficult according to the cost, structure complexity and reliability of the driver, so it is necessary to develop novel fast pulsed high current driver. The present art-of-state and trends of fast Z-pinch driver are summarized, and the typical conceptual designs and technological methods on ICF/HY PRS (plasma radiation source) and destroying-level super X-ray simulators in USA and Russia are outlined, such as HCEI's UGXX1 driver and new Saturn driver based on fast linear transformer driver (FLTD) and novel driver based on fast Marx generator (FMG) with current of 15 MA. The crucial technological problems and requirements to investigate in the future are presented. (authors)

Transition in x-ray yield, mass scaling observed in the high-wire-number, plasma-shell regime

International Nuclear Information System (INIS)

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

1999-01-01

Initial calculations, based on classical transport coefficients and carried out to predict the efficiency with which the implosion kinetic energy of aluminum Z pinches could be thermalized and converted into kilovolt x-rays, predicted a sharp transition between m 2 and m yield scaling, where m is the aluminum array mass. Later, when ad hoc increases in the heat conductivity and artificial viscosity were introduced into these calculations and the densities that were achieved on axis were sharply reduced, the transition from m 2 to m scaling was found to have shifted, but was otherwise still fairly sharp and well-defined. The location of these breakpoint curves defined the locus of implosion velocities at which the yields would obtain their maximum for different mass arrays. The first such mass breakpoint curve that was calculated is termed hard, while the second is termed soft. Early 24, 30, and 42 aluminum wire experiments on the Saturn accelerator at the Sandia National laboratories confirmed the predictions of the soft breakpoint curve calculations. In this talk, the authors present results from a more recent set of aluminum experiments on Saturn, in which the array mass was varied at a fixed array radius and in which the radius was varied for a fixed mass. In both sets of experiments, the wire numbers were large: in excess of 92 and generally 136 or 192. In this high-wire-number regime, the wire plasmas are calculated to merge to form a plasma shell prior to significant radial implosion. Large wire number has been found to improve the pinch compressibility, and the analysis of these experiments in the shell regime shows that they come very close to the original predictions of the hard breakpoint curve calculations. A discussion of these detailed comparisons will be presented

Space and time resolved observations of plasma dynamics in a compressional gas embedded Z-pinch

International Nuclear Information System (INIS)

Soto, L.; Chuaqui, H.; Favre, M.; Saavedra, R.; Wyndham, E.; Aliaga-Rossel, R.; Mitchell, I.

1996-01-01

Recent experiments in a gas embedded compressional Z-pinch are presented. The experiments have been carried out in H 2 at 1/3 atm, using a pulse power generator capable of delivering a dl/dt > 10 12 A/s. The pinch is initiated by a focused laser pulse, which is coaxial with a cylindrical DC microdischarge. This configuration results in double column pinch at early times, which at current rise evolves into a gas embedded compressional Z-pinch. Diagnostics used are Rogowski coil, single frame holographic interferometry, and holographic shadowgraphy, visible streak camera images from which current, density, line density, pinch radius and plasma motion are obtained. The pinch is characterized by a maximum on axis density which is much higher than the expected value from the filling pressure, with a Bennett temperature of 40 eV at 130 kA. The results shown confirm the high degree of compression achievable with the composite preionization scheme. (author). 4 figs., 5 refs

Los Alamos Compact Toroid, fast liner, and High-Density Z-Pinch programs

International Nuclear Information System (INIS)

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

1982-01-01

The compact Toroid and High Density Z-Pinch are two of the plasma configurations presently being studied at Los Alamos. This paper summarizes these two programs along with the recently terminated Fast Liner Program. Included in this discussion is an analysis of compact Toroid formation techniques showing the tearing and reconnection of the fields that separate the spheromak from the radial fields of the coaxial source, and the final equilibrium state of the elongated FRC in the theta-pinch coil. In addition the typical dimensions of the geometry of the Fast Liner experiments are delineated Z-pinch and electrode assembly is displayed as is a graphic of the temporal behavior of the current required for radial equilibrium. Spheromak is examined in terms of formation, gross stability, and equilibrium and field reversed configuration is discussed in terms of gross stability, equilibrium, and confinement scaling

Determining the resistance of X-pinch plasma

International Nuclear Information System (INIS)

Zhao Shen; Zhu Xin-Lei; Zhang Ran; Luo Hai-Yun; Zou Xiao-Bing; Wang Xin-Xin; Xue Chuang; Ning Cheng; Ding Ning; Shu Xiao-Jian

2013-01-01

The current and the voltage of an X-pinch were measured. The inductance of the X-pinch was assumed to be a constant and estimated by the calculation of the magnetic field based on the well-known Biot—Savart's Law. The voltage of the inductance was calculated with L · di/dt and subtracted from the measured voltage of the X-pinch. Then, the resistance of the X-pinch was determined and the following results were obtained. At the start of the current flow the resistance of the exploding wires is several tens of Ohms, one order of magnitude, higher than the metallic resistance of the wires at room temperature, and then it falls quickly to about 1 Ω, which reflects the physical processes occurring in the electrically exploding wires, i.e., a current transition from the highly resistive wire core to the highly conductive plasma. It was shown that the inductive contribution to the voltage of the X-pinch is less than the resistive contribution. For the wires we used, the wires' material and diameter have no strong influence on the resistance of the X-pinch, which may be explained by the fact that the current flows through the plasma rather than through the metallic wire itself. As a result, the current is almost equally divided between two parallel X-pinches even though the diameter and material of the wires used for these two X-pinches are significantly different. (physics of gases, plasmas, and electric discharges)

Reduction of thermal expansion in Z-pinches by electron beam assisted magnetic field generation

International Nuclear Information System (INIS)

Heikkinen, J.A.; Karttunen, S.J.

1989-01-01

Weak radial expansion of a Z-pinch plasma column during its strong initial ohmic heating phase is expected when the generation of a confining magnetic field is assisted by a correctly formed electron beam pulse. Appropriate one-dimensional magnetohydrodynamic equations are numerically solved, and the observed increase of plasma radius as a function of time for various discharge parameters is compared to a normal Z-pinch discharge initiation. (author)

High-temperature dynamic hohlraums on the pulsed power driver Z

International Nuclear Information System (INIS)

Nash, T.J.; Derzon, M.S.; Chandler, G.A.; Leeper, R.; Fehl, D.; Lash, J.; Ruiz, C.; Cooper, G.; Seaman, J.F.; McGurn, J.; Lazier, S.; Torres, J.; Jobe, D.; Gilliland, T.; Hurst, M.; Mock, R.; Ryan, P.; Nielsen, D.; Armijo, J.; McKenney, J.; Hawn, R.; Hebron, D.; MacFarlane, J.J.; Petersen, D.; Bowers, R.; Matuska, W.; Ryutov, D.D.

1999-01-01

In the concept of the dynamic hohlraum an imploding Z pinch is optically thick to its own radiation. Radiation may be trapped inside the pinch to give a radiation temperature inside the pinch greater than that outside the pinch. The radiation is typically produced by colliding an outer Z-pinch liner onto an inner liner. The collision generates a strongly radiating shock, and the radiation is trapped by the outer liner. As the implosion continues after the collision, the radiation temperature may continue to increase due to ongoing PdV (pressure times change in volume) work done by the implosion. In principal, the radiation temperature may increase to the point at which the outer liner burns through, becomes optically thin, and no longer traps the radiation. One application of the dynamic hohlraum is to drive an ICF (inertial confinement fusion) pellet with the trapped radiation field. Members of the dynamic hohlraum team at Sandia National Labs have used the pulsed power driver Z (20 MA, 100 ns) to create a dynamic hohlraum with temperature linearly ramping from 100 to 180 eV over 5 ns. On this shot zp214 a nested tungsten wire array of 4 and 2 cm diam with masses of 2 and 1 mg imploded onto a 2.5 mg plastic annulus at 5 mm diam. The current return can on this shot was slotted. It is likely the radiation temperature may be increased to over 200 eV by stabilizing the pinch with a solid current return can. A current return can with nine slots imprints nine filaments onto the imploding pinch. This degrades the optical trapping and the quality of the liner collision. A 1.6 mm diam capsule situated inside this dynamic hohlraum of zp214 would see 15 kJ of radiation impinging on its surface before the pinch itself collapses to a 1.6 mm diam. Dynamic hohlraum shots including pellets were scheduled to take place on Z in September of 1998. copyright 1999 American Institute of Physics

High Temperature Dynamic Hohlraums on the Pulsed Power Driver Z

International Nuclear Information System (INIS)

Armijo, J.; Chandler, G.A.; Cooper, G.; Derzon, M.S.; Fehl, D.; Gilliland, T.; Hawn, R.; Hebron, D.; Hurst, M.; Jobe, D.; Lash, J.; Lazier, S.; Leeper, R.; McGurn, J.; McKenney, J.; Mock, R.; Nash, T.J.; Nielsen, D.; Ruiz, C.; Ryan, P.; Seaman, J.F.; Torres, J.

1999-01-01

In the concept of the dynamic hohlraum an imploding z-pinch is optically thick to its own radiation. Radiation may be trapped inside the pinch to give a radiation temperature inside the pinch greater than that outside the pinch. The radiation is typically produced by colliding an outer Z-pinch liner onto an inner liner. The collision generates a strongly radiating shock, and the radiation is trapped by the outer liner. As the implosion continues after the collision the radiation temperature may continue to increase due to ongoing PdV (pressure times change in volume) work done by the implosion. In principal the radiation temperature may increase to the point at which the outer liner burns through, becomes optically thin, and no longer traps the radiation. One application of the dynamic hohlraum is to drive an ICF (inertial confinement fusion) pellet with the trapped radiation field. Members of the dynamic hohlraum team at Sandia National Labs have used the pulsed power driver Z (20 LMA, 100 ns) to create a dynamic hohlraum with temperature linearly ramping from 100 to 180 eV over 5 ns. On this shot zp214 a nested tungsten wire array of 4 and 2 cm diameters with masses of 2 and 1 mg imploded onto a 2.5 mg plastic annulus at 5 mm diameter. The current return can on this shot was slotted. It is likely the radiation temperature may be increased to over 200 CV by stabilizing the pinch with a solid current return can. A current return can with 9 slots imprints 9 filaments onto the imploding pinch. This degrades the optical trapping and the quality of the liner collision. A 1.6 mm diameter capsule situated inside this dynamic hohlraum of zp214 would see 15 kJ of radiation impinging on its surface before the pinch itself collapses to a 1.6 mm diameter. Dynamic hohlraum shots including pellets are scheduled to take place on Z in September of 1998

Radiative collapse of a Bennett-relaxed z-pinch

International Nuclear Information System (INIS)

Turner, L.

1989-01-01

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 4πm/sub e//e 2 μ/sub o/; i.e., 3.55 /times/ 10 14 m/sup /minus/1/. 6 refs., 2 figs

Electron temperature measurement in Z-pinch

International Nuclear Information System (INIS)

Gerusov, A.V.; Orlov, M.M.; Terent'ev, A.R.; Khrabrov, V.A.

1987-01-01

Measurement of temperature of emitting plasma sheath in noncylindrical Z-pinch in neon at the stage of convergence to the axis, based on comparing the intensity of spectral lines belonging to Ne1, Ne2, is performed. Line intensity relation dependence was determined using calculations according to emitting-collision model. Spectra were recorded by electron-optical converter and relative intensity was determined by subsequent photometry of photolayer. Cylindric symmetrical MHD-calculations during which temperature and the observed line intensity relation were determined, are conducted

Migration of plasma points in the Z-pinch

International Nuclear Information System (INIS)

Afonin, V.I.

1995-01-01

The paper deals with the generation of a spontaneous magnetic field in Z-pinch sausage-type instability plasma and the effect of magnetic field on sausage-type instability movement. The presented evaluations of spontaneous magnetic fields and their role in the migration of plasma points are in a satisfactory agreement with the experimental data. 8 refs

Collapse of Z-pinch necks for inertial fusion

International Nuclear Information System (INIS)

Yan'kov, V.V.

1989-01-01

The ignition is possible under the condition of collapring z-pinch neck up to the diameter 10 -4 cm. The current pulse with duration 10 -7 s and 10 7 A must be applied to a cylinder of condensed D-T mixture in order to obtain the parameter ρr≥0.4 g/cm 2 . 22 refs

Experimental study of the 'NOVA' Z-pinch equipment working as vacuum-gap

International Nuclear Information System (INIS)

Acuna, H.; Bernal, L.; Cortazar, D.; Iglesias, G.; Pouzo, J.

1990-01-01

The Z-pinch device 'NOVA' (2 kjoule, 10 kV, 250 kA) is operated as a vacuum gap. The plasma is generated in high vacuum (10 -5 mb) by the material let loose from the copper electrodes. Many strong compressions (micro pinches) are produced in the pinch column over the first quarter of the current period. This is detected by the observable pulses in the dI/dt signal. Hard X-rays generated in coincidence with the micro pinches are detected using a scintillator-photomultiplier system. This work studies the plasma evolution, by taking pictures of the pinch with obturation times of about 15 ns, temporally correlated with the dI/dt signal. Instabilities of types m=0 and m=1 are observed. (Author). 3 refs., 6 figs

1- to 10-keV x-ray backlighting of annular wire arrays on the Sandia Z-machine using bent-crystal imaging techniques

International Nuclear Information System (INIS)

Rambo, Patrick K.; Wenger, David Franklin; Bennett, Guy R.; Sinars, Daniel Brian; Smith, Ian Craig; Porter, John Larry Jr.; Cuneo, Michael Edward; Rovang, Dean Curtis; Anderson, Jessica E.

2003-01-01

Annular wire array implosions on the Sandia Z-machine can produce >200 TW and 1-2 MJ of soft x rays in the 0.1-10 keV range. The x-ray flux and debris in this environment present significant challenges for radiographic diagnostics. X-ray backlighting diagnostics at 1865 and 6181 eV using spherically-bent crystals have been fielded on the Z-machine, each with a ∼0.6 eVspectral bandpass, 10 (micro)m spatial resolution, and a 4 mm by 20mm field of view. The Z-Beamlet laser, a 2-TW, 2-kJ Nd:glass laser(λ = 527 nm), is used to produce 0.1-1 J x-ray sources for radiography. The design, calibration, and performance of these diagnostics is presented.

Wire Array Solar Cells: Fabrication and Photoelectrochemical Studies

Science.gov (United States)

Spurgeon, Joshua Michael

Despite demand for clean energy to reduce our addiction to fossil fuels, the price of these technologies relative to oil and coal has prevented their widespread implementation. Solar energy has enormous potential as a carbon-free resource but is several times the cost of coal-produced electricity, largely because photovoltaics of practical efficiency require high-quality, pure semiconductor materials. To produce current in a planar junction solar cell, an electron or hole generated deep within the material must travel all the way to the junction without recombining. Radial junction, wire array solar cells, however, have the potential to decouple the directions of light absorption and charge-carrier collection so that a semiconductor with a minority-carrier diffusion length shorter than its absorption depth (i.e., a lower quality, potentially cheaper material) can effectively produce current. The axial dimension of the wires is long enough for sufficient optical absorption while the charge-carriers are collected along the shorter radial dimension in a massively parallel array. This thesis explores the wire array solar cell design by developing potentially low-cost fabrication methods and investigating the energy-conversion properties of the arrays in photoelectrochemical cells. The concept was initially investigated with Cd(Se, Te) rod arrays; however, Si was the primary focus of wire array research because its semiconductor properties make low-quality Si an ideal candidate for improvement in a radial geometry. Fabrication routes for Si wire arrays were explored, including the vapor-liquid-solid growth of wires using SiCl4. Uniform, vertically aligned Si wires were demonstrated in a process that permits control of the wire radius, length, and spacing. A technique was developed to transfer these wire arrays into a low-cost, flexible polymer film, and grow multiple subsequent arrays using a single Si(111) substrate. Photoelectrochemical measurements on Si wire array

Electron beam generation in z-pinch discharges

Energy Technology Data Exchange (ETDEWEB)

Vikhrev, V.V.; Baronova, E.O. [Kurchatov Inst., Moscow (Russian Federation). Russian Research Center

1997-12-31

Numerical modelling of the process of electron beam generation in z-pinch discharges are presented. The proposed model represents the electron beam generation under turbulent plasma conditions. Strong current distribution inhomogeneity in the plasma column and the zigzag drift current motion through the plasma have accounted for the adequate generation process investigation. Electron beam is generated near the maximum of compression and it is not related with the current break effect. (author)

Developments of sausages in a z-pinch with short-wave perturbation of a boundary

International Nuclear Information System (INIS)

Vikhrev, V.V.; Ivanov, V.V.; Rozanova, G.A.

1989-01-01

A numeric simulation of sausage evolution in z-pinch during short-wave excitation of the boundary of plasma column pinch is carried out. The simulation has shown that due to nonlinear development of sausages in a pinch plasma colomn the cavities filled with a magnetic field in a rarefied pinch plasma are formed. Simultaneously compact column of tense plasma whose temperature is much higher than the average temperature of pinch plasma column are formed on the pinch axis. In the region of inlet in the cavity plasma is radially directed due to ponderomotoric force 1/2 x jB up to velocities greatly increasing the thermal velocity of ions in a plasma column

Experimental studies of the MHD stability of non-circular Extrap Z-pinches

International Nuclear Information System (INIS)

Drake, J.R.

1985-01-01

Extrap Z-pinches, which can be sustained for many Alfven times, can be characterized as non-circular Z-pinch discharges bounded by a magnetic separatrix acting somewhat like a limiter. The magnetic separatrix is produced when a vacuum magnetic field, generated by currents in external conductors, combines with the self-magnetic field produced by the discharge current. The separatrix deforms the pinch cross-section and affects the equilibrium at the pinch boundary; both effects improve stability. Experiments have been performed which indicate that both effects are necessary for the successful generation of sustained Extrap discharges. In one experiment, the importance of the non-circularity of the cross-section was investigated. The deformation provided by the vacuum field can provide regions in the discharge where field lines have good curvature, which improves the stability of the configuration against internal modes. In configurations apparently lacking good curvature, discharges could not be sustained. In a second experiment, the dependence of the amplitude of global kink instabilities on the discharge current density profile were studied. The behaviour of the modes was consistent with that which would be expected for surface current-driven modes. (orig.)

Experimental studies of the MHD stability of non-circular extrap Z-pinches

International Nuclear Information System (INIS)

Drake, J.R.

1984-12-01

Extrap Z-pinches, which can be sustained for many Alfven times, can be characterized as non-circular Z-pinch discharges bounded by a magnetic separatrix acting somewhat like a limiter. The magnetic separatrix is produced when a vacuum magnetic field, generated by currents in external conductors, combines with the self-magnetic field produced by the discharge current. The separatrix deforms the pinch cross-section and affects the equilibrium at the pinch boundary; both effects improve stability. Experiments have been performed which indicate that both effects are necessary for the successful generation of sustained Extrap discharges. In one experiment, the importance of the non-circularity of the cross-section was investigated. The deformation provided by the vacuum field can provide regions in the discharge where field lines have good curvature, which improves the stability of the configuration against internal modes. In configurations apparently lacking good curvature, discharges could not be sustained. In a second experiment, the dependence of the amplitude of global kink instabilities on the discharge current density profile were studied. The behaviour of the modes was consistent with that which would be expected for surface current-driven modes. (Author)

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

International Nuclear Information System (INIS)

Leeper, R.J.; Alberts, T.E.; Asay, J.R.

2001-01-01

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 7.5x10 7 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. (author)

Time resolved observations of helical disruptions in a gas embedded Z-pinch

International Nuclear Information System (INIS)

Favre, M.; Chuaqui, H.; Bruzzone, H.; Soto, L.; Wyndham, E.

1990-01-01

Multiframe holographic interferometry has been applied to a gas embedded Z-pinch driven by a 1.5 ω, 100 kV coaxial line generator. The Z-pinch is triggered by a 1.06 μm, 10 ns laser pulse, at the onset of the applied voltage. A hydrogen background pressure of 0.33 atmospheres, with a 3 cm interelectrode separation is used. The laser output is also doubled and it is passed through an optical system giving two or more pulses separated by up to 10 ns for the optical diagnostics. The complete evolution of the helical instability is observed and the main features are discussed. (Author)

Scaling the Shear-flow Stabilized Z-pinch to Reactor Conditions

Science.gov (United States)

McLean, H. S.; Schmidt, A.; Shumlak, U.; Nelson, B. A.; Golingo, R. P.; Cleveau, E.

2015-11-01

We present a conceptual design along with scaling calculations for a pulsed fusion reactor based on the shear-flow-stabilized Z-pinch device. Experiments performed on the ZaP device, at the University of Washington, have demonstrated stable operation for durations of 20 usec at ~100kA discharge current for pinches that are ~1 cm in diameter and 100 cm long. The inverse of the pinch diameter and plasma energy density scale strongly with pinch current and calculations show that maintaining stabilization durations of ~7 usec for increased discharge current (~15x) in a shortened pinch (10 cm) results in a pinch diameter of ~200 um and plasma conditions that approach those needed to support significant fusion burn and energy gain (Ti ~ 30keV, density ~ 3e26/m3, ntau ~1.4e20 sec/m3). Compelling features of the concept include operation at modest discharge current (1.5 MA) and voltage (40kV) along with direct adoption of liquid metals for at least one electrode--technological capabilities that have been proven in existing, commercial, pulse power devices such as large ignitrons. LLNL-ABS-674920. This work performed under the auspices of the U.S. Department of Energy ARPAe ALPHA Program by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

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

Energy Technology Data Exchange (ETDEWEB)

Hughes, M. C., E-mail: mchugs@uw.edu; Shumlak, U., E-mail: mchugs@uw.edu; Golingo, R. P., E-mail: mchugs@uw.edu; Nelson, B. A., E-mail: mchugs@uw.edu; Ross, M. P., E-mail: mchugs@uw.edu [Aerospace and Energetics Research Program, University of Washington, Seattle, WA 98195 (United States)

2014-12-15

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

Model of enhanced energy deposition in a Z-pinch plasma

International Nuclear Information System (INIS)

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

2000-01-01

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

The Magpie dense z-pinch project

International Nuclear Information System (INIS)

Chittenden, J.; Choi, P.; Mitchell, I.; Dangor, A.E.; Haines, M.G.

1990-01-01

The authors present a design study on the Mega Ampere Generator for Plasma Implosion Experiments (MAGPIE), a project currently under construction at Imperial College London, to study radiative collapse of a dense Z-pinch plasma created from a 20 um diameter cryogenic hydrogen fiber. The 2 TW generator is composed of four individual 2.4 MV Marx banks of the HERMES III type design with a maximum stored energy of 336 kJ. They drive four 5 ohm Pulse Forming Lines which are combined into a single 1.25 MA in 150 ns to a 150 nH load

A Reactor Development Scenario for the FUZE Shear-flow Stabilized Z-pinch

Science.gov (United States)

McLean, H. S.; Higginson, D. P.; Schmidt, A.; Tummel, K. K.; Shumlak, U.; Nelson, B. A.; Claveau, E. L.; Golingo, R. P.; Weber, T. R.

2016-10-01

We present a conceptual design, scaling calculations, and a development path for a pulsed fusion reactor based on the shear-flow-stabilized Z-pinch device. Experiments performed on the ZaP device have demonstrated stable operation for 40 us at 150 kA total discharge current (with 100 kA in the pinch) for pinches that are 1cm in diameter and 100 cm long. Scaling calculations show that achieving stabilization for a pulse of 100 usec, for discharge current 1.5 MA, in a shortened pinch 50 cm, results in a pinch diameter of 200 um and a reactor plant Q 5 for reasonable assumptions of the various system efficiencies. We propose several key intermediate performance levels in order to justify further development. These include achieving operation at pinch currents of 300 kA, where Te and Ti are calculated to exceed 1 keV, 700 kA where fusion power exceeds pinch input power, and 1 MA where fusion energy per pulse exceeds input energy per pulse. This work funded by USDOE ARPAe ALPHA Program and performed under the auspices of Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-697801.

The effect of sheared axial flow on nonlinear Z-pinch dynamics

International Nuclear Information System (INIS)

Kassapakis, N.

2000-01-01

A two dimensional Eulerian fluid code has been used to study three problems related to Z-pinch and laser produced plasmas. a) The nonlinear evolution of a localised m=0 MHD mode neck is studied in order to extract some scaling laws for the size and form of the artificial neck. We examine whether the ubiquitous m=0 instability could be beneficially used to assist in the formation of a transient localised dense plasma. The results obtained were in satisfactory agreement with experiments and other theoretical work where available. b) The development of the m=0 instability on a Z-pinch although beneficial in the previous case, is detrimental from a stability point of view and thus to the utilisation of the device as a fusion reactor by itself. This is because the timescales of the instability development are faster than the confinement time needed for fusion to occur. Sheared axial flow is a proposed mechanism for the non-linear saturation of this particular instability. Indeed the linear growth rate also can be substantially reduced. It is hoped that it can inhibit the growth of the instabilities or at least delay their development sufficiently for fusion to take place. The numerical study of the effect of sheared axial flow on the nonlinear dynamics of the Z-pinch carried out, demonstrates that sheared flow with velocity u z z >4 Alfven speed other modes, of the Kelvin-Helmholtz type, are excited which take over from the fastest growing mode in the static case. c) The expansion of the ablated plasma in laser-solid interactions is an important phenomenon for a plethora of reasons one of which is ICF. The simulations were in direct agreement with previous experimental work regarding the bulk properties of the ablation surface. They also provided justification for some assumptions made during the analysis of the observations and helped to confirm the calibration of the diagnostics timewise. The most striking feature of the experiments, namely the density dip on the

Z-Pinch at extreme energies: Nanofocus of less than 1J. Plasma Focus of 400 J. Gas embedded Z-pinch operating at MA

International Nuclear Information System (INIS)

Pavez Morales, Cristian A

2007-01-01

anisotropic of 42.5% of the total production of neutrons is obtained with this technique. Finally, the average energy and the spectral distribution of neutrons at 900 from the axis of the pinch were measured by using the time of flight technique and an array of photomultipliers where it is possible to observe a maximum in the distribution around 2.5 MeV and a second diffused peak around 2.8 MeV. The Nanofocus device was electrically characterized. The plasma dynamics was studied by means of ultrafast photography in the visible spectrum reporting the formation of a dynamic coaxial discharge (plasma focus type) which is characterized by the formation and subsequent breaking of plasma column over the anode. The emission of radiation was studied by means of X-rays detection techniques with and without time resolution. From the signals of the photomultiplier, x-ray emission starts in the moment of the electrical break, and the maximum emission is previous to the moment of maximum current. An effective energy for radiation of 4.2keV is obtained from the detection technique with photography film and stepped filters. In the gas embedded Z-pinch experiment, a couple of conical electrodes were used to determine a preferential area of electrical break in the gas and then to form the discharge channel. The information of the channel structure, the same as its electronic density, was obtained using refractive optical techniques. A singularity was observed near to the cathode with a electronic density of the order of 4x10 24 m -3 immersed in a plasma column of density of the order of 1x10 24 m -3 . For those discharges where the formation of the plasma channel was well defined, it is possible to observe compression of the column and 3 He detectors give signals corresponding up to 5 x 10 5 neutrons per pulse. Moreover, macroscopic instabilities are not observed during the time in which the discharge is studied by means of optical diagnosis. With this, it is obtained that times of stability

Interferometric characterization of density dynamics of an ultradense Z-pinch plasma

International Nuclear Information System (INIS)

Ackenhusen, J.G.; Bach, D.R.

1979-01-01

We have measured the spatially and temporally resolved density in a Z-pinch plasma by holographic interferometry. The high electron density (4 x 10 19 e/cm 3 ), short density scale length (100 μm), and low temperature (about 20 eV) make the plasma source suitable for simulation of laser-pellet interaction experiments at 10.6-μm laser wavelengths. A cinema of density evolution, indicating plasma pinching and subsequent relaxation, provides an experimental view of plasma dynamics which is then compared to simple theoretical models

Characterization of laser-cut copper foil X-pinches

Science.gov (United States)

Collins, G. W.; Valenzuela, J. C.; Hansen, S. B.; Wei, M. S.; Reed, C. T.; Forsman, A. C.; Beg, F. N.

2016-10-01

Quantitative data analyses of laser-cut Cu foil X-pinch experiments on the 150 ns quarter-period, ˜250 kA GenASIS driver are presented. Three different foil designs are tested to determine the effects of initial structure on pinch outcome. Foil X-pinch data are also presented alongside the results from wire X-pinches with comparable mass. The X-ray flux and temporal profile of the emission from foil X-pinches differed significantly from that of wire X-pinches, with all emission from the foil X-pinches confined to a ˜3 ns period as opposed to the delayed, long-lasting electron beam emission common in wire X-pinches. Spectroscopic data show K-shell as well as significant L-shell emission from both foil and wire X-pinches. Fits to synthetic spectra using the SCRAM code suggest that pinching foil X's produced a ˜1 keV, ne ≥ 1023 cm-3 plasma. The spectral data combined with the improved reliability of the source timing, flux, and location indicate that foil X-pinches generate a reproducible, K-shell point-projection radiography source that can be easily modified and tailored to suit backlighting needs across a variety of applications.

Study of soft X-ray energy spectra from gas-puff Z-pinch plasma

International Nuclear Information System (INIS)

Zou Xiaobing; Wang Xinxin; Zhang Guixin; Han Min; Luo Chengmu

2006-01-01

A ROSS-FILTER-PIN spectrometer in the spectral range of 0.28 keV-1.56 keV was developed to study the soft X-ray radiation emitted from gas-puff Z-pinch plasma. It is composed of five channels covering the energy interval of interest without gaps. Soft X-ray spectral energy cuts were determined by the L absorption edges of selected filter elements (K absorption edges being used for light filter elements), and the optimum thickness of filter material was designed using computer code. To minimize the residual sensitivity outside the sensitivity range of each channel, element of the first filter was added into the second filter of all the Ross pair. To diminish the area of each filter, PIN detector with small sensitive area of 1 mm 2 was adopted for the spectrometer. A filter with small area is easy to fabricate and would be helpful to withstand the Z-pinch discharge shock wave. With this ROSS-FILTER-PIN spectrometer, the energy spectra of soft X-ray from a small gas-puff Z-pinch were investigated, and the correlation between the soft X-ray yield and the plasma implosion state was also studied. (authors)

A Reactor Development Scenario for the FuZE Sheared-Flow Stabilized Z-pinch

Science.gov (United States)

McLean, Harry S.; Higginson, D. P.; Schmidt, A.; Tummel, K. K.; Shumlak, U.; Nelson, B. A.; Claveau, E. L.; Forbes, E. G.; Golingo, R. P.; Stepanov, A. D.; Weber, T. R.; Zhang, Y.

2017-10-01

We present a conceptual design, scaling calculations, and development path for a pulsed fusion reactor based on a flow-stabilized Z-pinch. Experiments performed on the ZaP and ZaP-HD devices have largely demonstrated the basic physics of sheared-flow stabilization at pinch currents up to 100 kA. Initial experiments on the FuZE device, a high-power upgrade of ZaP, have achieved 20 usec of stability at pinch current 100-200 kA and pinch diameter few mm for a pinch length of 50 cm. Scaling calculations based on a quasi-steady-state power balance show that extending stable duration to 100 usec at a pinch current of 1.5 MA and pinch length of 50 cm, results in a reactor plant Q 5. Future performance milestones are proposed for pinch currents of: 300 kA, where Te and Ti are calculated to exceed 1-2 keV; 700 kA, where DT fusion power would be expected to exceed pinch input power; and 1 MA, where fusion energy per pulse exceeds input energy per pulse. This work funded by USDOE ARPA-E and performed under the auspices of Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-734770.

Performance of a Liner-on-Target Injector for Staged Z-Pinch Experiments

Science.gov (United States)

Conti, F.; Valenzuela, J. C.; Narkis, J.; Krasheninnikov, I.; Beg, F.; Wessel, F. J.; Ruskov, E.; Rahman, H. U.; McGee, E.

2016-10-01

We present the design and characterization of a compact liner-on-target injector, used in the Staged Z-pinch experiments conducted on the UNR-NTF Zebra Facility. Previous experiments and analysis indicate that high-Z gas liners produce a uniform and efficient implosion on a low-Z target plasma. The liner gas shell is produced by an annular solenoid valve and a converging-diverging nozzle designed to achieve a collimated, supersonic, Mach-5 flow. The on-axis target is produced by a coaxial plasma gun, where a high voltage pulse is applied to ionize neutral gas and accelerate the plasma by the J-> × B-> force. Measurements of the liner and target dynamics, resolved by interferometry in space and time, fast imaging, and collection of the emitted light, are presented. The results are compared to the predictions from Computational Fluid Dynamics and MHD simulations that model the injector. Optimization of the design parameters, for upcoming Staged Z-pinch experiments, will be discussed. Advanced Research Projects Agency - Energy, DE-AR0000569.

Dynamics of sausage instabilities of a gas-puff Z-pinch

International Nuclear Information System (INIS)

Sopkin, Yu.V.; Dorokhin, L.A.; Koshelev, K.N.; Sidelnikov, Yu.V.

1991-01-01

The early stage of the sausage instability in a gas-puff Z-pinch has been registered in VUV and soft X-rays with a 10 ns framing camera. We hypothesize that the rings of plasma expanding from the sausage instability enable an alternative current path to dominate the formation of 'micropinches'. (orig.)

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

International Nuclear Information System (INIS)

Hartman, C.W.; Carlson, G.; Hoffman, M.; Werner, R.

1977-01-01

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 re-circulated power are projected, based on a flow-through pinch cycle for which overall Q values can approach 10. The conceptual reactors are characterized by simplicity, small minimum size (100MW(e)) and by the potential for minimal radioactivity hazards. (author)

Data processing for elliptical crystal spectrometer used in Z-pinch diagnostic

International Nuclear Information System (INIS)

Li Jing; Xie Weiping; Huang Xianbin; Yang Libing; Cai Hongchun; Xiao Shali

2010-01-01

Elliptical crystal spectrometers are key instruments to detect the line spectra of soft X-rays in Z-pinch diagnostics. This paper deals with the data processing for an elliptical crystal spectrometer. Taking the diagnostic results obtained in a neon gas-puff Z-pinch experiment as an example, the detailed processes, such as changing the optical density to X-ray intensity according a calibrated film response curve, determining the X-ray energy of the measured spectrum using the energy and the order number of scanned point of identified spectral lines, and correcting the intensity of spectrum using the formula given by Henke are discussed. In the Henke's formula, the effect of nonuniform dispersion, integrated reflectivity of crystals and transmission of X-ray filters are considered. The final unfolding results are presented, including the relative intensities of several neon K-shell lines (H α , He α and He β , etc.) given by Lorentz fitting. The relative errors of the spectral intensities are also briefly discussed. (authors)

Preliminary results from the flow-through z-pinch experiments: ZaP

International Nuclear Information System (INIS)

Shumlak, U.; Nelson, B.A.; Goilingo, R.P.; Tang, D.; Crawford, E.; Hartog, D.J.D.; Holly, D.J.

1999-01-01

The stabilizing effect of an axial flow on the m = 1 kink instability in z-pinches has been studied numerically by reducing the linearized ideal MHD equations to a one-dimensional eigenvalue equation for the radial displacement. A diffuse z-pinch equilibrium is chosen that is made marginally stable to the m = 0 sausage mode by tailoring the pressure profile. The principal result reveals that a sheared axial flow does stabilize the kink mode when the shear exceeds a threshold value which is inversely proportional to the wavelength of the mode. This threshold value can be satisfied with a peak flow which is less than the Alfven speed for certain wavelengths. Additionally, the m = 0 sausage mode is driven from marginal stability into the stable regime which suggests that the equilibrium pressure profile control can be relaxed. The flow stabilization agrees with experimental observations. The details of the theoretical development will be presented

Thermal poling of multi-wire array optical fiber

DEFF Research Database (Denmark)

Huang, Lin; An, Honglin; Hayashi, Juliano G.

2018-01-01

We demonstrate in this paper thermal poling of multi-wire array fibers, which extends poling of fibers with two anodes to similar to 50 and similar to 500 wire array anodes. The second harmonic microscopy observations show that second order nonlinearity (SON) layers are developed surrounding all...... the rings of wires in the similar to 50 anode array fiber with poling of 1.8kV, 250 degrees C and 30min duration, and the outer rings of the similar to 500 anode array fiber at lower poling temperature. Our simulations based on a two-dimensional charge dynamics model confirm this can be explained...

Experimental study on gas-puff Z-pinch load characteristics on yang accelerator

International Nuclear Information System (INIS)

Ren Xiaodong; Huang Xianbin; Yang Libing; Dan Jiakun; Duan Shuchao; Zhang Zhaohui; Zhou Shaotong

2010-01-01

A supersonic single-shell gas-puff load has been developed for Z-pinch experiments on 'Yang' accelerator. Using a fast responding pressure probe to measure the supersonic gas flow, impact pressure at different position and plenum pressure were acquired, which were combined with gas dynamics formulas to determine gas pressures and densities. The radial density profile displays that positions of gas shell varies with axial position, and the gas densities on axis increases as the distance from nozzle increases. Integral radial densities indicates that the linear mass density peaks at nozzle exit and decreases as increasing the distance from nozzle. Using single-shell supersonic gas-puff load, Z-pinch implosion experiments were performed on 'Yang' accelerator. Primary analysis of implosion process was presented, and computational trajectories of imploding plasma shell using snowplow model are in agreement with the experimental results. (authors)

Ramp discharge in Z-pinch

Energy Technology Data Exchange (ETDEWEB)

Gaber, W.H.; Beshara, A.B.; El-Bialy, A.B.; Masoud, M.M. [Plasma and Nuclear Fusion Dept., N.R.C., Atomic Energy Authority, Enshass (Egypt)

2004-07-01

A ramp Z-pinch discharge is designed and built in order to increase the pinch ratio and obtain a maximum contraction, and to increase the temperature. The discharge chamber is a cylindrical Pyrex tube of 25 cm long, 18.5 cm, 20 cm inner and outer diameter and two circular Aluminum plates of radius 15 cm separated by 21 cm are inserted into the tube. The tube is filled with He gas at 0.1 mbar. Two capacitor banks are used, the first bank 30 {mu}F and the second fast bank 1.3 {mu}F. The charging voltage was 8 kV for both banks. The discharge current and voltage of each bank are measured by potential divider and Rogowski coil respectively. Also the plasma inductance and resistance are obtained for each case. The plasma inductance has its peak value 300 nH at 4 {mu}s, while the plasma resistance has it minimum 8 m{omega} at the same time in the case of conventional discharge (single bank). In the case of ramp discharge, the inductance has two peaks 440 nH, 380 nH at 4 {mu}s, 9.5 {mu}s respectively, while the resistance has two minimum 4 m{omega}, 20 m{omega} at at 4 {mu}s, 9.5 {mu}s respectively. The temperature has been measure spectroscopically by using relative continuum intensity ratio method. The temperature has its peak value 38 eV at 4 {mu}s for single bank case, while it larger peak value 55 eV for ramp case. (orig.)

Electrostatic turbulence in the Z pinch corona

International Nuclear Information System (INIS)

Terry, R.E.

1994-01-01

The microstability of electrostatic waves in the periphery of a Z pinch is formulated and resolved for a new class of Vlasov meta-equilibria admitting self-similar solutions in the electron gyrokinetic limit. These equilibria are subject to strong radial motions, and a mild deviation from charge neutrality arises to maintain ion acceleration close to that of the magnetized electrons. A unique class of profiles in density, axial current, temperature, and drift speed defines these equilibria. They are characterized by (i) the interior pinch current, (ii) the interior number density, (iii) the parallel and perpendicular temperatures, (iv) the exterior axial electric field value at the initial time, and (v) the radial ion acceleration relative to that of the electrons. Unstable ion sound waves arise in this medium by coupling radial and axial free energy to azimuthal longitudinal oscillations. The waves grow only for a limited range of radial or axial Exb/B drift speeds and electron temperatures. The growth rate, which can be as large as 0.115ω pi , is found to scale proportional to plasma frequency over the density range from 10 12 to 10 18 ions cm -3

Soft X-ray radiation parameters of nested tungsten wire array

International Nuclear Information System (INIS)

Ning Jiamin; Jiang Shilun; Xu Rongkun; Xu Zeping; Li Zhenghong; Yang Jianlun

2011-01-01

Implosions with nested tungsten wire array were performed at the Angara-5-1 facility in Russian Research Centre. The experimental results of nested tungsten wire array are compared with those of single array. Radiation parameters of nested array are discussed based on four different dynamic models. When the implosions of outer and inner wire arrays are synchronized,the relatively uniform distribution of inner layer plasma will improve the uniformity of outer layer plasma. As compared with single array, nested array has an increase of 32% in X-ray radiation power. (authors)

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

International Nuclear Information System (INIS)

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

2003-01-01

Inertial confinement fusion capsule implosions absorbing up to 35 kJ of x-rays from a ∼220 eV dynamic hohlraum on the Z accelerator at Sandia National Laboratories have produced thermonuclear D-D neutron yields of (2.6±1.3) x 10 10 . Argon spectra confirm a hot fuel with T e ∼ 1 keV and n e ∼ (1-2) x 10 23 cm -3 . Higher performance implosions will require radiation symmetry control improvements. Capsule implosions in a ∼70 eV double-Z-pinch-driven secondary hohlraum have been radiographed by 6.7 keV x-rays produced by the Z-beamlet laser (ZBL), demonstrating a drive symmetry of about 3% and control of P 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

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

International Nuclear Information System (INIS)

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.; Cooper, Gary Wayne; Schroen, Diana Grace; Slutz, Stephen A.; MacFarlane, Joseph John; Leeper, Ramon Joe; Golovkin, I.E.; Mehlhorn, Thomas Alan; Mancini, Roberto Claudio

2003-01-01

Inertial confinement fusion capsule implosions absorbing up to 35 kJ of x-rays from a ∼220 eV dynamic hohlraum on the Z accelerator at Sandia National Laboratories have produced thermonuclear D-D neutron yields of (2.6 ± 1.3) x 10 10 . Argon spectra confirm a hot fuel with Te ∼ 1 keV and n e ∼ (1-2) x 10 23 cm -3 . Higher performance implosions will require radiation symmetry control improvements. Capsule implosions in a ∼70 eV double-Z-pinch-driven secondary hohlraum have been radiographed by 6.7 keV x-rays produced by the Z-beamlet laser (ZBL), demonstrating a drive symmetry of about 3% and control of P 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.

The effects of preionization level on a 'stabilized' z-pinch

International Nuclear Information System (INIS)

Silawatshananai, C.; Anderson, F.S.B.; Brennan, M.H.; Durance, G.; Jones, I.R.; Murray, E.L.; Tendys, J.

1980-02-01

The influence of the degree of preionization on the formation and properties of a conventional 'stabilized' Z-pinch has been studied experimentally for preionization levels ranging from 2% to 35%. It is concluded that there exists the possibility of using varying levels of preionization to tailor radial profiles of density and pressure, and hence to influence the value of βsub(theta)

Z-pinch driven hohlraums design for the 100 nanoseconds current time scale; Conception de cavites radiatives chauffees par plasma de striction magnetique en regime 100ns

Energy Technology Data Exchange (ETDEWEB)

Hamann, F

2003-12-15

This work estimates Z-pinch driven hohlraums capabilities to obtain high temperatures (>200 eV). Simple models are proposed to calculate the performances offered by currents of 5 to 100 MA in 100 ns. The one dimensional physics of the Z-pinch at the length scale of its thickness and the hydrodynamics instabilities are studied. Then the enhancement of hohlraums performances with double nested Z-pinches or the use of an axial magnetic field is analysed. Z-pinch direct drive approach for inertial confinement fusion is finally considered. All the presented results are based on theoretical and 2D numerical approach and on the analysis of experimental results which were obtained on the american 'Z' generator. Annexes recall radiation MHD equations and check their validity for Z-pinch implosion. (author)

Optimized debris stoppers for Z-pinches

Energy Technology Data Exchange (ETDEWEB)

Gondarenko, N A; Pereira, N R [Berkeley Research Associates, Springfield, VA (United States)

1997-12-31

A pulse power generator discharging through an array of wires or a gas cylinder creates a pulse of useful soft x-rays, which is usually followed by deleterious byproducts such as plasma, hot gases and droplets of metal from evaporated electrodes. Separating the extraneous material from the x-rays is done with a debris shield. Optimization of such shields is discussed. (author). 3 figs., 3 refs.

Electrodeposition of nickel nano wire arrays

International Nuclear Information System (INIS)

Nur Ubaidah Saidin; Kok Kuan Ying; Ng Inn Khuan; Nurazila Mat Zali; Siti Salwa Zainal Abidin

2010-01-01

Synthesis, characterization and assembly of one-dimensional nickel nano wires prepared by template directed electrodeposition are discussed in this paper. Parallel arrays of high aspect ratio nickel nano wires were electrodeposited using electrolytes with different cations and pH. The nano wires were characterized using X-ray diffractometry and scanning electron microscopy. It was found that the orientations of the electro deposited Ni nano wires were governed by the deposition current and the electrolyte conditions. Free standing nickel nano wires can be obtained by dissolving the template. Due to the magnetic nature of the nano wires, magnetic alignment was employed to assemble and position the free standing nano wires in the device structure. (author)

Modelling of capillary Z-pinch recombination pumping of boron extreme ultraviolet laser

Czech Academy of Sciences Publication Activity Database

Vrba, Pavel; Bobrova, N. A.; Sasorov, P. V.; Vrbová, M.; Hübner, Jakub

2009-01-01

Roč. 16, č. 7 (2009), 073105 1-073105 11 ISSN 1070-664X R&D Projects: GA ČR GA102/07/0275 Institutional research plan: CEZ:AV0Z20430508 Keywords : Boron * capillary * discharges (electric * laser ablation * optical pumping * plasma heating by laser * plasma kinetic theory * plasma magnetohydrodynamics * Z pinch Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.475, year: 2009 http://link.aip.org/link/? PHP /16/073105

An experimental study on Kr gas-puff Z-pinch

International Nuclear Information System (INIS)

Kuai Bin; Cong Peitian; Zeng Zhengzhong; Qiu Aici; Qiu Mengtong; Chen Hong; Liang Tianxue; He Wenlai; Wang Liangping; Zhang Zhong

2002-01-01

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

Nonlinear full two-fluid study of m=0 sausage instabilities in an axisymmetric Z pinch

International Nuclear Information System (INIS)

Loverich, J.; Shumlak, U.

2006-01-01

A nonlinear full five-moment two-fluid model is used to study axisymmetric instabilities in a Z pinch. When the electron velocity due to the current J is greater than the ion acoustic speed, high wave-number sausage instabilities develop that initiate shock waves in the ion fluid. This condition corresponds to a pinch radius on the order of a few ion Larmor radii

Opacity measurements of tamped NaBr samples heated by z-pinch X-rays

International Nuclear Information System (INIS)

Bailey, J.E.; Arnault, P.; Blenski, T.; Dejonghe, G.; Peyrusse, O.; MacFarlane, J.J.; Mancini, R.C.; Cuneo, M.E.; Nielsen, D.S.; Rochau, G.A.

2003-01-01

Laboratory measurements provide benchmark data for wavelength-dependent plasma opacities to assist inertial confinement fusion, astrophysics, and atomic physics research. There are several potential benefits to using z-pinch radiation for opacity measurements, including relatively large cm-scale lateral sample sizes and relatively-long 3-5 ns experiment durations. These features enhance sample uniformity. The spectrally resolved transmission through a CH-tamped NaBr foil was measured. The z-pinch produced the X-rays for both the heating source and backlight source. The (50±4) eV foil electron temperature and (3±1)x10 21 cm -3 foil electron density were determined by analysis of the Na absorption features. LTE and NLTE opacity model calculations of the n=2 to 3, 4 transitions in bromine ionized into the M-shell are in reasonably good agreement with the data

Instability heating of solid-fiber Z pinches

International Nuclear Information System (INIS)

Riley, R.A. Jr.

1994-02-01

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

Instability heating of solid-fiber Z pinches

Energy Technology Data Exchange (ETDEWEB)

Riley, Jr., Ronald Alan [Univ. of California, San Diego, CA (United States)

1994-02-01

The Los Alamos High Density Z Pinch-II (HDZP-II) facility is used to study the dynamics of z-pinch plasmas generated from solid fibers of deuterated polyethylene CD₂ with a range in radii of 3--60 μm. HDZP-II is a pulsed-power generator that delivers a current that rises to 700 kA in 100 ns through an inductive load. A multiframe circular schlieren records the evolution of the shape and size of the plasma on seven images taken at 10-ns intervals. These circular-schlieren images show very strong m=0 instability at the onset of current and a rapid radial expansion of the plasma. No higher-order instabilities are observed. An interferometer is used to infer the electron density and electron line density, giving a measure of the fraction of plasma contained within the outline of the circular-schlieren image at one time during the multiframe sequence. A three-channel x-ray crystal-reflection spectrometer provides the time-resolved, spatially-averaged electron temperature. The magnitude of the x-ray emission at these energies also gives qualitative information about the electron temperature and density at late times. A lower bound on the ion temperature is inferred from the particle pressure needed to balance the magnetic field pressure. The ion temperature rose above that of the electrons, strongly suggesting an additional heating term that puts energy directly into the ions. An ion heating term is proposed to explain the observed rapid radial expansion and elevated ion temperatures. This heating term is based on the assumption that the observed m=0 instabilities reconnect, enclosing magnetic flux which degenerates into turbulence in the plasma. A 0-D simulation is developed to investigate the relevance of different physical models to the data presented.

Sausage instability of the z-pinch in InSb

International Nuclear Information System (INIS)

Markus, M.; Huebner, K.

1975-01-01

A differential equation for the perturbations of a stationary equilibrium, which takes into account the effects of extrinsic carriers, degeneration, induction of electric field, generation and recombination of carriers is used to study the z-pinch in n-InSb at 77 K. The calculations for the azimuthal wave number m = 0 lead to three oscillating modes, one of which is unstable above a certain threshold of the axial wavelength. This instability is caused by the nonconservation of plasma carriers. (orig.) [de

Physics and applications of micro and fast z-pinch plasmas

International Nuclear Information System (INIS)

Masugata, Katsumi

2003-07-01

This is the proceedings of symposium on 'Physics and Application of Micro and Fast z-Pinch Plasma' held at National Institute for Fusion Science. Recent progress of experimental and theoretical works on high energy density plasmas produced by pulsed power is presented. Separate abstracts were presented for 4 of the papers in this report. The remaining 14 were considered outside the subject scope of INIS. (J.P.N.)

Phenomenological modeling of argon Z-pinch implosions

International Nuclear Information System (INIS)

Whitney, K.G.; Thornhill, J.W.; Deeney, C.; LePell, P.D.; Coulter, M.C.

1992-01-01

The authors investigate some of the effects of plasma turbulence on the K-shell emission dynamics of argon gas puff Z-pinch implosions. The increases that turbulence produces in the plasma viscosity, heat conductivity, and electrical resistivity are modeled phenomenologically using multipliers for these quantities in the MHD calculations. The choice of multipliers was made by benchmarking a 1-D MHD simulation of a Physics International Inc. argon gas puff experiment against the inferred densities and temperatures achieved in the experiment. These multipliers were then used to study the parametric dependence of the K-shell emission on the energy input to the argon plasma for a fixed mass loading. Comparisons between turbulent and non-turbulent argon implosions are made

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

International Nuclear Information System (INIS)

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

2011-01-01

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.

Particle orbits and non-ideal MHD stability of Z-pinches

International Nuclear Information System (INIS)

Faghihi, M.

1987-01-01

Particle orbits in a linear EXTRAP vacuum magnetic field configuration are computed. The results indicate that, with an applied electric field along the axis, the particles starting near the magnetic stagnation line would gain substantial energy in the 'free fall', and are the most efficient ones to participate in the ionization process. The acquired energy depends on the electric field strength; the required value of the field is determined. The influence of the pressure anisotropy on the small wavelength internal kink (m=1) mode instability in a Z-pinch, using a generalization of Freidbergs perpendicular MHD model, is investigated. It is found that the stability criterion can not be fulfilled without violation of the fire hose stability condition. This investigation is also performed using the double-adiabatic theory. A finite Larmor radius treatment of the small wavelength kink instabilities for a Z-pinch geometry is presented. It is shown that, when the gyroviscosity is included in the perpendicular MHD model, exponentially growing Alfven waves are predicted even in a homogeneous static equilibrium with isotropic plasma pressure. The Hall effect in the incompressible Hall fluid model is considered. It is found that the Hall parameter reduces the growth rates of the kink modes, but it does not yield complete stabilization (author)

Particle orbits and non-ideal MHD stability of Z-pinches

Energy Technology Data Exchange (ETDEWEB)

Faghihi, M.

1987-01-01

Particle orbits in a linear EXTRAP vacuum magnetic field configuration are computed. The results indicate that, with an applied electric field along the axis, the particles starting near the magnetic stagnation line would gain substantial energy in the 'free fall', and are the most efficient ones to participate in the ionization process. The acquired energy depends on the electric field strength; the required value of the field is determined. The influence of the pressure anisotropy on the small wavelength internal kink (m=1) mode instability in a Z-pinch, using a generalization of Freidbergs perpendicular MHD model, is investigated. It is found that the stability criterion can not be fulfilled without violation of the fire hose stability condition. This investigation is also performed using the double-adiabatic theory. A finite Larmor radius treatment of the small wavelength kink instabilities for a Z-pinch geometry is presented. It is shown that, when the gyroviscosity is included in the perpendicular MHD model, exponentially growing Alfven waves are predicted even in a homogeneous static equilibrium with isotropic plasma pressure. The Hall effect in the incompressible Hall fluid model is considered. It is found that the Hall parameter reduces the growth rates of the kink modes, but it does not yield complete stabilization

Analysis of Precursor Properties of mixed Al/Alumel Cylindrical Wire Arrays*

Science.gov (United States)

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

2012-10-01

Previous studies of mid-Z (Cu and Ni) cylindrical wire arrays (CWAs) on Zebra have found precursors with high electron temperatures of >300 eV. However, past experiments with Al CWAs did not find the same high temperature precursors. New precursor experiments using mixed Al/Alumel (Ni 95%, Si 2%, and Al 2%) cylindrical wire arrays have been performed to understand how the properties of L-shell Ni precursor will change and whether Al precursor will be observed. Time gated spectra and pinholes are used to determine precursor plasma conditions for comparison with previous Alumel precursor experiments. A full diagnostic set which included more than ten different beam-lines was implemented. Future work in this direction is discussed. [4pt] *This work was supported by NNSA under DOE Cooperative Agreements DE-FC52-06NA27588, and in part by DE-FC52-06NA27586, and DE-FC52-06NA27616. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.

Deformable wire array: fiber drawn tunable metamaterials

DEFF Research Database (Denmark)

Fleming, Simon; Stefani, Alessio; Tang, Xiaoli

2017-01-01

By fiber drawing we fabricate a wire array metamaterial, the structure of which can be actively modified. The plasma frequency can be tuned by 50% by compressing the metamaterial; recovers when released and the process can be repeated.......By fiber drawing we fabricate a wire array metamaterial, the structure of which can be actively modified. The plasma frequency can be tuned by 50% by compressing the metamaterial; recovers when released and the process can be repeated....

Radiative cooling of a cilindrical Z-pinch in the stage of plasma shett motion

International Nuclear Information System (INIS)

Gerusov, A.V.; Imshennik, V.S.

1982-01-01

Dinamics of a cylindrically symmetric Z-pinch in deiterium-neon mixture on the motion stage with volume radiation losses of energy of neon ions is considered. A two-temperature MHD model of Z-pinch is numerically calculated with various percentage of gases in mixture. It is found that radiation losses are essential in the dynamics of the discharqe. They decrease distribution of magnetic field and curreqt density. The temoerature of anode surface heated by absorbtion of radiation from the plasma sheath which forms in the discharge is obtained. The value of anode surface temperature prior to the arrival of the shock front is insufficient for operating of previously proposed mechanism of X-ray plasma focus regime. Another mechanism leading to X-ray regime being due to radiative cooiang as aiso suggested

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

International Nuclear Information System (INIS)

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

1996-01-01

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 z-pinch loads of interest to radiative collapse studies. This article describes the design and tests of the generator which has a novel configuration of lines and a new design of a magnetically insulated transmission line (MITL). In summary, the generator consists of four Marx generators each of the Hermes III type (2.4 MV, 84 kJ), each connected to 5 Ω pulse forming lines and trigatron gas switches. The power is fed into the matched 1.25 Ω vertical transfer line which feeds a diode stack and a short conical MITL in vacuum which concentrates the power into the z-pinch load. At 80% charge a current rising to 1.4 MA in 150 ns has been measured in a 15 nH inductive short. Similar results are obtained when using a plasma load. copyright 1996 American Institute of Physics

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

International Nuclear Information System (INIS)

Hammer, J.H.; Eddleman, J.L.; Springer, P.T.

1995-01-01

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

Cinematic Characterization of Convected Coherent Structures Within an Continuous Flow Z-Pinch

Science.gov (United States)

Underwood, Thomas; Rodriguez, Jesse; Loebner, Keith; Cappelli, Mark

2017-10-01

In this study, two separate diagnostics are applied to a plasma jet produced from a coaxial accelerator with characteristic velocities exceeding 105 m/s and timescales of 10 μs. In the first of these, an ultra-high frame rate CMOS camera coupled to a Z-type laser Schlieren apparatus is used to obtain flow-field refractometry data for the continuous flow Z-pinch formed within the plasma deflagration jet. The 10 MHz frame rate for 256 consecutive frames provides high temporal resolution, enabling turbulent fluctuations and plasma instabilities to be visualized over the course of a single pulse. The unique advantage of this diagnostic is its ability to simultaneously resolve both structural and temporal evolution of instabilities and density gradients within the flow. To allow for a more meaningful statistical analysis of the resulting wave motion, a multiple B-dot probe array was constructed and calibrated to operate over a broadband frequency range up to 100 MHz. The resulting probe measurements are incorporated into a wavelet analysis to uncover the dispersion relation of recorded wave motion and furthermore uncover instability growth rates. Finally these results are compared with theoretical growth rate estimates to identify underlying physics. This work is supported by the U.S. Department of Energy Stewardship Science Academic Program in addition to the National Defense Science Engineering Graduate Fellowship.

Imploding process and x-ray emission of shotgun z-pinch plasma

International Nuclear Information System (INIS)

Muto, Ryusuke; Takasugi, Keiichi; Miyamoto, Tetsu

2001-01-01

Rayleigh-Taylor instability was observed on the surface of a contracting z-pinch plasma. Wavelength of the instability was analyzed from the envelope of the profile, and it increased with implosion. Analysis with finite Larmor radius effect shows that there is some acceleration of ions during the contraction process. A suggestion to obtain macroscopically uniform plasma is to increase plasma current without heating the plasma. (author)

Imploding process and x-ray emission of shotgun z-pinch plasma

Energy Technology Data Exchange (ETDEWEB)

Muto, Ryusuke [Nihon University, College of Science and Technology, Tokyo (Japan); Takasugi, Keiichi; Miyamoto, Tetsu [Nihon University, Atomic Energy Research Institute, Tokyo (Japan)

2001-09-01

Rayleigh-Taylor instability was observed on the surface of a contracting z-pinch plasma. Wavelength of the instability was analyzed from the envelope of the profile, and it increased with implosion. Analysis with finite Larmor radius effect shows that there is some acceleration of ions during the contraction process. A suggestion to obtain macroscopically uniform plasma is to increase plasma current without heating the plasma. (author)

Optical and EUV studies of laser triggered Z-pinch discharges

OpenAIRE

Tobin, Isaac

2014-01-01

This thesis describes the results of experiments with two geometries of laser assisted discharge plasma. Both devices are designed for fast Z-pinch discharge, triggered by laser produced plasma generated by ablation of one or both electrodes. The laser plasma parameters are adjusted to control the plasma load while the discharge parameters are adjusted to yield a rate of rise of current greater than 1010 A/s. The expansion dynamics and emission characteristics of the plasma were analysed, wit...

Anodic Aluminum Oxide Templates for Nano wires Array Fabrication

International Nuclear Information System (INIS)

Nur Ubaidah Saidin; Kok, K.Y.; Ng, I.K.

2011-01-01

This paper reports on the process developed to fabricate anodic aluminium oxide (AAO) templates suitable for the fabrication of nano wire arrays. Anodization process has been used to fabricate the AAO templates with pore diameters ranging from 15 nm to 30 nm. Electrodeposition of parallel arrays of high aspect ratio nickel nano wires were demonstrated using these fabricated AAO templates. The nano wires produced were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that the orientations of the electrodeposited nickel nano wires were governed by the deposition current and electrolyte conditions. (author)

The quest for a z-pinch based fusion energy source—a historical perspective

Science.gov (United States)

Sethian, John

1997-05-01

Ever since 1958, when Oscar Anderson observed copious neutrons emanating from a "magnetically self-constricted column of deuterium plasma," scientists have attempted to develop the simple linear pinch into a fusion power source. After all, simple calculations show that if one can pass a current of slightly less than 2 million amperes through a stable D-T plasma, then one could achieve not just thermonuclear break-even, but thermonuclear gain. Moreover, several reactor studies have shown that a simple linear pinch could be the basis for a very attractive fusion system. The problem is, of course, that the seemingly simple act of passing 2 MA through a stable pinch has proven to be quite difficult to accomplish. The pinch tends to disrupt due to instabilities, either by the m=0 (sausage) or m=1 (kink) modes. Curtailing the growth of these instabilities has been the primary thrust of z-pinch fusion research, and over the years a wide variety of formation techniques have been tried. The early pinches were driven by relatively slow capacitive discharges and were formed by imploding a plasma column. The advent of fast pulsed power technology brought on a whole new repertoire of formation techniques, including: fast implosions, laser or field-enhanced breakdown in a uniform volume of gas, a discharge inside a small capillary, a frozen deuterium fiber isolated by vacuum, and staged concepts in which one pinch implodes upon another. And although none of these have yet to be successful, some have come tantalizingly close. This paper will review the history of this four-decade long quest for fusion power.

Influence of the inner diameters of capillary on the Z-Pinch plasma of the capillary discharge soft X-ray laser

International Nuclear Information System (INIS)

Jiang, Shan; Zhao, Yong-peng; Cui, Huai-yu; Li, Lian-bo; Ding, Yu-jie; Zhang, Wen-hong; Li, Wei

2015-01-01

In this paper, the effects of inner diameters on the Z-pinch plasma of capillary discharge soft X-ray laser were investigated with the 3.2 mm and 4.0 mm inner diameter alumina capillaries. The intensities of the laser emitted from the 3.2 mm and 4.0 mm inner diameter alumina capillaries were measured under different initial pressures. To understand the underlying physics of the experimental measurements, the Z-pinch plasma simulations had been conducted with a one-dimensional cylindrical symmetry Lagrangian magneto-hydrodynamics (MHD) code. The parametric studies of Z-pinch plasma, such as the electron temperature, the electron density and the Ne-like Ar ion density, were performed with the MHD code. With the experimental and the simulated results, the discussions had been conducted on the Z-pinch plasma of Ne-like Ar 46.9 nm laser with the 3.2 mm and 4.0 mm inner diameter alumina capillaries. The analysis had been made on the difference of the gain coefficients under the optimum pressures with both capillaries. Then, the effects of inner diameters on the optimum pressure and the pressure domain were analyzed. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Soft X-ray spectroscopic investigations in experiments on Z-pinch stabilization

International Nuclear Information System (INIS)

Pikuz, S.A.; Skobelev, I.Yu.

1996-01-01

X-ray spectroscopic methods were used to investigate the spatial distribution of Z-pinch plasma parameters. Experiments were carried out on the GAEL pulse line generator in Ecole Polytechnique (France) with different types of load. Obtained results for the concentration of electrons and plasma temperature showed that higher plasma homogeneity was obtained in experiments with complex load. Spectrograms demonstrate the stabilization effect of the A1-jet. (orig.)

Soft X-ray spectroscopic investigations in experiments on Z-pinch stabilization

Energy Technology Data Exchange (ETDEWEB)

Pikuz, S.A. [Rossijskaya Akademiya Nauk, Moscow (Russian Federation). Fizicheskij Inst.; Shelkovenko, T.A. [Rossijskaya Akademiya Nauk, Moscow (Russian Federation). Fizicheskij Inst.; Romanova, V.M. [Rossijskaya Akademiya Nauk, Moscow (Russian Federation). Fizicheskij Inst.; Etlicher, B. [Ecole Polytechnique, Palaseau (France). Lab. de Phys. des Mililux Ionises; Attelan, S. [Ecole Polytechnique, Palaseau (France). Lab. de Phys. des Mililux Ionises; Chuvatin, A.S. [Ecole Polytechnique, Palaseau (France). Lab. de Phys. des Mililux Ionises; Faenov, A.Ya. [MISDC VNIIFTRI, Moscow (Russian Federation); Skobelev, I.Yu. [MISDC VNIIFTRI, Moscow (Russian Federation)

1996-04-01

X-ray spectroscopic methods were used to investigate the spatial distribution of Z-pinch plasma parameters. Experiments were carried out on the GAEL pulse line generator in Ecole Polytechnique (France) with different types of load. Obtained results for the concentration of electrons and plasma temperature showed that higher plasma homogeneity was obtained in experiments with complex load. Spectrograms demonstrate the stabilization effect of the A1-jet. (orig.).

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

International Nuclear Information System (INIS)

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.

1999-01-01

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 approximately55 to approximately130 eV, and is in agreement with the Planckian relation P-T 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

X pinch a point x-ray source

International Nuclear Information System (INIS)

Garg, A.B.; Rout, R.K.; Shyam, A.; Srinivasan, M.

1993-01-01

X ray emission from an X pinch, a point x-ray source has been studied using a pin-hole camera by a 30 kV, 7.2 μ F capacitor bank. The wires of different material like W, Mo, Cu, S.S.(stainless steel) and Ti were used. Molybdenum pinch gives the most intense x-rays and stainless steel gives the minimum intensity x-rays for same bank energy (∼ 3.2 kJ). Point x-ray source of size (≤ 0.5 mm) was observed using pin hole camera. The size of the source is limited by the size of the pin hole camera. The peak current in the load is approximately 150 kA. The point x-ray source could be useful in many fields like micro lithography, medicine and to study the basic physics of high Z plasmas. (author). 4 refs., 3 figs

Parameter scaling toward high-energy density in a quasi-steady flow Z-pinch

Science.gov (United States)

Hughes, M. C.; Shumlak, U.; Nelson, B. A.; Golingo, R. P.; Claveau, E. L.; Doty, S. A.; Forbes, E. G.; Kim, B.; Ross, M. P.

2016-10-01

Sheared axial flows are utilized by the ZaP Flow Z-Pinch Experiment to stabilize MHD instabilities. The pinches formed are 50 cm long with radii ranging from 0.3 to 1.0 cm. The plasma is generated in a coaxial acceleration region, similar to a Marshall gun, which provides a steady supply of plasma for approximately 100 us. The power to the plasma is partially decoupled between the acceleration and pinch assembly regions through the use of separate power supplies. Adiabatic scaling of the Bennett relation gives targets for future devices to reach high-energy density conditions or fusion reactors. The applicability of an adiabatic assumption is explored and work is done experimentally to clarify the plasma compression process, which may be more generally polytropic. The device is capable of a much larger parameter space than previous machine iterations, allowing flexibility in the initial conditions of the compression process to preserve stability. This work is supported by DoE FES and NNSA.

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

Energy Technology Data Exchange (ETDEWEB)

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

1981-03-01

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.

Investigation of intense XUV emission of nitrogen-puff Z-pinch with small energy input

International Nuclear Information System (INIS)

Raus, J.; Krejci, A.; Piffl, V.

1992-01-01

Light elements like nitrogen or carbon are suggested as optimum working media for small Z-pinches (several kJ energy input). It is shown that such elements can be ionized up to K-shell ionization stages not only in hot-spots, but also in the bulk plasma. The yield of nitrogen K-shell radiation (about 10 J/shot) is therefore substantially higher than that of the conventionally used neon. In addition to pinch physics and radiation dynamics, such radiation could be of interest for applications in the 'water window' spectral region. (author) 1 tab., 4 figs., 8 refs

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

Energy Technology Data Exchange (ETDEWEB)

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

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.

Self-Organization Observed in Numerical Simulations of a Hard-Core Diffuse Z Pinch

International Nuclear Information System (INIS)

Makhin, V; Siemon, R E; Bauer, B S; Esaulov, A; Lindemuth, I R; Ryutov, D D; Sheehey, P T; Sotnikov, V I

2005-04-01

The evolution of an unstable plasma profile into a stable profile, which we term self-organization, appears to be a robust process. Although it was not termed self organization, the same effect has been noted in past simulations with the same code. The result has been made easier to discern by the introduction of z-averaged profiles. A recent report of PIC simulations in the hard-core z-pinch configuration also shows self-organization. Figures 3 and 4 in Reference 21 show how pressure profiles in a low-β PIC simulation relax from unstable to stable. The non-linear evolution of the interchange motion has been studied under controlled initial conditions that result in exponential growth of a mode with a prescribed axial wavelength. An interesting feature of such growth is an abrupt transition from coherent to incoherent motion, after which the z-averaged pressure, current, and temperature profiles become quasi stationary. According to our understanding of MAGO experiments, the observed plasma behavior is consistent with the expectation of self-organization, but the diagnostics are not sufficiently detailed thus far to make a definite conclusion. The results of this simulations reported in this paper add motivation to planned experiments on an inverse pinch at UNR

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

International Nuclear Information System (INIS)

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

1998-01-01

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 endash Taylor instabilities. The magnetic Rayleigh endash 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 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 1998 American Institute of Physics

Soft X-ray radiation power characteristics of tungsten wire arrays on Yang accelerator

International Nuclear Information System (INIS)

Zhang Siqun; Ouyang Kai; Huang Xianbin; Dan Jiakun; Zhou Rongguo; Yang Liang

2013-01-01

A series of experiments were carried out to research the X-ray radiation characteristics of tungsten wire arrays on Yang accelerator. In those experiments, we charged the Marx generator of 60 kV, and the load current of 0.85-1.00 MA, the rise time of 75-90 ns (10%-90%). A soft X-ray scintillator powermeter which responded flatly to 50-1800 eV X-rays was used to measure the power of soft X-ray emitted from implosion plasma. In this paper, we present the measuring results of time-resolved soft X-ray radiation power, and discuss the radiation characteristics of implosion plasma by analyzing the correlations of soft X-ray radiant power and the diameter, length, wire number of the tungsten wire arrays. The optimizing wire array configuration parameters on Yang are as follows: 8 mm array diameter, 15 mm wire length, and 24 wire number. We also present the radiant power difference in radial and axial directions of the wire arrays. (authors)

Physics of the dense Z-pinch in theory and in experiment with application to fusion reactor

Energy Technology Data Exchange (ETDEWEB)

Haines, M.G. (Imperial Coll. of Science and Technology, London (UK). Blackett Lab.)

1982-01-01

A new generation of Z-pinches employing high voltage, high current pulsed lines as power sources produce dense hot plasmas with enhanced stability properties. Three methods of Z-pinch formation are currently in use: (1) cylindrical collapse and compression of a pre-ionised gas; (2) laser initiation and Joule heating of a gas embedded pinch, and (3) hollow gas puff and subsequent collapse to the axis. The first two experimental conditions are relevant for fusion. A calculation of energy balance for satisfying Lawson conditions with axial and radial energy losses and radiation loss shows that a current of approximately 10/sup 6/ A and a line density of 6 x 10/sup 18/ m/sup -1/ are required. This leads to two coincidences of physical quantities that are very favourable for controlled fusion. The first is that at this line density and under pressure balance the ratio of the ion Larmor radius to pinch is of order 1 so that a marked stabilisation of the configuration is expected. The second coincidence is that the current is only just below the Pease-Braginskii limit; this will permit the possibility or radiative collapse to attain the high density (approximately 4 x 10/sup 27/ m/sup -3/) and small radius (approximately 20 ..mu..m) required for a compact (0.1 m long) discharge.

Maximum compression of Z-pinch in a gas with high atomic number

International Nuclear Information System (INIS)

Gerusov, A.V.

1989-01-01

An ideal system of equations with shock heating is used for describing of a Z pinch in a gas with high atomic number. In this case equations do not depend from the installation parameters. The approximate simple solution of such a system is presented. Numerical calculations of equations with radiative cooling and various dissipative effects have determined the employment conditions of ideal magnetohydrodynamic equation system. 10 refs

Specific features of implosion of metallized fiber arrays

Energy Technology Data Exchange (ETDEWEB)

Mitrofanov, K. N., E-mail: mitrofan@triniti.ru; Aleksandrov, V. V.; Gritsuk, A. N.; Grabovski, E. V.; Frolov, I. N.; Laukhin, Ya. N.; Breshkov, S. S. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)

2017-02-15

Implosion of metallized fiber arrays was studied experimentally at the Angara-5-1 facility. The use of such arrays makes it possible to investigate the production and implosion dynamics of plasmas of various metals (such as tin, indium, and bismuth) that were previously unavailable for such studies. The plasma production rates m-dot (in μg/(cm{sup 2} ns)) for different metals were determined and quantitatively compared. Varying the thickness of the metal layer deposited on kapron fibers (the total linear mass of the metal coating being maintained at the level of 220 μg/cm), the current and velocity of the plasma precursor were studied as functions of the thickness of the metal coating. The strong difference in the rates of plasma production from the metal coating and kapron fibers results in the redistribution of the discharge current between the Z-pinch and the trailing fiber plasma. The outer boundary of the plasma produced from the metal coating is found to be stable against instabilities typical of the final stage of implosion of conventional wire arrays.

Study of Plasma Flow Modes in Imploding Nested Arrays

Science.gov (United States)

Mitrofanov, K. N.; Aleksandrov, V. V.; Gritsuk, A. N.; Branitsky, A. V.; Frolov, I. N.; Grabovski, E. V.; Sasorov, P. V.; Ol'khovskaya, O. G.; Zaitsev, V. I.

2018-02-01

Results from experimental studies of implosion of nested wire and fiber arrays at currents of up to 4 MA at the Angara-5-1 facility are presented. Depending on the ratio between the radii of the inner and outer arrays, different modes of the plasma flow in the space between the inner and outer arrays were implemented: the sub-Alfvénic ( V r V A ) modes and a mode with the formation of the transition shock wave (SW) region between the cascades. By varying the material of the outer array (tungsten wires or kapron fibers), it is shown that the plasma flow mode between the inner and outer arrays depends on the ratio between the plasma production rates ṁ in / ṁ out in the inner and outer arrays. The obtained experimental results are compared with the results of one-dimensional MHD simulation of the plasma flow between the arrays. Stable implosion of the inner array plasma was observed in experiments with combined nested arrays consisting of a fiber outer array and a tungsten inner array. The growth rates of magnetic Rayleigh-Taylor (MRT) instability in the inner array plasma at different numbers of fibers in the outer array and different ratios between the radii of the inner and outer arrays are compared. Suppression of MRT instability during the implosion of the inner array plasma results in the formation of a stable compact Z-pinch and generation of a soft X-ray pulse. A possible scenario of interaction between the plasmas of the inner and outer arrays is offered. The stability of the inner array plasma in the stage of final compression depends on the character of interaction of plasma jets from the outer array with the magnetic field of the inner array.

Soft X-ray images of krypton gas-puff Z-pinches

International Nuclear Information System (INIS)

Qiu Mengtong; Kuai Bin; Zeng Zhengzhong; Lu Min; Wang Kuilu; Qiu Aici; Zhang Mei; Luo Jianhui

2002-01-01

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 μg/cm in these experiments. In the diagnostic system, a four-frame x-ray framing camera and a pinhole camera were employed. A novel feature of this camera is that it can give time-resolved x-ray images with four frames and energy-resolved x-ray images with two different filters and an array of 8 pinholes integrated into one compact assemble. As a typical experimental result, an averaged radial imploding velocity of 157 km/s over 14 ns near the late phase of implosion was measured from the time-resolved x-ray images. From the time-integrated x-ray image an averaged radial convergence of 0.072 times of the original size was measured. An averaged radial expansion velocity was 130 km/s and the maximum radial convergence of 0.04 times of the original size were measured from the time-resolved x-ray images. The dominant axial wavelengths of instabilities in the plasma were between 1 and 2 mm. The change in average photons energy was observed from energy spectrum- and time-resolved x-ray images

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

Institute of Scientific and Technical Information of China (English)

邱孟通; 蒯斌; 曾正中; 吕敏; 王奎禄; 邱爱慈; 张美; 罗建辉

2002-01-01

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 μg/cm in these experiments. In the diagnostic system, a four-frame x-ray framing camera and a pinhole camera were employed. A novel feature of this camera is that it can give time-resolved x-ray images with four frames and energy-resolved x-ray images with two different filters and an array of 8 pinholes integrated into one compact assemble. As a typical experimental result, an averaged radial imploding velocity of 157 km/s over 14 ns near the late phase of implosion was measured from the time-resolved x-ray images. From the time-integrated x-ray image an averaged radial convergence of 0.072 times of the original size was measured. An averaged radial expansion velocity was 130 km/s and the maximum radial convergence of 0.04 times of the original size were measured from the time-resolved x-ray images. The dominant axial wavelengths of instabilities in the plasma were between 1 and 2 mm. The change in average photons energy was observed from energy spectrum- and time-resolved x-ray images.

New Regimes of Implosions of Larger Sized Wire Arrays With and Without Modified Central Plane at 1.5-1.7 MA Zebra

Science.gov (United States)

Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Weller, M. E.; Shrestha, I.; Shlyaptseva, V. V.; Stafford, A.; Keim, S. F.; Petkov, E. E.; Lorance, M.; Chuvatin, A. S.; Coverdale, C. A.; Jones, B.

2013-10-01

The recent experiments at 1.5-1.7 MA on Zebra at UNR with larger sized planar wires arrays (compared to the wire loads at 1 MA current) have demonstrated higher linear radiation yield and electron temperatures as well as advantages of better diagnostics access to observable plasma regions. Such multi-planar wire arrays had two outer wire planes from mid-Z material to create a global magnetic field (gmf) and mid-Z plasma flow between them. Also, they included a modified central plane with a few Al wires at the edges to influence gmf and to create Al plasma flow in the perpendicular direction. The stationary shock waves which existed over tens of ns on shadow images and the early x-ray emissions before the PCD peak on time-gated spectra were observed. The most recent experiments with similar loads but without the central wires demonstrated a very different regime of implosion with asymmetrical jets and no precursor formation. This work was supported by NNSA under DOE Cooperative Agreement DE-NA0001984 and in part by DE-FC52-06NA27616. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

The stability of the High-Density Z-Pinch

International Nuclear Information System (INIS)

Glasser, A.H.; Nebel, R.A.

1989-01-01

Fiber-initiated High Density Z-Pinches at Los Alamos, NRL, and Karlsruhe have shown anomalously good stability. Kink modes are never seen, and sausage modes are at least delayed until late in the discharge. The success of these devices in reaching fusion conditions may depend on maintaining and understanding this anomalous stability. We have developed two numerical methods to study the stability in the regime where fluid theory is valid. While our methods are applicable to all modes, we will describe them only for the m = 0 sausage mode. The appearance of sausage modes late in the discharge and the total absence of kink modes suggest that an understanding of sausage modes is more urgent, and it is also simpler. 14 refs., 8 figs

The stability of the high-density z-pinch

International Nuclear Information System (INIS)

Glasser, A.H.; Nebel, R.A.

1989-01-01

Fiber-initiated High Density Z-Pinches at Los Alamos, NRL, and Karlsruhe have shown anomalously good stability. Kink modes are never seen, and sausage modes are at least delayed until late in the discharge. The success of these devices in reaching fusion conditions may depend on maintaining and understanding this anomalous stability. We have developed two numerical methods to study the stability in the regime where fluid theory is valid. While our methods are applicable to all modes, we will describe them only for the m=0 sausage mode. The appearance of sausage modes late in the discharge and the total absence of kink modes suggest that an understanding of sausage modes is more urgent, and it is also simpler

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

International Nuclear Information System (INIS)

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

1999-01-01

Z-pinches created using the Z accelerator generate approximately220 TW, 1.7 MJ radiation pulses that heat large (approximately10 cm 3 ) hohlraums to 100-150 eV temperatures for times of order 10 nsec. We are performing experiments exploiting this intense radiation to drive shock waves for equation of state studies. The shock pressures are typically 1-10 Mbar with 10 nsec duration in 6-mm-diameter samples. In this paper we demonstrate the ability to perform optical spectroscopy measurements on shocked samples located in close proximity to the z-pinch. These experiments are particularly well suited to optical spectroscopy measurements because of the relatively large sample size and long duration. The optical emission is collected using fiber optics and recorded with a streaked spectrograph. Other diagnostics include VISAR and active shock breakout measurements of the shocked sample and a suite of diagnostics that characterize the radiation drive. Our near term goal is to use the spectral emission to obtain the temperature of the shocked material. Longer term objectives include the examination of deviations of the spectrum from blackbody, line emission from lower density regions, determination of kinetic processes in molecular systems, evaluation of phase transitions such as the onset of metalization in transparent materials, and characterization of the plasma formed when the shock exits the rear surface. An initial set of data illustrating both the potential and the challenge of these measurements is described

Optimization of gas target production for Z-pinch implosions

International Nuclear Information System (INIS)

Semushin, S.; Etlicher, B.; Rouille, C.

1996-01-01

Optimization of shell parameters for further imploding in a Z-pinch has been done. The nozzle shape was selected with the help of two-dimensional gas dynamics computer simulation. The influence of the electrode configuration was taken into account during the optimization. Two types of nozzle are presented. The advanced design with three gaseous shells may use different gases. The other design is based on aluminium vapor jet. The designs were tested by interferometry. The resulting mass distributions are analyzed by a real experiment and by means of 2D MHD computer simulations. The new nozzles provide smaller zippering, higher radiation power and better reproducible results. (author). 4 figs., 4 refs

Neutron yield in experiments with Z-pinches in frozen deuterium filaments

International Nuclear Information System (INIS)

Meierovich, B.E.; Sukhorukov, S.T.

1991-01-01

Experiments on the properties of the neutron yield and stability of dense Z-pinches in frozen deuterium filaments two years ago have still not received a proper explanation. A discharge in a dielectric deuterium filament differs qualitatively in its behavior from one in a metal conductor. The authors assert attempts to interpret the experiment have not taken this fact properly into account. The enhanced stability and substantial neutron yield do not follow from the classical picture of a Bennett equilibrium in the current channel. The most important experimental characteristic of a discharge in frozen deuterium is the dependence of the neutron yield on the current strength at a given stage. The spread in the experimental points is quite large so one naturally prefers t describe the experimental data by means of a physically simple model and not go to a full-scale simulation of all the processes. When the deuterium is fully ionized the electron drift velocity is smaller than the thermal velocity, enabling calculation of the neutron yield by means of a self-similar model of the Z-pinch compression which treats electron degeneracy. To find the neutron yield it suffices to consider only the first half-period of the self-similar oscillations including the state of maximum compression. The subsequent evolution of the current channel, which is associated with radial expansion, does not contribute significantly to the neutron yield

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

Directory of Open Access Journals (Sweden)

D. V. Rose

2010-01-01

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

Measurement of soft X-ray power from high-power Z-pinch plasma

International Nuclear Information System (INIS)

Wang Wensheng; Qiu Aici; Sun Fengrong; Luo Jianhui; Zhou Haisheng; He Duohui

2003-01-01

A Ni-film bolometer driven by the pulsed constant-voltage supply was developed for measuring soft X-ray energy under 1 keV generated from the Qiang-Guang-I, while the measuring system of the soft X-ray power was established with an X-ray diode detector. Results of the soft X-ray energy and power measurements were obtained at the experiment of Kr gas-puff high-power Z-pinch plasma

High Energy Electron Detectors on Sphinx

Science.gov (United States)

Thompson, J. R.; Porte, A.; Zucchini, F.; Calamy, H.; Auriel, G.; Coleman, P. L.; Bayol, F.; Lalle, B.; Krishnan, M.; Wilson, K.

2008-11-01

Z-pinch plasma radiation sources are used to dose test objects with K-shell (˜1-4keV) x-rays. The implosion physics can produce high energy electrons (> 50keV), which could distort interpretation of the soft x-ray effects. We describe the design and implementation of a diagnostic suite to characterize the electron environment of Al wire and Ar gas puff z-pinches on Sphinx. The design used ITS calculations to model detector response to both soft x-rays and electrons and help set upper bounds to the spurious electron flux. Strategies to discriminate between the known soft x-ray emission and the suspected electron flux will be discussed. H.Calamy et al, ``Use of microsecond current prepulse for dramatic improvements of wire array Z-pinch implosion,'' Phys Plasmas 15, 012701 (2008) J.A.Halbleib et al, ``ITS: the integrated TIGER series of electron/photon transport codes-Version 3.0,'' IEEE Trans on Nuclear Sci, 39, 1025 (1992)

Signals analysis of fluxgate array for wire rope defaults

International Nuclear Information System (INIS)

Gu Wei; Chu Jianxin

2005-01-01

In order to detecting the magnetic leakage fields of the wire rope defaults, a transducer made up of the fluxgate array is designed, and a series of the characteristic values of wire rope defaults signals are defined. By processing the characteristic signals, the LF or LMA of wire rope are distinguished, and the default extent is estimated. The experiment results of the new method for detecting the wire rope faults are introduced

Effect of Pressure Anisotropy on the m = 1 Small Wavelength Modes in Z-Pinches

Science.gov (United States)

Faghihi, M.

1987-05-01

A generalization of Freidberg's perpendicular MHD model is used to investigate the effect of pressure anisotropy on the small wavelength internal kink (m = 1) mode instability in a Z-Pinch. A normal mode analysis of perturbed motion of an incompressible, collisionless and cylindrical plasma is performed. The stability criterion is (rΣB2)' = 0.

Z-pinch generated X-rays in static-wall-hohlraum geometry demonstrate potential for indirect-drive ICF studies

International Nuclear Information System (INIS)

Sanford, T.W.L.; Olson, R.E.; Mock, R.C.; Chandler, G.A.; Hebron, D.E.; 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.

2000-01-01

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 [Fusion Technol. 35, 260 (1999)]. A 2-μm-thick walled Cu cylindrical target of 8-mm diameter filled with 10 mg/cm 3 CH, for example, produces foot-pulse conditions of ∼85 eV for a duration of ∼10 ns, while a solid cylindrical target of 5-mm diameter and 14-mg/cm 3 CH generates first-step-pulse conditions of ∼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 ∼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) 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 10 -3 g/cm 3 or less. (authors)

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

Energy Technology Data Exchange (ETDEWEB)

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

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.

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

International Nuclear Information System (INIS)

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.

1999-01-01

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-microm-thick walled Cu cylindrical target of 8-mm diameter filled with 10 mg/cm 3 CH, for example, produces foot-pulse conditions of minus85 eV for a duration of approximately 10 ns, while a solid cylindrical target of 5-mm diameter and 14-mg/cm 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) 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

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

Energy Technology Data Exchange (ETDEWEB)

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

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.

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

International Nuclear Information System (INIS)

Sanford, Thomas W.L.; Bowers, Richard; Chandler, Gordon A.; Hebron, David E.; Leeper, Ramon J.; Matulska, W Alter; Mock, Raymond Cecil; Nash, Thomas J.; Olson, Craig L.; Peterson, Bob; Peterson, Darrell; Ruggles, Laurence E.; Simpson, Walter W.; Struve, Kenneth W.; Vesey, Roger A.

1999-01-01

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-microm-thick walled Cu cylindrical target of 8-mm diameter filled with 10 mg/cm 3 CH, for example, produces foot-pulse conditions of ∼85 eV for a duration of ∼10 ns, while a solid cylindrical target of 5-mm diameter and 14-mg/cm 3 CH generates first-step-pulse conditions of ∼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 ∼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) 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

Modelling high density phenomena in hydrogen fibre Z-pinches

International Nuclear Information System (INIS)

Chittenden, J.P.

1990-09-01

The application of hydrogen fibre Z-pinches to the study of the radiative collapse phenomenon is studied computationally. Two areas of difficulty, the formation of a fully ionized pinch from a cryogenic fibre and the processes leading to collapse termination, are addressed in detail. A zero-D model based on the energy equation highlights the importance of particle end losses and changes in the Coulomb logarithm upon collapse initiation and termination. A 1-D Lagrangian resistive MHD code shows the importance of the changing radial profile shapes, particularly in delaying collapse termination. A 1-D, three fluid MHD code is developed to model the ionization of the fibre by thermal conduction from a high temperature surface corona to the cold core. Rate equations for collisional ionization, 3-body recombination and equilibration are solved in tandem with fluid equations for the electrons, ions and neutrals. Continuum lowering is found to assist ionization at the corona-core interface. The high density plasma phenomena responsible for radiative collapse termination are identified as the self-trapping of radiation and free electron degeneracy. A radiation transport model and computational analogues for the effects of degeneracy upon the equation of state, transport coefficients and opacity are implemented in the 1-D, single fluid model. As opacity increases the emergent spectrum is observed to become increasingly Planckian and a fall off in radiative cooling at small radii and low frequencies occurs giving rise to collapse termination. Electron degeneracy terminates radiative collapse by supplementing the radial pressure gradient until the electromagnetic pinch force is balanced. Collapse termination is found to be a hybrid process of opacity and degeneracy effects across a wide range of line densities with opacity dominant at large line densities but with electron degeneracy becoming increasingly important at lower line densities. (author)

GIT 16: megajoule pulsed generator with plasma opening switch for Z-pinch loads

International Nuclear Information System (INIS)

Bugaev, S.P.; Volkov, A.M.; Kim, A.A.

1997-01-01

Megajoule complex GIT 16 reserved for perfecting technology of forming powerful impulse with the help of intermediate inductive storage and break contact in the form of plasma opening switches and for investigating of irradiating loading of Z-pinch type is presented. The characteristics of isolated complex elements are given and basic results characterizing microsecond plasma opening switches at the current level of same M A are described

X-ray heating of laboratory photoionized plasmas at Z

Science.gov (United States)

Mancini, R.; Lockard, T.; Mayes, D.; Loisel, G.; Bailey, J.; Rochau, G.; Abdallah, J.; Fontes, C.; Liedahl, D.; Golovkin, I.

2017-10-01

In separate experiments performed at the Z facility of Sandia National Laboratories two different samples were employed to produce and characterize photoionized plasmas. One was a gas cell filled with neon, and the other was a thin silicon layer coated with plastic. Both samples were driven by the broadband x-ray flux produced at the collapse of a wire array z-pinch implosion. Transmission spectroscopy of a narrowband portion of the x-ray flux was used to diagnose the charge state distribution, and the electron temperature was extracted from a Li-like ion level population ratio. To interpret the temperature measurement, we performed Boltzmann kinetics and radiation-hydrodynamic simulations. We found that non-equilibrium atomic physics and the coupling of the radiation flux to the level population kinetics play a critical role in modeling the x-ray heating of photoionized plasmas. In spite of being driven by similar x-ray drives, differences of ionization and charged state distributions in the neon and silicon plasmas are reflected in the plasma heating and observed temperatures. DOE OFES Grant DE-SC0014451 and ZFSP.

Neutron energy distribution function reconstructed from time-of-flight signals in deuterium gas-puff Z-pinch

Czech Academy of Sciences Publication Activity Database

Klír, D.; Kravárik, J.; Kubeš, J.; Rezac, K.; Ananev, S.S.; Bakshaev, Y. L.; Blinov, P. I.; Chernenko, A. S.; Kazakov, E.D.; Korolev, V. D.; Ustroev, G. I.; Juha, Libor; Krása, Josef; Velyhan, Andriy

2009-01-01

Roč. 37, č. 3 (2009), s. 425-432 ISSN 0093-3813 R&D Projects: GA MŠk(CZ) LC528; GA MŠk LA08024 Grant - others:IAEA(XE) RC 14817 Institutional research plan: CEZ:AV0Z10100523 Keywords : deuterium * fusion reaction * gas puff * Monte Carlo reconstruction * neutron energy spectra * neutron s * Z-pinch Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.043, year: 2009

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

International Nuclear Information System (INIS)

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

2012-01-01

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.

The mitigation effect of sheared axial flow on the rayleigh-taylor instability in Z-pinch plasma

International Nuclear Information System (INIS)

Zhang Yang

2005-01-01

A magnetohydrodynamic formulation is derived to investigate the mitigation effects of the sheared axial flow on the Rayleigh-Taylor (RT) instability in Z-pinch plasma. The dispersion relation of the compressible model is given. The mitigation effects of sheared axial flow on the Rayleigh-Taylor instability of Z-pinch plasma in the compressible and incompressible models are compared respectively, and the effect of compressible on the instability of system with sheared axial flow is discussed. It is found that, compressibility effects can stabilize the Rayleigh-Taylor/Kelvin-Helmholtz (RT/KH) instability, and this allows the sheared axial flow mitigate the RT instability far more effectively. The authors also find that, at the early stage of the implosion, if the temperature of the plasma is not very high, the compressible model is much more suitable to describing the state of system than the incompressible one. (author)

ANTHEM simulation of the early time magnetic field penetration of the plasma surrounding a high density Z-pinch

International Nuclear Information System (INIS)

Mason, R.J.

1989-01-01

The early time penetration of magnetic field into the low density coronal plasma of a Z-pinch fiber is studied with the implicit plasma simulation code ANTHEM. Calculations show the emission of electrons from the cathode, pinching of the electron flow, magnetic insulation of the electrons near the anode, and low density ion blow off. PIC-particle ion calculations show a late time clumping of the ion density not seen with a fluid ion treatment. 4 refs., 4 figs

A moving finite element model of the high density z-pinch

International Nuclear Information System (INIS)

Glasser, A.H.

1989-01-01

This paper presents the results of computations of the behavior of the fiber-initiated high density Z-pinch (HDZP). It purpose is twofold. One is to study the behavior of the physical system itself as an interesting controlled fusion experiment. The main result of this study is a demonstration of the relaxation of the full inertial behavior of the pinch to simplified self-similar behavior in which the forces on the system are in near balance. The moving free boundary and violent initial behavior of this configuration require carful treatment. This leads to the other purpose of the work, to use this realistic physical system as a test-bed for a general-purpose 1-dimensional code based on moving finite elements. A key step in accomplishing this goal has been the recognition that numerical stability of the discretized equations has required the use of nonconservative quantities as the fundamental dependent variables to be discretized. The main result of this work is a code which is capable of treating a very general class of nonlinear, time-dependent fluid equations. copyright 1989 Academic Press, Inc

Development of Z-pinch optical guiding for laser-plasma accelerator

International Nuclear Information System (INIS)

Hosokai, Tomonao; Kando, Masaki; Dewa, Hideki; Kotaki, Hideyuki; Kondo, Shuji; Kanazawa, Shuhei; Nakajima, Kazuhisa; Horioka, Kazuhiko

2000-01-01

We have proposed optical guiding of intense laser pulse by fast Z-pinch for channel guided laser wakefield acceleration (LWFA). It has been developed based on capillary discharge-pumped X-ray laser technique. The discharge driven by current of 4.8 kA with a rise time of 15 ns through preionized helium gas could produce an uniform guiding channel with good reproducibility. With this new guiding method an intense Ti-Sapphire laser pulse (λ=790 nm, 2.2 TW, 90 fs, 1 x 10 17 W/cm 2 ) was transported through the channel over a distance of 2 cm corresponding to 12.5 times the Rayleigh length. (author)

Measurements of VUV lines on dense Z-pinch plasma

International Nuclear Information System (INIS)

Bertschinger, G.

1980-01-01

The transition n = 1 to n = 2 has the most simple structure of all hydrogen transitions and the corresponding spectralline Ly-α is therefore very appropriate to reveal discrepancies between theory and experiment. In this work mainly the Ly-α spectral line of neutral hydrogen has been studied. The electron density of the Z-pinch amounts to 1.5 x 10 24 m -3 with an electron temperature of about 1.2 x 10 5 K. In this parameter range the plasma can still be studied with spectroscopic methods in the visible spectral region. Based on a space and time resolved measurement of the continuous emission spectra the plasma parameters can be determined independent of line broadening. (orig./HT) [de

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

International Nuclear Information System (INIS)

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

1994-01-01

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 3

Effect of gyroviscosity on the small axial wavelength internal kink instability in the Z-pinch

International Nuclear Information System (INIS)

Scheffel, J.; Faghihi, M.

1987-03-01

The effect of ion gyroviscosity on the stability of m=1 small axial wavelength kinks in a z-pinch with purely poloidal magnetic field is investigated by normal mode methods. We use the Incompressible FLR MHD model; a collisionless fluid model introduced to include Finite Larmor Radius effects. For vanishing Larmor radius, a stability criterion which coincides with that of ideal MHD is found; the Kadomtsev criterion 2rdp/dr+m/sp2/B/sp2///my//sb0/> or = 0. This criterion predicts instability unless the current density becomes singular at the centre of the pinch. When the Larmor radius terms of the ion pressure tensor are included, we find that marginally unstable (ideal) modes are stabilized. (authors)

Characteristics of x-ray radiation from a gas-puff z-pinch plasma

International Nuclear Information System (INIS)

Akiyama, N.; Takasugi, K.

2002-01-01

Characteristics of x-ray radiation from Ar gas-puff z-pinch plasma have been investigated by changing delay time of discharge from gas puffing. Intense cloud structure of x-ray image was observed at small delay time region, but the total x-ray signal was not so intense. The x-ray signal increased with increasing the delay time, and hot spots of x-ray image also became intense. Electron temperature was evaluated from x-ray spectroscopic data, and no significant difference in temperature was observed. (author)

Three-fluid MHD-model of a current shell in Z-pinch

International Nuclear Information System (INIS)

Bazdenkov, S.V.; Vikhrev, V.V.

1975-01-01

Formation and motion of the current shell in a power pulsed discharge (Z-pinch) are discussed. One-dimmensional nonstationary problem about a discharge in deuterium is solved in the three-liquid magnetohydrodynamic approximation with regard for gas ionization and motion of neutral atoms. It is shown that after the shell removal there remains a large quantity of an ionized gas near an isolating chamber wall. The quantity is sufficient that a secondary breakdown may take place in the ionized gas. The moving current shell has a double structure, i.e. a current ''piston'' and a current layer in the shock wave front

Filamentation and networking of electric currents in dense Z-pinch plasmas

International Nuclear Information System (INIS)

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

2001-01-01

The results of high-resolution processing using the multilevel dynamical contrasting method of earlier experiments on linear Z-pinches are presented which illustrate formation of a dynamical percolating network woven by long-living filaments of electric current. A qualitative approach is outlined which treats long-living filaments as a classical plasma formation governed by the long-range quantum bonds provided, at the microscopical level, by nanotubes of elements of optimal valence. The self-similarity of structuring in laboratory and cosmic plasmas is shown, and examples are found of nanotube-like and/or fullerene-like structures of cosmic length scales. (author)

Filamentation and networking of electric currents in dense Z-pinch plasmas

International Nuclear Information System (INIS)

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

1999-01-01

The results of high-resolution processing using the multilevel dynamical contrasting method of earlier experiments on linear Z-pinches are presented which illustrate formation of a dynamical percolating network woven by long-living filaments of electric current. A qualitative approach is outlined which treats long-living filaments as a classical plasma formation governed by the long-range quantum bonds provided, at the micro-scopical level, by nanotubes of elements of optimal valence. The self-similarity of structuring in laboratory and cosmic plasmas is shown, and examples are found of nanotube-like and/or fullerene-like structures of cosmic length scales. (author)

Theory of neutron spectra from d-d-reactions in the linear z-pinch and the plasma focus

International Nuclear Information System (INIS)

Deutsch, R.; Kaeppeler, H.J.

1982-05-01

Because of a finite gyroradius effect, the equilibrium probability density function of the ions in the azimuthal magnetic field of a linear z-pinch becomes anisotropic. This density function was derived by solving the Vlasov equation and used to determine the neutron spectra produced in the deuterium plasma of a z-pinch. The neutron spectra were calculated for two models, differing in the energy distribution of the fast ions. A background plasma with 'slow' ions was also considered. The interactions of the fast ions with the slow ions and 'beam-beam' interactions between fast ions were considered. Typical spectra for arbitrary directions to the cylindrical axis are given. The anisotropy factors were calculated. Considering the influence of the azimuthal magnetic field on the equilibrium density function of the deuterons, the well known particularities of the neutron spectra are obtained without any of the contradictions typical of the traditional models. (orig.)

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

International Nuclear Information System (INIS)

DERZON, MARK S.

2000-01-01

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

Upper pinch radius limit in EXTRAP

International Nuclear Information System (INIS)

Lehnert, B.

1989-12-01

A simple static equilibrium model of the Z-pinch is considered where a hot plasma core is surrounded by a cold-mantle (gas blanket). The pinch radius, defined as the radial extension of the fully ionized plasma core, is uniquely determined by the plasma particle. momentum and heat balance equations. In Extrap configurations an octupole field is introduced which imposes a magnetic separatrix on Z-pinch geometry. This makes the conditions for Extrap equilibrium 'overdetermined' when the characteristic pinch radium given by the plasma parameters tends to exceed the characteristic radius of the magnetic separatrix. In this case no conventional pinch equilibrium can exist, and part of the current which is forced into the plasma discharge by external sources must be channelled outside of the separatrix, i.e. into the surrounding support structure of the Extrap conductors and the vessel walls. A possibly existing bootstrap current in the plasma boundary layer is further expected to be 'scraped off' in this case. The present paper gives some illustrations of the marginal case of this upper pinch radius limit, in a state where the pinch current is antiparallel to the external rod currents which generate the octupole field. (authors)

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

International Nuclear Information System (INIS)

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

1999-01-01

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

Hybrid simulations of current-carrying instabilities in Z-pinch plasmas with sheared axial flow

International Nuclear Information System (INIS)

Sotnikov, Vladimir I.; Makhin, Volodymyr; Bauer, Bruno S.; Hellinger, Petr; Travnicek, Pavel; Fiala, Vladimir; Leboeuf, Jean-Noel

2002-01-01

The development of instabilities in z-pinch plasmas has been studied with three-dimensional (3D) hybrid simulations. Plasma equilibria without and with sheared axial flow have been considered. Results from the linear phase of the hybrid simulations compare well with linear Hall magnetohydrodynamics (MHD) calculations for sausage modes. The hybrid simulations show that sheared axial flow has a stabilizing effect on the development of both sausage and kink modes

The physics of the high density Z-pinch

International Nuclear Information System (INIS)

Glasser, A.H.; Hammel, J.E.; Lewis, H.R.

1988-01-01

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

The dense Z-pinch project at Imperial College

International Nuclear Information System (INIS)

Haines, M.G.; Dangor, A.E.; Choi, P.; Mitchell, I.; Coppins, M.; Chittenden, J.P.; Culverwell, I.D.; Bayley, J.; Power, A.

1990-01-01

The Science and Engineering Research Council has recently awarded a grant of over L0.8M to build a large new Z-pinch driven by a high voltage pulsed power generator. The generator will be 4 Marx generators in parallel which together will supply up to 2MA at 2.85MV for 200ns. When the load is a frozen fibre of hydrogen, it is predicted that radiative collapse above the Pease-Bragniskii current will lead to ultra high density (10 4 x solid density) at 10 to 20 KeV temperature. Deuterium-tritium fibres would lead to conditions close to thermonuclear breakeven. Scaled experiments at lower currents reveal anomalous stability due to finite Larmor radius effects in one case or to a low magnetic Lundquist number in another. The theory of stability has been extensively studied in many regimes, and it is found the ideal MHD occupies a small fraction of parameter space. (author) 7 refs., 3 figs

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

Energy Technology Data Exchange (ETDEWEB)

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

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.

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

International Nuclear Information System (INIS)

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.

1999-01-01

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

An analytic model of radiative collapse of a Z-pinch

International Nuclear Information System (INIS)

Haines, M.G.

1989-01-01

There is a critical current I PB of about 1 MA (the Pease-Braginskii current) at which Ohmic heating and bremsstrahlung losses balance in a Z-pinch under pressure equilibrium. An analytic zero-dimensional model shows the process of radiative collapse when the prescribed current exceeds the critical current. In particular for a linearly rising current radiative collapse is complete when the current is 3 I PB . However, in practice the voltage limitation imposed by an external circuit prevents such a total collapse, and by including this in the model a maximum density (10 30 -10 32 m -3 )can occur followed by an expansion and damped oscillation about an equilibrium at which the current equals the Pease-Braginskii current. In the absence of alpha-particle pressure the maximum density is limited by the resistance of the narrow column, the large voltage across which (∼10 8 V) is balanced essentially bu a large negative LI; it occurs when the current is I PB [(δ-1)/(δ-2)] 1/2 where δ=7/3+4/3 In(R/a), where a is the pinch radius and R is the radius of the current return. The minimum current following maximum density is shown to be greater than I PB /√2. Degeneracy effects can be included in the model. (author) 5 refs., 1 fig

An analytic model of radiative collapse of a Z-pinch

International Nuclear Information System (INIS)

Haines, M.G.

1989-01-01

There is a critical current I PB of about 1 MA (the Pease-Braginskii current) at which Ohmic heating and Bremsstrahlung losses balance in a Z-pinch under pressure equilibrium. An analytic zero-dimensional model shows the process of radiative collapse when the prescribed current exceeds the critical current. In particular for a linearly rising current radiative collapse is complete when the current is √3 I PB . However in practice the voltage limitation imposed by an external circuit prevents such a total collapse, and by including this in the model a maximum density (∼ 10 30 -10 32 m -3 ) can occur followed by an expansion and damped oscillation about an equilibrium at which the current equals the Pease-Braginskii current. In the absence of alpha-particle pressure the maximum density is limited by the resistance of the narrow column, the large voltage across which (∼ 10 8 V) is balanced essentially by a large negative LI radical; it occurs when the current is I PB [(δ-1)/(δ-2)] 1/2 where δ = 7/3+4/3 1n (R w /a), where a is the pinch radius and R w is the radius of the current return. The minimum current following maximum density is shown to be greater than I PB /√2. Degeneracy effects can be included in the model. (author)

Departures from thermal equilibrium in a dense Z-pinch plasma

International Nuclear Information System (INIS)

Neufeld, C.R.

1979-01-01

This paper presents on analysis of several features of the emission spectrum obtained from a dense hydrogen Z-pinch plasma. The spectrum is characterized by an extremely broad H/sub β/ line and by the absence of an emission line at the H/sub b/ wavelength. Comparison with theory shows that the spectrum is inconsistent with the assumption of a thermal or collision-dominated plasma. The assumption of a substantial overpopulation of the atomic-hydrogen excited levels, ascribed to a rising degree of plasma ionization, provides a satisfactory description of the observed spectrum. This result illustrates the difficulty of establishing valid equilibrium criteria for transient plasmas, even in the case of plasma densities as high as 10 19 cm -3

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

International Nuclear Information System (INIS)

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

1996-08-01

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

A solvable self-similar model of the sausage instability in a resistive Z pinch

International Nuclear Information System (INIS)

Lampe, M.

1991-01-01

A solvable model is developed for the linearized sausage mode within the context of resistive magnetohydrodynamics. The model is based on the assumption that the fluid motion of the plasma is self-similar, as well as several assumptions pertinent to the limit of wavelength long compared to the pinch radius. The perturbations to the magnetic field are not assumed to be self-similar, but rather are calculated. Effects arising from time dependences of the z-independent perturbed state, e.g., current rising as t α , Ohmic heating, and time variation of the pinch radius, are included in the analysis. The formalism appears to provide a good representation of ''global'' modes that involve coherent sausage distortion of the entire cross section of the pinch, but excludes modes that are localized radially, and higher radial eigenmodes. For this and other reasons, it is expected that the model underestimates the maximum instability growth rates, but is reasonable for global sausage modes. The net effect of resistivity and time variation of the unperturbed state is to decrease the growth rate if α approx-lt 1, but never by more than a factor of about 2. The effect is to increase the growth rate if α approx-gt 1

Stability properties of a toroidal z-pinch in an external magnetic multipole field

International Nuclear Information System (INIS)

Eriksson, H.G.

1987-01-01

MHD stability of m=1, axisymmetric, external modes of a toroidal z-pinch immersed in an external multipole field (Extrap configuration) is studied. The description includes the effects of a weak toroidicity, a non-circular plasma cross-section and the influence of induced currents in the external conductors. It is found that the non-circularity of the plasma cross-section always has a destabilizing effect but that the m=1 mode can be stabilized by the external feedback if the non-circularity is small. (author)

Simulation of the dynamics of sausage development in a z pinch with a high rate of thermonuclear heat production

International Nuclear Information System (INIS)

Vikhrev, V.V.; Rozanova, G.A.

1993-01-01

The development of the sausage instability in a z pinch is accompanied by the formulation of a high-temperature plasma. This high-temperature region initiates a wave of thermonuclear burning propagating along the pinch. A numerical solution of the MHD equations has been carried out, taking into account plasma energy losses through radiation and thermonuclear heating. Results of calculations on the growth of the sausage instability are presented for ρr = 0.23 g/cm 2 . It is accompanied by the development of a stable wave of thermonuclear burning. 12 refs., 4 figs

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

International Nuclear Information System (INIS)

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

2012-01-01

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.

Diagnostics on Z (invited)

International Nuclear Information System (INIS)

Nash, T. J.; Derzon, M. S.; Chandler, G. A.; Fehl, D. L.; Leeper, R. J.; Porter, J. L.; Spielman, R. B.; Ruiz, C.; Cooper, G.; McGurn, J.

2001-01-01

The 100 ns, 20 MA pinch-driver Z is surrounded by an extensive set of diagnostics. There are nine radial lines of sight set at 12 o above horizontal and each of these may be equipped with up to five diagnostic ports. Instruments routinely fielded viewing the pinch from the side with these ports include x-ray diode arrays, photoconducting detector arrays, bolometers, transmission grating spectrometers, time-resolved x-ray pinhole cameras, x-ray crystal spectrometers, calorimeters, silicon photodiodes, and neutron detectors. A diagnostic package fielded on axis for viewing internal pinch radiation consists of nine lines of sight. This package accommodates virtually the same diagnostics as the radial ports. Other diagnostics not fielded on the axial or radial ports include current B-dot monitors, filtered x-ray scintillators coupled by fiber optics to streak cameras, streaked visible spectroscopy, velocity interferometric system for any reflector, bremsstrahlung cameras, and active shock breakout measurement of hohlraum temperature. The data acquisition system is capable of recording up to 500 channels and the data from each shot is available on the Internet. A major new diagnostic presently under construction is the BEAMLET backlighter. We will briefly describe each of these diagnostics and present some of the highest-quality data from them

Plasma dynamics studies on the Los Alamos Solid Fiber Z-Pinch

International Nuclear Information System (INIS)

Riley, R.A.; Scudder, D.W.; Shlachter, J.S.

1993-01-01

The Los Alamos High Density Z Pinch-II (HDZP-II) experiments is being used to study the dynamics of z-pinch plasmas generated from thin solid fibers of deuterated polyethylene (CD 2 ). A model has been developed which incorporates anomalous heating due to instability-generated turbulence. HDZP-II uses a pulsed-power generator that delivers a current of up to 1 MA with a 100 ns rise-time through an inductive load. The surface of the solid fiber, with a 5-cm length and 3-50μm radius, immediately ionizes and rapidly expands in radius. As the plasma is heated, more and more of the fiber is ablated until the entire fiber is ionized. The fully ionized fiber continues to expand radially. Diagnostics include a multi-frame shadowgraph, a three channel X-ray crystal reflection monochromometer, a single frame point-diffraction interferometer, neutron detectors, and generator monitors. The shadowgraph provides the plasma shape in seven frames taken at 10-ns intervals. This has shown very strong m=0 instability at the onset of current, even for small pre-pulse currents. The interferometer provides the plasma line density and, assuming cylindrical symmetry, the electron density. This is used to open-quotes calibrateclose quotes how much of the plasma is contained in the shape given by the shadowgraphs. The author have chosen a small enough aperture to have most of the plasma in the shadowgraph. The X-ray monochromometer provides the electron temperature as a function of time. The temperature generally rises to 90 eV at 40 ns into the current and remains very flat until near the end of the current ramp. The results from these diagnostics and their bearing on anomalous turbulent heating will be presented

X-Pinch soft x-ray source for microlithography

International Nuclear Information System (INIS)

Glidden, S.C.; Hammer, D.A.; Kalantar, D.H.; Qi, N.

1993-01-01

The x-pinch soft x-ray source is described for application in submicron resolution lithography. Experiments have been performed to characterize the radiation emitted from magnesium wire x-pinch plasmas using an 80 ns, ≤500 kA pulse. Yields of 14.2 J averaged over three independent calibrated diagnostics at 445 kA have been measured in magnesium K-shell radiation (predominantly 8.4 angstrom to 9.4 angstrom or 1.5 keV to 1.3 keV) from a submillimeter source, with as little as 5-10% of the yield below the 6.74 angstrom silicon absorption edge. A new ≤700 kA, 100 ns pulser being used for x-pinch physics experiments is described. The design of a 40 pulse per second pulsed power system and wire loading mechanism for exposing a resist in 1 second at a distance 40 cm is presented

Experimental astrophysics with high power lasers and Z pinches

Energy Technology Data Exchange (ETDEWEB)

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

2004-12-10

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.

Dense X-pinch plasmas for x-ray microlithography

International Nuclear Information System (INIS)

Kalantar, D.H.; Hammer, D.A.; Qi, N.; Mittal, K.C.

1990-01-01

The authors report experimental results from a study of the radiation emission from aluminum and magnesium x-pinch experiments. The single cross x-pinch, driven by the 0.5 TW, 40ns pulse width Lion accelerator, consists of 2-8 fine wires stretched between the output electrodes of Lion so as to touch at a single point. The wires were twisted up to 360 degrees at the crossing point. The number and size of Al and Mg wires were varied in order to optimize the K-shell line radiation. Diagnostics used for the experiments included pinhole photography, streak imaging, filtered photoconducting diodes and x-ray crystal spectroscopy. The source size and distribution are determined through x-ray pinhole photographs. The radiation energy spectrum is determined by x-ray spectroscopy and attenuation through filters. Energy intensities were obtained from the filtered photoconducting diodes

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

International Nuclear Information System (INIS)

Nielsen, P.D.

1981-06-01

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

A heuristic model for the nonlinear Rayleigh--Taylor instability in fast Z pinches

International Nuclear Information System (INIS)

Hussey, T.W.; Roderick, N.F.; Shumlak, U.; Spielman, R.B.; Deeney, C.

1995-01-01

A simple, heuristic model for the early nonlinear phase of the Rayleigh--Taylor instability (RTI) in thin-cylindrical-shell Z-pinch implosions has been developed. This model is based on the fact that, as the field--plasma interface is deformed, there is a component of the applied force that acts to move mass from the low mass per unit area bubble region into the higher mass per unit area spike region. The resulting reduced mass per unit area of the bubble causes it to be preferentially accelerated ahead of the spike. The pinch begins to radiate as the bubble mass first reaches the axis, and it continues to radiate while the mass that is entrained within the spikes and within unperturbed parts of the shell also arrives on axis. This model relates the time at which the bubble arrives on axis to an initial wavelength and amplitude of a single mode of the RTI. Then, by comparing this to the time at which the unperturbed mass reaches the axis, one estimates pinch thermalization time, a quantity that is determined experimentally. Experimental data, together with analytic models, have been used to choose appropriate initial wavelength and amplitude both for foils and for certain gas puff implosions. By noting that thermalization time is a weak function of these parameters, it is argued that one may use the same values for an extrapolative study of qualitatively similar implosions