Download or read book Z pinch Diagnostics Plasma and Liner Instabilities and New X ray Techniques written by and published by . This book was released on 1996 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pulse power experiments of the last several decades have contributed greatly to the understanding of high temperature and high density plasmas and, more recently, to the study of hydrodynamic effects in thick imploding cylinders. Common to all these experiments is the application of a large current pulse to a cylindrically symmetric load, with the resulting Lorenz force compressing the load to produce hydrodynamic motion and/or high temperature, high density plasma. In Los Alamos, Pulsed power experiments are carried out at two facilities. Experiments at low current (from several million to ten million Amperes) are conducted on the Pegasus II capacitor bank. Experiments with higher currents (10's to 100's MA range) are performed in Ancho Canyon with the explosively driven Procyon and MAGO magnetic flux compression generator systems. In this paper, the authors present a survey of diagnostic capabilities and results from several sets of experiments. First, they discuss the initiation and growth of instabilities in plasmas generated from the implosion of hollow z-pinches in the pegasus and Procyon experiments. Next they discuss spectroscopic data from the plasmas produced by the MAGO system. They also show time resolved imaging data from thick ((approximately) .4 mm) liner implosions. Finally, the authors discuss improvements to x-ray and visible light imaging and spectrographic diagnostic techniques. The emphasis of this paper is not so much a detailed discussion of the experiments, but a presentation of imaging and spectroscopic results and the implications of these observations to the experiments.

Download or read book Study of the Internal Structure Instabilities and Magnetic Fields in the Dense Z pinch written by and published by . This book was released on 2016 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 æm. 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 [mu]m 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 plasma will be studied to estimate its contribution to the Doppler broadening of x-ray lines. Development of "necks" and "hot spots" will be studied with high-resolution UV diagnostics, an x-ray streak camera, and x-ray spectroscopy. Laser initiation of hot spots in Z pinches will be tested. A Faraday rotation diagnostic at 266 nm will be applied to 1-10 MG magnetic fields. For magnetic fields B20 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 1020-1021cm-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 of hot spots. A further upgrade to energy of 250-J is suggested for laser-Z-pinch interaction. A picosecond regime will be used for optical gating. A 10-TW Tomcat laser at NTF is available for the high energy UV laser probing of the Z-pinch. Two graduate students will develop new optical and x-ray diagnostics, carry out experiments, and process experimental data. Other students will be involved in the design and fabrication of loads, supporting regular optical and x-ray diagnostics, and data processing. The new plasma diagnostics may be applied to HEDP experiments at NTF and other multi-MA generators. The feasibility of the research plan is based on the experience of the scientific team in Z-pinch plasma physics, laser physics, development of new plasma diagnostics, and the experimental capability of NTF. The experimental group of Dr. V.V. Ivanov (UNR) collaborates with a group for Z pinch MHD modeling of Dr. J.P. Chittenden (Imperial College, London), and theoretical group of Dr. D.D. Ryutov (LLNL). The suggested research ideas are supported by preli ...

Download or read book Dense Z Pinches written by Jack Davis and published by American Institute of Physics. This book was released on 2002-12-13 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: This conference was a topical meeting in the area of high energy density plasma physics as it relates to magnetically imploded/confined plasmas: Z-pinches. Scientists interested in plasmas for fusion and other applications at temperatures around a million degrees centigrade with strong magnetic fields and intense radiation fluxes will be interested in this conference. The physics of the plasmas discussed in this conference include magneto-hydrodynamics and instabilities, fusion mechanisms, radiation transport, mega-ampere pulsed power, atomic physics, spectroscopy and x-ray imaging. This proceeding provides a snapshot of the field internationally.

Download or read book Dense Z Pinches written by Jeremy Chittenden and published by AIP Conference Proceedings / P. This book was released on 2006-01-06 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings volume summarizes the state-of-the-art in Z-pinch research pertaining to applications in inertial confinement fusion, x-ray radiation sources and high energy density plasma physics. Topics include: wire array Z-pinches, single wires and fibers, X-pinches, gas-puffs, plasma focus, capillary discharges and soft X-ray lasers, pulsed power drivers, diagnostic techniques and spectroscopy, as well as theoretical concepts.

Download or read book Z pinches as Intense X ray Sources for High Energy Density Physics Application written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fast z-pinch implosions can convert more than 10% of the stored electrical energy in a pulsed-power accelerator into x rays. These x rays are produced when an imploding cylindrical plasma, driven by the magnetic field pressure associated with very large axial currents, stagnates upon the cylindrical axis of symmetry. On the Saturn pulsed-power accelerator at Sandia National Laboratories, for example, currents of 6 to 8 MA with a risetime of less than 50 ns are driven through cylindrically-symmetric loads, producing implosions velocities as high as 100 cm/[mu]s and x-ray energies as high as 500 kJ. The keV component of the resulting x-ray spectrum has been used for many years 8 a radiation source for material response studies. Alternatively, the x-ray output can be thermalized into a near-Planckian x-ray source by containing it within a large cylindrical radiation case. These large volume, long-lived radiation sources have recently been used for ICF-relevant ablator physics experiments as well as astrophysical opacity and radiation-material interaction experiments. Hydromagnetic Rayleigh-Taylor instabilities and cylindrical load symmetry are critical, limiting factors in determining the assembled plasma densities and temperatures, and thus in the x-ray pulse widths that can be produced on these accelerators. In recent experiments on the Saturn accelerator, these implosion nonuniformities have been minimized by using uniform-fill gas puff loads or by using wire arrays with as many a 192 wires. These techniques produced significant improvements in the pinched plasma quality, Zn reproducibility, and x-ray output power. X-ray pulse widths of less than 5 ns and peak powers of 75[+-]10 TW have been achieved with arrays of 120 tungsten wires. These powers represent greater than a factor of three in power amplification over the electrical power of the Saturn n accelerator, and are a record for x-ray powers in the laboratory.

Download or read book Cylindrical Liner Z pinches as Drivers for Converging Strong Shock Experiments written by Guy C. Burdiak and published by Springer. This book was released on 2014-06-06 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: The thesis represents the development of an entirely new experimental platform for generating and studying converging radiative shock waves. It was discovered that the application of large magnetic pressures to gas-filled cylindrical metallic tubes could sequentially produce three shocks within the gas. A comprehensive set of instrumentation was devised to explore this system in detail and an exceptionally thorough experimental and theoretical study was carried out in order to understand the source of the shock waves and their dynamics. The research is directed towards some of the most interesting topics in high energy density physics (HEDP) today, namely the interaction of HED material with radiation and magnetic fields, with broad applications to inertial confinement fusion (ICF) and laboratory plasma astrophysics. The work has already generated significant international interest in these two distinct research areas and the results could have significant importance for magnetic ICF concepts being explored at Sandia National Laboratories in the US and for our understanding of the very strong shock waves that are ubiquitous in astrophysics.

Download or read book Physics of High Density Z Pinch Plasmas written by Michael A. Liberman and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 285 pages. Available in PDF, EPUB and Kindle. Book excerpt: A "z pinch" is a deceptively simple plasma configuration in which a longitudinal current produces a magnetic field that confines the plasma. Z-pinch research is currently one of the fastest growing areas of plasma physics, with revived interest in z-pinch controlled fusion reactors along with investigations of new z-pinch applications, such as very high power x-ray sources, high-energy neutrons sources, and ultra-high magnetic fields generators. This book provides a comprehensive review of the physics of dense z pinches and includes many recent experimental results.

Download or read book Initiation Ablation Precursor Formation and Instability Analysis of Thin Foil Liner Z pinches written by Isaac Curtis Blesener and published by . This book was released on 2012 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents the results of mostly experimental work studying the early-time behavior of thin foil liners as compared to wire-array Z-pinches. It involves three studies, covering initiation, ablation and precursor formation, and instability analysis. Initiation was studied by observing the optical emission of various thickness (0.6-23.5 um Cu) liners using a streak camera. It was found that thinner liners initiated sooner, more quickly, and more uniformly than thicker liners. This correlated well with both an increase in instantaneous dJ/dt at the time of first emission as well as the inductive voltage at the time of first emission. The threshold for uniform initiation was dJ/dt>3.5x1016 Acm[-]2 s[-]1 . Uniform initiation is important for liners because nonuniformities could lead to enhanced instabilities and poor liner performance (compression, x-ray production, etc.). Ablation and precursor formation of wire-arrays (16x75 um Cu) and liners (6 um Cu) were studied using r-[theta] density maps and radial mass profiles created by an axial X pinch radiography diagnostic. These images show very strong differences in this stage of the Z-pinch. Wire-arrays develop complex, azimuthally varying ablation structures that lead to dense precursors. Liners, however, show significantly reduced and azimuthally uniform ablation leading to an order of magnitude less dense precursor on axis. This is likely due to the discrete versus continuous nature of wire-arrays versus liners. With wire-arrays, plasma that is created on the outside of the wires can reach the array axis by being swept through the gaps between the stationary wire cores. In contrast, liners have no "gaps" for plasma to flow through. Therefore, any plasma that is created on the outside of the liner is trapped there until the bulk of the liner moves with the implosion. Consequently, only the plasma that is created on the inside of the liner is able to contribute to precursor formation. This is an important result because reduced precursor formation is important for fuel compression and heating in MagLIF. Less precursor can also lead to enhanced x-ray production because there is less mass on axis to cushion the conversion of kinetic energy into x-rays during the implosion and stagnation phases. Finally, in the instability studies, it was observed in laser shadowgraph images that liners develop a much larger amplitude instability on their outside surface as compared to wire-arrays. This is an important discovery and could be detrimental to liner performance (compression, x-ray production, etc.) because it could lead to enhanced magnetic Rayleigh-Taylor (MRT) instability during the implosion phase. The reason for the larger instability in liners is again probably due to the fact that plasma builds up on the outside of the liners with no where to go. A possible source of the enhanced instability was found using 2D (xy) PERSEUS simulations comparing the results of MHD and Hall MHD simulations. The instability only developed in the Hall MHD case. The 2D nature of the simulation, along with all simulation parameters being equal between the two cases, rules out the possibility of MRT or m=0 for the cause of the instability (in the simulation). It was found that the Hall term was responsible for causing a shear-flow instability that developed later in time to resemble the experimental results.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 1102 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fusion Energy Update written by and published by . This book was released on 1986 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book STAR written by and published by . This book was released on 1973 with total page 888 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Report of NRL Progress written by Naval Research Laboratory (U.S.) and published by . This book was released on 1976 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Plasma Physics Index written by and published by . This book was released on 1982 with total page 732 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design of the PST A Diagnostic for 1 D Imaging of Fast Z Pinch Power Emissions written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fast Z-pinch technology developed on the Z machine at Sandia National Laboratories can produce up to 230 TW of thermal x-ray power for applications in inertial confinement fusion (ICF) and weapons physics experiments. During implosion, these Z-pinches develop Rayleigh-Taylor (R-T) instabilities which are very difficult to diagnose and which functionally diminish the overall pinch quality. The Power-Space-Time (PST) instrument is a newly configured diagnostic for measuring the pinch power as a function of both space and time in a Z-pinch. Placing the diagnostic at 90 degrees from the Z-pinch axis, the PST provides a new capability in collecting experimental data on R-T characteristics for making meaningful comparisons to magneto-hydrodynamic computer models. This paper is a summary of the PST diagnostic design. By slit-imaging the Z-pinch x-ray emissions onto a linear scintillator/fiber-optic array coupled to a streak camera system, the PST can achieve[approximately]100[micro]m spatial resolution and[approximately]1.3 ns time resolution. Calculations indicate that a 20[micro]m thick scintillating detection element filtered by 1,000[angstrom] of Al is theoretically linear in response to Plankian x-ray distributions corresponding to plasma temperatures from 40 eV to 150 eV, By calibrating this detection element to x-ray energies up to 5,000 eV, the PST can provide pinch power as a function of height and time in a Z-pinch for temperatures ranging from[approximately]40 eV to[approximately]400 eV. With these system pm-meters, the PST can provide data for an experimental determination of the R-T mode number, amplitude, and growth rate during the late-time pinch implosion.

Download or read book Energy Research Abstracts written by and published by . This book was released on 1993-11 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dense Z pinches written by and published by . This book was released on 1994 with total page 760 pages. Available in PDF, EPUB and Kindle. Book excerpt: