Author: Publisher: ISBN: Category : Languages : en Pages : 44
Book Description
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.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
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.
Author: Michael A. Liberman Publisher: Springer Science & Business Media ISBN: 1461214246 Category : Science Languages : en Pages : 285
Book Description
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.
Author: Michael A. Liberman Publisher: Springer ISBN: 0387985689 Category : Science Languages : en Pages : 277
Book Description
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.
Author: Publisher: ScholarlyEditions ISBN: 1490107819 Category : Science Languages : en Pages : 1198
Book Description
Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2013 Edition is a ScholarlyEditions™ book that delivers timely, authoritative, and comprehensive information about High Energy Physics. The editors have built Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about High Energy Physics in this book to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2013 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Author: David Arthur Chalenski Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Data presented are the culmination of experiments studying the combined effects of polarity, contact and current risetime on wire array z-pinches operated on the 1 MA, 100-200 ns Cornell University COBRA pulsed power generator. Data were collected on 16-wire, 12.5 [MICRO SIGN]m f aluminum z-pinch arrays in both negative and positive polarity, with soldered and non-soldered contacts, and with slow and fast risetimes (100ns and 200ns). A minimum of five shots were collected for each of the eight cases to obtain statistical significance. The initiation, ablation, implosion and stagnation phases were compared for the various cases. Polarity was modified via a 12 nH bolt-on convolute, rotatable to provide positive or negative polarity with similar inductance in each case, allowing sideby-side comparisons. Contact was modified by applying Pb60Sn40 solder to the cathode wire-electrode contact point or leaving the array unsoldered. The current risetime was varied between a 100 ns "short" pulse and 200 ns "long" pulse by utilizing current-pulse shaping capabilities of the COBRA pulsed power generator. These experiments aimed to build upon previous research by Duselis et al. (2004), which showed that polarity, contact and current risetime have significant impact on energy deposited and uniformity of expansion of single wires under low-current (
Author: Publisher: ISBN: Category : Aeronautics Languages : en Pages : 700
Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author: Publisher: ISBN: Category : Languages : en Pages : 34
Book Description
Recent improvements in z-pinch wire array load design at Sandia National Laboratories have led to a substantial increase in pinch performance as measured by radiated powers of up to 280 TW in 4 ns and 1.8 MJ of total radiated energy. Next generation, higher current machines will allow for larger mass arrays and comparable or higher velocity implosions to be reached, possibly extending these result.dis the current is pushed above 20 MA, conventional machine design based on a 100 ns implosion time results in higher voltages, hence higher cost and power flow risk. Another approach, which shifts the risk to the load configuration, is to increase the implosion time to minimize the voltage. This approach is being investigated in a series of experimental campaigns on the Saturn and Z machines. In this paper, both experimental and two dimensional computational modeling of the fist long implosion Z experiments will be presented. The experimental data shows broader pulses, lower powers, and larger pinch diameters compared to the corresponding short pulse data. By employing a nested array configuration, the pinch diameter was reduced by 50% with a corresponding increase in power of> 30%. Numerical simulations suggest load velocity is the dominating mechanism behind these results.
Author: Publisher: ISBN: Category : Languages : en Pages : 14
Book Description
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 ...
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Author: Michael A. Liberman
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Author: David Arthur Chalenski
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