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Plasma Science, IEEE Transactions on

Issue 8 • Date Aug. 2010

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Displaying Results 1 - 25 of 32
  • Table of contents

    Page(s): C1 - 1717
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    Freely Available from IEEE
  • IEEE Transactions on Plasma Science publication information

    Page(s): C2
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  • Special Issue on Megagauss Physics and Technology

    Page(s): 1718
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  • On Ultrahigh Magnetic-Field Generation Using Solid-State Liner System

    Page(s): 1719 - 1722
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    A scheme of a device intended for amplification of an axial magnetic field by a system of solid-state cylindrical liners is described in this paper. A 1-D magnetohydrodynamic model used in this paper is stated briefly. Calculation results of ultrahigh magnetic-field generation using one-, two-, and three-stage liner systems are presented. View full abstract»

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  • High-Magnetic-Field Generation by Magnetic Flux Compression in Imploding Plasma Liners

    Page(s): 1723 - 1725
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    The MIG generator was used in a magnetic flux compression experiment to produce a high magnetic field inside a dielectric tube located along the axis of an imploding plasma liner. With a liner current of ~ 1 MA and a tube diameter of 2-5 mm, magnetic fields of up to 60 T with a quasi-steady pulse duration of 100 ns and more were produced. The high magnetic field region is protected from the liner plasma and radiation by the tube wall, and it can be used to study the physical phenomena that occur in high and ultrahigh magnetic fields. The physical processes responsible for the evolution of the magnetic field in a dielectric tube are discussed. View full abstract»

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  • Computer Model of Megagauss Multilayer Quasi-Force-Free Magnet With Balanced End Parts

    Page(s): 1726 - 1730
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    The choice of end parts shape and their numerical analysis are very important for quasi-force-free magnet design. Different variants of the magnet implementation are presented and corresponding dimensions limits and mechanical stresses are presented in the paper. View full abstract»

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  • Models of Magnets With the Quasi-Force-Free Winding Manufactured From the Thin Solid Sheets or Transposed Conductors

    Page(s): 1731 - 1738
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    Advantages of different types of layer structures are examined, and the effect of duration of a pulse magnetic field on mechanical strength and winding heating is investigated. The results gained on simple models made from weak-strength materials have confirmed calculated estimations and have revealed some features to manufacture such systems. These are necessity to provide accurate placement of a conductor on a rated current line and its subsequent hard fixing from a possible displacement. Comparison of one-layer quasi-force-free magnets with conventional magnets shows the advantage of the first ones. View full abstract»

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  • Experimental and Numerical Studies of Megagauss Magnetic-Field Generation at LANL-NHMFL

    Page(s): 1739 - 1749
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    The LANL-NHMFL Megagauss Facility has a well-established history of generating ultrahigh magnetic fields beyond 200 T for a broad range of applications. Using the 2-D Loughborough filamentary modeling, a detailed numerical analysis of the single-turn technique was performed. Single-turn calculations for the standard coil (10 × 10 × 3.2 mm) proved to be extremely accurate up to 40-kV capacitor bank charging, corresponding to a field of 185 T, and also revealed important aspects to be observed during experimentation. For pushing the boundaries toward 500 T, a major effort is under way to perform fast electromagnetic flux compression using a pulsed-power system mainly based on the same capacitor bank. Full details of the design for the new arrangement are given, and based on a well-proven 2-D filamentary modeling, the complex phenomena expected during the flux-compression process are highlighted. View full abstract»

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  • A Two-Stage Power Amplifier for the MOL Stand

    Page(s): 1750 - 1753
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    In the Russian State Research Center, Troitsk Institute of Innovation and Fusion Research, the first two power-amplifier cascades of the MOL stand are put into operation. This paper presents the description of the stand stages and the results of experiments on the current amplification. In the experiment, under the MOL's charging current of 20 kA, the second-stage output current of 1.6 MA was obtained. View full abstract»

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  • Explosive Electrophysical Complex EMIR: Current State and Perspectives

    Page(s): 1754 - 1757
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    This paper presents results of investigations aimed at the creation of high-power explosive sources of soft X-ray radiation (SXR) for thermonuclear-target ignition. Successful tests of basic elements of the power system of such sources: a disk magnetocumulative generator of 480-mm diameter and explosive-current opening switch, have been carried out. These elements will provide current pulses of 50, ... , 70 MA amplitude at rise time of 0.5, ..., 1 μs. The technology aimed at generation of the SXR, powered from the explosive-current sources, is developed. SXR pulses of 55-ns length and energy of ~ 800 kJ have been recorded at a liner current of 14 MA with a rise time of 1 μs. Analysis of the experimental data is carried out using a 2-D MHD code. The most probable scenario of implosion of single and nested array liners is determined. A conclusion about the perspectives of the developed direction and its competitiveness with stationary facilities is made. View full abstract»

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  • Helical Magneto-Cumulative Generators for Plasma Focus Powering

    Page(s): 1758 - 1761
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    High-inductive helical magneto-cumulative generators (MCGs) of 50- and 80-mm diameters intended for a plasma focus (PF) powering are created in VNIIEF. High energy gain, efficient operation into loads to 50 nH, and the possibility of application in combination with the current opening switches are the distinctive features of the generators. Having small sizes and masses, these generators produce current pulses from 400 kA to 1 MA with the rise time of ~ 0.5 μs powered with the energy less than 100 J. This paper presents results of experimental research during which the high stability of the MCG operation both on the current amplitude and operation time is shown. Results of the experiments on the PF powered from the MCG, operated in the regime of the magnetic flux extra compression, are presented. The yield of 1012 neutronsper pulse was recorded in the tests with the MCG-80 and PF with D-T mixture. View full abstract»

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  • Disk Magnetocumulative Generator of 480-mm Diameter for Explosive EMIR Facility

    Page(s): 1762 - 1767
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    The first test of a disk magnetocumulative generator (DMCG) with high explosive charges of 480-mm diameter was carried out in the frameworks of a program on creation of an explosive EMIR facility, intended for high-power soft X-ray radiation pulses generation.The generator consists of five disk elements. The inductive load was equal to ~ 7 nH. The generator was twice larger than model DMCG240, successfully tested earlier. A comparison of calculation and experimental results is carried out. View full abstract»

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  • Disk Magneto-Cumulative Generator With Explosive Current Opening Switch

    Page(s): 1768 - 1772
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (530 KB) |  | HTML iconHTML  

    The first test of a pulsed power system consisting of a five-element disk magneto-cumulative generator with high-explosive charges of 240 mm diameter and an explosive current opening switch with ribbed barrier was carried out in the frameworks of a program for creating an explosive complex EMIR, intended for the generation of high-power soft X-ray radiation pulses. A current pulse of ~ 9 MA with a characteristic rise time of ~ 0.6 μs was recorded at opening of the generator circuit with the current of ~ 15 MA into a ~ 7 nH inductance load. View full abstract»

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  • Problems of Creation of High-Efficient Magnetocumulative Generators. Electric Strength of Helical Magnetocumulative Generators

    Page(s): 1773 - 1779
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    Helical MCGs have a wide range of output characteristics, and they are frequently used in pulsed-power experiments. The absence of electric breakdowns at compression of a magnetic flux in the generator volume is one of the important factors of stable and efficient operation of fast helical MCGs. This paper considers the problems associated with both a decrease of maximum voltages in the MCG circuit and an increase of electric strength of the generator elements. The direction of possible electric breakdowns, i.e., their localization, is shown experimentally. The influence of shock-compressed air on the electric strength of the device is also presented. The use of solid (film) insulation on the stator windings is important. A value of the magnetic flux losses in the winding insulation is determined experimentally. View full abstract»

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  • Limitations of the Fast Operation of Helical Magneto-Cumulative Generators

    Page(s): 1780 - 1783
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    A requirement of current rise-time shortening on the final stage of a magnetocumulative generator (MCG) operation (a requirement to increase the fast operation of the generator) comes from a necessity to decrease a premature thermal or ponderomotive effect of a current pulse on loads elements. These requirements mean an increase of the MCG power, and finally, they are associated with obtaining maximum possible energy density in the loads. This paper considers different factors that limit the power of the helical MCG and experimentally shows possibility of significant increase of the helical-generator's fast operation due to application of additional elements in the stator, change of a liner shape, and use of two-sided initiation of a high-explosive charge. View full abstract»

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  • Miniature Explosively Driven High-Current Transverse-Shock-Wave Ferromagnetic Generators

    Page(s): 1784 - 1793
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    Comprehensive studies of explosively driven ferromagnetic generators (FMGs) have been performed. It has been experimentally established that the initial magnetostatic energy stored in the magnetic element of the FMG (determined by the magnet's maximum energy product (BH)max and its volume), not the residual magnetic flux density Br, is the principal parameter that determines the output energy and the amplitude of the signals produced by the generator. Systematic studies were carried out with miniature high-current FMGs containing Nd2Fe14B high-energy hard ferromagnetic elements having a wide range of sizes. Utilization of transverse-shock demagnetization of Nd2Fe14B magnets (shock wave propagates across the magnetization vector mmb M) instead of longitudinal-shock demagnetization dramatically changed the design of the FMGs and reduced the mass of the explosives used by two orders of magnitude in comparison with that used in longitudinal FMGs. Data for the initial magnetic flux and shock-induced magnetic flux change in Nd2 Fe14B magnets are presented. It was shown that FMGs with a volume of 25 cm3 are capable of producing pulsed currents with amplitudes of up to 4.4 kA and rise times of 23 μs in the seed coil of a magnetic flux compression generator. View full abstract»

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  • Modeling and Simulation of Simple Flux-Trapping FCGs Utilizing PSpice Software

    Page(s): 1794 - 1802
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    A novel modeling and simulation method for flux-trapping flux-compression generators (FT-FCGs) is presented, which utilizes PSpice circuit-simulation software to solve complex differential equations derived from circuit analysis. The primary motivation for the model development is the desire for a technique to rapidly design and prototype FT-FCGs for use as drivers in high-power microwave sources. The derivation of FT-FCG equations will be given, both in the ideal (lossless) and nonideal cases. For the nonideal case, three flux conservation coefficients are added to the equations to account for intrinsic flux loss in the circuit. Time-varying inductance curves are calculated using zero-dimensional models found in literature and adapted to fit this model. A simple FT-FCG design is used as an example to show the steps taken to complete a simulation. The same design was also fabricated and tested for comparison with predicted results from the model. A comparison of the waveforms acquired through simulation and experiment was found to result in good agreement for a given set of values for the flux conservation coefficients. A discussion of the derived equations, both lossless and nonideal, is given, as well as a discussion on the investigation of the impact of the three flux constants on the circuit. Analysis is offered on the results of this investigation, and conclusions are given on the effectiveness of this model to predict FT-FCG behavior. View full abstract»

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  • Calculation Studies of Operational Faults of Multielement Disk MCG

    Page(s): 1803 - 1807
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    A calculation simulation of multielement disk magnetocumulative systems is carried out. Effect of failure of one or several detonators in a system of high-explosive (HE) charge initiation and axial shift of the detonators relative to a symmetry plane of the HE charges on the operation efficiency of the multielement disk magnetocumulative generator is considered. The considered models allow explaining the results of the experiments in the case of similar situations. View full abstract»

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  • Magnetohydrodynamic Modeling of Diffusive Megagauss Magnetic Fields Generated in Plasma

    Page(s): 1808 - 1814
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    The spatial and temporal dynamics of a self-generated magnetic field (SMF) in plasma is investigated within the framework of electron magnetohydrodynamics. The equation that governs the generation and evolution of the diffusive magnetic field is solved as an initial value problem for a general source that includes both thermal and radiative sources and by accounting for retardation effects. Analytical expressions for the space-time development of the SMF are obtained in a closed form for both bounded plasmas and plasmas of infinite extent. For a typical laser-produced plasma, using an oscillating Gaussian source with a source strength equal to that of the thermoelectric source, numerical results show generated fields of magnitudes just about 10 MG. View full abstract»

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  • Numerical Simulations of Thick-Aluminum-Wire Behavior Under Megaampere-Current Drive

    Page(s): 1815 - 1821
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    A series of experiments to study the behavior of thick wires (0.5-2 mm in diameter) driven by currents of about 1 MA has recently been conducted on the Zebra facility at the University of Nevada, Reno. The objective of these experiments was to study plasma formation on the surface of conductors under the influence of megagauss magnetic fields. Laser shadowgraphy, filtered optical and extreme ultraviolet photodiodes, and extreme ultraviolet spectroscopy used in the experiments provided data on radial expansion of wires and on plasma radiation. This paper focuses on numerical simulations of these experiments. Simulations with wires having diameters up to 1.6 mm demonstrated plasma formation with temperatures above 3 eV, which is in preliminary agreement with the experiment. For 2-mm-diameter wires, although plasma can be observed in the simulations, it has substantially smaller optical thickness than in the simulations of the smaller diameter wires, and the radiation fluxes prove to be much lower. This can shed light on the experimental results where the radiation of the 2-mm wires was very weak. The simulated time dependences of the wire radii agree rather well with the experimental results obtained using laser diagnostics and visible-light imaging. The experimental data of the photodiodes also agree well with the simulated time dependence of the detected radiation. View full abstract»

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  • Calculation Method of Radiation Spectral Transfer in Frameworks of Two-Dimensional Magnetohydrodynamic Code FLUX-rz

    Page(s): 1822 - 1827
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    A magnetohydrodynamic model of irradiating Z-pinch is the basis of a 2-D (in Euler cylindrical coordinates r-z) computer code FLUX-rz developed in VNIIEF (Russia). Earlier, the code considered the thermal radiation transfer in one-group (gray) diffusion approximation. This paper presents a modification of the FLUX-rz code in which we realized a multigroup diffusion model of the radiation transfer. Efficiency of an improved algorithm has been demonstrated by sample calculations of Shot 52 and Shot 567 on Z-machine at Sandia National Laboratories (U.S.). View full abstract»

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  • Design Improvements to High-Explosive Pulsed-Power Isentropic-Compression Experiments

    Page(s): 1828 - 1834
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    A series of 1-D isentropic-compression experiments (ICE) has been initiated using the high-explosive pulsed-power (HEPP) system. Accurate high-stress isentropic equation-of-state (EOS) data had been reported using the HEPP-ICE system. A number of important advantages of the system were demonstrated, including higher stresses, higher accuracy, and larger sample sizes than those of other methods. Several potential design improvements have since been identified and tested. The storage inductor was eliminated, and the experiment was performed before the output of the plate flux compression generator could short-circuit itself. This eliminated the loss of current that occurs when the generator plates bounce apart. A new design of explosively formed fuse opening switch was employed with a multipoint initiation system that reduced the explosive mass, significantly reduced the timing jitter by eliminating air gaps, and minimized flux losses. In addition, with this new switch, the resistance-versus-time profile may be adjusted by controlling the initiation times of its four quadrants. Anomalous results were obtained with the new switch. The results of using this switch in an EOS experiment on pure tantalum are reported. View full abstract»

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  • Electromagnetic Transients Under Shock Compression of Condensed Matter

    Page(s): 1835 - 1839
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    Specific features of electromagnetic transients in condensed matter, caused by the dynamic character of shock compression, are studied. The governing parameters and the characteristic times and lengths determining the global electromagnetic pattern in the conductor are found. The structure of current waves is revealed for dielectric-metal and metal-metal transitions under shock compression. View full abstract»

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  • Interaction of a High-Enthalpy Plasma Jet With Surfaces and Chemically Active Media

    Page(s): 1840 - 1849
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    Results on possible applications of generated by electrodynamics accelerator high-enthalpy plasma flows in various technological processes are presented. The possibility of using magneto hydrodynamics (MHD) plasma accelerators as tools for modification of solid surfaces and for initiation of chemical reactions due to interaction of a high-enthalpy flow with a gas medium is demonstrated. Mathematical models of these accelerators were developed and tested. View full abstract»

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  • Surface Discharges in Strong Magnetic Fields

    Page(s): 1850 - 1855
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    In studying a number of processes, such as plasma confinement by magnetic field and magnetized-plasma confinement with walls, magnetic implosion of liners transiting to the plasma state during electric explosion, liner compression of magnetized plasma, magnetic-flux transfer through the insulator surface, etc., one needs to take into account surface discharges induced by magnetic-flux transfer toward the plasma or insulator (H-pressed discharge) or out of the insulator (H-thrown discharge). These discharges cause magnetic flux and energy losses (in the H-pressed discharge) or limit the energy fluxes delivered to the system and can lead to hydrogen plasma contamination with the insulator material (in the H-thrown discharge). The problem of magnetized-plasma cooling at the condensed matter/plasma interface is related to the H -pressed discharge problem. Such a problem as strong magnetic field diffusion into metal, which is very important for megagauss field generation and various applications, can also be attributed to the surface-discharge problems. If a metal is in contact with a dense magnetized plasma, surface discharges may occur near their interface, where the metal may explode and become a plasma. This paper presents the classification and the overview of the mentioned surface discharges in strong magnetic fields and considers general and specific features of these discharges. View full abstract»

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Aims & Scope

IEEE Transactions on Plasma Sciences focuses on plasma science and engineering, including: magnetofluid dynamics and thermionics; plasma dynamics; gaseous electronics and arc technology.

 

 

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Editor-in-Chief
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