Publications
223 results found
Hall GN, Bland SN, Lebedev SV, et al., 2009, Modifying Wire-Array Z-Pinch Ablation Structure and Implosion Dynamics Using Coiled Wires, Pages: 520 -529-520 -529, ISSN: 0093-3813
Harvey-Thompson AJ, Lebedev SV, Bland SN, et al., 2009, Quantitative analysis of plasma ablation using inverse wire array Z pinches, PHYSICS OF PLASMAS, Vol: 16, ISSN: 1070-664X
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- Citations: 41
Ciardi A, Lebedev SV, Frank A, et al., 2009, EPISODIC MAGNETIC BUBBLES AND JETS: ASTROPHYSICAL IMPLICATIONS FROM LABORATORY EXPERIMENTS, Astrophysical Journal Letters, Vol: 691, Pages: L147-L150, ISSN: 2041-8213
Collimated outflows (jets) are ubiquitous in the universe, appearing around sources as diverse as protostars and extragalactic supermassive black holes. Jets are thought to be magnetically collimated, and launched from a magnetized accretion disk surrounding a compact gravitating object. We have developed the first laboratory experiments to address time-dependent, episodic phenomena relevant to the poorly understood jet acceleration and collimation region. The experimental results show the periodic ejections of magnetic bubbles naturally evolving into a heterogeneous jet propagating inside a channel made of self-collimated magnetic cavities. The results provide a unique view of the possible transition from a relatively steady-state jet launching to the observed highly structured outflows.
Suzuki-Vidal F, Lebedev SV, Ciardi A, et al., 2009, Formation of episodic magnetically driven radiatively cooled plasma jets in the laboratory, Astrophysics and Space Science, Vol: 322, Pages: 19-23, ISSN: 1572-946X
We report on experiments in which magneticallydriven radiatively cooled plasma jets were produced by a1 MA, 250 ns current pulse on the MAGPIE pulsed powerfacility. The jets were driven by the pressure of a toroidalmagnetic field in a “magnetic tower” jet configuration. Thisscenario is characterized by the formation of a magneticallycollimated plasma jet on the axis of a magnetic “bubble”,confined by the ambient medium. The use of a radial metallicfoil instead of the radial wire arrays employed in our previouswork allows for the generation of episodic magnetictower outflows which emerge periodically on timescales of∼30 ns. The subsequent magnetic bubbles propagate withvelocities reaching ∼300 km/s and interact with previouseruptions leading to the formation of shocks.
Suzuki-Vidal F, Lebedev SV, Ciardi A, et al., 2009, Formation of Episodic Magnetically Driven Radiatively Cooled Plasma Jets in Laboratory Experiments, Pages: 195-204, ISSN: 1570-6591
We report on experiments in which magnetically driven radiatively cooled plasma jets were produced by a 1 MA, 250 ns current pulse on the MAGPIE pulsed power facility. The jets were driven by the pressure of a toroidal magnetic field in a “magnetic tower” jet configuration. This scenario is characterized by the formation of a magnetically collimated plasma jet on the axis of a magnetic cavity, confined by the ambient medium. The use of a radial metallic foil instead of the radial wire arrays employed in our previous work allows for the generation of episodic magnetic tower outflows which emerge periodically on timescales of ∼ 30 ns. The subsequent magnetic bubbles propagate with velocities reaching ∼ 300 km/s and interact with previous eruptions. This setup also allowed for the addition of a neutral gas above the foil in order to study the effect of the ambient density on the dynamics of both the early time hydrodynamic jet formed from plasma ablated from the foil and of the subsequent magnetic tower outflows.
Hall GN, Bland SN, Lebedev SV, et al., 2009, Modifying Wire Array Z-pinch Ablation Structure and Implosion Dynamics Using Coiled Arrays, 7th International Conference on Dense Z-Pinches, Publisher: AMER INST PHYSICS, Pages: 89-+, ISSN: 0094-243X
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- Citations: 4
Niasse N, Chittenden JP, Bland SN, et al., 2009, 3D MHD Simulations of Radial Wire Array Z-pinches, Publisher: AIP, Pages: 125-128-125-128
Bott SC, Haas DM, Eshaq Y, et al., 2009, Effect of Current Rise-time on the Formation of Precursor Structures and Mass Ablation Rate in Cylindrical Wire Array Z-Pinches, 7th International Conference on Dense Z-Pinches, Publisher: AMER INST PHYSICS, Pages: 25-+, ISSN: 0094-243X
Harvey-Thompson AJ, Lebedev SV, Bland SN, et al., 2009, Quantitative Analysis of Plasma Ablation Using Inverse Wire Array Z-pinches, 7th International Conference on Dense Z-Pinches, Publisher: AMER INST PHYSICS, Pages: 105-+, ISSN: 0094-243X
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- Citations: 2
Ampleford DJ, Lebedev SV, Ciardi A, et al., 2009, Astrophysical Jets with Conical Wire Arrays: Radiative Cooling, Rotation & Deflection, 7th International Conference on Dense Z-Pinches, Publisher: AMER INST PHYSICS, Pages: 83-+, ISSN: 0094-243X
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- Citations: 1
Bott SC, Haas DM, Eshaq Y, et al., 2008, Quantitative Measurements of Wire Ablation in Tungsten <i>X</i>-pinches at 80 kA, IEEE TRANSACTIONS ON PLASMA SCIENCE, Vol: 36, Pages: 2759-2764, ISSN: 0093-3813
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- Citations: 10
Palmer JBA, Bott SC, Bland SN, et al., 2008, Radiography of foam targets in wire-array <i>Z</i>-pinches, IEEE TRANSACTIONS ON PLASMA SCIENCE, Vol: 36, Pages: 1272-1273, ISSN: 0093-3813
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- Citations: 3
Green JS, Beg FN, Bland SN, et al., 2008, Dynamics of multiple-wire X-pinches, IEEE TRANSACTIONS ON PLASMA SCIENCE, Vol: 36, Pages: 1288-1289, ISSN: 0093-3813
Ampleford DJ, Jones B, Bott SC, et al., 2008, Radiography of modulated wire array <i>Z</i>-pinches, IEEE TRANSACTIONS ON PLASMA SCIENCE, Vol: 36, Pages: 1270-1271, ISSN: 0093-3813
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- Citations: 5
Hall GN, Chittenden JP, Bland SN, et al., 2008, Modifying wire-array z-pinch ablation structure using coiled arrays, PHYSICAL REVIEW LETTERS, Vol: 100, ISSN: 0031-9007
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- Citations: 25
Ampleford DJ, Lebedev SV, Ciardi A, et al., 2008, Supersonic radiatively cooled rotating flows and jets in the laboratory, PHYSICAL REVIEW LETTERS, Vol: 100, ISSN: 0031-9007
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- Citations: 36
Ampleford DJ, Lebedev SV, Bland SN, et al., 2007, Dynamics of conical wire array Z-pinch implosions, PHYSICS OF PLASMAS, Vol: 14, ISSN: 1070-664X
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- Citations: 39
Ciardi A, Lebedev SV, Frank A, et al., 2007, The evolution of magnetic tower jets in the laboratory, Physics of Plasmas, Vol: 14, ISSN: 1089-7674
The evolution of laboratory produced magnetic jets is followed numerically throughthree-dimensional, nonideal magnetohydrodynamic simulations. The experiments are designed tostudy the interaction of a purely toroidal field with an extended plasma background medium. Thesystem is observed to evolve into a structure consisting of an approximately cylindrical magneticcavity with an embedded magnetically confined jet on its axis. The supersonic expansion producesa shell of swept-up shocked plasma that surrounds and partially confines the magnetic tower.Currents initially flow along the walls of the cavity and in the jet but the development ofcurrent-driven instabilities leads to the disruption of the jet and a rearrangement of the field andcurrents. The top of the cavity breaks up, and a well-collimated, radiatively cooled, “clumpy” jetemerges from the system.
Bland SN, Lebedev SV, Chittenden JP, et al., 2007, Implosion and stagnation of wire array Z pinches - art. no. 056315, 48th Annual Meeting of the Division of Plasma Physics of the APS, Pages: 56315-56315
Detailed measurements of the dynamics of aluminum wire array Z pinches from immediately prior to implosion until stagnation and dissipation on axis are presented. Before implosion, the -0.5 mm axial modulation seen in earlier laser probing images is observed as ablation on the surface of the wire cores facing away from the array axis. This results in the complete ablation of sections of the wire cores and a redistribution of current at the start of implosion. The dynamics of implosion are then strongly influenced by the number of wires in the array. With only eight wires, discrete snowplough bubbles expand from each wire toward the precursor. There is little, if any, correlation between the bubbles from adjacent wires, and a large temporal spread over which the bubbles arrive at the precursor is observed, along with a long rise time, low power soft x-ray pulse. With 32 or more wires, bubbles from adjacent wires merge close to the array edge to form an imploding sheath. The front edge of the sheath is well defined with a small spatial spread, and upon reaching the precursor, the start of a fast rising high power soft-x-ray pulse is seen. As x-ray emission increases, the stagnating column on axis starts to decrease in diameter, reaching a minimum at peak x-ray emission, which also coincides with the time when the rear edge of the snowplough reaches the column. Thereafter, the stagnated column is seen to go unstable, and trailing mass left behind during the implosion is accelerated toward the axis. Intense x-ray emission ends as this mass becomes cleared out. (C) 2007 American Institute of Physics.
Ciardi A, Lebedev SV, Frank A, et al., 2007, The evolution of magnetic tower jets in the laboratory - art. no. 056501, 48th Annual Meeting of the Division of Plasma Physics of the APS, Pages: 56501-56501
The evolution of laboratory produced magnetic jets is followed numerically through three-dimensional, nonideal magnetohydrodynamic simulations. The experiments are designed to study the interaction of a purely toroidal field with an extended plasma background medium. The system is observed to evolve into a structure consisting of an approximately cylindrical magnetic cavity with an embedded magnetically confined jet on its axis. The supersonic expansion produces a shell of swept-up shocked plasma that surrounds and partially confines the magnetic tower. Currents initially flow along the walls of the cavity and in the jet but the development of current-driven instabilities leads to the disruption of the jet and a rearrangement of the field and currents. The top of the cavity breaks up, and a well-collimated, radiatively cooled, "clumpy" jet emerges from the system. (C) 2007 American Institute of Physics.
Bland SN, Lebedev SV, Chittenden JP, et al., 2007, Implosion and stagnation of wire array Z pinches, 48th Annual Meeting of the Division of Plasma Physics of the APS, Publisher: AIP Publishing, ISSN: 1070-664X
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- Citations: 24
Bott SC, Lebedev SV, Bland SN, et al., 2007, The formation of precursor structures in cylindrical and "4 x 4" wire arrays, 33rd International Conference on Plasma Science, Publisher: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, Pages: 165-170, ISSN: 0093-3813
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- Citations: 4
Ampleford DJ, Ciardi A, Lebedev SV, et al., 2007, Jet deflection by a quasi-steady-state side wind in the laboratory, 6th International Conference on High Energy Density Laboratory Astrophysics, Publisher: SPRINGER, Pages: 29-34, ISSN: 0004-640X
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- Citations: 15
Ciardi A, Lebedev SV, Frank A, et al., 2007, 3D MHD simulations of laboratory plasma jets, 6th International Conference on High Energy Density Laboratory Astrophysics, Publisher: SPRINGER, Pages: 17-22, ISSN: 0004-640X
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- Citations: 6
Douglass JD, Pikuz SA, Shelkovenko TA, et al., 2007, Structure of the dense cores and ablation plasmas in the initiation phase of tungsten wire-array Z pinches, PHYSICS OF PLASMAS, Vol: 14, ISSN: 1070-664X
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- Citations: 33
Ampleford DJ, Lebedev SV, Ciardi A, et al., 2007, Laboratory modeling of standing shocks and radiatively cooled jets with angular momentum, 6th International Conference on High Energy Density Laboratory Astrophysics, Publisher: SPRINGER, Pages: 51-56, ISSN: 0004-640X
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- Citations: 11
Bland SN, Bott SC, Hall GN, et al., 2006, Diagnostics for studying the dynamics of wire array <i>Z</i> pinches, 16th Topical Conference on High-Temperature Plasma Diagnostics, Publisher: AMER INST PHYSICS, ISSN: 0034-6748
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- Citations: 5
Bland SN, Ampleford DJ, Bott SC, et al., 2006, Use of Faraday probing to estimate current distribution in wire array z pinches - art. no. 10E315, 16th Topical Conference on High-Temperature Plasma Diagnostics, Pages: E315-E315
In order to understand the formation and dynamics of plasma in wire array z-pinch experiments, measurements of the distribution of current throughout the array are required. We present details of two Faraday probing diagnostics aimed at exploring the magnetic fields and hence distribution of current in an array. An imaging Faraday system utilizes a short laser pulse to make estimates of the current distribution in the precursor column formed on axis before implosion. In a second system, a rod of high Verdet constant glass is placed close to the wires of an array and the polarization of a cw laser passing through the rod is monitored to examine the variance of current with time. (c) 2006 American Institute of Physics.
Bland SN, Ampleford DJ, Bott SC, et al., 2006, Use of Faraday probing to estimate current distribution in wire array <i>z</i> pinches, 16th Topical Conference on High-Temperature Plasma Diagnostics, Publisher: AMER INST PHYSICS, ISSN: 0034-6748
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- Citations: 12
Bott SC, Lebedev SV, Ampleford DJ, et al., 2006, Dynamics of cylindrically converging precursor plasma flow in wire-array <i>Z</i>-pinch experiments, PHYSICAL REVIEW E, Vol: 74, ISSN: 1539-3755
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- Citations: 61
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