Plasma flows during the ablation stage of an over-massed pulsed-power-driven exploding planar wire array

We characterize the plasma flows generated during the ablation stage of an over-massed exploding planar wire array, fielded on the COBRA pulsed-power facility (1 MA peak current, 250 ns rise time). The planar wire array is designed to provide a driving magnetic field (80-100 T) and current per wire distribution (about 60 kA), similar to that in a 10 MA cylindrical exploding wire array fielded on the Z machine. Over-massing the arrays enables continuous plasma ablation over the duration of the experiment. The requirement to over-mass on the Z machine necessitates wires with diameters of 75-100 $\mu$m, which are thicker than wires usually fielded on wire array experiments. To test ablation with thicker wires, we perform a parametric study by varying the initial wire diameter between 33-100 $\mu$m. The largest wire diameter (100 $\mu$m) array exhibits early closure of the AK gap, while the gap remains open during the duration of the experiment for wire diameters between 33-75 $\mu$m. Laser plasma interferometry and time-gated XUV imaging are used to probe the plasma flows ablating from the wires. The plasma flows from the wires converge to generate a pinch, which appears as a fast-moving ($V \approx {100}$ kms$^{-1}$) column of increased plasma density ($\bar{n}_e \approx 2 \times 10^{18}$ cm$^{-3}$) and strong XUV emission. Finally, we compare the results with three-dimensional resistive-magnetohydrodynamic (MHD) simulations performed using the code GORGON, the results of which reproduce the dynamics of the experiment reasonably well.Comment: 14 pages; 14 figure

Volume 02

Introduction from Dean Dr. Charles Ross Mike\u27s Nite: New Jazz for an Old Instrument by Joseph A. Mann Investigation of the use of Cucumis Sativus for Remediation Of Chromium from Contaminated Environmental Matrices: An Interdisciplinary Instrumental Analysis Project by Kathryn J. Greenly, Scott E. Jenkins, and Andrew E. Puckette Development of GC-MS and Chemometric Methods for the Analysis of Accelerants in Arson Cases by Scott Jenkins Building and Measuring Scalable Computing Systems by Daniel M. Honey and Jeffery P. Ravenhorst Nomini Hall: A Case Study in the Use of Archival Resources as Guides for Excavation at An Archaeological Site by Jamie Elizabeth Mesrobian Two Stories: In Ohio and How to Stay Out of the Brazilian Army by Thomas Scott Forgerson des Hommes/Stealing the Steel in Zola\u27s Men by Jay Crowell Paul Gauguin\u27s Escape into Primitivism by Sarah Spangenberg Lee Krasner, Abstract Expressionist by Amy S. Eason Artist Book “Paris” by Kenny Wolfe Artist Book “Sequence of Every Day” by Liz Hale Artist Book “Apple Tree” by Rachel Bouchard Artist Book “Not so Pretty in Pink” by Will Semonco Artist Book “Look into the Moon” by Carley York Artist Books “Extra” and “Green” by Ryan Higgenbothom Artist Book “Re-growing Appalachia” by Adrienne Heinbaugh Artist Books “Cheeziest”, “Uh-oh” and “The Girl with the Glasses” by Melissa Dorton “Self-Reflection” by Madeline Hunter Artist Book “The Princess and the Frog” by June Ashmore “Hunter’s Niche” and “The Wild” by Clark Barkley “To Thine Own Self be True” by Jay Haley “Not Funny” Ten-Minute Play Festiva

‘This restless enemy of all fertility’: exploring paradigms of coastal dune management in Western Europe over the last 700 years

Drifting sand has inundated settlements and damaged agricultural land along the coasts of Western Europe for the last 700 years. The need to control sand migration has been an important driver of the management of coastal sand dunes and here we analyse original archival materials to provide new insights into historically changing coastal dune management practices. Records of coastal sand movement in Denmark, The Netherlands, Britain, Ireland and France were reviewed and three distinct management approaches were identified. The ways in which these approaches have played out in space and time were examined with particular reference to records from landed estates in Britain and Ireland. We demonstrate how historical evidence can be used to inform contemporary debates on dune management strategy and practice. We propose a new place-based approach to the future management of coastal dunes that can incorporate both expert and locally produced ‘knowledges’ and that is underpinned by an understanding of how both natural forces and human interventions have shaped these dune landscapes over time

Generation and transport of a low energy intense ion beam

The paper describes experiments on the generation and transport of a low energy (70-120 keV), high intensity (10-30 A/cm(2)) microsecond duration H+ ion beam (IB) in vacuum and plasma. The IB was generated in a magnetically insulated diode (MID) with an applied radial B field and an active hydrogen-puff ion source. The annular IB, with an initial density of j(i)similar to10-20 A/cm(2) at the anode surface, was ballistically focused to a current density in the focal plane of 50-80 A/cm(2). The postcathode collimation and transport of the converging IB were provided by the combination of a "concave" toroidal magnetic lens followed by a straight transport solenoid section. With optimized MID parameters and magnetic fields in the lens/solenoid system, the overall efficiency of IB transport at the exit of the solenoid 1 m from the anode was similar to 50% with an IB current density of 20 A/cm(2). Two-dimensional computer simulations of post-MID IB transport supported the optimization of system parameters. (C) 2004 American Institute of Physics

Formation of radiatively cooled, supersonically rotating, plasma flows in Z-pinch experiments: Towards the development of an experimental platform to study accretion disk physics in the laboratory

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