Oblique shock structures formed during the ablation phase of aluminium wire array z-pinches

A series of experiments has been conducted in order to investigate the azimuthal structures formed by the interactions of cylindrically converging plasma flows during the ablation phase of aluminium wire array Z pinch implosions. These experiments were carried out using the 1.4 MA, 240 ns MAGPIE gen...

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Bibliographic Details
Published in:Physics of plasmas 2013-02, Vol.20 (2)
Main Authors: Swadling, G. F., Lebedev, S. V., Niasse, N., Chittenden, J. P., Hall, G. N., Suzuki-Vidal, F., Burdiak, G., Harvey-Thompson, A. J., Bland, S. N., De Grouchy, P., Khoory, E., Pickworth, L., Skidmore, J., Suttle, L.
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ABLATION
ALUMINIUM
Aluminum
Arrays
COLLISIONS
COMPARATIVE EVALUATIONS
Dynamics
ELECTRON DENSITY
INTERACTIONS
LONGITUDINAL PINCH
MACH NUMBER
MACH-ZEHNDER INTERFEROMETER
MAGNETOHYDRODYNAMICS
Mathematical models
PLASMA
PLASMA DENSITY
PLASMA DIAGNOSTICS
Plasmas
SHOCK WAVES
STREAMS
THOMSON SCATTERING
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Summary:A series of experiments has been conducted in order to investigate the azimuthal structures formed by the interactions of cylindrically converging plasma flows during the ablation phase of aluminium wire array Z pinch implosions. These experiments were carried out using the 1.4 MA, 240 ns MAGPIE generator at Imperial College London. The main diagnostic used in this study was a two-colour, end-on, Mach-Zehnder imaging interferometer, sensitive to the axially integrated electron density of the plasma. The data collected in these experiments reveal the strongly collisional dynamics of the aluminium ablation streams. The structure of the flows is dominated by a dense network of oblique shock fronts, formed by supersonic collisions between adjacent ablation streams. An estimate for the range of the flow Mach number (M = 6.2-9.2) has been made based on an analysis of the observed shock geometry. Combining this measurement with previously published Thomson Scattering measurements of the plasma flow velocity by Harvey-Thompson et al. [Physics of Plasmas 19, 056303 (2012)] allowed us to place limits on the range of the Z¯Te of the plasma. The detailed and quantitative nature of the dataset lends itself well as a source for model validation and code verification exercises, as the exact shock geometry is sensitive to many of the plasma parameters. Comparison of electron density data produced through numerical modelling with the Gorgon 3D MHD code demonstrates that the code is able to reproduce the collisional dynamics observed in aluminium arrays reasonably well.
ISSN:1070-664X
1089-7674
DOI:10.1063/1.4790520