Measurement and modeling of the implosion of wire arrays with seeded instabilitiesa

• Published in: Physics of plasmas 2006-05, Vol.13 (5)
• Main Authors: Jones, Brent, Garasi, Christopher J., Ampleford, David J., Deeney, Christopher, Mehlhorn, Thomas A., Bland, Simon N., Lebedev, Sergey V., Chittenden, Jeremy P., Bott, Simon C., Palmer, James B. A., Hall, Gareth N., Rapley, Jack
• Format: Article
• Language: English
• ISSN: 1070-664X; 1089-7674
• DOI: 10.1063/1.2174833

In order to study wire array Z-pinch instabilities, perturbations have been seeded by etching 15 μ m diameter aluminum wires to introduce 20% modulations in radius with a controlled axial wavelength. These perturbations seed additional imploding structures that are studied experimentally on the 1 MA , 250 ns MAGPIE generator [S. V. Lebedev et al. , Plasma Phys. Control. Fusion 47, A91 (2005)] and with three-dimensional magnetohydrodynamic calculations using the ALEGRA-HEDP [A. C. Robinson and C. J. Garasi, Comput. Phys. Commun. 164, 408 (2004)] and GORGON [J. P. Chittenden et al. , Plasma Phys. Control. Fusion 46, B457 (2004)] codes. Simulations indicate that current path nonuniformity at discontinuities in the wire radius result in perturbation-induced magnetic bubble formation. Imploding bubbles originating from discontinuities are observed experimentally, and their collision on axis determines the start of the main x-ray pulse rise. These mechanisms likely govern dynamics of standard wire array Z pinches, and tailoring the profile of imploding mass may allow x-ray pulse shaping for inertial confinement fusion applications.