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Ablation dynamics in coiled wire-array Z-pinches

Authors :
J. P. Chittenden
Patrick Knapp
David Hammer
Francisco Suzuki-Vidal
Ryan D. McBride
Gareth Hall
Simon Bland
Bruce Kusse
John Greenly
George Swadling
David Chalenski
S. A. Pikuz
Sergey Lebedev
A. J. Harvey-Thompson
K. S. Blesener
Isaac Blesener
T. A. Shelkovenko
Publication Year :
2013
Publisher :
American Institute of Physics (AIP), 2013.

Abstract

Experiments to study the ablation dynamics of coiled wire arrays were performed on the MAGPIE generator (1 MA, 240 ns) at Imperial College, and on the COBRA generator at Cornell University's Laboratory of Plasma Studies (1 MA, 100 ns). The MAGPIE generator was used to drive coiled wires in an inverse array configuration to study the distribution of ablated plasma. Using interferometry to study the plasma distribution during the ablation phase, absolute quantitative measurements of electron line density demonstrated very high density contrasts between coiled ablation streams and inter-stream regions many millimetres from the wire. The measured density contrasts for a coiled array were many times greater than that observed for a conventional array with straight wires, indicating that a much greater axial modulation of the ablated plasma may be responsible for the unique implosion dynamics of coiled arrays. Experiments on the COBRA generator were used to study the complex redirection of plasma around a coiled wire that gives rise to the ablation structure exhibited by coiled arrays. Observations of this complex 3D plasma structure were used to validate the current model of coiled array ablation dynamics [Hall et al., Phys. Rev. Lett. 100, 065003 (2008)], demonstrating irrefutably that plasma flow from the wires behaves as predicted. Coiled wires were observed to ablate and implode in the same manner on both machines, indicating that current rise time should not be an issue for the scaling of coiled arrays to larger machines with fast current rise times.

Details

Language :
English
Database :
OpenAIRE
Accession number :
edsair.doi.dedup.....6bee7b511113fe3726c776eead820b18