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Title: Seeded Perturbations in Wire Array Z-Pinches

Abstract

Controlled seeding of perturbations is employed to study the evolution of wire array z-pinch implosion instabilities which strongly impact x-ray production when the 3D plasma stagnates on axis. Wires modulated in radius exhibit locally enhanced magnetic field and imploding bubble formation at discontinuities in wire radius due to the perturbed current path. Wires coated with localized spectroscopic dopants are used to track turbulent material flow. Experiments and MHD modeling offer insight into the behavior of z-pinch instabilities.

Authors:
; ; ; ; ; ; ;  [1];  [2]; ; ; ; ; ; ; ;  [3];  [4]; ;  [5]
  1. Sandia National Laboratories, PO Box 5800, Albuquerque, NM 87185 (United States)
  2. Ktech Corp., Albuquerque, NM 87123 (United States)
  3. Blackett Laboratory, Imperial College, London, SW7 2BZ (United Kingdom)
  4. Mission Research Corp., Albuquerque, NM 87110 (United States)
  5. Department of Physics, University of Nevada, Reno, NV 89557 (United States) (and others)
Publication Date:
OSTI Identifier:
20729296
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 808; Journal Issue: 1; Conference: 6. international conference on dense Z-pinches, Oxford (United Kingdom), 25-28 Jul 2005; Other Information: DOI: 10.1063/1.2159320; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COMPUTERIZED SIMULATION; DISTURBANCES; DOPED MATERIALS; ELECTRIC CURRENTS; EXPLODING WIRES; IMPLOSIONS; LONGITUDINAL PINCH; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; PLASMA; PLASMA INSTABILITY; PLASMA SIMULATION; X RADIATION

Citation Formats

Jones, B., Deeney, C., McKenney, J.L., Garasi, C.J., Mehlhorn, T.A., Robinson, A.C., Wunsch, S.E., Coverdale, C.A., LePell, P.D., Bland, S.N., Lebedev, S.V., Chittenden, J.P., Bott, S.C., Ampleford, D.J., Palmer, J.B.A., Hall, G.N., Rapley, J., Oliver, B.V., Safronova, A.S., and Kantsyrev, V.. Seeded Perturbations in Wire Array Z-Pinches. United States: N. p., 2006. Web. doi:10.1063/1.2159320.
Jones, B., Deeney, C., McKenney, J.L., Garasi, C.J., Mehlhorn, T.A., Robinson, A.C., Wunsch, S.E., Coverdale, C.A., LePell, P.D., Bland, S.N., Lebedev, S.V., Chittenden, J.P., Bott, S.C., Ampleford, D.J., Palmer, J.B.A., Hall, G.N., Rapley, J., Oliver, B.V., Safronova, A.S., & Kantsyrev, V.. Seeded Perturbations in Wire Array Z-Pinches. United States. doi:10.1063/1.2159320.
Jones, B., Deeney, C., McKenney, J.L., Garasi, C.J., Mehlhorn, T.A., Robinson, A.C., Wunsch, S.E., Coverdale, C.A., LePell, P.D., Bland, S.N., Lebedev, S.V., Chittenden, J.P., Bott, S.C., Ampleford, D.J., Palmer, J.B.A., Hall, G.N., Rapley, J., Oliver, B.V., Safronova, A.S., and Kantsyrev, V.. Thu . "Seeded Perturbations in Wire Array Z-Pinches". United States. doi:10.1063/1.2159320.
@article{osti_20729296,
title = {Seeded Perturbations in Wire Array Z-Pinches},
author = {Jones, B. and Deeney, C. and McKenney, J.L. and Garasi, C.J. and Mehlhorn, T.A. and Robinson, A.C. and Wunsch, S.E. and Coverdale, C.A. and LePell, P.D. and Bland, S.N. and Lebedev, S.V. and Chittenden, J.P. and Bott, S.C. and Ampleford, D.J. and Palmer, J.B.A. and Hall, G.N. and Rapley, J. and Oliver, B.V. and Safronova, A.S. and Kantsyrev, V.},
abstractNote = {Controlled seeding of perturbations is employed to study the evolution of wire array z-pinch implosion instabilities which strongly impact x-ray production when the 3D plasma stagnates on axis. Wires modulated in radius exhibit locally enhanced magnetic field and imploding bubble formation at discontinuities in wire radius due to the perturbed current path. Wires coated with localized spectroscopic dopants are used to track turbulent material flow. Experiments and MHD modeling offer insight into the behavior of z-pinch instabilities.},
doi = {10.1063/1.2159320},
journal = {AIP Conference Proceedings},
number = 1,
volume = 808,
place = {United States},
year = {Thu Jan 05 00:00:00 EST 2006},
month = {Thu Jan 05 00:00:00 EST 2006}
}
  • The impact of 3D structure on wire array z-pinch dynamics is a topic of current interest, and has been studied by the controlled seeding of wire perturbations. First, Al wires were etched at Sandia, creating 20% radial perturbations with variable axial wavelength. Observations of magnetic bubble formation in the etched regions during experiments on the MAGPIE accelerator are discussed and compared to 3D MHD modeling. Second, thin NaF coatings of 1 mm axial extent were deposited on Al wires and fielded on the Zebra accelerator. Little or no axial transport of the NaF spectroscopic dopant was observed in spatially resolvedmore » K-shell spectra, which places constraints on particle diffusivity in dense z-pinch plasmas. Finally, technology development for seeding perturbations is discussed.« less
  • Controlled seeding of perturbations is employed to study the evolution of wire array z-pinch implosion instabilities which strongly impact x-ray production when the 3D plasma stagnates on axis. Wires modulated in radius exhibit locally enhanced magnetic field and imploding bubble formation at discontinuities in wire radius due to the perturbed current path. Wires coated with localized spectroscopic dopants are used to track turbulent material flow. Experiments and MHD modeling offer insight into the behavior of z-pinch instabilities.
  • X-pinch radiography was used to analyze the interaction between streams of coronal plasma and on-axis foam targets in wire array z-pinch experiments on the MAGPIE generator (1 MA,240 ns). The implosion of the x-pinch, used in place of a current return conductor to the load, provided a short (<2 s) small ({approx}5 {mu}m) intense burst of soft x-rays, ideal for point projection backlighting. Timimg of the x-pinch was adjusted via the mass of its wires, allowing us to study the evolution of the foam during the experiment. Choice of the x-pinch materials, filters, and recording film determined the probing radiation,more » and hence the plasma/foam densities were resolved. Quantitative results will be discussed.« less
  • We are investigating several techniques to obtain time-dependent magnetic field measurements in wire-array Z-pinches and X-pinches. One general approach is to use 'remote sensing' methods whereby a very small sensor material is placed in the plasma and then is investigated to extract useful information. Faraday rotation of polarized laser light traversing a small area through thin film waveguides coupled to a fine optical fiber is a possibility. While these films may not survive for long in a dense Z-pinch, they may provide useful information for a significant fraction of the current pulse. We also discuss results of experiments conducted usingmore » magnetic CoPt thin films to obtain the maximum magnetic field seen by the film near the end of the load current pulse.« less