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Title: Evidence and mechanisms of axial-radiation asymmetry in dynamic hohlraums driven by wire-array Z pinches

Abstract

Dynamic hohlraums driven by arrays consisting of large numbers of tungsten wires in Z pinches exhibit differences in radiation emitted from REHs (radiation exit holes) symmetrically located at either end of the hohlraum [Sanford et al., Phys. Plasmas 10, 1187 (2003)]. Significantly greater peak power is radiated from the top (anode) REH relative to the bottom (cathode) REH. Spectral measurements of tungsten M-shell emission (2-2.4 keV) indicate the peak radiated power from either REH anticorrelates with the fraction of wire-array tungsten plasma inferred to sweep across (or into the field of view of) the REH near the time of peak axial emission. In all cases, greater M-shell emission relative to the total emission in the band 1.4-4 keV is measured at the bottom REH in comparison to the top REH. The decrease in peak power radiated from the bottom REH relative to the top appears to be due, in part, to an increase in localized opacity arising from the presence of increased wire-array tungsten plasma near the bottom REH. The asymmetry in both peak axial power and pulse shape is largely removed by adding two thin annular pedestals extending 3 mm into the anode-cathode gap from either electrode, just radiallymore » outboard of the REHs. The pedestals are designed to prevent the radial flow of tungsten plasma from prematurely crossing the REHs. A polarity effect [Sarkisov et al., Phys. Rev. E 66, 046413(6) (2002)] during wire initiation may offer one possible explanation for the underlying cause of such a tungsten-related axial power asymmetry.« less

Authors:
; ; ; ; ; ; ; ; ; ;  [1]
  1. Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)
Publication Date:
OSTI Identifier:
20698343
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 12; Journal Issue: 2; Other Information: DOI: 10.1063/1.1850479; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; EMISSION; EXPLODING WIRES; LONGITUDINAL PINCH; M SHELL; PLASMA; PLASMA DIAGNOSTICS; TUNGSTEN

Citation Formats

Sanford, T W.L., Nash, T J, Mock, R C, Peterson, D L, Watt, R G, Chrien, R E, Apruzese, J P, Clark, R W, Roderick, N F, Sarkisov, G S, Haines, M G, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, Naval Research Laboratory, Washington, DC 20375, University of New Mexico, Albuquerque, New Mexico 87131, Ktech Corporation, Albuquerque, 1030 Eubank Boulevard, Albuquerque, New Mexico 87123, and Blackett Laboratory, Imperial College, London SW7 2BZ. Evidence and mechanisms of axial-radiation asymmetry in dynamic hohlraums driven by wire-array Z pinches. United States: N. p., 2005. Web. doi:10.1063/1.1850479.
Sanford, T W.L., Nash, T J, Mock, R C, Peterson, D L, Watt, R G, Chrien, R E, Apruzese, J P, Clark, R W, Roderick, N F, Sarkisov, G S, Haines, M G, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, Naval Research Laboratory, Washington, DC 20375, University of New Mexico, Albuquerque, New Mexico 87131, Ktech Corporation, Albuquerque, 1030 Eubank Boulevard, Albuquerque, New Mexico 87123, & Blackett Laboratory, Imperial College, London SW7 2BZ. Evidence and mechanisms of axial-radiation asymmetry in dynamic hohlraums driven by wire-array Z pinches. United States. https://doi.org/10.1063/1.1850479
Sanford, T W.L., Nash, T J, Mock, R C, Peterson, D L, Watt, R G, Chrien, R E, Apruzese, J P, Clark, R W, Roderick, N F, Sarkisov, G S, Haines, M G, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, Naval Research Laboratory, Washington, DC 20375, University of New Mexico, Albuquerque, New Mexico 87131, Ktech Corporation, Albuquerque, 1030 Eubank Boulevard, Albuquerque, New Mexico 87123, and Blackett Laboratory, Imperial College, London SW7 2BZ. 2005. "Evidence and mechanisms of axial-radiation asymmetry in dynamic hohlraums driven by wire-array Z pinches". United States. https://doi.org/10.1063/1.1850479.
@article{osti_20698343,
title = {Evidence and mechanisms of axial-radiation asymmetry in dynamic hohlraums driven by wire-array Z pinches},
author = {Sanford, T W.L. and Nash, T J and Mock, R C and Peterson, D L and Watt, R G and Chrien, R E and Apruzese, J P and Clark, R W and Roderick, N F and Sarkisov, G S and Haines, M G and Los Alamos National Laboratory, Los Alamos, New Mexico 87545 and Naval Research Laboratory, Washington, DC 20375 and University of New Mexico, Albuquerque, New Mexico 87131 and Ktech Corporation, Albuquerque, 1030 Eubank Boulevard, Albuquerque, New Mexico 87123 and Blackett Laboratory, Imperial College, London SW7 2BZ},
abstractNote = {Dynamic hohlraums driven by arrays consisting of large numbers of tungsten wires in Z pinches exhibit differences in radiation emitted from REHs (radiation exit holes) symmetrically located at either end of the hohlraum [Sanford et al., Phys. Plasmas 10, 1187 (2003)]. Significantly greater peak power is radiated from the top (anode) REH relative to the bottom (cathode) REH. Spectral measurements of tungsten M-shell emission (2-2.4 keV) indicate the peak radiated power from either REH anticorrelates with the fraction of wire-array tungsten plasma inferred to sweep across (or into the field of view of) the REH near the time of peak axial emission. In all cases, greater M-shell emission relative to the total emission in the band 1.4-4 keV is measured at the bottom REH in comparison to the top REH. The decrease in peak power radiated from the bottom REH relative to the top appears to be due, in part, to an increase in localized opacity arising from the presence of increased wire-array tungsten plasma near the bottom REH. The asymmetry in both peak axial power and pulse shape is largely removed by adding two thin annular pedestals extending 3 mm into the anode-cathode gap from either electrode, just radially outboard of the REHs. The pedestals are designed to prevent the radial flow of tungsten plasma from prematurely crossing the REHs. A polarity effect [Sarkisov et al., Phys. Rev. E 66, 046413(6) (2002)] during wire initiation may offer one possible explanation for the underlying cause of such a tungsten-related axial power asymmetry.},
doi = {10.1063/1.1850479},
url = {https://www.osti.gov/biblio/20698343}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 2,
volume = 12,
place = {United States},
year = {Tue Feb 01 00:00:00 EST 2005},
month = {Tue Feb 01 00:00:00 EST 2005}
}