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Title: Effect of trailing mass on scaling of X-ray power in wire array Z-pinches

Abstract

At the time of the X-ray pulse a fraction of the total current remains in a low density trailing plasma surrounding the stagnated plasma column. The corresponding reduction of the magnetic energy delivered to the radiating pinch affects the radiation power. In a model presented in this paper we assume that the division of current between the pinch and the trailing mass is controlled by the onset of ion acoustic turbulence in the trailing plasma. We will discuss the scaling of the radiation power with the amplitude and rise-time of the current, with array diameter and mass predicted by the model, and compare predictions with experimental data from the Z facility.

Authors:
 [1];  [2]; ;  [3]
  1. Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)
  2. Laboratory of Plasma Studies, Cornell University, Ithaca, NY 14853 (United States)
  3. Sandia National Laboratories, Albuquerque, NM 87185-1193 (United States)
Publication Date:
OSTI Identifier:
20729299
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: 10.1063/1.2159323; (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; AMPLITUDES; COMPARATIVE EVALUATIONS; ELECTRIC CURRENTS; EXPLODING WIRES; ION ACOUSTIC WAVES; IONS; LINEAR Z PINCH DEVICES; LONGITUDINAL PINCH; PLASMA; PLASMA DENSITY; PULSE RISE TIME; PULSES; TURBULENCE; X RADIATION

Citation Formats

Lebedev, S.V., Hammer, D.A., Cuneo, M.E., and Sinars, D.B. Effect of trailing mass on scaling of X-ray power in wire array Z-pinches. United States: N. p., 2006. Web. doi:10.1063/1.2159323.
Lebedev, S.V., Hammer, D.A., Cuneo, M.E., & Sinars, D.B. Effect of trailing mass on scaling of X-ray power in wire array Z-pinches. United States. doi:10.1063/1.2159323.
Lebedev, S.V., Hammer, D.A., Cuneo, M.E., and Sinars, D.B. Thu . "Effect of trailing mass on scaling of X-ray power in wire array Z-pinches". United States. doi:10.1063/1.2159323.
@article{osti_20729299,
title = {Effect of trailing mass on scaling of X-ray power in wire array Z-pinches},
author = {Lebedev, S.V. and Hammer, D.A. and Cuneo, M.E. and Sinars, D.B.},
abstractNote = {At the time of the X-ray pulse a fraction of the total current remains in a low density trailing plasma surrounding the stagnated plasma column. The corresponding reduction of the magnetic energy delivered to the radiating pinch affects the radiation power. In a model presented in this paper we assume that the division of current between the pinch and the trailing mass is controlled by the onset of ion acoustic turbulence in the trailing plasma. We will discuss the scaling of the radiation power with the amplitude and rise-time of the current, with array diameter and mass predicted by the model, and compare predictions with experimental data from the Z facility.},
doi = {10.1063/1.2159323},
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}
}
  • Abstract not provided.
  • X-ray production by imploding wire-array Z pinches is studied using radiation magnetohydrodynamics simulation. It is found that the density distribution created by ablating wire material influences both x-ray power production, and how the peak power scales with applied current. For a given array there is an optimum ablation rate that maximizes the peak x-ray power, and produces the strongest scaling of peak power with peak current. This work is consistent with trends in wire-array Z pinch x-ray power scaling experiments on the Z accelerator.
  • A multicolor, time-gated, soft x-ray pinhole imaging instrument is fielded as part of the core diagnostic set on the 25 MA Z machine [M. E. Savage et al., in Proceedings of the Pulsed Power Plasma Sciences Conference (IEEE, New York, 2007), p. 979] for studying intense wire array and gas puff Z-pinch soft x-ray sources. Pinhole images are reflected from a planar multilayer mirror, passing 277 eV photons with <10 eV bandwidth. An adjacent pinhole camera uses filtration alone to view 1-10 keV photons simultaneously. Overlaying these data provides composite images that contain both spectral as well as spatial information,more » allowing for the study of radiation production in dense Z-pinch plasmas. Cu wire arrays at 20 MA on Z show the implosion of a colder cloud of material onto a hot dense core where K-shell photons are excited. A 528 eV imaging configuration has been developed on the 8 MA Saturn generator [R. B. Spielman et al., and A. I. P. Conf, Proc. 195, 3 (1989)] for imaging a bright Li-like Ar L-shell line. Ar gas puff Z pinches show an intense K-shell emission from a zippering stagnation front with L-shell emission dominating as the plasma cools.« less
  • A systematic experimental study of annular aluminum-wire {ital Z}-pinches on a 20-TW electrical generator shows that the measured spatial characteristics and emitted x-ray power agree more closely with rad-hydro simulations when large numbers of wires are used. The measured x-ray power increases first slowly and then rapidly with decreasing interwire gap spacing. Simulations suggested that this increase reflects the transition from implosion of individual wire plasmas to one of an azimuthally symmetric plasma shell. In the plasma-shell regime, x-ray powers of 40TW are achieved. {copyright} {ital 1996 The American Physical Society.}