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Title: Increase in the energy density of the pinch plasma in 3D implosion of quasi-spherical wire arrays

Abstract

Results are presented from experimental studies of the characteristics of the soft X-ray (SXR) source formed in the implosion of quasi-spherical arrays made of tungsten wires and metalized kapron fibers. The experiments were carried out at the Angara-5-1 facility at currents of up to 3 MA. Analysis of the spatial distribution of hard X-ray emission with photon energies above 20 keV in the pinch images taken during the implosion of quasi-spherical tungsten wire arrays (QTWAs) showed that a compact quasi-spherical plasma object symmetric with respect to the array axis formed in the central region of the array. Using a diffraction grazing incidence spectrograph, spectra of SXR emission with wavelengths of 20–400 Å from the central, axial, and peripheral regions of the emission source were measured with spatial resolutions along the array radius and height in the implosion of QTWAs. It is shown that the emission spectra of the SXR sources formed under the implosion of quasi-spherical and cylindrical tungsten wire arrays at currents of up to 3 MA have a maximum in the wavelength range of 50–150 Å. It is found that, during the implosion of a QTWA with a profiled linear mass, a redistribution of energy in the emissionmore » spectrum takes place, which indicates that, during 3D implosion, the energy of longitudinal motion of the array material additionally contributes to the radiation energy. It is also found that, at close masses of the arrays and close values of the current in the range of 2.4{sup −3} MA, the average energy density in the emission source formed during the implosion of a quasi-spherical wire array is larger by a factor of 7 than in the source formed during the implosion of a cylindrical wire array. The experimental data were compared with results of 3D simulations of plasma dynamics and radiation generation during the implosion of quasi-spherical wire arrays with a profiled mass by using the MARPLE-3D radiative magnetohydrodynamic code, developed at the Keldysh Institute of Applied Mathematics, Russian Academy of Sciences.« less

Authors:
 [1];  [2]; ; ; ; ;  [1];  [2]; ; ;  [1];  [3]
  1. Troitsk Institute for Innovation and Fusion Research (Russian Federation)
  2. Russian Academy of Sciences, Keldysh Institute of Applied Mathematics (Russian Federation)
  3. Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)
Publication Date:
OSTI Identifier:
22314723
Resource Type:
Journal Article
Resource Relation:
Journal Name: Plasma Physics Reports; Journal Volume: 40; Journal Issue: 12; Other Information: Copyright (c) 2014 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CYLINDRICAL CONFIGURATION; EMISSION SPECTRA; ENERGY DENSITY; EXPERIMENTAL DATA; HARD X RADIATION; IMPLOSIONS; PINCH EFFECT; PLASMA; SOFT X RADIATION; SPHERICAL CONFIGURATION; TUNGSTEN

Citation Formats

Aleksandrov, V. V., E-mail: alexvv@triniti.ru, Gasilov, V. A., Grabovski, E. V., Gritsuk, A. N., E-mail: griar@triniti.ru, Laukhin, Ya. N., Mitrofanov, K. N., Oleinik, G. M., Ol’khovskaya, O. G., Sasorov, P. V., Smirnov, V. P., Frolov, I. N., and Shevel’ko, A. P.. Increase in the energy density of the pinch plasma in 3D implosion of quasi-spherical wire arrays. United States: N. p., 2014. Web. doi:10.1134/S1063780X14110014.
Aleksandrov, V. V., E-mail: alexvv@triniti.ru, Gasilov, V. A., Grabovski, E. V., Gritsuk, A. N., E-mail: griar@triniti.ru, Laukhin, Ya. N., Mitrofanov, K. N., Oleinik, G. M., Ol’khovskaya, O. G., Sasorov, P. V., Smirnov, V. P., Frolov, I. N., & Shevel’ko, A. P.. Increase in the energy density of the pinch plasma in 3D implosion of quasi-spherical wire arrays. United States. doi:10.1134/S1063780X14110014.
Aleksandrov, V. V., E-mail: alexvv@triniti.ru, Gasilov, V. A., Grabovski, E. V., Gritsuk, A. N., E-mail: griar@triniti.ru, Laukhin, Ya. N., Mitrofanov, K. N., Oleinik, G. M., Ol’khovskaya, O. G., Sasorov, P. V., Smirnov, V. P., Frolov, I. N., and Shevel’ko, A. P.. Mon . "Increase in the energy density of the pinch plasma in 3D implosion of quasi-spherical wire arrays". United States. doi:10.1134/S1063780X14110014.
@article{osti_22314723,
title = {Increase in the energy density of the pinch plasma in 3D implosion of quasi-spherical wire arrays},
author = {Aleksandrov, V. V., E-mail: alexvv@triniti.ru and Gasilov, V. A. and Grabovski, E. V. and Gritsuk, A. N., E-mail: griar@triniti.ru and Laukhin, Ya. N. and Mitrofanov, K. N. and Oleinik, G. M. and Ol’khovskaya, O. G. and Sasorov, P. V. and Smirnov, V. P. and Frolov, I. N. and Shevel’ko, A. P.},
abstractNote = {Results are presented from experimental studies of the characteristics of the soft X-ray (SXR) source formed in the implosion of quasi-spherical arrays made of tungsten wires and metalized kapron fibers. The experiments were carried out at the Angara-5-1 facility at currents of up to 3 MA. Analysis of the spatial distribution of hard X-ray emission with photon energies above 20 keV in the pinch images taken during the implosion of quasi-spherical tungsten wire arrays (QTWAs) showed that a compact quasi-spherical plasma object symmetric with respect to the array axis formed in the central region of the array. Using a diffraction grazing incidence spectrograph, spectra of SXR emission with wavelengths of 20–400 Å from the central, axial, and peripheral regions of the emission source were measured with spatial resolutions along the array radius and height in the implosion of QTWAs. It is shown that the emission spectra of the SXR sources formed under the implosion of quasi-spherical and cylindrical tungsten wire arrays at currents of up to 3 MA have a maximum in the wavelength range of 50–150 Å. It is found that, during the implosion of a QTWA with a profiled linear mass, a redistribution of energy in the emission spectrum takes place, which indicates that, during 3D implosion, the energy of longitudinal motion of the array material additionally contributes to the radiation energy. It is also found that, at close masses of the arrays and close values of the current in the range of 2.4{sup −3} MA, the average energy density in the emission source formed during the implosion of a quasi-spherical wire array is larger by a factor of 7 than in the source formed during the implosion of a cylindrical wire array. The experimental data were compared with results of 3D simulations of plasma dynamics and radiation generation during the implosion of quasi-spherical wire arrays with a profiled mass by using the MARPLE-3D radiative magnetohydrodynamic code, developed at the Keldysh Institute of Applied Mathematics, Russian Academy of Sciences.},
doi = {10.1134/S1063780X14110014},
journal = {Plasma Physics Reports},
number = 12,
volume = 40,
place = {United States},
year = {Mon Dec 15 00:00:00 EST 2014},
month = {Mon Dec 15 00:00:00 EST 2014}
}
  • Results are presented from experimental studies of the spatial distribution of the density of matter in the central part of the discharge gap and the formation of the temporal profile of the X-ray power in the course of implosion of quasi-spherical wire arrays at discharge currents of up to 4 MA. The spatial distribution of the X-ray intensity in the central part of the discharge gap and the temporal profile of the X-ray power are used as implosion characteristics of quasi-spherical wire arrays. The quasi-spherical arrays were formed by the radial stretching of unstrained wires of initially cylindrical and conicalmore » wire arrays under the action of the electrostatic field. The temporal profile of the output X-ray pulse in the photon energy range of 0.1-1 keV is shown to depend on both the geometrical parameters of the quasi-spherical array and the longitudinal distribution of its mass. It is found that a 40% increase in the wire mass due to deposition of an additional mass in the equatorial region of a quasi-spherical array leads to a 15% increase in the average current radius of the pinch and a 30% decrease in the X-ray yield. Experiments with quasi-spherical arrays made of kapron fibers with deposited Al and Bi conducting layers were also carried out. It is demonstrated that application of such arrays makes it possible to control the profile and duration of the generated X-ray pulse by varying the mass, material, and location of the deposited layer. It is found that deposition of an additional mass in the form of a thin Bi stripe on tungsten wires near the cathode end of the array allows one to mitigate the influence of the cathode zipper effect on the pinch compression and formation of the X-ray pulse in tungsten arrays.« less
  • Quasi-spherical (QS) implosion of wire arrays and its impact on the foam target have been studied on the 100 ns 1.5 MA Qiangguang-I facility, which suggests that a high quality impact between the QS implosion and foam target can be achieved by adjusting load's initial shape carefully to match the external magnetic pressure. Implosions of loads with H/d ∼ 1.2 were studied with a self-emission x-ray pinhole image system and a dark field schlieren system. The radially developed spike-like instabilities indicate the spherical convergence of plasma. The observed radiation on the foam target surface suggests satisfying implosion symmetry and wire-foam impact simultaneity. Anmore » average implosion speed of 10.5 × 10{sup 6 }cm/s was obtained with an optical streak image system. The derived peak kinetic energy density ∼2.1 kJ/cm is remarkably higher than cylindrical cases, which agree with the expectations.« less
  • We describe {ital Z}-pinch experiments imploding an aluminum-plasma jet onto a coaxial, micron-diameter wire. Spatially resolved x-ray pinhole images and time resolved x-ray data indicate that energy is supplied initially to the aluminum-jet plasma and subsequently transferred to the wire. The resultant pinch appears more uniform (stable) than a wire-only or jet-only pinch and demonstrates that an imploding-plasma liner will couple energy from a pulsed-power generator to a micron-diameter-sized plasma channel.
  • The study of implosion dynamics and spectroscopy of X-pinches and wire arrays with Al wires alloyed or coated with other near-Z or higher-Z materials is discussed. In particular, X-pinches from two combined Al 5056 and Mo wires and composed from four identical Al 5056 (5%Mg) wires and Cu clad Al (90% Al and 10%Cu) are studied. In addition, wire arrays with Alumel wires (95% Ni and 5% Al) and with Al 5056 wires (uncoated) and coated with 5% NaF are investigated. Spatially-resolved and integrated x-ray spectral data and time integrated and time-gated pinhole x-ray images accumulated in these X-pinch andmore » wire array experiments on the UNR 1MA Zebra generator are analyzed. Modeling of K-shell radiation from Mg provides K-shell plasma parameters for all Al 5056 wire experiments, whereas modeling of L-shell radiation from Ni, Cu, and Mo provide parameters for L-shell plasmas. The importance of using different materials or dopants for understanding of implosion dynamics of different wire materials is illustrated.« less
  • Results are presented from time-integrated measurements of soft X-ray emission from Z-pinches during the implosion of simple and nested wire arrays. The blackening density distribution obtained with the help of a pinhole camera is recalculated into the time-integrated Z-pinch radiance. It is found that, in the case of a simple wire array, up to 70% of the total SXR energy emitted during a discharge is radiated from the axial region, the rest of energy being radiated from plasma jets, whereas in the case of a nested wire array, more than 90% of the SXR energy is radiated from the axialmore » region.« less