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Title: Effect of the axial magnetic field on a metallic gas-puff pinch implosion

Abstract

The effect of an axial magnetic field B{sub z} on an imploding metallic gas-puff Z-pinch was studied using 2D time-gated visible self-emission imaging. Experiments were performed on the IMRI-5 generator (450 kA, 450 ns). The ambient field B{sub z} was varied from 0.15 to 1.35 T. It was found that the initial density profile of a metallic gas-puff Z-pinch can be approximated by a power law. Time-gated images showed that the magneto-Rayleigh–Taylor instabilities were suppressed during the run-in phase both without axial magnetic field and with axial magnetic field. Helical instability structures were detected during the stagnation phase for B{sub z} < 1.1 T. For B{sub z} = 1.35 T, the pinch plasma boundary was observed to be stable in both run-in and stagnation phases. When a magnetic field of 0.3 T was applied to the pinch, the soft x-ray energy was about twice that generated without axial magnetic field, mostly due to longer dwell time at stagnation.

Authors:
; ; ; ;  [1];  [1];  [2];  [3]
  1. Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk 634055 (Russian Federation)
  2. (Russian Federation)
  3. Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States)
Publication Date:
OSTI Identifier:
22600143
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 23; Journal Issue: 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; DENSITY; EMISSION; HELICAL INSTABILITY; IMAGES; IMPLOSIONS; MAGNETIC FIELDS; PLASMA; RAYLEIGH-TAYLOR INSTABILITY; SOFT X RADIATION; STAGNATION; TWO-DIMENSIONAL SYSTEMS

Citation Formats

Rousskikh, A. G., Zhigalin, A. S., Frolova, V., Yushkov, G. Yu., Baksht, R. B., Oreshkin, V. I., Tomsk Polytechnic University, Tomsk 634050, and Velikovich, A. L.. Effect of the axial magnetic field on a metallic gas-puff pinch implosion. United States: N. p., 2016. Web. doi:10.1063/1.4953048.
Rousskikh, A. G., Zhigalin, A. S., Frolova, V., Yushkov, G. Yu., Baksht, R. B., Oreshkin, V. I., Tomsk Polytechnic University, Tomsk 634050, & Velikovich, A. L.. Effect of the axial magnetic field on a metallic gas-puff pinch implosion. United States. doi:10.1063/1.4953048.
Rousskikh, A. G., Zhigalin, A. S., Frolova, V., Yushkov, G. Yu., Baksht, R. B., Oreshkin, V. I., Tomsk Polytechnic University, Tomsk 634050, and Velikovich, A. L.. 2016. "Effect of the axial magnetic field on a metallic gas-puff pinch implosion". United States. doi:10.1063/1.4953048.
@article{osti_22600143,
title = {Effect of the axial magnetic field on a metallic gas-puff pinch implosion},
author = {Rousskikh, A. G. and Zhigalin, A. S. and Frolova, V. and Yushkov, G. Yu. and Baksht, R. B. and Oreshkin, V. I. and Tomsk Polytechnic University, Tomsk 634050 and Velikovich, A. L.},
abstractNote = {The effect of an axial magnetic field B{sub z} on an imploding metallic gas-puff Z-pinch was studied using 2D time-gated visible self-emission imaging. Experiments were performed on the IMRI-5 generator (450 kA, 450 ns). The ambient field B{sub z} was varied from 0.15 to 1.35 T. It was found that the initial density profile of a metallic gas-puff Z-pinch can be approximated by a power law. Time-gated images showed that the magneto-Rayleigh–Taylor instabilities were suppressed during the run-in phase both without axial magnetic field and with axial magnetic field. Helical instability structures were detected during the stagnation phase for B{sub z} < 1.1 T. For B{sub z} = 1.35 T, the pinch plasma boundary was observed to be stable in both run-in and stagnation phases. When a magnetic field of 0.3 T was applied to the pinch, the soft x-ray energy was about twice that generated without axial magnetic field, mostly due to longer dwell time at stagnation.},
doi = {10.1063/1.4953048},
journal = {Physics of Plasmas},
number = 6,
volume = 23,
place = {United States},
year = 2016,
month = 6
}
  • The four-frame high-speed electrooptical camera backed by an automatic image capturing and processing system has been used to investigate the evolution of the gas-puff Z-pinch. The sequence of four images of the pinch continuum radiation (the exposure of each frame was 1 ns, the time separation of frames was 10 or 20 ns) enabled the study of the pinch-forming phase (zipper effect, compression), the stagnation of plasma on the axis, as well as the pinch decay (disintegration, collapsing of the plasma column) and the determination of the velocities of individual processes.
  • An argon annular puff-gas z-pinch has been experimentally investigated during the early phase of the current pulse using a magnetic flux probe and streak interferometry. The current is seen to follow the flared outer edge of the gas jet and to be returned primarily at axial positions z<15 mm by six posts supporting the wire mesh anode. A theoretical estimate of the skin depth agrees with the measured approx.1-cm thickness of the current sheath. The electron to neutral density ratio is determined to be peaked both near the posts and near the cathode.
  • This paper presents the physical characteristics of the z-pinch implosion plasma. Experiments were carried out on a small gas-puff z-pinch plasma device. A three-frame Mach-Zehnder interferometer was developed to measure implosion plasma. Some important physical parameters of plasma implosion process were obtained. At the same time, the soft x-ray energy spectra range from 0.2 {approx} 1.5 keV and the energy spectra of ion beam emitted from the z-pinch plasma were measured.
  • Experiments on the Z accelerator with deuterium gas puff implosions have produced up to 3.9x10{sup 13} ({+-}20%) neutrons at 2.34 MeV ({+-}0.10 MeV). Experimentally, the mechanism for generating these neutrons has not been definitively identified through isotropy measurements, but activation diagnostics suggest multiple mechanisms may be responsible. One-, two-, and three-dimensional magnetohydrodynamic (MHD) calculations have indicated that thermonuclear outputs from Z could be expected to be in the (0.3-1.0)x10{sup 14} range. X-ray diagnostics of plasma conditions, fielded to look at dopant materials in the deuterium, have shown that the stagnated deuterium plasma achieved electron temperatures of 2.2 keV and ionmore » densities of 2x10{sup 20} cm{sup -3}, in agreement with the MHD calculations.« less
  • We have performed [ital Z]-pinch experiments in which an aluminum plasma jet is imploded onto a coaxial, micrometer-diameter wire. X-ray pinhole images and temporally resolved x-ray data indicate that energy is initially supplied to the aluminum plasma jet, then transferred to the wire at the peak compression of the implosion. When a dc magnetic field is applied axially, growth of instabilities of the imploding aluminum plasma are reduced, and the production of x rays from the embedded wire is enhanced. These experiments demonstrate that an imploding plasma liner efficiently couples energy from a pulsed power generator into a micrometer-sized-diameter channel.