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Title: The inverse skin effect in the Z-pinch and plasma focus

Abstract

The inverse skin effect and its influence on the dynamics of high-current Z-pinch and plasma focus discharges in deuterium are analyzed. It is shown that the second compression responsible for the major fraction of the neutron yield can be interpreted as a result of the inverse skin effect resulting in the axial concentration of the longitudinal current density and the appearance of a reversed current in the outer layers of plasma pinches. Possible conditions leading to the enhancement of the inverse skin effect and accessible for experimental verification by modern diagnostics are formulated.

Authors:
;  [1]
  1. Russian Federal Nuclear Center—All-Russian Research Institute of Experimental Physics (Russian Federation)
Publication Date:
OSTI Identifier:
22614093
Resource Type:
Journal Article
Resource Relation:
Journal Name: Plasma Physics Reports; Journal Volume: 42; Journal Issue: 8; Other Information: Copyright (c) 2016 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; COMPRESSION; CONCENTRATION RATIO; CURRENT DENSITY; DEUTERIUM; LAYERS; LINEAR Z PINCH DEVICES; NEUTRONS; PLASMA FOCUS; SKIN EFFECT

Citation Formats

Usenko, P. L., E-mail: otd4@expd.vniief.ru, and Gaganov, V. V. The inverse skin effect in the Z-pinch and plasma focus. United States: N. p., 2016. Web. doi:10.1134/S1063780X16080109.
Usenko, P. L., E-mail: otd4@expd.vniief.ru, & Gaganov, V. V. The inverse skin effect in the Z-pinch and plasma focus. United States. doi:10.1134/S1063780X16080109.
Usenko, P. L., E-mail: otd4@expd.vniief.ru, and Gaganov, V. V. 2016. "The inverse skin effect in the Z-pinch and plasma focus". United States. doi:10.1134/S1063780X16080109.
@article{osti_22614093,
title = {The inverse skin effect in the Z-pinch and plasma focus},
author = {Usenko, P. L., E-mail: otd4@expd.vniief.ru and Gaganov, V. V.},
abstractNote = {The inverse skin effect and its influence on the dynamics of high-current Z-pinch and plasma focus discharges in deuterium are analyzed. It is shown that the second compression responsible for the major fraction of the neutron yield can be interpreted as a result of the inverse skin effect resulting in the axial concentration of the longitudinal current density and the appearance of a reversed current in the outer layers of plasma pinches. Possible conditions leading to the enhancement of the inverse skin effect and accessible for experimental verification by modern diagnostics are formulated.},
doi = {10.1134/S1063780X16080109},
journal = {Plasma Physics Reports},
number = 8,
volume = 42,
place = {United States},
year = 2016,
month = 8
}
  • The Lee model couples the electrical circuit with plasma focus dynamics, thermodynamics, and radiation. It is used to design and simulate experiments. A beam-target mechanism is incorporated, resulting in realistic neutron yield scaling with pinch current and increasing its versatility for investigating all Mather-type machines. Recent runs indicate a previously unsuspected 'pinch current limitation' effect. The pinch current does not increase beyond a certain value however low the static inductance is reduced to. The results indicate that decreasing the present static inductance of the PF1000 machine will neither increase the pinch current nor the neutron yield, contrary to expectations.
  • No abstract prepared.
  • The main point of the comment [Appl. Phys. Lett. 94, 076101 (2009)] is that Eq. (2) and consequentially Eq. (3) of the commented paper [Appl. Phys. Lett. 92, 021503 (2008)] require correction. The alternative equation suggested in the comment is derived using Kirchhoff's voltage rule. The comment consider only the energy distribution in the inductive components and the resultant equation confirms a progressive lowering of the I{sub pinch}/I{sub peak} ratio as the static inductance L{sub 0} is reduced, lowering from 0.87 to 0.31 as L{sub 0} is reduced from 100 to 5 nH according to the revised formula corresponding tomore » Eq. (3), compared to 0.63-0.25 according to Eq. (3). This progressive lowering of the ratio I{sub pinch}/I{sub peak} due to the inductive energy distribution is one of two factors responsible for the pinch current limitation. The other factor is the progressive reduction in the L-C interaction time compared to the current dip duration denoted by {delta}{sub cap} in Eq. (2). The comment does not deal with {delta}{sub cap} at all; hence, its conclusion based on inductive energy distribution only is not useful, since in the low L{sub 0} region when pinch current limitation begins to manifest, {delta}{sub cap} becomes more and more the dominant factor. In any case, the results of the paper do not depend on Eqs. (2) and (3), which are used in the paper only for illustrative purposes.« less
  • Correlation of neutron emission with pinch energy for a Mather-type plasma focus energized by a single capacitor 12.5 muF, 21 kV (2.7 kJ) is investigated by employing time resolved and time integrated detectors for two different anode shapes. The maximum average neutron yield of about 1.3x10{sup 8} per shot is recorded with cylindrical anode, that increases to 1.6x10{sup 8} per shot for tapered anode. At optimum pressure the input energy converted to pinch energy is about 24% for cylindrical anode as compared to 36% for tapered anode. It is found that the tapered anode enhances neutron flux about 25+-5% bothmore » in axial and radial directions and also broadens the pressure range for neutron emission as well as pinch energy. The neutron yield and optimum gas filling pressures are found strongly dependent on the anode shape.« less