Implosion dynamics of condensed Z-pinch at the Angara-5-1 facility
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MA DYNAMICS
Implosion Dynamics of Condensed Z-Pinch at the Angara-5-1 Facility V. V. Aleksandrovа, E. V. Grabovskiа, A. N. Gritsukа, I. V. Volobuevb, E. D. Kazakovc, Yu. G. Kalininc, V. D. Korolevc*, Ya. I. Laukhinа, S. F. Medovshchikovа, K. N. Mitrofanovа, G. M. Oleinikа, V. G. Pimenovd, E. A. Smirnovac, G. I. Ustroevc, and I. N. Frolovа а
Troitsk Institute for Innovation and Fusion Research, Troitsk, Moscow, 142190 Russia b Lebedev Physical Institute, Russian Academy of Sciences, Moscow, 119991 Russia c National Research Center “Kurchatov Institute,” Moscow, 123182 Russia d Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, 119991 Russia *e-mail: [email protected] Received November 14, 2016; in final form, February 3, 2017
Abstract―The implosion dynamics of a condensed Z-pinch at load currents of up to 3.5 MA and a current rise time of 100 ns was studied experimentally at the Angara-5-1 facility. To increase the energy density, 1- to 3-mm-diameter cylinders made of a deuterated polyethylene−agar-agar mixture or microporous deuterated polyethylene with a mass density of 0.03–0.5 g/cm3 were installed in the central region of the loads. The plasma spatiotemporal characteristics were studied using the diagnostic complex of the Angara-5-1 facility, including electron-optical streak and frame imaging, time-integrated X-ray imaging, soft X-ray (SXR) measurements, and vacuum UV spectroscopy. Most information on the plasma dynamics was obtained using a ten-frame X-ray camera (Е > 100 eV) with an exposure of 4 ns. SXR pulses were recorded using photoemissive vacuum X-ray detectors. The energy characteristics of neutron emission were measured using the time-offlight method with the help of scintillation detectors arranged along and across the pinch axis. The neutron yield was measured by activation detectors. The experimental results indicate that the plasma dynamics depends weakly on the load density. As a rule, two stages of plasma implosion were observed. The formation of hot plasma spots in the initial stage of plasma expansion from the pinch axis was accompanied by short pulses of SXR and neutron emission. The neutron yield reached (0.4–3) × 1010 neutrons/shot and was almost independent of the load density due to specific features of Z-pinch dynamics. DOI: 10.1134/S1063780X17080025
1. INTRODUCTION According to theoretical estimates [1, 2], in order for the thermonuclear reaction to be ignited in the Z-pinch neck and then to expand over the entire pinch, it is sufficient to transmit a current of 10 MA through a 1-mm-diameter column made of a condensed D–T mixture with a mass density of 0.2 g/cm3. To experimentally verify these estimates, as well as to study the possibility of creating hot dense plasma by means of small-size condensed loads imploding under the action of megampere currents, we have performed a series of experiments. Thus, experiments on the implosion of microheterogeneous solid loads at currents of 2–3 MA and a current rise time of 100 ns [3– 5] made it possible to match the
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