Study of the implosion of foam-wire loads at the Angara-5-1 facility
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MA DYNAMICS
Study of the Implosion of Foam–Wire Loads at the Angara51 Facility K. N. Mitrofanov, E. V. Grabovski, V. V. Aleksandrov, I. N. Frolov, G. M. Oleinik, Ya. N. Laukhin, A. N. Gritsuk, P. V. Sasorov, and S. F. Medovshchikov Troitsk Institute for Innovation and Fusion Research, Troitsk, Moscow, 142190 Russia email: [email protected] Received April 12, 2012; in final form, June 18, 2012
Abstract—Results are presented from experiments on studying the compactness of compression of imploding nested foam–wire loads at currents of up to 4 MA at the Angara51 facility. The degree of pinch compression was estimated from the dynamics of the spatial distribution of the current (magnetic field) and the shape of the soft Xray pulse. The load consisted of nested cascades, one of which being a wire array and the other being a hollow or solid lowdensity cylinder made of agaragar foam with a wall thickness of 100–200 µm. In some experiments, one of the cascades was made of C20H17O6 solidstate organic acid foam. The radial dis tribution of the magnetic field inside the nested cascades of the imploding foam–wire load (both between the cascades and inside the inner cascade) was measured using tiny magnetic probes. The measured radial distri butions of the magnetic field are compared with the magnetic field configuration calculated using a one dimensional MHD code simulating the implosion of a nested foam–wire load. It is shown that the spatial structure of the current and magnetic field during the implosion of such a load is determined by the develop ment of supersonic and subsonic magnetized plasma flows in its cascades. The specific features of pinch for mation and methods for the compensation of the nonsimultaneous pinch compression between the anode and the cathode (the zipper effect) during the implosion of a nested foam–wire load are analyzed. DOI: 10.1134/S1063780X12110098
1. INTRODUCTION In the past two decades, substantial progress has been achieved in using highcurrent facilities for the implosion of wirearray loads with the purpose of gen erating high power Xray pulses [1–4]. The experi ments carried out at the Z facility (Sandia Laborato ries, United States) demonstrated that soft Xray (SXR) pulses (hν > 200 eV) with a duration of ~5– 8 ns, a power of ~280 TW, and an energy of ~1.8 MJ can be generated using wire arrays consisting of a large number of wires (more than 100) at a current of 20 MA. The SXR parameters achieved at the Z facility are close to those of the SXR pulse generated at the NIF highpower laser system designed at the Liver more National Laboratory (United States) for experi ments on the ignition of thermonuclear fuel in indi rectdrive targets [5]. These results encouraged further interest in studies of a Zpinch discharge as an energy driver for the compression of indirectdrive targets in different inertial confinement fusion (ICF) systems [6]. Promising Zpinchbased Xray sources [1–4] for the irradiation of thermonuclear targets have been studied within the ICF progr
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