Tungsten quasispherical wire loads with a profiled mass
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ALS AND TECHNOLOGIES FOR NEW POWER SOURCES
Tungsten Quasispherical Wire Loads with a Profiled Mass E. V. Grabovskii, V. V. Dzhangobegov*, G. M. Oleinik, and R. N. Rodionov State Research Center of the Russian Federation Troitsk Institute for Innovation and Fusion Research (TRINITI), ul. Pushkovykh 12, Troitsk, Moscow oblast, 142190 Russia *email: [email protected] Received February 16, 2015
Abstract—Wire arrays made from micrometer tungsten wires with linear mass profiled along their height are developed for experiments on the generation of Xray radiation upon pinch compression with a current of ~3 MA at a pulse duration of ~100 ns. Wires are imaged with a scanning electron microscope, and their diam eter is determined. It is shown that the arrays have such a profile of height distribution of linear mass that allows for compact spherical compression upon current implosion. Keywords: Zpinch, wire array, current implosion, Xray radiation, cathode sputtering. DOI: 10.1134/S1063778815140070
INTRODUCTION The advances in compression of cylindrical assem blies of micrometer wires (wire arrays) with highcur rent units that are used to generate intense Xray radiation pulses [1] stimulated the interest in study ing the Zpinch discharge as an energy driver for dif ferent setups implementing inertial confinement fusion (ICF) [2, 3]. The experiments on target irradi ation in the “double liner” (“dynamic hohlraum”) setup that were conducted at the Z machine (Sandia National Laboratories, United States) yielded impres sive results: an energy of 20 kJ was absorbed by a spher ical target with a size of 1.7 mm [3]. However, ICF requires a target exposure of about 2.5 MJ/cm2 [4]. The results of calculations detailed in [5] showed that the radiation intensity obtained by current compres sion in a quasispherical “double liner” system may be increased by a factor of 4–5 relative to that in the case of compression in cylindrical geometry. This effect is achieved as a result of additional axial cumulation of kinetic energy of plasma fluxes upon quasispherical implosion. Quasispherical wire arrays (QWAs) are often fabri cated by elongating electrostatically the wires of an initially cylindrical load [6–8]. However, it was shown in [5] that compact spherical implosion requires the unit load surface mass mS to vary with poloidal angle θ as mS ~ sin–2(θ). A technique for depositing additional amounts of material onto certain sections of the liner wires by vacuum thermal sputtering was developed at the Troitsk Institute for Innovation and Fusion Research in order to fabricate loads with a profiled mass [7]. A disadvantage of this technique is that only lowmeltingpoint metals (bismuth, aluminum, or indium) may be used as the sputtered material, while
loads are made primarily from tungsten wires. The resulting QWAs are made of two materials that differ considerably in their physical properties. TUNGSTEN QWAS WITH A PROFILED MASS We propose a radically new technique for the fabri cation of tungsten wire arrays with linear mas
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