Wires Properties Z-Pinch Systems
Obtaining of Theoretical and Experimental Data on Transport Coefficients for the Wires Using in Z-Pinches Implosion
Tech Area / Field
- FUS-ICS/Inertial Confinement Systems/Fusion
8 Project completed
Senior Project Manager
Lapidus O V
Siberian Branch of RAS / Institute of High Current Electronics, Russia, Tomsk reg., Tomsk
- VNIITF, Russia, Chelyabinsk reg., Snezhinsk
- National Nuclear Security Administration U.S.Department of Energy, USA, MD, Germantown\nEcole Polytechnique Federale de Lausanne / Laboratoire de Physique de Milieux Ionisés, France, Palaiseau\nSandia National Laboratories, USA, NM, Albuquerque
The goal of the project is to create an experimental base and a software for simulation of the explosion and expansion of inpidual wires in wire arrays.
The prospects for using Z-pinches, and, in particular, wire arrays, in inertial confinement fusion became realistic after experiments performed at Sandia Laboratories (USA). As we further proceed to the region of parameters at which ICF becomes realizable with Z-pinches, magnetohydrodynamic simulation of imploding wire arrays allowing one to predict potentialities of one or another experimental scheme plays an increasingly important part. At the same time, it is impossible to perform MHD calculations of imploding wire arrays without knowledge of the dependences of the transport coefficients (conductivity) on the parameters of the current flowing through a wire for inpidual exploding wires.
The difficulties encountered in constructing these dependences are related to the features of the explosion of thin metal wires in vacuum. As an inpidual wire explodes, a plasma column with the density and temperature nonuniformly distributed in radius. The plasma near the plasma-vacuum interface is completely ionized and has a comparatively low density. At the same time, the material in small-radius regions (in the near-axis region) is in the double-phase state being a mixture of a liquid and a vapor. At present no analytical expression for the conductivity is available which could describe adequately the dependence of on temperature and density for all phase states existing simultaneously in an exploding wire. We suggest to estimate the conductivity of heavy metals such as tungsten by the parametric formula [Bakulin Yu.D., KouropatenkoV.F., Louchinsky A.V. Magnetohydrodynamic simulation of exploding wires,: Soviet Physics - Technical Physics, vol.20,1976]:
where s1 is the conductivity of the metal at normal density, F(T,d ) is a function of the order of unity, is the relative density of the material, scr is the conductivity at the critical point, and dcr is the density of the metal at the critical point. The quantity scr is determined based on experimental data. Earlier the authors of the project successfully used parametric expressions for conductivity in matrix form s = f (T,d ) in MHD calculations of the electrical explosion of aluminum and copper wires.
The work will be performed by teams from two institutions: the Institute of High Current Electronics of the RAN SD (Tomsk) and the All-Russian Research Institute of Technical Physics (Snezhinsk).
It is expected to obtain the following specific results:
• Based on experimental data, a conductivity matrix will be constructed for heavy metals in the region of phase-to-phase transitions at rise rates of the current through a wire of 1016-1017 A/(s.cm2);
• A two-dimensional MHD code will be developed to simulate the behavior of inpidual wires in a wire array with the use of the conductivity matrix obtained.
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