2-D Numerical Simulation of Nested Z-Pinch Powered from Disk Magneto-Cumulative Generator

Developed in RFNC-VNIIEF pulsed energy source, based on ten-elements disk (of 240 mm diameter) magneto-cumulative generator (DMCG-240) with electro- explosive foil current opening switch (EFOS), makes it possible to form a current pulse having an amplitude up to ~20 MA and a rise time of-1-1.5 mus in a liner load. Available experimental data on K-line generation of different chemical elements using gas-puff and multi-wire Z-pinches at long (0.8 mus-1 mus) implosion times show that at these times for reproducibility and enhancement of generating X-ray power the liner system in the form of several nested cascades can be employed successfully. For effective conversion of the stored electromagnetic energy of the source into the kinetic energy of the imploding Z-pinch at sub-nanosecond current rise front the initial radius of the most-external cascade should be large enough (6-10 cm). In this paper we present the result of numerical simulation of the experiment at DMCG-240 with EFOS facility on soft X-ray radiation pulse generation in configuration of nested Z-pinch. The calculations are held on Eulerian difference grid in the frameworks of two- dimensional (in r-z plane) radiation magnetic hydrodynamics (RMHD) taking into account equations of electro-technical circuit.

I. Problem Statement

In the considered experiment the nested liner load, located into a vacuum cylindrical chamber with a radius cm, consists of two cylindrical coaxially embedded multi-wire arrays. Initially the outer assembly is located on the radius cm and consists of tungsten wires of diameter with length cm and has a total mass mg; the inner assembly is located on the radius cm and consists of similar wires. Selected ratios of the cascades parameters, where an outer liner is twice heavier than the inner one and is located on twice as much radius, are “classical” ratios and successfully tested in different Z-pinch experiments [3], [4].