Modelling the interaction of nested wire arrays in imploding Z-pinches

Summary form only given. We present the results of two dimensional magnetohydrodynamic simulations of nested array collisions. Results for nested tungsten arrays on the "Z" generator at Sandia National Laboratories, show that elements of all three modes are at work. The fraction of the circumference occupied by the exploded inner array wires determines the fraction of momentum transferred between arrays at collision. For large numbers of wires in the inner array, the momentum transfer is large and a hydrodynamic collision mode results. For much lower numbers of wires in the inner, the outer array material is free to pass through the gaps and a transparent inner mode results. In all cases, flux compression is found to enhance the level of momentum transfer. A zero dimensional model was modified to mock-up the different effects of nested array interactions and used to provide scaling of X-ray power with array diameters and masses. Maximum powers were obtained for the transparent inner mode with light inner arrays. However some artificial mechanism for limiting current flow in the inner array was required since flux compression appears to excite the Rayleigh-Taylor instability in the inner array.