Particle-in-cell simulations of electron flow in the post-hole convolute of the Z accelerator

The three-dimensional, particle-in-cell code QUICKSILVER [J. P. Quintenz , Lasers Part. Beams 12, 283 (1994)] is now being used to simulate the inner region of the Z accelerator [R. B. Spielman , Phys. Plasmas 5, 2105 (1998)] at Sandia National Laboratories. The simulations model electron flow and a node losses in the double post-hole convolute, which couples four radial, m agnetically insulated transmission lines (MITLs) in parallel to a single MI TL that drives a Z-pinch load. To efficiently handle the large range in the magnetic field, 0 <B < 200 T, the particle pusher is modified to subcycle the electron advance relative to the field solver. Results from a series of simulations using a constant-impedance load are presented. The locations o f electron losses to the anode in the convolute are in qualitative agreemen t with damage to the Z hardware. The electron energy deposited in these ano de regions rapidly heats the surface to temperatures above 400 degreesC-the threshold at which anode plasma formation is expected. (C) 2001 American I nstitute of Physics.