Comparison of the performance of the upgraded Z with circuit predictions

Since the completion of the ZR upgrade of the Z accelerator at the Sandia National Laboratories in the fall of 2007, many shots have been taken on the accelerator, and there has been much opportunity to compare circuit-code predictions of the performance of the machine with actual measurements. We therefore show comparisons of measurements, and describe a full-circuit, 36-line Bertha circuit model of the machine. The model has been used for both short-pulse and long-pulse (tailored pulse) modes of operation. We also present the as-built circuit parameters of the machine and indicate how these were derived. We discuss enhancements to the circuit model that include 2D effects in the water lines, but show that these have little effect on the fidelity of the simulations. Finally, we discuss how further improvements can be made to handle azimuthal coupling of the multiple lines at the vacuum insulator stack.