Detailed Simulation of the CYGNUS

In this paper, we present the results from particle- in-cell simulations of the nominally 2-MV 40-kA CYGNUS ra- diographic machine using a standard rod pinch diode. The rod pinch electron-beam diode consists of a small-diameter high- atomic-number anode extending through a thin cathode aper- ture. A significant shot-to-shot variation of the photon spectrum emerging from the anode can introduce an error in interpreting the radiograph. We present the results from these integrated simulations of the electron and photon generation and quantify the sensitivities on the photon distribution. Index Terms—Bremsstrahlung, diodes, pulse power systems, simulation.