Coupling power flow from the mercury MIVA into a rod-pinch diode

The mercury machine at NRL, formerly known as KALIF-HELIA [P. Hoppe et al., June 17-22, 2001] at Forschungszentrum Karlsruhe (Germany), is a magnetically-insulated inductive voltage adder (MIVA), nominally delivering a 50-ns, 6-MV, 360-kA, 2.2-TW power pulse into a 16-/spl Omega/ load [R. J. Commisso et al., R. J. Allen et al., P. F. Ottinger et al., 2003]. Mercury is capable of operating in both positive and negative polarities with little penalty in pulsed-power output. Polarity reversal is achieved by insertion of the tapered center conductor into the opposite end of the MIVA. In this work, particle-in-cell (PIC) simulations [B. Goplen et al., 1995; D. R. Welch et al., 2001] are used to investigate the power flow within the magnetically-insulated transmission line (MITL) in both polarities. Of particular importance is the efficiency of operation when an over-matched 50-/spl Omega/ rod-pinch-diode load is couple to the MITL, operated in either positive [G. Cooperstein et al., 2001] or negative [G. Cooperstein et al., 2003] polarity. Such a diode is used for radiographic applications because of the small, high brightness radiation source produced by the electron pinch at the end of the diode's anode rod [R. J. Commisso et al., 2002]. Simple positive and negative polarity diode geometries are studied in preparation for initial rod-pinch diode experiments on mercury.