Time-resolved voltage measurements of imploding radiation sources at 6 MA with a vacuum voltmeter

A vacuum-voltmeter[ 1 ] (VVM) was fielded on the Saturn pulsed-power generator during a series of 12-MA short-circuit, 6-MA aluminum wire-array z-pinch, and 6 MA argon Plasma Radiation Source (PRS) shots. The VVM was connected to the convolute structure in the vacuum chamber above the load. This arrangement permitted the VVM to directly measure the time-resolved voltage between the ground side of the magnetically insulated transmission line (MITL) anode and the negative high-voltage cathode feed to the load. The time-resolved voltage and the separately-measured load current are used to determine several dynamic properties during the wire or gas-puff load implosion, namely, the inductance, L(t), coupled energy delivered to the load, Ecoupled(t), and the load radius, r(t). We report here the results of these tests for a fixed inductance short-circuit load and a 12-cm diameter, argon gas-puff load. We correlate the time dependent electrical parameters with the radiation output from the imploding loads. In particular, we observe electrical energy being delivered to the pinch during and after the radiation pulse.[2][3]