Time-Resolved Voltage Measurements of Imploding Radiation Sources with a Vacuum Voltmeter at 6 MA

A vacuum-voltmeter (WM) 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 WM was mounted inside the conical, magnetically-insulated-transmission-line (MITL) structure, in the vacuum chamber above the load. This arrangement permitted the WM to directly measure the time-resolved voltage between the ground side of the 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 as the wire or gas-puff load implodes, namely, the inductance, L(t), net energy delivered to the load, E_n(t), and the load diameter, a(t). We report here the results of these tests for a fixed inductance short-circuit load, a 2-cm diameter wire-array 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 the radiation pulse.