Characterization of electron and ion current flow in very large aspect-ratio terawatt diodes employing heated and unheated anodes

Electron-beam-focusing experiments using tapered hollow cathodes have been performed at power levels exceeding 1012 W and with diode aspect ratios (radius/anode-cathode spacing) of 24 and 45 (uncorrected for plasma motion). The spatial distributions of both the electron (using collimated p-i-n diodes) and ion currents (using quartz pressure gauges and Faraday cups) were measured simultaneously. Efficient electron-beam pinches were produced at large R/d (approx. =24) using a diode configuration that employed a small-diameter cathode and heated anode