Evaluating emission characteristics of field emission cathodes over long pulse durations

The cathode test stand (CTS) at LANL is designed for voltages up to 500kV and utilizes a PFN which can deliver pulse durations up to 2.6 μs. We are able to measure the emission characteristics of various field emitters on the CTS over a large range of long pulse lengths. Diagnostics include cathode emission imaging, current density (J(x,y)) and emittance measurements with a scintillator coupled with a pepperpot mask and temporal characterization with B-dots and E-dots. In addition, a multi-frame camera has been employed, providing the ability to track J(x,y) on the scintillator throughout time. Here, we will show the extracted characteristics of a given cathode material for several pulse durations. In addition, we describe the correlation between the beam brightness and cathode material.