Emission characteristics for a diode with various cathode geometries *

The cathode test stand at LANL consists of a diode capable of voltages up to 500kV driven by a PFN capable of providing a 2.6us pulse. The test stand is used to evaluate field emission over a range in pulse length. Using diagnostic tools such as E-dots, B-dots, and a scintillator coupled with a pepperpot, we are able to measure the voltage, current, emittance, and distribution of the beam pulse. In order to optimize the current and emittance of the electron beam, Xenos is used to create different diode set-ups and different cathode geometries. The extracted current, emittance, current density, and various other parameters are then compared for different cathode geometries, recesses, and sizes. Experimental data collected on the test stand under similar circumstances is then compared to the simulated results.