Physics Commons^™

Thermal Emittance And Lifetime Of Alkali-Antimonide Photocathodes Grown On Gaas And Molybdenum Substrates Evaluated In A -300 Kv Dc Photogun, Y. Wang, M. A. Mamun, P. Adderley, B. Bullard, J. Grames, J. Hansknecht, C. Hernandez-Garcia, G. A. Krafft, G. Palacios-Serrano, M. Poelker, M. L. Stutzman, R. Suleiman, M. Tiefenback, S. Wijethunga, J. Yoskowitz, S. Zhang

Physics Faculty Publications

Cs_xK_ySb photocathodes grown on GaAs and molybdenum substrates were evaluated using a –300 kV dc high voltage photogun and diagnostic beam line. Photocathodes grown on GaAs substrates, with varying antimony layer thickness (estimated range from < 20 nm to > 1 um), yielded similar thermal emittance per rms laser spot size values (~0.4 mm mrad / mm) but very different operating lifetime. Similar thermal emittance was obtained for a photocathode grown on a molybdenum substrate but with markedly improved lifetime. For this photocathode, no decay in quantum efficiency was measured at 4.5 mA average current and with peak current 0.55 A …