Stability of transmission mode GaAs (Cs,O) photocathodes

The influence of illumination intensity and residual gases on the stability of negative electron affinity GaAs (Cs,O) photocathodes during operation w as investigated in the present work. A comparison was made between the stab ility of photocathodes installed in activation chamber and tube body. Studi es of the activated GaAs photocathode surface and the surface of GaAs photo cathode with sensitivity decaying to zero were made using Auger electron sp ectroscopy. It was found that the degradation of GaAs photocathodes stems m aingly from the interaction of harmful residual gases and photocathode surf ace.