Laser illuminated high current photocathodes
1983; Elsevier BV; Volume: 16; Issue: 1-2 Linguagem: Inglês
10.1016/0378-5963(83)90072-7
ISSN1878-1071
AutoresL. R. Danielson, C. Lee, P. E. Oettinger,
Tópico(s)Gyrotron and Vacuum Electronics Research
ResumoPhotocathodes stimulated by broadband and monochromatic (laser) light have been studied in situ in ultra high vacuum systems. Lifetests were performed for cesium antimonide photocathodes illuminated by white light at current densities of 50 μA/cm2. The cathode photocurrent was sensitive to cathode temperature and background pressure and relatively independent of anode voltage under UHV conditions. Auger analysis revealed that besides cesium and antimony, oxygen was often present on the cathodes. Small oxygen concentrations caused the photocurrent to increase, and larger oxygen concentrations caused a decline in the photocurrent. Mass spectrometer measurements indicated that the most likely source of the oxygen was residual water vapor. Higher photocurrent densities of 13 mA/cm2 have been obtained from cesium antimonide photocathodes using an argon ion laser. This current was stable during the 20 h duration of a lifetest. Even larger pulsed current densities of 30 A/cm2 have been generated from a multialkali phototube illuminated by a ruby laser.
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