The quantum efficiency of dispenser photocathodes: Comparison of theory to experiment

The quantum efficiency (QE) characteristics of commercially available dispenser cathodes were measured, giving QEs of (for Scandate) 6.5×10−5, 2.0×10−4, and 8.0×10−4, and (for M-type) 3.0×10−4, 1.4×10−3, and 2.6×10−3, for wavelengths of 532, 355, and 266nm, respectively, corresponding to harmonics of an Nd:YAG laser. A time-dependent photoemission model was developed to analyze the data, as well as dispenser and metal photocathode data in the literature, and quantitatively good agreement is found, demonstrating the utility of the code as a predictive estimator of performance.