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Graduate Student Seminar - 09/23/2011

"Modeling the Quantum Efficiency of Controlled Porosity Dispenser Photocathodes"

by Zhigang Pan

Friday, September 23, 2011 -- 12:00 p.m.
Large Conference Room, 1207 Energy Research Facility

Advisor:  Professor Patrick O'Shea

A theoretical model of diffusion, evaporation, and rejuvenation of cesium on the surface of a controlled porosity dispenser (CPD) photocathode is developed. Quantum efficiency (QE) maps over the photocathode surface are obtained and reported. For activation temperatures within the range of 400K-1000K, simulation found differences of less than 10% between the QE maximum and minimum over the surface, suggesting reasonable coverage uniformity at these temperatures. Significant changes in the QE map near the pores and across the surface suggest that the emittance can change depending on the temperature. Extensions to the model are discussed.

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