Studies of linear and nonlinear photoelectric emission for advanced accelerator applications

Various electron emission properties of accelerator photocathodes were studied using short pulse lasers. The quantum efficiencies (QEs) of copper and magnesium were compared before and after above-damage threshold laser cleaning. Changes in the emission properties of copper photocathodes used in the UCLA RF photoinjector gun were observed by mapping the QEs of the cathode surfaces. The electron yield of thin copper films resulting from back-side illumination was measured. Multiphoton (nonlinear) emission was studied as a means of creating ultrashort electron bunches, and an RF gun Parmela simulation investigated the broadening of such pulses as they propagate down the beam line.