O. Siegmund, J. McPhate UCB, SSL 1 8in Photocathode 2 nd Try 8” PC/Seal Test Chamber –<10 -9 Torr base vacuum, RGA operational, fully baked Chamber configured for 8in depositions 5mm thick, 8.7” polished B33 window –NiCr border electroded Deposited Na 2 KSb photocathode RGA record for entire process Cathode everywhere but extreme corners – However, cathode very blue, shows signs of contamination (window surface??).

O. Siegmund, J. McPhate UCB, SSL 2 8” bialkali 2 nd Process Shooting the cathode Window post deposit – 9” PC Proper contact! Only small corner uncoated.

O. Siegmund, J. McPhate UCB, SSL 3 8” Process #2 -Na 2 KSb Uniformity measurements worse in middle and corners. Indicative of a conductivity problem. Not unexpected for a thin cathode. Need conductor “X” stripes. Cathode is very blue, multiply QE by 1.1 to account for process tank window transmission. Also decayed during deposition process – indicative of insufficient alkali pressure and possible window contamination.

O. Siegmund, J. McPhate UCB, SSL 4 8” Cathode Process Plan Second cathode is thin – blue and shows signs of window contamination, poor conductivity First bake out cathode and shoot a second for extra data Add a conductor “X” and border and clean a new window Upgrade alkali channels to 40mm to increase pressure Investigate window surface condition for tin/contamination Continue process runs