GaAs Photocathode Performance 40 cm Photocathode Ball cathode Drive Laser GaAs Photocathode Performance Photocathode QE~6% after initial activation Photocathode delivers ~200 C between re-cesiations Typical day of operations draws ~35 Coulombs About 96% of previous QE is recovered with each re-cesiation 12 activated cathodes and close to 40 re-cesiations performed on a single GaAs wafer in one year
Demonstrated DC Photocathode Gun performance Pulsed operation at 8 mA/pulse (110 pC/bunch) in 16 ms-long pulses at 2 Hz repetition rate CW operation at 9.1 mA (75 MHz) with 122 pC/bunch Routinely delivers 5 mA CW and pulse current at 135 pC/bunch for FEL operations 400 A peak current at wiggler Vacuum environment: 4.0E-11 Torr, 99.9% H2
7% QE 2% QE
Cathode camera image taken while running 7 mA CW
Transverse halo contributes to energy spread
10 kW Upgrade FEL photocathode performance after vacuum improvements
RGA