1. WP10.6 Advanced Photocathodes Developement DESYJacek Sekutowicz HZBThorsten Kamps HZDRJochen Teichert IOE MUTHenryk Fiedorowicz IPJRobert Nietubyć BNLJohn Smedley MBIIngo Will TJNAFPeter Kneisel

2. Introduction Pb DAC Motivation To construct an injector for high quality electron beam of parameters dedicated for specific applications. High bunch charge for pulse FEL and high average current for ERL and CW FELs. The part of the proposed programme is an improvement of CARE and Eucard achievements - Pb/Nb films for SRF injector, another part is an expansion to the field of DAC photocathodes and constrution of unique laser for Pb cathode excitation. Hobicat at HZB, May 2011 IPJ, September 2011 UV laser

3. Organisation deposition, treatment and structural studies injector cavity measurementslaser IOE (MBI) IPJHZB HZDR DESY Pb DAC design & engineering SR testsinjector tests Advanced Photocathodes Developement

4. Baseline programme and fundamental deliverables New deposition system built and operating, Pb samples layers without laser flattening. Thickness and cleanliness improvement design → construction → samples deposition Prototype M9IPJ Pb sample layers deposited and flatten with the laser (optimized procedure), Post-deposition microdroplets removal and morphology improvement, filtering elimination Measurements of electron beam emitted from a plug sample photocathodes morphology influence on the performance Structural studies of Pb/Nb films. XRD, PES, ReportM12IPJ, IOE ReportM18HZB IPJ ReportM24HZDR Pb

5. Pb spot deposited on the e-gun cavity wall, flatted with the laser, QE and emittance measured in cold test Spot flattening → Installation → cleaning → Q measurements → QE measurements → e-beam diagnostics Measurements at HZB Injector cavity preparation Improved design in term of electromagnetic field, additional cavity enables more tests Construction → comissioning → baseline Q tests → Pb Q test Laser 206 nm, 20 ps, 100 kHz, 1 W, An unique and dedicated laser providing UV pulses of short duration, high energy and high repetition rate is unavoidable to operate high average current an injector furnished with Pb photocathode Fundamental generator → Amplifier + puls shaping → Harmonics converter → assembly → comissioning → installation at Hobicat Baseline programme and fundamental deliverables Report M18DESY PrototypeM30, IOE (MBI) ReportM36HZB, DESY, IPJ, IOE Pb

6. Design and engineering of cathode insert with diamond amplifier SR test of DAC cell Cell will be provided by BNL and tested at BESSY II beamline at HZB ReportM36HZB, HZDR Report M30HZB BNL ReportM18HZDR, HZB DAC Baseline programme and fundamental deliverables Test DAC in DC/SRF gun setup at HZDR and/or HZB Test will be done at HZDR or HZB

7. Costs classification deliverable kEUR at 100% kEUR at 75%. kEUR at 50% PbPb New deposition systemIPJ100 Pb sample layers deposited and flatten IOE IPJ, 15 5 20 5 20 Structural studies of Pb/Nb films. XRD, PES, HZB IPJ 20 15 5 20 5 20 Measurements of electron beam emitted from a plug sample photocathodes HZDR IPJ 10 5 15 5 15 Injector cavity preparationDESY119100 Laser 206 nm, 20 ps, 100 kHz, 1 W HZB IOE 50 582 0 496 0 260 Pb spot deposited on the e- gun cavity, cold tests DESY HZB IOE IPJ 40 30 17 27 40 15 0 25 40 15 0 25 DACDAC Design and engineering of cathode insert with diamond amplifier HZB HZDR 80 100 60 85 60 85 SR test of DAC cell ?HZB4115 Test DAC in DC/SRF gun setup at HZDR and/or HZB HZB HZDR 46 74 21 56 21 56

8. Costs classification deliverable kEUR at 100% kEUR at 75%. Implications kEUR at 50% Implications PbPb New deposition system100 Construction costs are ridgid100 Pb sample layers deposited and flatten 3525Only annealing, pulse ablation is cancelled 25 Structural studies of Pb/Nb films. XRD, PES, 3525Less number of samples, only those annealed 25 Measurements of electron beam emitted from a plug sample photocathodes 20 The easiest way to study the performance 20 Injector cavity preparation119100Preliminary photocathode deposition and tests measurements will not be possible before the final implementation at Hobicat. A risk rises significantly 100 Laser 206 nm, 20 ps, 100 kHz, 1 W632496λ ≤ 215 nm, τ = 20 ps, no pulse shaping, f = 100kHz P av = 1 W The lack of pulse shaping deteriorates e-beam quality by the energy spread and reduces the bunch charge. 260λ = 215 nm, τ = 30 ps, no pulse shaping, f = 20kHz, P av = 0.5 W Long pulses and low repetition preclude the high average power tests. In such conditions only partial tests are possible. The system would require substantial reconstruction to be operated in FEL linacs Pb spot deposited on the e-gun cavity, cold tests 11480Shorter beamtime available for final tests at Hobicat 80 DACDAC Design and engineering of cathode insert with diamond amplifier 180145 Less number of prototypes for lab and SR tests 145 SR test of DAC cell4115 Compromises in the transport vessel to get DAC inside SR beamline endstation 15 Test DAC in DC/SRF gun setup at HZDR and/or HZB 12077 Test at one station only 77 13961083837 (60%)Σ