1. Sven LedererPITZ-Collaboration meeitng 27 th -28 th of Oct. 2011 First Photocathodes from DESY Sven Lederer PITZ-Collaboration meeting 27 th -28 th of Oct 2011

2. Sven LedererPITZ-Collaboration meeitng 27 th -28 th of Oct. 2011 Preparation system Set-up for QE-measurements and -maps port for transport box/ load-lock port for future SAFEM preparation chamber

3. Sven LedererPITZ-Collaboration meeitng 27 th -28 th of Oct. 2011 >First three real cathodes produced >#22.6 >Plug produced at LASA >Plug polished at LASA >Photo-emissive film deposited at DESY >#613.1 >Plug produced at DESY >Plug polished at DESY (estimated roughness factor 2 higher than #22.6) >Photo-emissive film at DESY >#625.1 >Plug produced at DESY >Plug polished at DESY (estimated roughness factor 2 higher than #22.6) >Photo-emissive film at DESY >In addition new carrier design from LASA: worked really nice! First cathodes

4. Sven LedererPITZ-Collaboration meeitng 27 th -28 th of Oct. 2011 Spectral response > W: work function of material, for Cs 2 Te sum of energy band gap E G and electron affinity E A, > parameter m gives information on emission process cathodeE g +E a mQE (262 nm) #22.63.54 eV1.877.89 % #613.13.66 eV1.210.23 % #625.13.611.311.12 %

5. Sven LedererPITZ-Collaboration meeitng 27 th -28 th of Oct. 2011 #625.1 #22.6#613.1

6. Sven LedererPITZ-Collaboration meeitng 27 th -28 th of Oct. 2011 S. Lederer, Beschleunigerbetriebsseminar, Grömitz 26.-29.09.2011 Cathode operation – #22.6 >Start-up operation with 150  s RF-pulse length and extremely slow ramp-up but continued with 150  s >Full RF-power (6.2 MW) reached >Only two directional coupler vacuum interlocks >Mainly PM interlocks during ramp up of RF-power, but they are not necessarily caused by the cathode No information on signal behaviour and height because of pulse transformers (still)! Without them one could learn much more! Start-up to 3.8 MW operation @ 3.8 MW 6.2 MW operation and pulse length increase

7. Sven LedererPITZ-Collaboration meeitng 27 th -28 th of Oct. 2011 S. Lederer, Beschleunigerbetriebsseminar, Grömitz 26.-29.09.2011 Cathode operation – #613.1 >Full RF-power reached >A few directional coupler vacuum interlocks >Mainly PM interlocks and majority of them only during changes of RF-power, but they are not necessarily caused by the cathode No information on signal behaviour and height because of pulse transformers (still)! Without them one could learn much more!

8. Sven LedererPITZ-Collaboration meeitng 27 th -28 th of Oct. 2011 Cathode operation – #625.1 No information on signal behaviour and height because of pulse transformers (still)! Without them one could learn much more! >Full RF-power (6.2 MW) at 650  s reached >A few coupler vacuum interlocks >Mainly PM interlocks, during the initial ramp up, but they are not necessarily caused by the cathode

9. Sven LedererPITZ-Collaboration meeitng 27 th -28 th of Oct. 2011 CathodeQE (45 MV/m)QE (60 MV/m) #22.611.0 %11.4 % #613.19.6 %12.2 % #625.113.5 %13.7 % QE measurements – pulsed mode 3.8 MW (FLASH) 6.2 MW (XFEL) Launch phase ~ 38 deg w.r.t. zero crossing (adjusted by hand)

10. Sven LedererPITZ-Collaboration meeitng 27 th -28 th of Oct. 2011 #625.1 Pulsed QE maps at P = 3.8 MW. >Homogeneity especially at edges should be improved! >Trial of a bit higher distance cathode surface – mask (currently 200  m, may be 300  m for next ones >During first real maintenance mask to be investigated #613.1 QE-maps – pulsed mode #22.6

11. Sven LedererPITZ-Collaboration meeitng 27 th -28 th of Oct. 2011 >Dark current level acceptable but still to be improved >dc most probably driven by particles Dark current

12. Sven LedererPITZ-Collaboration meeitng 27 th -28 th of Oct. 2011 >Dark current images at 3.8 MW RF-power >Comparable shapes >One additional emitter visible for cathode #613.1 >Most probable the reason for the increased dc Dark current #22.6 #613.1

13. Sven LedererPITZ-Collaboration meeitng 27 th -28 th of Oct. 2011 >Special tool box for FLASH: >Cs 2 Te photocathode >Mo plug >BGO-scintillator >45 deg mirror Next box to be produced

14. Sven LedererPITZ-Collaboration meeitng 27 th -28 th of Oct. 2011 >Quite successful test of the cathodes >Continued studies necessary – esp. at PITZ >Long term stability >Routinely QE measurements and QE-maps under defined conditions >Full potential of interlock sensors to be used >Thanks for making the tests possible even if it was during the start of the shut-down >Thanks esp. to the guys supporting me during the shifts Closing