1. AWAKE workshop, Greifswald, September 24 th -26 th, 2014Steffen Döbert, BE-RF AWAKE electron source update

2. Coordination Steffen Coordination Steffen Beam dynamics Öznur, Steffen Beam dynamics Öznur, Steffen Magnets Jeremie Bauche Magnets Jeremie Bauche WP 5 electron source Power converters Christophe Mutin?? Power converters Christophe Mutin?? Beam Diagnostics Lars Jensen, Triumf Beam Diagnostics Lars Jensen, Triumf Vacuum Jan Hansen Vacuum Jan Hansen Machine interlock Bruno Puccio Machine interlock Bruno Puccio Commissioning All,Steffen Commissioning All,Steffen Survey Jean-Frederic Fuchs Survey Jean-Frederic Fuchs Magnet interlock Markus Zerlauth Magnet interlock Markus Zerlauth RF gun Eric Chevallay RF gun Eric Chevallay LLRF W. Hoefle LLRF W. Hoefle Klystron system Gerry McMonagle Klystron system Gerry McMonagle Booster structure Graeme Burt Booster structure Graeme Burt RP Helmut Vincke RP Helmut Vincke Work structure

3. AWAKE electron source schematic Length ~ 4 m FC E,  E MS BPT Laser +Diagnostics RF GUN Emittance Incident, Reflected Power and phase Spectrometer Corrector MTV VPI FCT Accelerator MTV, Emittance Matching triplet BPT Incident, Reflected, transmitted Power Klystron A, 

4. Awake electron beam requirements decided ParameterBaseline Phase 2Range to check Beam Energy16 MeV10- 20 MeV Energy spread (  ) 0.5 %< 0.5 % ? Bunch Length (  ) 4 ps0.3-10 ps Beam Focus Size (  ) 250  m 0.25 – 1mm Normalized Emittance (rms)2 mm mmrad0.5 - 5 mm mrad Bunch Charge0.2 nC0.1 - 1 nC Let’s assume gaussian or truncated gaussian distributions for transverse phase space for time being For the longitudinal we will simulate gaussian and somewhat more uniform distribution depending what we can expect from the laser

5. Beam instrumentation InstrumentHow manyResolutionWho BPMs3 ~ 50  m Triumf, new Screen3 20  m ? CERN, partly existing Multi slit1< mm mradCERN, partly existing FCT1 10 pCCERN, existing Faraday Cup1 10 pCTriumf, new Spectrometer110 keVCERN, MTV Streak Camera1< psCERN, merging point

6. Electron source layout

7. Laser table needs to be integrated as well

8. Electron source layout

9. Height of the beam line ?

10. Electron source layout Comments:  Layout is advancing  Some conflicts with the overall length  Need to optimise cathode accelerating structure distance  Need to specify quadrupoles  Study cathode loading system options  Study shielding design and layout

11. PHIN Emittance measurements for Awake 22.8.2014 Laser size: ~ 1 mm sigma, Charge 0.2, 0.7, 1.0 nC, Energy 5.5 – 6 MeV Normalized emittance for 0.2 nC: 3.2 mm mrad ( big errors !) E n (1nC): 5.5 mm mrad E n (0.7 nC): 4.6 mm mrad PHIN emittance measurements

12. PHIN Emittance measurements for Awake 22.8.2014 Laser size: ~ 1 mm sigma, Charge 0.2, 0.7, 1.0 nC, Energy 5.5 – 6 MeV Normalized emittance for 0.7 nC: 4.6 mm mrad ( big errors !) PHIN emittance measurements

13. Charge dependence is roughly sqrt as it should be PHIN emittance measurements

14. Parmela simulation with r= 1mm, E=85 MV/m, Q=0.2 nC   = 3.2 mm mrad ( by chance) PHIN to AWAKE

15. Parmela simulation with r= 0.5mm, E=100 MV/m, Q=0.2 nC   = 1.3 mm mrad PHIN to AWAKE

16. Electron beam source time line and milestones Milestone Tentative dateKey IssuesRemarks Beam line designDec-14not all components defined yet Gun configuration, cathodesDec-14Laser parameters, space constraints Baseline simulations fixedDec-14Collaboration Booster designDec-14CollaborationSpecs: 7/2014 Booster delivered to CERNMar-16 Diagnostics specifiedDec-14Collaboration and performance Infrastructure definitionDec-14not all needs defined Rough integration modelDec-14 Detailed integration modelDec-15 Fabrication drawingsJun-15fabrication will go one in 2015 and 2016 Infrastructure installation2015-2016 depends on schedule Installation in CTF2Jun-16needs decision what exactly to test Tests in CTF2 finishedDec-16 Installation start in CNGSJan-17 Commissioning startOct-17 Ready to send electron beamDec-17 Steffen Doebert, Awake TB 19.5.2014

17. Laser requirements Have been extensively discussed in the last few month See Christoph’s presentation Base line scenario defined, ask Amplitude for UV beam Keep and study option of a load lock system to allow for different cathode materials and under vacuum preparation Synchronisation scheme has been discussed, looks like we (CERN) generates the necessary 3 GHz from the laser 88 MHz master clock Laser path length compensation under study

18. Electron source design Oznur Mete, Cockcroft

19. Booster structure Graeme Burt, Lancaster Some rough numbers 1 m long constant gradient structure f= 2998.55 MHz Q ~ 15000 r/Q ~ 70 M   V= 15 MV T f = 280 ns, 2a ~ 2 cm Po = 11 MW PHIN gun needs about 10 MW for 85 MV/m Roughly 30 MW needed to power the injector (one klystron)

20. AWAKE electron booster Constant gradient 2  /3 travelling wave structure at 2.99855 GHz 30 cells is just under 1 metre long 9.6 MW input power gives 15 MV. Average group velocity is 1.23% c giving a filling time of 273 ns. Still need to evaluate single vs dual feed

21. Next steps  Continue layout work, need better few of laser equipment close to the source and cathode handling  Continue simulations and iterate with layout  Work on overall integration, klystron, waveguides, …  Safety file  Vacuum simulation urgently needed to understand impact  Define synchronisation scheme and LLRF  Electron source shielding design, necessary ?

22. Conclusions  The electron source WP takes shape and we got started  Many aspects have been discussed and we are getting closer to something like a complete specification  Beam requirements clearly defined now and seem in reach  Contributions from collaborations and hardware available at CERN much clearer now  Laser and Instrumentation needs well defined  We are making progress !

23. End

24. Starting points for calculations  Proton line: the top mirror in vacuum before the laser core tunnel  Electron line: intersection of the “electron” laser beam with the vertical plane formed by 2 vacuum mirrors for “proton” beam 727 98 Valentine and Mikhail

25. 7387 320 1188 vertica l 19929 7387+1188+320+19929 = 28824 mm Proton line: path to plasma cell

26. Electron line: path to photocathode 9846 1087 vertical 1320 500817 Optical table 1000x1800 9846+1087+1320+500+817 = 13570 mm

27. Electron beam path from photocathode to plasma cell 4627 377 3683 736 1536 4319 4627+377*4+3683+736+1536+4319 = 16409 mm

28. Summary  Proton line path to plasma cell = 28824 mm Electron line: laser path + electron path = 29979 mm difference = - 1155 mm is to be compensated by delaying the “proton” pulse (could it exist in the main amplifier ?) Delays due to compressor, THG, UV stretcher, telescope, are not counted! A variable delay of 0 - 200 mm in the electron line is required

29. Data acquisition Signal typeHow many Data acquisitionRemarks Laser intensity2 waveforms or sample/hold, CERN ADC’sTo be defined by laser team Laser shape2CERN MTV acqTo be defined by laser team Rf signals10Waveforms ADC, > 100 Ms Beam intensity, FCT, F-Cup2Integration, sample/hold, CERN ADC BPM’s12 Integration, sample/hold, ADCCollaboration with Triumf MTV’s3 CCD image, CERN MTV acq. Vacuum signalsCERN standard, PVSSVacuum group Power supplies, settings and status CERN standard, FESAPower group All CERN solutions will result in a FESA equipment which can be published and shared in the control system to any user. The electron source will not need data from other experiments to operate Timing information from the laser is needed to synchronise and adjust the electron beam

30. Laser update  We still assume using copper cathodes  Prefer a solution where Amplitude delivers a UV laser beam This means they take care of the compression and the 3 rd harmonic generation. CERN would then transport the UV to the gun and cathode.  UV pulse required: Wavelength: 262 nm; 500 uJ pulse energy and a FWHM pulse length of 10 ps. This pulse would guarantee the base line parameters and the 1 nC option.  For the short pulse 0.3 ps we would need only 50 uJ in the UV assuming that we would have to produce only 0.1 nC of charge (limited by ablation)  Pulse compression independent from the one for the proton beam Independent pulse picker allowing to use only some pulses out of the 10 Hz rep. rate.  The specification for an IR beam would be a pulse energy of 50 mJ. We will still try to investigate the space constraints and keep the option to use different cathodes.