CTF 3 photoinjector Konrad Elsener for the Photoinjector

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CTF 3 photoinjector Konrad Elsener for the Photoinjector Team We acknowledge the support of

CTF 3 photoinjector Konrad Elsener for the Photoinjector Team We acknowledge the support of the European Community Research Infrastructure Activity under the FP 6 “Structuring the European Research Area” programme (CARE, contract number RII 3 -CT-2003 -506395) 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 1

CTF 3 photoinjector: A successful collaboration inside JRA “PHIN” – Charge Production with PHoto

CTF 3 photoinjector: A successful collaboration inside JRA “PHIN” – Charge Production with PHoto INjectors University of Milano INFN Frascati M. Divall (“consultant”) CEA (Califes laser) 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 2

A huge effort in all the labs involved – a big THANK YOU to

A huge effort in all the labs involved – a big THANK YOU to everyone (apologies for not mentioning any individual names) 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 3

Outline 1. Introduction 2. Overview: Photoinjector for CTF 3 3. Recent progress - Installation

Outline 1. Introduction 2. Overview: Photoinjector for CTF 3 3. Recent progress - Installation RF gun - Laser system - Photocathode 4. First electron beam results 5. Summary and Outlook 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 4

1. Introduction • two photoinjectors at CERN CALIFES (probe-beam in CLEX) PHIN (initially on

1. Introduction • two photoinjectors at CERN CALIFES (probe-beam in CLEX) PHIN (initially on test-bench in CTF 2 building, later to become CTF 3 drive beam injector) - normal conducting RF guns (inspired by CERN “gun IV”) - Cs-Te photocathodes - pulsed UV laser light to produce electrons • differences in the design parameters 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 5

Injector with thermionic gun DL = Delay Loop (factor 2) CR = Combiner Ring

Injector with thermionic gun DL = Delay Loop (factor 2) CR = Combiner Ring (factor 4) Drive Beam Accelerator DL CR CLEX TL 2 CALIFES PHIN 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 6

Main challenges – CTF 3 “PHIN” electron beam (2007) trains of 10 ps pulses

Main challenges – CTF 3 “PHIN” electron beam (2007) trains of 10 ps pulses at 1. 5 GHz (synch. 3 GHz): 1908 pulses in 1272 ns long train (odd/even sub-pulses, 140. 7 ns) 2. 3 n. C per pulse, charge stability 0. 25% -> 3. 5 A current in the pulse train need 370 n. J UV laser pulse energy. . . . for given 3% photocathode quantum efficiency need 15 k. W IR laser power in the pulse train repetition rate: 5 Hz 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 7

2. Overview: Photoinjector for CTF 3 Main Design Parameters (2007) PHIN RF frequency [GHz]

2. Overview: Photoinjector for CTF 3 Main Design Parameters (2007) PHIN RF frequency [GHz] RF power [MW] 30 beam energy [Me. V] 5 -6 beam current [A] 3. 5 number of bunches 1908 bunch spacing [ps] 666. 7 charge per bunch [n. C] repetition rate [Hz] 2 December 2008 2. 9985 2. 3 5 bunch length FWHM [ps] < 10 rms. energy spread [%] <2 n. emittance [p mm mrad] < 25 vacuum pressure [mbar] < 2 x 10 -10 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener lifetime of the photocathode ? 8

vacuum requirements 2 x 10 -10 mbar are a challenge -> 5 ion pumps

vacuum requirements 2 x 10 -10 mbar are a challenge -> 5 ion pumps to further improve the dynamic behavior of pressure: -> 42 holes (d=4 mm) between RF gun and NEG chamber courtesy LAL 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 9

17 Jan 2007 – LAL (presentation R. Roux) 2 December 2008 CTF 3 photoinjector

17 Jan 2007 – LAL (presentation R. Roux) 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 10

29 April 2008 – LAL (photo G. Bienvenu) 2 December 2008 CTF 3 photoinjector

29 April 2008 – LAL (photo G. Bienvenu) 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 11

3 a. Recent Progress - Installation 19 June 2008 – CERN (CTF 2) 2

3 a. Recent Progress - Installation 19 June 2008 – CERN (CTF 2) 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 12

cathode manipulator RF gun 7 June 2008 – CERN (CTF 2) 2 December 2008

cathode manipulator RF gun 7 June 2008 – CERN (CTF 2) 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener diagnostics (emittance meas. + spectrometer) 13

16 September 2008 – CERN (CTF 2) 2 December 2008 CTF 3 photoinjector CARE

16 September 2008 – CERN (CTF 2) 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 14

3 b. Recent Progress - Laser 400 ms amplification window for AMP 1 Macro

3 b. Recent Progress - Laser 400 ms amplification window for AMP 1 Macro pulse Micro pulses at 1. 5 GHz ~667 ps; 10 W 1. 5 GHz Nd: YLF Oscillator + Nd: YLF Preamplifier 1047 nm 3 -pass Nd: YLF amplifier Dt Dt UV 4 2 December 2008 Green Optical gate (Pockels cell) PC Dt 2 IR 2 pass Nd: YLF amplifier Pulse picker CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 200 ms amplification window for AMP 2 Macro pulse 15

laser beam after 2 nd amplifier 6 5 4 3 power [k. W] 2

laser beam after 2 nd amplifier 6 5 4 3 power [k. W] 2 1 0 0 100 200 300 400 time [ms] N. B. Output Amplifier 1: 3 k. W – as specified Output Amplifier 2: 6 k. W – factor ~2 missing 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 16

laser beam after pockels cell (observed with photodiode + scope) 2 ms 667 ps

laser beam after pockels cell (observed with photodiode + scope) 2 ms 667 ps 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 17

conversion to UV IR GREEN energy within 2 ms gate Amp 1 @90 amps

conversion to UV IR GREEN energy within 2 ms gate Amp 1 @90 amps PC on 2 ms ( Best Result ) (4. 15 -1. 33)m. J std=0. 06 m. J ~1. 2 m. J Std=0. 016 m. J 0. 398 m. J Std=0. 012 133. 3 n. J * in a micro pulse ~44 % efficiency Amp 1 + Amp 2 @90 amps PC on 2 ms UV Energy within 2 ms gate (12. 3 -4. 2)m. J std=0. 26 m. J ~34 % efficiency 3. 23 m. J Std=0. 07 m. J 0. 692 m. J Std=0. 024 40% efficiency ~234 n. J * in a micro pulse 22% efficiency * measured on laser table – nominal 370 n. J on photocathode 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 18

more details on the laser system: Massimo Petrarca today at 15: 30 in Room

more details on the laser system: Massimo Petrarca today at 15: 30 in Room A 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 19

3 c. Recent Progress - Photocathode No. 167 (Cs-Te co-evap. ) data taken in

3 c. Recent Progress - Photocathode No. 167 (Cs-Te co-evap. ) data taken in DC-gun, 80 k. V (-> 8 MV/m) caution: CTF 3 photoinj. specification QE not measured since January QE in RF gun tends to be smaller 29 Nov. 2007 2 December 2008 Xmas break 9 Jan. 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 20

end of October 2008 – ready to go ! 2 December 2008 CTF 3

end of October 2008 – ready to go ! 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 21

4. First electron beam results ! PRELIMINARY ! - RF conditioning with Cu plug,

4. First electron beam results ! PRELIMINARY ! - RF conditioning with Cu plug, solenoids OFF - RF conditioning with Cu plug, solenoids ON - RF conditioning with Cs. Te cathode - 5 Nov. : first beam Timing problem laser vs. RF pulse; Short dark current pulse at the end of rf pulse clearly visible; Intensity roughly equal to a single bunch 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 22

- 6 Nov. 2008: first electron beam - RF phase adjusted; solenoid currents lowered

- 6 Nov. 2008: first electron beam - RF phase adjusted; solenoid currents lowered - optimised first MTV screen beam spot 1. 55 m downstream of RF gun: FWHM ~ 5 mm 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 23

Beam current – 1. 3 ms train (2000 bunches) Beam Position Monitor Sum Signal

Beam current – 1. 3 ms train (2000 bunches) Beam Position Monitor Sum Signal Faraday Cup electron beam train-to-train intensity fluctuations (BPM): r. m. s < 6% (5 minutes) 2 December 2008 laser beam train-to-train UV energy fluctuations in laser room: r. m. s < 3% (500 trains) CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 24

Phase scan, 50 ns e-beam pulse train 100 deg. 2 December 2008 CTF 3

Phase scan, 50 ns e-beam pulse train 100 deg. 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 25

Beam size scan Asymmetry in beam focusing behavior; problem seems to be in horizontal

Beam size scan Asymmetry in beam focusing behavior; problem seems to be in horizontal plane, behavior in vertical seems ~ OK Cause? Laser spot asymmetry, alignment, RF-asymmetry, solenoid alignment – to be checked in 2009 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 26

Energy measurement, 90 deg. Spectrometer background (dark-current) subtracted Measured nominal energy with small energy

Energy measurement, 90 deg. Spectrometer background (dark-current) subtracted Measured nominal energy with small energy spread (calibration to be checked) 5. 3 Me. V with 27 ke. V (0. 5 %) r. m. s. energy spread 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 27

Overview of Results PHIN design achieved Nov. 2008 RF power [MW] unloaded 13 13

Overview of Results PHIN design achieved Nov. 2008 RF power [MW] unloaded 13 13 beam energy [Me. V] 5 -6 5. 3 beam current [A] 3. 5 < 0. 2* number of bunches 1908 < 3000 bunch spacing [ps] 666. 7 2. 3 < 0. 1* 5 0. 8 bunch length FWHM [ps] < 10 ? rms. energy spread [%] <2 <1 charge per bunch [n. C] repetition rate [Hz] * combination of low QE (old cathode); laser energy not nominal; possibly laser beam not well centred on cathode (diagnostics !) 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 28

5. Summary and Outlook • after years of work, and a huge effort by

5. Summary and Outlook • after years of work, and a huge effort by all partners we had FIRST BEAM in the PHIN CTF 3 photoinjector ! • many of the beam parameters measured are already the nominal parameters + stability is quite good ! • All in all, a GREAT ACHIEVEMENT ! • next run: March 2009 (3 – 4 weeks) • workplan: 3 new photocathodes; (availability of klystron) improved laser amplifier 2 improved laser beam diagnostics improved electron beam diagnostics (screen sensitivity) -> significant increase of electron intensity -> detailed emittance measurements 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 29

5. Summary and Outlook • later in 2009: further improvements on laser system (conversion

5. Summary and Outlook • later in 2009: further improvements on laser system (conversion crystals, amplifiers) additional work: phase-coding availability of klystron ? - cf. CTF 3 general schedule A lot of work ahead but good prospects to reach much higher intensity in 2009 ! 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 30

Extra Slides 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented

Extra Slides 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 31

2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K.

2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 32

4. Status of the photocathodes Cs – Te photocathodes (theoretically: Cs 2 Te) successfully

4. Status of the photocathodes Cs – Te photocathodes (theoretically: Cs 2 Te) successfully used at CTF 2 progress in recent years: co-evaporation of Cs and Te onto copper substrate photocathode production • “in-situ” for CALIFES (cf. CTF 2) • in the photoemission lab for PHIN 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 33

4. Status of photocathodes 4 b) Photocathodes for PHIN – Photoemission Laboratory DC- gun

4. Status of photocathodes 4 b) Photocathodes for PHIN – Photoemission Laboratory DC- gun ~ 1. 4 m transport carrier 2 December 2008 preparation chamber CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener manipulator 34

4. Status of photocathodes 4 b) Photocathodes for PHIN view inside the preparation chamber

4. Status of photocathodes 4 b) Photocathodes for PHIN view inside the preparation chamber special features: observe photoelectron production by UV during the evaporation process quartz monitors are calibrated co-evaporation of Te and Cs (masks!) 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 35

4. Status of photocathodes 4 b) Photocathodes for PHIN on the “arm” inside the

4. Status of photocathodes 4 b) Photocathodes for PHIN on the “arm” inside the transport carrier: up to 4 plugs 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 36

4. Status of photocathodes 4 b) Photocathodes for PHIN 1992 -2002 large number of

4. Status of photocathodes 4 b) Photocathodes for PHIN 1992 -2002 large number of photocathodes produced (e. g. 58 Cs-Te for CTF 2 drive beam). . . work in the lab. . . Dec. 2006 photocathode No. 166 (before bake-out of the vacuum system) -> Quantum Efficiency in DC gun 6. 2% 2007 tests, bake-out, calibration of thickness monitors, improvements to masks, etc. Nov. 2007 photocathode No. 167 produced under “correct conditions” 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 37

12 June 2008 – CERN (CTF 2) 2 December 2008 CTF 3 photoinjector CARE

12 June 2008 – CERN (CTF 2) 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 38

19 August 2008 – CERN (CTF 2) 2 December 2008 CTF 3 photoinjector CARE

19 August 2008 – CERN (CTF 2) 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 39

26 October 2008 – CERN (CTF 2) 2 December 2008 CTF 3 photoinjector CARE

26 October 2008 – CERN (CTF 2) 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 40

Energy measurement, Phase scan Very reasonable behavior 2 December 2008 CTF 3 photoinjector CARE

Energy measurement, Phase scan Very reasonable behavior 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 41

Emittance= 4. 88 mm mrad CTF 3 photoinjector 2 December 2008 ‘to good to

Emittance= 4. 88 mm mrad CTF 3 photoinjector 2 December 2008 ‘to good to be true’ CARE 08 Highlight Talk – presented by K. Elsener Öznür Mete 42

RF GUN CTF 2 , Simulations ref E= 5. 4 Me. V DE/E= 0.

RF GUN CTF 2 , Simulations ref E= 5. 4 Me. V DE/E= 0. 6 % bl = 6. 8 ps (FWHM) en = 15. 5 mm 2 December 2008 CTF 3 photoinjector CARE 08 Highlight Talk – presented by K. Elsener 43

Beam parameter summary PHIN design achieved Nov. 2008 2. 9985 RF power [MW] unloaded

Beam parameter summary PHIN design achieved Nov. 2008 2. 9985 RF power [MW] unloaded 13 13 beam energy [Me. V] 5 -6 5. 3 beam current [A] 3. 5 < 0. 2* number of bunches 1908 3000 bunch spacing [ps] 666. 7 2. 3 < 0. 1* 5 0. 8 bunch length FWHM [ps] < 10 ? rms. energy spread [%] <2 <1 n. emittance [p mm mrad] < 25 yes < 2 x 10 -10 < 4 x 109 * RF frequency [GHz] charge per bunch [n. C] repetition rate [Hz] vacuum pressure [mbar] * photocathode QE < 0. 5% (factor 8 -11) cathode prod. Dec. 2007 laser micropulse energy < 0. 2 m. J (factor 2 -3) CTF 3 photoinjector 2 December 2008 * NEG not yet activated CARE 08 Highlight Talk – presented by K. Elsener 44