AWAKE workshop, Greifswald, September 24th-26th, 2014

Steffen Döbert, BE-RF

AWAKE electron source

update

CoordinationSteffen

Beam dynamicsÖznur, Steffen

MagnetsJeremie Bauche

WP 5 electron source

Power convertersChristophe Mutin??

Beam DiagnosticsLars Jensen, Triumf

VacuumJan Hansen

Machine interlockBruno Puccio

CommissioningAll,Steffen

SurveyJean-Frederic Fuchs

Magnet interlockMarkus Zerlauth

RF gunEric Chevallay

LLRFW. Hoefle

Klystron systemGerry McMonagle

Booster structureGraeme Burt

RPHelmut Vincke

Work structure

AWAKE electron sourceschematic

Length ~ 4 m

FC

E, DE

MS

BPT

Laser +Diagnostics

RF GUN

Emittance

Incident, Reflected Power and phase

Spectrometer

Corrector

MTV

VPI

FCT

AcceleratorMTV,

Emittance

Matching triplet

BPT

Incident, Reflected, transmitted Power

Klystron

A,f

Awake electron beamrequirements decided

Parameter Baseline Phase 2 Range to check

Beam Energy 16 MeV 10- 20 MeV

Energy spread (s) 0.5 % < 0.5 % ?

Bunch Length (s) 4 ps 0.3-10 ps

Beam Focus Size (s) 250 mm 0.25 – 1mm

Normalized Emittance (rms) 2 mm mmrad 0.5 - 5 mm mrad

Bunch Charge 0.2 nC 0.1 - 1 nC

Let’s assume gaussian or truncated gaussian distributions for transverse phase space for time beingFor the longitudinal we will simulate gaussian and somewhat more uniform distribution depending what we can expect from the laser

Beam instrumentation

Instrument How many Resolution Who

BPMs 3 ~ 50 mm Triumf, new

Screen 3 20 mm ? CERN, partly existing

Multi slit 1 < mm mrad CERN, partly existing

FCT 1 10 pC CERN, existing

Faraday Cup 1 10 pC Triumf, new

Spectrometer 1 10 keV CERN, MTV

Streak Camera 1 < ps CERN, merging point

Electron source layout

Electron source layoutLaser table needs to be integrated as well

Electron source layout

Electron source layout

Height of the beam line ?

Electron source layout

Comments:

Layout is advancingSome conflicts with the overall

lengthNeed to optimise cathode

accelerating structure distanceNeed to specify quadrupolesStudy cathode loading system

optionsStudy shielding design and layout

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

50 100 150 200 250

50

100

150

200

250

300

350

-4 -2 0 2 4 6-1.6

-1.55

-1.5

-1.45

-1.4

-1.35

-1.3x 10

5

Normalized emittance for 0.2 nC: 3.2 mm mrad ( big errors !)

En (1nC): 5.5 mm mradEn(0.7 nC): 4.6 mm mrad

PHIN emittance measurements

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 !)

50 100 150 200 250

50

100

150

200

250

300

350

-4 -2 0 2 4 6 83.15

3.2

3.25

3.3

3.35

3.4

3.45

3.5

3.55x 10

5

PHIN emittance measurements

0 0.2 0.4 0.6 0.8 1 1.20

1

2

3

4

5

6

Charge (nC)

Em

itta

nce

no

rm (

mm

mra

d)

Charge dependence is roughly sqrt as it should be

PHIN emittance measurements

Parmela simulation with r= 1mm, E=85 MV/m, Q=0.2 nC

e = 3.2 mm mrad ( by chance)

50 100 150 200 250

2

4

6

z

Em

i x

50 100 150 200 2500

0.1

0.2

z

Bea

m S

ize

x (c

m)

PHIN to AWAKE

Parmela simulation with r= 0.5mm, E=100 MV/m, Q=0.2 nC

e = 1.3 mm mrad

0 50 100 150 200 2500

10

20

z

En

erg

y (M

eV)

0 50 100 150 200 2500

1

2

3

z

bu

nch

len

gth

(p

s)

PHIN to AWAKE

0 50 100 150 200 2500

1

2

z

Em

i x

0 50 100 150 200 2500

0.05

0.1

z

Bea

m S

ize

x (c

m)

Electron beam source time line and milestones

MilestoneTentative date Key Issues Remarks

Beam line design Dec-14 not all components defined yet  Gun configuration, cathodes Dec-14 Laser parameters, space constraintsBaseline simulations fixed Dec-14 CollaborationBooster design Dec-14 Collaboration Specs: 7/2014Booster delivered to CERN Mar-16    Diagnostics specified Dec-14 Collaboration and performanceInfrastructure definition Dec-14 not all needs defined  Rough integration model Dec-14    Detailed integration model Dec-15    Fabrication drawings Jun-15 fabrication will go one in 2015 and 2016  Infrastructure installation 2015-2016   depends on scheduleInstallation in CTF2 Jun-16 needs decision what exactly to test  Tests in CTF2 finished Dec-16    Installation start in CNGS Jan-17    Commissioning start Oct-17    

Ready to send electron beam Dec-17    

Steffen Doebert, Awake TB 19.5.2014

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

Electron source design

Oznur Mete, Cockcroft

Booster structure

Graeme Burt, Lancaster

Some rough numbers1 m long constant gradient structuref= 2998.55 MHzQ ~ 15000r/Q ~ 70 MWDV= 15 MVTf= 280 ns, 2a ~ 2 cmPo = 11 MW

PHIN gun needs about 10 MW for 85 MV/m

Roughly 30 MW needed to power the injector (one klystron)

AWAKE electron booster• Constant gradient 2p/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

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 ?

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 !

End

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

7387320

1188vertica

l 19929

7387+1188+320+19929 = 28824 mm Proton line: path to plasma cell

Electron line: path to photocathode

9846

1087vertical

1320

500 817

Optical table 1000x1800

9846+1087+1320+500+817 = 13570 mm

Electron beam path from photocathode to plasma cell

4627

377

377

377

377

3683

736

1536

4319

4627+377*4+3683+736+1536+4319 = 16409 mm

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

Data acquisitionSignal type How

manyData acquisition Remarks

Laser intensity 2 waveforms or sample/hold, CERN ADC’s To be defined by laser team

Laser shape 2 CERN MTV acq To be defined by laser team

Rf signals 10 Waveforms ADC, > 100 Ms

Beam intensity, FCT, F-Cup 2 Integration, sample/hold, CERN ADC

BPM’s 12 Integration, sample/hold, ADC Collaboration with Triumf

MTV’s 3 CCD image, CERN MTV acq.

Vacuum signals CERN standard, PVSS Vacuum group

Power supplies, settings and status

CERN standard, FESA Power 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

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 3rd 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.