Post on 11-Jan-2016
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.