Dogleg Beam-loading Experiment
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Transcript of Dogleg Beam-loading Experiment
Status and plans
Dogleg Beam-loading Experiment
J.L. Navarro (CERN), for the Dogleg Team
Workshop, 3 – 7 February 2014
J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Outline
- What are we studying in dogleg and Why?
- The Dogleg experiment layout
- Current status…: Phase I and results
- …and plans: Phase II
- Summary
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Where…?
The study is focused on the accelerating structures of the Main Beam Linac
• Traveling waves cavities• Nominal gradient ~ 100 MV/m• Nominal RF pulse length ~ 240 ns (160 ns flat top)• Peak Power ~ 61 MW• Max. Surf. Field ~ 230MV/m
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
What and Why?
Strong Accelerating fields (~100 MV/m)
Problem of Break Downs (BD): Very fast (10 ns – 100 ns) and localized dissipation of stored energy in the structure.
Luminosity Reduction:
Max DB rate allow for CLIC specifications:3 10-7 BD pulse-1 m-1
T24TD18T18TD24TD24r05TD26CC
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Unloaded Accelerating Gradient MV/m
Log(
BDR)
1/p
ulse
/m
Undesired effects:• Loss of acceleration• Damage in the structure• Kick in the beam• …
J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
CLIC nominal
Unloaded
Beam loading effect
BD never studied in loaded structures
Unloaded
Loaded
Curr
ent i
ncre
ase
Beam Loading modifies the gradient distribution along the structure
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
The Dogleg experiment
Two phases experiment:I. Beam only:
a) Optic designb) Hardware installationc) Beam commissioning
II. RF + Beam (middle 2014):a) RF commissioningb) Structure conditioningc) RF + beam studies
Done
CERN’s T24 (12WNDSvg1.8 KEK N1)Inner volumeThanks to A. Grudiev for HFSS model
Main goal: Measure and comparison (unloaded vs loaded) of the BD rate in a T24 structure
Tapered linearlyNot Damped2 coupling cells + 24 cells
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Experiment layoutExperiment located in the Dogleg Line of the CTF3 Linac (old PETS Line)
Beam side: CTF3 Drive Beam modified to mimic CLIC main beam Pulse compression to reach ~125 MeV at structure Nominal current of ~1.2 A Pulse length up to 250 ns
RF side: 90 MW RF power delivered by XBox1 35 Meters of low loss waveguide 60 MW RF power at the structure
Instrumentation side: Fixed 6mm collimator to protect the structure BPM upstream and downstream Movable slit to clean up beam
XBox1
Dogleg
Movable slitUpstream BPM
CollimatorStructure
Downstream BPM
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
RF wave guide installation
CTF2 CTF3Xbox1 wall
0.87 0.8
• The round group delay time is 230 ns (~35 m).• To provide nominal CLIC RF pulse, XBOX1 klystrons needs to deliver 36 MW x
1.5s
S21 Reconstructed(Xiaowei Wu)
8/22
Overall waveguide
efficiency ~ 67%
J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Optics design
0.0 2. 4. 6. 8. 10. 12. 14. 16. 18. 20.s (m)
0.0
10.
20.
30.
40.
50.
60.
βx(
m),
βy(m
)
-0.4
-0.3
-0.2
-0.1
0.0
0.1
0.2
Dx
(m)βx βy Dx
Objective: Transport the beam trough the Linac up to the structure requiring… - Full transmission efficiency - Minimum beam size on average inside the structure
Maximize relative distances between aperture and beam size (M. Dayyani). MAD model by F. Tecker.
Structure
Structure
Beam envelope
Re-matched
optics for
last running
Linac+dogle
g
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Data Acquisition System: Phase ISISAcq card
Accelerating Structure
Diode Box
BPM 240 BPM 280
PSR (108 dBm)
PSI (108 dBm)
PER
PEI (105 dBm)
Tunel
Beam
3 dBCable ...450A (-68 dB)
3 dB
3 dB
Cable 451A (-69 dB)
Cable ...452A (-69 dB)
~40 dBm
~40 dBm
~36 dBm
Cable ...453A (-18.46 dB)
Online Software monitoring: Produced power from the beam Reflected power (Break-down) BPMs current (looses) Online BD detection
SIS 3320 250MHz 12bit ADC
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Phase I Results: Running of May 2013C
P.B
HC
010
5
CP.
BP
M 0
115
CP.
QF
C 0
110
CP.
QF
C 0
130
CP.
QD
C 0
120
CP.
VP
I 012
5
CP.
BH
C 0
145
CP.
SL
H 0
107
S
Upstream and downs stream BPMs~ 90% transmission with no nominal optics
Horizontal orbit very offsetLimited by broken movable slit
Broken slit
No transmission with nominal optics due to big steering induced in the quads.
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Phase I Results: Running of May 2013
Raw signal from OASIS
Input reflected channel
Output transmitted channel
Two different pulses length at ~1.3 A…
70 mV
~9 MW
… and some break down
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
- Theoretical prediction- BPM 240 current (before structure)- BPM 280 current (after structure)
Phase I Results: Running of May 2013
Upstream BPM shows the correct tendency with a
systematic error in power
It suggest loses at the very end or after the structure.
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Phase I Results: Running of May 2013
3.3 dB error in upstream BPM
2.4 dB error in downstream BPM
- Theoretical prediction- BPM 240 current (before structure)- BPM 280 current (after structure)
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Phase I Results: Running of May 2013
Measured power scaled down by 3dB.
Shape reproduced……but error in calibration
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Phase I Results: Running of May 2013Summary of first run:• No transmission with nominal optics• 90% with experimental optics• First RF beam induced signals and break downs observed• ~ 3dB of error in calibration• Theoretical pulse shape reproduced• Movable slit broken
During summer shutdown: The slit was repaired (mechanical parts and cabling) The surveyors measured components alignment (more than 1.5 mm for some quads) The acquisition system was recalibrated using TWT (Thanks to L. Timeo, S.F. Rey)
Thanks to S. Doebert, F. Tecker and T. Wisznowski for a great job when repairing the slit by ourselves.
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Phase I Results: Running of Dec 2013We reach ~ 80% of transmission with almost the nominal optics (only one quad lowered)
As expected some quads introduce steering and needs to be realigned (done during Christmas shutdown.)
Dispersion is closed and we have some margin to improve transmission
17/22
J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Phase I Results: Running of Dec 2013And from the RF side:
Theoretical model fits within
experimental uncertainties
Data from May 2013
Data from Dec 2013(after DAQ recalibration)
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- Theoretical prediction- BPM 240 current (before structure)- BPM 280 current (after structure)
J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Dogleg Beam-loading Experiment
Phase I summary: Technical problems with slit solved Successful calibration RF waveguide installed with overall RF efficiency of 67%. Acceptable (80%) transmission with nominal optics (better after realignment) Realignment of components done during Christmas shutdown
19/22
Two phases experiment:I. Beam only:
a) Optic designb) Hardware installationc) Beam commissioning
II. RF + Beam (middle 2014):a) RF commissioningb) Structure conditioningc) RF + beam studies
Phase II approaching!!
Status…
… and prospects.
J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Data Acquisition System: Phase II
Acqusition Board
Acquisition Board
PXI LabviewAcquisition
system (250MHz)
OASIS Acquisition
PC
Accelerating Structure
Pulse compressor 8 IQ
demodulatorsRange: ???
TWT4 KW
Klystron50 MW
IN K
LY
Unused
To HP8900D for interock
PKI
PKR
BPM 240
BPM 280
PLI
PLR
PSR (108 dBm)
PSI (108 dBm)
PER
PEI (105 dBm)
Tunel
Beam
3 dBCable ...450A (-68 dB)
TTL to NIM converter
3 dB
3 dB
Cable 451A (-69 dB)
Cable ...452A (-69 dB)
Dogleg Acq SystemJ.L. Navarro – BE/OP
S. F. Rey, L. Timeo – BE/RFDecember 2nd, 2013 – V1.2
ORGANISATION EUROPEENNE POUR LA RECHERCHE NUCLEAIRE EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH
Laboratoire Européen pour la Physique des Particules
European Laboratory for Particle Physics
Log detectors
Range:-40 to -10 dBm
-49 dB
-49 dB
-45 dB
?? dB
~40 dBm
~40 dBm
~36 dBm
TimingCX.SMEAS-RFX2
TTL to ??? converter
?? dB
?? dB
?? dB
Cable name Channel Max. P. (MW) Max. P(dBm) Coupler (dB) Power (dBm) Cable T. (dB) Power (dBm) Splitter (dB) Power (dBm) Att. (dB) Cable 2 log (dB) Input ADC (dBm)???? PKR 50 106.9897 106.9897 0 106.9897 106.9897…450A PSI 60 107.781513 48.6 59.1815125 17.9 41.2815125 3 38.2815125 49 0 -10.7184875…451A PSR 60 107.781513 48.7 59.0815125 18.1 40.9815125 3 37.9815125 48 0 -10.0184875…452A PEI 30 104.771213 49.1 55.6712125 18.5 37.1712125 3 34.1712125 45 0 -10.82878745
Cable ...453A (-18.46 dB)
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Tentative Planning
Ready for and exciting dogleg
2014 campaign!
• Xbox will be connected in the next weeks
• Some time for synchronization, calibration, conditioning…
• Specific slot reserved for dogleg during summer restarting.
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Thanks for your attention
M. DayyaniS. DoebertJ.L. NavarroS.F. ReyF. Tecker L. Timeo T. WisznowskiAll operators
CTF3
M. FilippovaD. GudkovP. GuyardS. LebetA. OlyuninG. RiddoneA. SamochkineI. SyratchevA. SolodkoP. De Souza
RF/PM XBOX
S. CurtA. DegiovanniG. McMonagleJ. Tagg B. WoolleyX. Wu
TE-VCS
E. Paju
Special thanks to A. Grudiev for very useful discussions and material.
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J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Thanks for your attention
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New VISTARBy D. Gamba
J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Backup: CLIC Nominal parameters 24/22
J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
BackupAccelerating gradients achieved in tests.
Status: 4-9-2012
loaded
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26
Structure under test:CERN’s T24 (12WNDSvg1.8 KEK N1)No damping
Backup (I. Syrachev. CLIC Workshop 2013)
27
Insertion losses of the input/output waveguide network (splitter and bends) is -0.15 dB (=0.967)
-49.32
-52.04
Calibration (I. Syrachev. CLIC Workshop 2013)
28Backup
29Backup
J.L. Navarro. CLIC Workshop, 3 - 7 January 2013
Phase I Results: Running of Dec 2013And from the RF side:
Theoretical model fits within
experimental uncertainties
Data from May 2013
Data from Dec 2013(after DAQ recalibration)
P[MW]=1.91 I2
P[MW]=3.17 I2
P[MW]=2.62 I2
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31Dog-leg waveguide line installation status.
All the components are installed. Connected to accelerated structure and closed for vacuum. Vacuum leaks checked (tight).
Ready to be connected to XBOX1.
32RF power transmission measurements
S11 data
Short circuit(+offset)
Matched load
S21 Reconstructed(Xiaowei Wu)
Transmission (simulated)
Reflection
• The measured RF power transmission efficiency is 80%.• Reflection is below -27dB.• The group delay time is 75 ns (~23.5 m).
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CTF2 CTF3Xbox1 wall
0.87 0.8
Overall power transmission efficiency
• The overall measured RF power transmission efficiency is 67%.• The round group delay time is 230 ns (~35 m).• To provide nominal CLIC RF pulse, XBOX1 klystrons needs to deliver 36 MW x 1.5s