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CTF3 Drive Beam studies results & Program. Piotr Skowroński for the CTF3 team. Factor 4 recombined beam Routine 14A 280ns. CTF3 routinely delivers 14A beam for the experiments in CLEX From injector 4.1 A, ~1200 ns, dE /E 2.5% FWHM After the Stretching chicane: 4 A, 1120ns - PowerPoint PPT Presentation
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CTF3 Drive Beam studies results &Program
Piotr Skowroński for the CTF3 team
30 December 2013CLIC Workshop 20131
CLIC Workshop 2013
Factor 4 recombined beamRoutine 14A 280ns
CTF3 routinely delivers 14A beam for the experiments in CLEX From injector 4.1 A, ~1200 ns, dE/E 2.5% FWHM After the Stretching chicane: 4 A, 1120ns Extracted from Combiner Ring: 16 A, 280ns
Quality check: recombined pulse stored for few extra turns CLEX: Stable 14 A
It is not certain how much it is a real loss or BPM calibration issue
Measured RF form factors 0.9 – 0.95 Bunch length 17 ps It allowed x4 rep. rate increase to 3.2 Hz
for TBTS night runs
30 December 20132
CLIC Workshop 2013
Losses and Short term Stability (Jitter)
2012 we ran lower R56 optics tails lost in the Stretcher Beam intensity jitter showing off already there Still achieving the same final performance in CLEX
In 2012 the calibration of BPIs and their nonlinearity were corrected still calibration is not 100% certain (see Ben Constance talk )
30 December 20133
the Stretcher(Frascati Chicane) ― 2011
― 2012• BPIs
Tobias Persson
CLIC Workshop 2013
Orbit issuesThere are issues with the orbit at Delay Loop injection and ejection
The beam ends up too low after passing the septa Combiner Ring behind the first bend and in the last arc (horizontal) At the end of TL2 strong steering in horizontal to pass through the
CLEX wallThe reasons are continuously investigated Several alignment campaigns done Magnet checks Improvements are clear, but still the situation is not fully
satisfactoryUsing the magnetics correctors bluntly leads to spurious dispersion and eventually to lossesPlan to use more sophisticated beam based steering over all of the lines Variant of Dispersion Free Steering that targets nominal dispersion
pattern
30 December 20134
CLIC Workshop 2013
CR recombination with new attenuator for the 2nd RF deflector
Closure within 1mm
30 December 20135
(BPI charging up)(not real)RF bump RF bump
CLIC Workshop 2013
DispersionThe dispersion is well controlledNeed to be careful with strong steerers which can spoil dispersionControlled with 2 different measurement methods Scaling all magnetic elements Change of beam energy along the pulse with MKS15 pulse compression
Watch the step in BPM traces
30 December 20136
Horoizontal
BPM/BPI traces along pulse with energy step
Lower EnergyHigher Energy Lower EnergyHigher Energy
Vertical
Bad BPI
CLIC Workshop 2013 30 December 20137
Factor 4 recombined beamEmittance in mm mrad
LINAC Girder 10Horizontal: 40-> 60
Vertical 40 -> 60
CLEX EntranceHorizontal: 170-> 350
Vertical 125 -> 200
CR ExtractionHorizontal: 75-> 150
(?)Vertical 37 -> 100 (?)
Behind StretcherHorizontal: 60-> 90
Vertical 40 -> 80
CTSHorizontal: 60-> 90
Vertical 40 -> 80
CLIC Workshop 2013
Emittance issuesEmittance growth over TL1 and CRThe emittance is blown up with several mechanisms Orbit closure in Combiner Ring Bad orbit Mismatch to the closed CR solution Chroma Non linear dispersion
30 December 20138
CLIC Workshop 2013
Emittance StudiesInfluence of bad orbit on emittance Particles orbitate around fixed point of phase space
It is defined by the magnetic centres of quads If chroma is not corrected (natural negative) particles with higher
momentum rotate slower, with lower momentum – faster Bigger the momentum spread and chroma faster the beam fills up
the phase space: decoherence In CTF3 sigma dp/p ≈ 1%, CR chroma ≈ -13/-9 per turn
30 December 20139
Simulations by Javier Barranco
• turn 3• turn 2• turn 1• Injection, offset 1mm
Emittance growth vs. turn nb. for different injection orbit errors
CLIC Workshop 2013
Emittance StudiesInfluence of bad orbit on emittance Particles orbitate around fixed point of phase space
It is defined by the magnetic centres of quads If chroma is not corrected (natural negative) particles with higher
momentum rotate slower, with lower momentum – faster Bigger the momentum spread and chroma faster the beam fills up
the phase space: decoherence In CTF3 sigma dp/p ≈ 1%, CR chroma ≈ -13 per turn
30 December 201310
Simulations by Javier BarrancoMeasurement by Tobias PerssonEmittance vs. orbit error
CLIC Workshop 2013
Transverse mismatchSimilarly transverse mismatch leads to the emittance growth through decoherence
30 December 201311
Measured beating: Twiss parameters vs number of turns
Simulations by Javier Barranco
• Injection, mismatched Twiss• Turn 1• turn 2 – dumped on closed
Twiss• turn 3
turn no. turn no.
CLIC Workshop 2013
Emittance: the way to goStability! Obviously, if the beam constantly drifts there is no way to optimize it Culprit: the RF pulse compression A lot was done during last year and more will be done, see Tobias
Persson’s talk Hopefully very soon we can concentrate fully on beam optimization rather than keeping the beam in place
More sophisticated automatic orbit correction DFS variant, targeting the model dispersion, i.e. minimize spurious
dispersion Davide Gamba started his contract in January and will take care of it
Automatic orbit closure in Combiner Ring and Delay Loop Davide also will take care of it
Beta beating removalChromatic correction Needs good closed orbit correction first,
Otherwise sextupoles feed-down to quadrupole, change focusing and lead to losses
New optics likely needs to be commissionedThe current one is not symmetric over the cell while sextupoles are connected in series
It would also facilitate fine optimizations of the ring optics30 December 201312
CLIC Workshop 2013
Optics issues
In couple of places disagreements between the model and the measured optics still observed The Stretcher Chicane TL2
Quite large experimental corrections needed to remove beta and dispersion beatingExtensive optics measurements were done towards the end of the last run Ben Constance will summarize his findings in the following
presentation
30 December 201313 Ben Constance
CLIC Workshop 2013
Factor 8
Had it only for couple of weeks in 2012: TWTs problems A spare TWT was ordered in autumn Another spare will be ordered very soon
With 2 TWTs satellites were at 0.6A levelThe biggest issue is the DL orbit closure and its stability Davide made the automatic tool for that
30 December 201314
CLIC Workshop 2013
Phase SwitchingRunning with only 2 TWTs exposed long lasting switching effects which makes factor 8 much more difficult to operate from the start Careful tuning of the low level RF already improved the situation,
but did not remove the effect Will keep looking into this issue Should be minimized with 3 TWTs operational
30 December 201315
CLIC Workshop 2013
Further topics
Several topics are covered in detail in the following talks Status of optics control Bunch length Stability and feedbacks TBL results Profile measurements BPM system status Phase measurements
30 December 201316
CLIC Workshop 2013
Program 2013-2014Factor 8 and experiments with 30A drive beam During this and previous runs fully recombined beam (factor 8)
was available only for short times due to failures of 1.5GHz RF sources
Ordered 2 additional TWTsTest Beam Line (TBL) From 20 A to 30 A, deceleration in the 30%-50% range Dispersion free steering, optics studies
Also extend to high current/large decelerationTwo-Beam Test Stand (TBTS) Structures conditioning
Two new structures installed last summerOvernight runs
Wake-field monitor testsBoth with and without the drive beam
RF pulse shaping testsThe dog-leg experiment: break down rates in presence of beam loadingPhoto gun (PHIN) experiments in CTF2 hall Requires only one klystron Last run in 2013
Two-beam modules in 201430 December 201317
CLIC Workshop 2013
Phase Feed Forward System
30 December 201318 18
Phase monitor
Not just a single experiment – series of related studies: • Measure phase and energy jitter, identify sources,
devise & implement cures, extrapolate to CLIC• Show principle of CLIC fast feed-forward
Fast kickers
Drive beam phase feed-forward concept @ CLIC
Close link to collaborating partners:
INFN-LNF: Phase monitors, strip-line kickersOxford University/JAI: feedback electronics, amplifiers
DRIVE BEAM LINAC
CLEXCLIC Experimental Area
DELAY LOOP
COMBINERRING
10 m
Phase & energy measurement
Fast feed-forward kicker in final
compression line
Phase feed-forward @ CTF3
Phase stability 2.5° @ 12GHz
0.2° @ 1GHz
Phase stability 0.2° @ 12GHz
FONT5 board(Oxford)
Stripline kicker (INFN-
LNF)
CLIC Workshop 2013
Phase Feed Forward
30 December 201319
Phase monitor(INF-LNF, EuCARD)
• Phase monitor tests – 2 monitors installed in summer 2012
• System installation in spring 2013• First system tests planned in
summer 2013
Experiment on the effect of Beam-Loading on Breakdown Rate
30 December 2013CLIC Workshop 201320
•CLEX
• LINAC
• DELAY LOOP
• COMBINER RING
• BL - BDR experiment
From X-band klystron
X-band structure TD24
X-band components
1 A, 240 ns pulse from CTF3 linac
G. Riddone, A. Solodko
Beam loading reduces field locally in the structure ⇨ is it the break-down rate lower (or higher)?• CLEX probe beam has only limited current/pulse length, CLEX Drive
beam has limited rep rate ⇨ use CTF3 drive beam and klystron driven X-band structure
• Reactivate the old ‘30 GHz PETS’ line, 1 A DB current, can reach 50 Hz• Measure BDR with/without beam to get a direct comparisonPresent schedule: Install in winter shutdown 2012-2013
Run experiment in 2013
CLIC Workshop 2013 30 December 201321
3D model of integration of the first CLIC Module in CLEX (2013)
CLEX - Three two-beam modules(2014)
TBTS PETS tankModule T0
Present schedule:First module installation: end
2013(At least one year of testing)Module string installation end
2014
Drive Beam line
Main Beam
line
Two-Beam Modules
CLIC Workshop 2013 30 December 201322
Schedule 2013 (as of September)
Modifications from
last month
CLIC Workshop 2013
Schedule 2013 (as of September)
30 December 201323
Modifications from last month
CLIC Workshop 2013
Schedule 2013
Short winter shutdown: Stop the machine on December 14th and restart operation with beam on
January 21 7 weeks before the LHC stop
Some new equipment will be installed and most of the cabling work will be done
Install demineralizing stationRunning until all media and services are availableSecond, longer shutdown starting end of April till end of July The longer maintenance of the RF system will be done This shutdown may shift later depending on running conditions,
advancement of other activities and readiness of new hardware.CTF3 would restart in August and run until the end of the yearThe dog-leg installation should be completed during May-June, and the beam-loading experiment may start as soon as klystrons 2 to 7 are available.PHIN run also possible in summer, in the shadow of modulator-klystron maintenance of the 2nd half of the CTF3 Linac.
30 December 201324
CLIC Workshop 2013
Known issuesand planned solutions
Demineralized water will not be available from mid-May to mid-August Postpone winter shutdown to May Initial plan: installation of local demineralizing station
Filter cartridges must be periodically regeneratedNot enough man power for thisAccepting to stop for the whole period, still would like to install the system
Access: no operators in CCC/CPS island Moving the control to CSA and to the CTF control room
Possible interruptions of control services Moving some services locally (f.g. ctf3op home directories)
Asking to concentrate all the potentially disrupting interventions, preferably to our summer shutdown
30 December 201325
CLIC Workshop 2013
Conclusion
2012 was very successful Improved the beam stability and quality It allowed increasing repetition rate for over night
TBTS runs Increased over night availability of the drive beam
Still a lot ahead of us Factor 8 with 30A delivered to CLEX Further emittance reduction Stability
EnergyCurrentPhase
30 December 201326
CLIC Workshop 2013 30 December 201327
Modifications from
last month
Modifications from
last month