ECE at SPS and LHC Hofle CERN BERFFB o n behalf of a multilab team CERN SLAC LBNL LNFINFN W Hofle ECLOUD12 La Biodola Elba Italy 09062012 June 9 2012 1 focused on damping intrabunch transverse oscillations for proton bunches ID: 798579
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Slide1
Transverse Feedbacks against ECE at SPS and LHCHofleCERN BE-RF-FBon behalf of a multi-lab teamCERN – SLAC – LBNL – LNF-INFN
W. Hofle @ECLOUD12 - La Biodola, Elba, Italy
09.06.2012
June 9, 2012
1
Slide2focused on damping intra-bunch transverse oscillations for proton bunchesderiving specifications for a High band width feedback
for the SPS from
simulations see talk by
K. Li in this workshop,
activity with
headtail and WARP codes started in 2008 demonstrated damping of headtail instability caused by ecloud future: extend to TMCI caused by impedance (SPS, then PS and LHC ?)prototype hardware development for machine studies and “demonstrator” for proof of principle experiment in SPS see overview talk by J. Foxdesigns for new kickers, impedance (SLAC – LBNL – LNF-INFN)collaborating team: J. Cesaratto, J.D. Fox, M. Pivi, K. Pollock, C. Rivetta, O. Turgut, S. Uemura (SLAC)G. Arduini, W. Hofle, K. Li, G. Rumolo, B. Salvant (CERN)M. Furman, M. Venturini, S. De Santis, Z. Paret, R. Secondo, J.-L. Vay (LBNL) A. Drago, S. Gallo, F. Marcellini, M. Zobov (LNF-INFN)AcknowledgementsCERN PS team: H. Damerau, S. Gilardoni, A. Blas
Multi lab effort
W. Hofle @ECLOUD12 - La Biodola, Elba, Italy
June 9, 2012
2
s
upported by
US-LARP
CERN SPS LIU Project
Slide3June 9, 2012W. Hofle @ECLOUD12 - La Biodola, Elba, Italy3/38
Current
CERN Accelerator Complex
LHC
: 450
GeV to 7 TeV, protons400 MHzSPS: 26 GeV/c to 450 GeV, protons for LHC200 MHzPS: Protons 1.4 GeV – 26 GeV/c3 – 10 MHz, 13 MHz, 20 MHz, 40 MHz, 80 MHzbunch structure of 25 ns createdPSB: 50 MeV to 1.4 GeV, future: 160 MeV to 2 GeV0.6-1.7 MHz, 1.2-3.4 MHz LINAC2 (protons), 200 MHzto be replaced by LINAC4 (H- , under construction) 352 MHz
Slide4June 9, 2012W. Hofle @ECLOUD12 - La Biodola, Elba, Italy4
First
observations in SPS
o
n pick-ups of transverse feedback 1998/1999
…Top trace: 20 ms/divBottom trace: 1 ms /div 14.06.992-3 1012 protons/batchLHC beam25 ns bunch spacing01.09.982-3 1012 protons/batchLHC beam25 ns bunch spacingObservation:baseline drifts on pick-up signals during the passage of an LHC batchwhat is going on?p
resented at Ecloud ‘07
1 turn
72 bunches
@ 25ns spacing
Slide5June 9, 2012W. Hofle @ECLOUD12 - La Biodola, Elba, Italy5
…
Magnetic
solenoid field can suppress the effect
electrons
without solenoidwith solenoid (100 gauss)horizontal
horizontal
vertical
vertical
The resonant build-up of the electron generation can be disrupted
by applying a magnetic solenoid field
scales 1
m
s/div
p
resented at
Ecloud
‘07
Slide6PS: at very last part of beam manipulations when 25 ns spaced bunches are shortened horizontal coupled bunch instability, also intra bunch motion ?
SPS:
all along the cycle at 25 ns bunch spacing strong horizontal coupled bunch instability and
vertical single bunch instability with intra bunch motion
LHC:
single bunch instability under study see talk by H. Bartosik; also intra bunch motion ? signature of ecloud with its development along batchwithout mitigation instabilities lead to beam lossesand transverse emittance blow-up with direct impact onluminosity performance in LHCMitigation: Transverse FeedbacksTransverse instabilities caused by ecloud in LHC and its injectorsW. Hofle @ECLOUD12 - La Biodola, Elba, ItalyJune 9, 20126
Slide7June 9, 2012W. Hofle @ECLOUD12 - La Biodola, Elba, Italy7/38
Accelerator
Digital / analogue processing
Power / kicker / bandwidth
Status
PS Booster
(protons)
50 MeV – 1.4
GeV
kin. E
.
(future: 160 MeV to 2
GeV
kin E)
n
o
ecloud
, long bunches
multi turn injection from
Linac
2
analogue beam offset signal suppression, analogue delay (cables & switches)
100 W, 50
W
stripline
Limited to 13 MHz in operation
But built for 100 MHz bandwidth, baseband
H-plane:
used and required
V-plane: beam stable w/o
FB
u
pgrade
planned
PS
(protons, ions)
1.4
GeV
– 25
GeV
(kinetic E
)
(future injection at 2
GeV
)
ecloud
observed
when beam bunched at 25 ns
Spacing, coupled bunch
d
igital
system,
synergy
with LHC Damper for
The low level digital
processing
80 MHz clock frequency
2 kW solid state power amplifier; 112
W
stripline
(0.9 m length), planned with ~30 MHz bandwidth in baseband, lower cut-off ~50 kHz
2012 under commissioning
injection damping and feedback
will be beneficial in particular for high intensity CNGS beams and LHC beams. Currently horizontal instabilities are cured by introducing coupling to the vertical plane which constrains the tunes
SPS
(protons, ions)
(14 – 450)
GeV/c protons FT (26 – 450) GeV/c LHC beamecloud observed and isa potential limitation for 25 nsspacingdigital notch filter and 1T-delay (Altera FPGA, 80 MHz clock)commissioned in 2000/2001tetrode amplifiers with two30 kW tetrodes in push-pull directly coupled to a kicker (base band); feedback bandwidth ~10 kHz to 20 MHz2001 upgraded for LHC beamsH-plane: used in operationV-plane: used in operationused and required for operationabove 5x1012 protons (max ~5.5x1013 ppp accelerated)SPS High Bandwidth Feedbackdigital @ 4 – 5 GS/s clockunder study, GHz BWFeasibility StudyLHC (protons, ions)protons: 450 GeV/c – 7 TeV/cecloud observed and is a potential limtation for 25 nsspacingdigital notch filter and 1T-delay,built-in diagnostics14 bit DAC / DACAltera FPGA, 40/80 MHz clock2 um rms resolutiontetrode amplifiers with two30 kW tetrodes in push-pull directly coupled to kicker (base band) similar to SPS system3 kHz -> 20 MHz2010 fully commissionedinjection dampingfeedback used in ramp and physics, essential
Transverse Feedback Systems
in LHC and its injectors
Slide8From established LHC operation to LHC High Luminosity operationStatimportant for injectors:two very different scenarios:
25 ns bunch spacing50 ns bunch spacing
LIU (“LHC
Injector U
pgrade”)
project addresses upgradesin the injector chain(LINAC)PSBPSSPSto meet HL requirementsW. Hofle @ECLOUD12 - La Biodola, Elba, ItalyJune 9, 20128LHC2012 OPLHC nominalHL-LHC25 nsHL-LHC50 nsEnergy4 TeV7 Tev7 Tev7 Tev# Bunches1380280828081404bunch spacing [ns]50252550p/bunch [1011]1.551.15 (0.58A)2.2 (1.11 A)3.5 (0.88
A)
gex,y
[mm]
2.3
3.75
2.5
3.0
Peak lumi [10
34
]
0.66
1.0
7.2
8.3
Lumi
levelling
no
no
5x10
34
5x10
34
#Pile up
34
25
123
247
Status from May 2012 (L. Rossi @LARP CM18)
2014+
Future upgrade
today
Slide9Increase performance higher brightnessLINAC4 (H- linac) is being constructedraise of injection energy into PSB from 50
MeV to 160 MeV
(LINAC4)increase injection energy into PS (space charge limits) 1.42
GeV
SPS: RF upgrade (power),
Q20 optics (lower gT) TMCIvacuum chamber coating in SPS as part of ecloud mitigationhigh bandwidth feedbackLLRF upgrades in PSB,PS,SPS with additional long./cavity feedbacksupgrades for beam transfer, collimation, scraping, instrumentationIncrease reliability and lifetimes until 2030 approximatelyspares, radio-protection, replacement of aging equipmentProject timeline: “baseline” completed after LS2 (long shutdown 2 of LHC) > 2017/2018: LIU “baseline” beam commissioning constraints: two long shutdowns LS1 and LS2 for modifications and major installations; LS1 to start at end of 2012LIU project: Goals and MeansW. Hofle @ECLOUD12 - La Biodola, Elba, ItalyJune 9, 20129
Slide10objective: cure transverse “single bunch” instability by feedbacktwo collective effects are limiting the SPS performance as LHC injectore-cloudTMCIsimilarities: both effects cause vertical
intra bunch instabilityhigh chromaticity suppresses instability to a certain extent
feedback expected to permit running at low chromaticity and at intensities beyond which high chromaticity is an established cure
particular important to maintain small transverse emittances
Motivation for high bandwidth feedback in SPSW. Hofle @ECLOUD12 - La Biodola, Elba, ItalyJune 9, 201210
Slide11coherent signals visible for both ecloud and TMCI instabilityprovided reaction time (few turns) shorter than growth times feedback in principle should workFeedback as cure
Frequency (0-2.5 GHz)
turns
sum
difference (delta)
instability growing(TMCI)signals up to 1.6 GHzR. de Maria et al.DIPAC 2009, MOPD17W. Hofle @ECLOUD12 - La Biodola, Elba, ItalyJune 9, 201211
Slide12e-cloud vertical instability
frequency
turns
sum
difference (delta)
instability growingsignals up to 1.2 GHzR. de Maria et al.DIPAC 2009, MOPD17artifact from pick-up(beam pipe cut-off)quadrupolar motion (longitudinal)at injectiondue to voltagemismatchW. Hofle @ECLOUD12 - La Biodola, Elba, ItalyJune 9, 201212
Slide13e-cloud vertical instabilityW. Hofle @ECLOUD12 - La Biodola, Elba, ItalyJune 9, 201213
Slide14RF, low radiationspecial instrumentationno RF infrastructure
extraction CNGS/LHC
injection
slow extraction
radiation high
current transverse FBextraction LHCLSS3 layout to be studiedby working group under LIUled by E. Montesinos (BE-RF)alternative locationbase line locationfor wide band TFBW. Hofle @ECLOUD12 - La Biodola, Elba, ItalyJune 9, 201214Implementation in SPS: possible locations for transverse feedbacks in SPS
Slide15New kickers W. Hofle @ECLOUD12 - La Biodola, Elba, Italy
short (array of) striplines
, slotted wave guides, cavities ?Location: dispersion
supressor, flat vacuum chamber
Frequency reach < 1.5 GHz
Cabling can be prepared in LS1 (2013/2014)June 9, 201215
Slide16June 9, 2012W. Hofle @ECLOUD12 - La Biodola, Elba, Italy16
SPS aperture
Slide17W. Hofle @ECLOUD12 - La Biodola, Elba, ItalyAperture available for feedback kickers and pick-ups in dispersion suppressorsJune 9, 2012
17
under review:
H. BartosikY.
Papaphilippou
aperture available determined by fixed target beams (14 GeV/c)circular or rectangular vacuum chamber possible input to design of kicker
Slide18Boundary conditions:LS1: 2012LS2: 2017+Phase 1: The demonstrator end 2012 minimum goal: damp head tail motion of single bunch existing equipment (amplifiers, BPWs as kicker and PU)
“drive experiments” see presentations in this session
electronics (LARP), close FB loop
all design specifications for phase 2: end of 2012
Phase 2:
New pick-up, new kicker, consolidated electronics, higher power amplifiers, preparation of LSS3 in LS1 for installation of equipment at the end of LS1 or later in a short winter shutdown post-LS1 feedback on multi-bunch beam in presence of e-cloud decide on final implementation and LSS3 vs. LSS5 before LS2R&D and staged implementation: The Path (1)W. Hofle @ECLOUD12 - La Biodola, Elba, ItalyJune 9, 201218
Slide19Phase 3: Final implementation in LS2 depending on desired energy range upgrade power and if impossible to install in LSS3 for reasons of space or radiation
move to LSS5
add kicker modules if required design and construct final electronics (profit from latest technology)
commission after LS2
R&D and staged implementation: The Path (2)
W. Hofle @ECLOUD12 - La Biodola, Elba, ItalyJune 9, 201219
Slide20“a” Schedule new pick-up design and construction
Year 4
Year 3
Year 2
Year 1
Year 5Phase 1:201720142013
2012
2011
2015
2016
2018
Year 6
Year 7
demonstrator
power amplifiers for phase 2 tendering (s)
kickers design and construction
phase 2 beam tests
Phase 2:
review for
phase 2:
Phase 3:
implementation
go / no-go
phase 3:
June 9, 2012
W. Hofle @ECLOUD12 - La Biodola, Elba, Italy
20
Slide21W. Hofle @ECLOUD12 - La Biodola, Elba, ItalyJune 9, 201221
SLAC committed to provide the yet
missing part for the demonstrator
J. D.
Fox
Slide22simulations with impedance model of SPS for TMCI/FB neededaddress full parameter space with ecloud simulationsR&D also need to cover exotic beams, very high single bunch intensities for LHC MDs,
feedback for other bunch spacings (5ns ?)
R&D recommended also for possible implementation in LHC (SPS is “test bed”), PS (?)
design report with choices for kickers at end of phase 1 (end of 2012)
impedance of kickers (!)Immediate future towards a designreport at end of 2012W. Hofle @ECLOUD12 - La Biodola, Elba, ItalyJune 9, 201222
Slide23June 9, 2012W. Hofle @ECLOUD12 - La Biodola, Elba, Italy23Kicker options
all kicker options need evaluation of the
impact of their beam coupling impedancefrom machine point of view a lower impedance structure is preferredm
ake impedance only as high as necessary, in case more kick strength required, installation of more power is always an optionComputation of required power needs input from
headtail
or from the demonstratorexperiments
Slide24Striplines (1)A
single 10-cm long stripline seems to be able to provide the necessary transverse kick up to 750 MHz
, with acceptable power figures and required voltage.
Its response time is capable of targeting at least head and tail of the bunch with independently selected kicks.
If a response up to
1.5 GHz is required to deal with the TMCI, multiple shorter striplines ( 4 x 5 cm long) can provide the necessary transverse impedance over the entire frequency range up from DC.We have validated our analytical estimates with 3D electromagnetic simulations, which can also provide information on the field uniformity, etc.Such 3D simulations will be the tool of choice for a careful design of the stripline kicker once a choice is made.S. De SantisZ. Paret, LBNLJune 9, 2012W. Hofle @ECLOUD12 - La Biodola, Elba, Italy24
Slide25Stripline (2)
100 mm
20 mm
30 mm
40 mm
59 mmS. De SantisZ. Paret, LBNLJune 9, 2012W. Hofle @ECLOUD12 - La Biodola, Elba, Italy25
Slide26Stripline (3)
A 5 cm long stripline offers maximum shunt impedance at 1.5 GHz, equal to about 250 Ω. The required deflecting voltage increases to 3.1 kV therefore multiple striplines are needed.
GHz
Ω
4×5 cm
10 cmTotal impedanceFrequency (MHz)V/modulePmax (W)/mod.Pavg (W)/mod.15008001300260Adding four 5 cm stripline modules is sufficient to obtain manageable values for voltage and power figures at 1.5 GHz and can possibly replace the single 10 cm module at lower frequencies! S. De SantisZ. Paret, LBNLJune 9, 2012
W. Hofle @ECLOUD12 - La Biodola, Elba, Italy26
Slide27W. Hofle @ECLOUD12 - La Biodola, Elba, ItalyJune 9, 201227
Slotted waveguide kicker (1)
Slide28W. Hofle @ECLOUD12 - La Biodola, Elba, ItalyJune 9, 201228
Slotted waveguide kicker (2)
Slide29Kicker #1
Kicker #2
Kicker #3
Type
Stripline
Cavity, TM110 defl. modeCavity, TM110 defl. mode3-dB bandwidthDC – 400 MHz800 ± 16 MHz1200 ± 16 MHzLength17 cm15 cm10 cmFilling time0.6 ns10 ns10 nsQL---25
38
Shunt Impedance
≈ 1.5 kΩ (@ DC)
≈ 1.5 kΩ (@ 800 MHz)
≈ 2.2
kΩ
(@ 1200 MHz)
Resulting transverse voltage transferred to the beam as a function of the frequency, a
ssuming
the system
of
kickers
driven
by a 1 kW source.
June 9, 2012
W. Hofle @ECLOUD12 - La Biodola, Elba, Italy
29
A
. Gallo,
F.
Marcellini
,
LNF-INFN
Proposal by A. Gallo and F.
Marcellini
Stripline
plus cavities (1)
need check in
headtail
Slide30Verify with simulations that the wanted cavity parameters (frequency, Q and shunt impedance) are feasible.Simple geometry considered:single cell cavities input/output
wgs coupled by means of 2 identical and large aperturesworking mode: TM110
Rectangular beam pipe (100x36 mm^2) assumed.
June 9, 2012
W. Hofle @ECLOUD12 - La Biodola, Elba, Italy
30A. Gallo,F. Marcellini, LNF-INFNProposal by A. Gallo and F. MarcelliniStripline plus cavities (2)
Slide31Extension to PS and LHC: Comparison with SPSHigh bandwidth feedback R&D for hardwaredirectly applicable to PS and LHCapplication to LHC and for SPS at top energy may require higher sampling rate than the present hardware (4 GS/s), 12 GS/s seems current
technology barrier, still very expensiverequired power at 7 TeV
in LHC also a concernaddress bandwidth and power for full parameter space in simulations for LHC, PS and SPS along the ramp
potential to damp within bunch oscillations observed both in PS (transition) and in LHC not
related to
ecloudW. Hofle @ECLOUD12 - La Biodola, Elba, ItalyJune 9, 201231PSSPSLHCnominalenergy (inj) GeV1.4 (kin.)26450top energy GeV264507bunch spacing [ns]252525cycle length3.6 s18 sapproximatelyup to many hours time with ecloudfew msfull cycle
entire store
scrubbing
Noyes
yesbunch lengths
3.7 ns
3.7
ns – 1.7 ns
1.7-
1.25 ns
e
xpect to require 3x bandwidth & sampling rate
f
or LHC system at top energy when compared
w
ith SPS at injection (scaling with bunch length)
Slide32What happens before the extraction of
LHC beam
from the PS?
80 MHz (h = 168)
40 MHz (h = 84)
4s = 14 ns11 ns4 ns
Adiabatic shortening
Bunch rotation
Bunch splittings
Extraction
H.
Damerau
see also talk by Ch.
Bhat
at this workshop
PS: no time for scrubbing (low duty cycle !)
e
cloud
observed, but no intra bunch instability (yet ?)
June 9, 2012
W. Hofle @ECLOUD12 - La Biodola, Elba, Italy
32
Slide33S
, DR
, DV signals
E.
Métral
et al., 2003S. Aumon, 2010also candidate for cure by high bandwidth feedbackif it were / became a limitationTransverse instability in PS at transition
Slide34Summary W. Hofle @ECLOUD12 - La Biodola, Elba, ItalyMulti
lab effort ramped up, for kicker design study collaborators from LNF-INFN
Frascati recently joined
Simulations: first results from Kevin Li confirm previous results, very encouraging
Hardware (SLAC) critical for demonstrator
tests in 2012Evaluate impedance and aperture from kickers (down select process !)Shutdown 1 preparations and design report at end of year are next milestonesResults in SPS also applicable to PS and LHC, challenging in case of LHCJune 9, 201234