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LIU evolution. H. Damerau, R. Garoby, B. Goddard, S. Gilardoni, K. Hanke , D. Manglunki, M. Meddahi , B. Mikulec, L. Ponce, E. Shaposhnikova , M . Vretenar Acknowledge work from ABP, ABT, RF, OP, BI, STI, EPC , MSC, VSC , …. and US-LARP collaborators. Contents. - PowerPoint PPT Presentation
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LIU evolution
H. Damerau, R. Garoby, B. Goddard, S. Gilardoni, K. Hanke, D. Manglunki, M. Meddahi, B. Mikulec, L. Ponce, E. Shaposhnikova,
M. Vretenar
Acknowledge work from ABP, ABT, RF, OP, BI, STI, EPC, MSC, VSC, ….
and US-LARP collaborators
Contents• Post LS2 HL-LHC requirements• Corresponding LIU beam requirements• 2012 proton injector chain performance• Limitations and mitigations• Unknowns, risks and remaining issues• Post LS2 expected performance• Conclusion
2
HL-LHC beam parameters at 7 TeV
3
Stretched Baseline Parameters following 2nd HL-LHC/LIUemail M. Zerlauth- O.Brüning, 8 November 2012
Parameter nominal 25ns 50nsnb 2808 2808 1404Nb 1.15E+11 2.2E+11 3.5E+11εn [mm-mrad] 3.75 2.50 3
Corresponding required beam parameters through injector chain
4B. Goddard, Chamonix 12
Assumptions:
2012 injector beam parameters
5
ACHIEVEDin201250 ns bunch trains at LHC
injection
50 ns bunch trains at start of collisions
25 ns bunch trains at LHC
injection
Number of bunches (nb) 1374 1374 2808
Protons/bunch (Nb) 1.7·1011 1.6·1011 1.1·1011
Norm. trans. emittance (en)[mm.mrad] 1.6 2.4 2.8
HL-LHCREQUESTS50 ns bunch trains at LHC
injection
50 ns bunch trains at start of collisions
25 ns bunch trains at LHC
injectionNumber of bunches (nb) 1404 1404 2808
Protons/bunch (Nb) 3.7·1011 3.5·1011 2.3·1011
Norm. trans. emittance (en)[mm.mrad] 2.7 3 2.3
6
2012 Performance and limitations at SPS ejection
6
Large improvement is required for either 25 or 50 ns beam!
0.0 0.5 1.0 1.5 2.0 2.50.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
BunchIntensity[e11]
Emittance(x+y)/2[um]
HL-LHC
SPS450GeV25ns
SPSRFpow
erSPSLong.inst.
SPSeCloud
2012
PotentialwithPSBatch
Compression
PSB-50MeV
PS-1.4GeV
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.00.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
BunchIntensity[e11]Em
ittance(x+y)/2[um]
PSB-50MeV
SPS450GeV50ns
SPSkickerheatin
gSPSLong.instab.
HL-LHC
2012
PS-1.4GeV
2012resultswithPSBatchcompression
Limitations: 25 nsspace charge/brightness
• PSB: exy [mm] -0.42 Nb [e12] / DQy, with 160 MeV injection– Confident to run with DQy of at least -0.4– Need 3.4e12 in 1.9 mm: potential for 3.4e12 in 1.7 mm (OK)
• PS: exy [mm] -0.26 Nb [e12] / DQy , with 2 GeV injection– Confident to run with DQy of at least -0.26 (operational beam reached -0.28)– Need 3.2e12 in 2.0 mm: potential for 3.2e12 in 3.0 mm (Not OK)– Cannot digest fully what PSB can provide– Need to increase DQy to -0.37 to reach the required brightness
• SPS: exy [mm] -1.22 Nb [e12] / DQy, with Q20 optics at 26 GeV– Reasonably confident to run with DQy -0.15 (single bunch brightness)– Need 2.5e11 in 2.1 mm: potential for 2.5e11 in 2.0 mm (OK)
For 25 ns: suggests limit will be PS, as PSB delivers more than PS can digest7
Limitations: 50 nsspace charge/brightness
• PSB: exy [mm] -0.42 Nb [e12] / DQy, with 160 MeV injection– Confident to run with DQy of at least -0.4– Need 2.7e12 in 2.2 mm: potential for 3.4e12 in 1.7 mm (easy!)
• PS: exy [mm] -0.26 Nb [e12] / DQy , with 2 GeV injection– Confident to run with DQy of at least -0.26 (operational beam reached -
0.28)– Need 2.6e12 in 2.4 mm: potential for 2.6e12 in 2.4 mm (Just OK)
• SPS: exy [mm] -1.22 Nb [e12] / DQy, with Q20 optics at 26 GeV– Reasonably confident to run with DQy -0.15 (single bunch brightness)– Need 4.0e11 in 2.5 mm: potential for 4.0e11 in 3.3 mm (Not OK)– Need to increase DQy to -0.2 to reach the required brightness
For 50 ns: PSB and PS OK, limit in SPS8
Other limitations and actions• SPS TMCI : single bunch
– Q20 now used: above ~3.6e11 per bunch (Q’=0)• PS longitudinal phase plane: – Should increase limits from present ~1.7e11 to ~3e11 p+/b while keeping
the beam splitting quality– Combine effects of different actions:• New longitudinal damper using dedicated broad band cavity• Fast RF feedback systems upgraded on all High Power RF systems• One turn-delay feedbacks renovated• More RF voltage at 40 MHz installed for better SPS capture efficiency
• PS-SPS transfer parameters – Larger longitudinal emittance required for beam stability both in the PS
and SPS, but its leads to higher capture losses in the SPS.– Simulations predict a significant gain by optimising the PS bunch rotation
with spare RF cavities. First MD results are very encouraging – Helga Timkó et al.
SPS longitudinal instabilitiesP. Baudrenghien, W. Höfle, E. Shaposhnikova, US LARP collaborators
• Longitudinal stability: 25 ns beam unstable at 2-3e10 p+/b , Q26– Presently mitigated with controlled long. emittance blow up (0.6 eVs) and
800 MHz RF voltage used in bunch shortening mode– Q20 has increased the threshold on flat top by factor 1.6– Both 25 and 50 ns beams, affected
• After upgrade (double 200 MHz RF power, 6 shorter assemblies – vs. 4 today -> reduced impedance) :– At reach: 2.3e11 p+/b for 25 ns, and >3.4e11 p+/b for 50 ns– Planned upgrades of the 800 MHz low and high power equipment are
mandatory. US-LARP collaboration has been, and still is, essential.– Higher power will only remove limitation from the beam loading, but not
from longitudinal instabilities with high intensity since cannot have much larger longitudinal emittance at injection to the LHC -> should find the source of this instability
10
ecloud• PS: observed but not yet a limitation
– Transverse damper proved to be effective to damp instability observed– Studies are ongoing to investigate HL-LHC regime– Mitigations being investigated (coating, double bunch rotation, …)
• SPS: potentially a major performance limit (beamloss, vacuum, ecloud instability and incoherent emittance growth) – Scrubbing for 25 ns could be tough…StSt chambers, OP limitations…– But in 2012 machine in good shape – no limit from ecloud. Crucial to
have 2 weeks to investigate scrubbing after LS1 (to decide between scrubbing and coating)
– aC coating now fully validated as mitigation (still LIU baseline)– HBW feedback could cure vertical single bunch ECI –much work on-
going – indispensable US-LARP collaboration (with W. Höfle and team)
11
‘Operational’ limitations• Mainly in SPS (to date)
– Heating of extraction kickers: should be ‘solved’ with final shielded MKE in LS1. Expect limit to be at least twice present beam power -ABP, ABT groups
– Outgassing of dump and impact on injection kickers MKP vacuum: extra differential pumping and sectorisation planned. Effect is mainly a limitation for scrubbing and setting up, rather than LHC filling –ABP, ABT, VAC groups
– ZS sparking was previously a concern, but 2012 performance has been very good. Still working on ‘ppm’ voltage modulation as mitigation – EPC, ABT, CO groups
– New beam intercepting and protection devices needed (major simulation & design efforts from STI)
• BI development for measuring with adequate accuracy reduced beam sizes, higher brightness and intensity
12
Essential MDs
13
Introduction & welcome [R. Garoby]
Setting the scene [G. Rumolo]
PSBPresent performance of LHC beams [B. Mikulec]
Space charge measurements [A. Molodozhentsev]
RF aspects (Finemet®, Digital LLRF, damper) [A. Findlay]
PS
Space charge measurements [R. Wasef]
Transverse studies [S. Gilardoni]
Longitudinal studies [H. Damerau]
PS-SPS transmission [H. Timkò]
SPS
Performance with Q20 optics [H. Bartosik]
Electron cloud: status and perspectives [G. Iadarola]
Longitudinal beam quality [T. Argyropulos]
High bandwidth damper [B. Goddard on behalf of W. Höfle]
LIU Beam studies Review – organised by Giovanni Rumolo - 28 August 2012
Giovanni Rumolo - LMC 17 Oct. 12
Expected performance after LS2
14
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.50.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
BunchIntensity[e11]
Emittance(x+y)/2[um]
SPSDQ
=-0.15
SPS450GeV25nsPS-2GeVDQ=-0.26
PSB-160Me
VDQ=
-0.44
SPSRFpow
erLongitu
dinalinsabilities
PSRFpo
wer
Longitu
dinalinsabilitiesHL-LHC
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.00.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
BunchIntensity[e11]
Emittance(x+y)/2[um]
SPSDQ=-0.15
SPS450GeV50ns
PS-2GeVDQ=-0.26
PSB-16
0MeV
DQ=-0
.44
SPSRFpow
erLongitu
dinalinsabilities
PSLon
gitudinalinsabilities
SPSTM
CIlimit
HL-LHC
LIU preferred option is 25 ns
Unresolved questions/issues• Electron cloud
– aC coating or scrubbing (+HBW damper) in SPS?– Is ecloud going to be an issue in PS?
• Prospects for increasing (already ambitious) target for PS longitudinal stability for 50 ns beam?
• Prospect for PS significantly exceeding -0.26 in space charge tune shift for 25 ns beam?– Study to assess maximum tolerable Laslett tune shift with no
resonance compensation.– One quarter resonance excited by Space charge under study – Alternative schemes : longer bunches, resonance compensation,
acceleration/deceleration, dedicated injection optics ….
15
R.G. – 28/08/2012 16 LIU Beam Studies Review
LIU Project Timeline
2012
2015
2016
2017
2013
2018
LS1 for injectors
LS2 for injectors
2019
2014
01/2016 Strip
ping foil a
nd
instrumentati
on test
stand
during L
4 beam relia
bility r
un
07/2016 Start
complete H
-
injection re
gion “m
ontage
à blanc”
assembly
.
12/2016 all injecti
on hardware
components
should be av
ailab
le,
“read
y for P
SB in
stalla
tion”, if n
eeded
W.Weterings – 11/10/2012
Baseline start of installation in the PSB is beginning of LS2 (~January 2018)
HL-LH
C-LARP
2012
mee
ting @
Fras
cati PSB
-PS
trans
fer 1.
4
GeV
2 GeV
SPS a
C coat
ing,
200
MHz p
ower
upgr
ade
comple
ted
Injec
tors
commiss
ioned
Conclusions (I)
17
• For HL-LHC era, requirements are challenging• 25 ns: need x2 present intensity, >x2 present brightness• 50 ns: need x2.2 present intensity, 30% above present brightness
• Baseline LIU does not reach HL-LHC ‘point-like’ requirements.• To even get close:
• Need all planned upgrades to be fully effective, and to approach single bunch limits with multi-bunch operation
• Need “stretch” loss/blowup levels in injectors, with HL-LHC ≤10% blowup, and losses of around 3%...
• Limits are different for 25 and 50 ns production• PSB performance sufficient with 160 MeV injection for both• 25 ns: PS space charge tune shift (2 GeV injection fixed by PSB). • 50 ns: brightness in SPS, PS longitudinal stability, PS beam loading
Conclusions (II)
18
• Not totally impossible to approach HL-LHC request, providing 1. Losses and blowup can eventually be reduced to “stretch” levels2. PS can run with higher space charge tune shift, nearer DQ ≈ -0.323. PS longitudinal stability can improve significantly above present
expectation (today at 1.7e11, LIU baseline 3e11, need 3.7e11)4. SPS can increase brightness limit, to DQ ≈ -0.17
• Realistic time for re-commissioning after LS2 to be foreseen• LS2 will be ‘LIU shutdown’…• Planning and organisation of this should start now!
• Support from US-LARP is acknowledged, much needed , and should continue (space charge studies in PS, damper systems in SPS, Beam dynamics through injector chains, SPS LLRF upgrades…)
19
Introductory remarks
Q20 optics: experience from deployment• Q20 deployed in SPS and TLs, now working operationally – H. Bartosik , Y.
Pappaphilipou , BTP, RF, OP et al.• More stability in SPS and slightly lower exy to LHC as result (0.1-0.2 um)• In the SPS: more orbit fluctuation than with Q26 at the ejection point creating
larger oscillations in the TL – being analysed – Eliana Gianfelice et al.• Satellites as well as the 6 b have a bigger profile and more tails – Karel Cornelis –
Wolfgang Bartmann
21
Lene Drosdal
satellite bunches
22
Trajectory stability from IQCBPM Variations TI8
Q26
Q20 Slightlyworse?
Lene Drosdal
Re-commissioning after LS2• Will not be “plug n play” to recover pre-LS2 performance• Three ‘new’ injectors to startup, together
– PSB: new ramp to 2 GeV, (maybe) new H- injection at 160 MeV, new RF, new instrumentation, new beam transfer
– PS: new 2 GeV injection, new longitudinal FB, new instrumentation– SPS: (probably) rebuilt after ecloud coating (744 MBs, 216 MQs), ‘new’ RF
200 MHz, new high bandwidth FB, new orbit and BLM system, new scraper and TL collimators
• Normal startup: 1-2 weeks per machine• Must count months per machine to recover pre-LS2 performance
– A concrete LS2 plus commissioning plan to work on (in 2012)• Will certainly take period LS2-LS3 to reach baseline LIU goals
23
24
25
26
SPS beam loading• SPS 200 MHz: x2 power, 46 (shorter) cavities, -20% impedance
– Will allow 10 MV at extraction for 3 A RF current (now 1.5 A)– Need to operate existing power plants in pulsed mode (0.751.05 MW)
• After upgrade: same voltage available as now (if pulsed) for 2.3e11 p+/b (25 ns) and 4.6e11 p+/b (50 ns).
27E.Shaposhnikova