B.Goddard for the LIU-SPS team

• List of actions and planning of implementation • Studies • Impact on other users • SPS performance for LHC and other users in the different scenarios • Potential risks

SPS Upgrade Plans

The invaluable input from E.Shaposhnikova, G.Rumolo, M.Meddahi, R.Garoby, K.Cornelis, J.M.Jimenez, M.Taborelli, E.Montesinos, Y.Papaphilippou, W.Höfle, L.Jensen, T.Bohl, R.Losito, M.Arruat M.Gourber-Pace, S.Mathot , H.Bartosik, D.Manglunki and all other members of the LIU project is gratefully acknowledged.

Overview

• Targets and assumptions• Baseline hardware modifications• Design studies• Key milestones, decision points and planning• Technical issues• 2012 MD and activities• Expected performance potential for LHC and other users• Potential risks• Ions• Conclusion

p+: Targets from HL-LHC

Target: 250-300 fb-1 per year

O.Brüning, HI-LUMI event 16-18 November 2011

Extracted from SPS

• Requires slightly more: LHC losses and blowup– 2.2×1011 p+/b in 2.3 mm at 25 ns– 3.6×1011 p+/b in 2.7 mm at 50 ns

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Assumed deliverables from SPS • For 2012

– Towards ultimate intensity for 50 ns, in smaller than nominal emittance– Nominal intensity for 25 ns, in nominal emittance– Studies above ultimate intensity with 50 ns– Studies with small emittance, nominal intensity for 25 ns

• Period LS1-LS2– Towards lower emittances for nominal intensity for 25 ns– Towards lower emittances for twice nominal intensity for 50 ns

• Period LS2-LS3– Recover pre-LS2 performance in Y(LS2+1)– Towards 2.3x1011 p+/b and 3.2 mm emittance for 25 ns beams– Towards 2.7x1011 p+/b and 2.7 mm emittance for 50 ns beam– Studies with lower emittances/higher intensities

• After LS3– Approach HL-LHC requirements for both 25 and 50 ns beams

Planned baseline upgrades

• Double power of 200 MHz RF system (LSS3, BA/BB3);• Electron cloud mitigation – in-situ aC coating of all dipole and

quadrupole vacuum chambers;• Major upgrades of MOPOS and BLMs, plus other new or upgraded

BI systems;• New High Bandwidth transverse feedback system;• Upgraded pickups for present high power damper system;• Upgraded passive protection devices in extractions and transfer

lines TI 2 and TI 8 (relocation plus new devices);• Improved vacuum sectorisation – arcs and near critical equipment;• Complete the impedance reduction of MKE and dump kickers.

Studies and decision dates

• Full review of ecloud mitigation option: end 2012– Review measurement, technology and simulations– Decided and endorse full aC coating of machine

• Change to low gamma-transition Q20 optics: end 2012– May need extra bumpers for LSS1 injection chicane

• New scraper design study: end 2012– Localise losses and improve reliability

• New MKE/extraction study/prototyping: mid 2013 – Further reduce kicker impedance with totally

new kicker and extraction design

• Beam dump design study/prototyping: mid 2013– Safe absorption of higher brightness beams– Removal/mitigation of operational limitations

LIU-SPS related consolidation

• MOPOS and wirescanner consolidation – Take into account LIU-SPS requirements, shared resources

• MKDV switch and generator consolidation – Coordinate with eventual beam dump upgrade

• 200 MHz driver/controls & Faraday cage consolidation – Coordinate with 200 MHz upgrade, LL upgrades

• 800 MHz upgrades– Coordinate with beam dynamics needs and 200 MHz upgrade

• Possible main dipole coil consolidation– Coordinate with aC vacuum chamber coating

• Other high impact consolidation activities to consider– LV/control recabling campaigns– Infrastructure work

Assumed constraints and planning

• Constraints (working assumptions)– Injectors OFF in 2013, for 12 months– Injectors OFF in 2018, for 12 months (min. for SPS 200 MHz)

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Technical issues and progress• ecloud – amorphous carbon coating

– Feasibility of Hollow Cathode method demonstrated in 2011– Confidence in lifetime, handling and static vacuum behaviour– Treatment of vacuum chambers inside magnets – no magnet opening– Definition of extra sectorisation completed– For 2012, explain dynamic pressure rise (test zone installed)

• Beam induced heating/outgassing of components – Still limitation for high duty factor MD/LHC filling cycles– Complete MKE serigraphy should help (after MKE conditioning...)– Reviewing general impedance reduction (kickers & other elements)

• 200 MHz: good progress with building, services and amplifiers – Shorter main couplers needed to fit new layout in LSS3– Design needs to be launched, prototyped and validated

• Transverse damper relocation to LSS3 not possible. Stays in LSS2.– No space available with 200 MHz rearrangement

Technical issues and progress• Beam instrumentation

– Specifications for upgrades being defined (dynamic ranges, bunch by bunch, presently foreseen upgrades/new instruments, LIU requirements)

– Half-day review of BI deliverables with LIU plus experts (April 2012)– OP and other SPS users requirements being taken into account

• Dump limitations for MDs and high duty factor operation– Outgassing of TIDVG affecting MKP, and forbidden zone 37-105 – Extra differential pumping and sectorisation planned– Not very strong limitation for LIU – to be studied in 2012-13

• Exit windows and TEDs– Intensity/transverse emittance limits to be defined (I, e)

• Compensation of injection doglegs for Q20 optics– Test of principle in 2012; finalise requirements for any additional bumpers

• High bandwidth damper development– Need to demonstrate closed-loop and damping of head-tail instability in 2012– Then specification and prototype construction (HBW pickups and dampers).

Short timescales to be ready for end 2014.

MD studies for 2012• Scrubbing tests in week 13

– Key question: can we scrub SPS below SEY 1.3; can scrubbing replace coating?– Efficiency of scrubbing with uncaptured beam– Most interesting techniques not available (5 ns or 10+15 ns spacings from PS)– Monitor and qualify scrubbing under different beam/chamber conditions– Validate simulation models on scrubbing times (like for LHC)– Some new setups for validation of aC coating

• Beam dynamics and beam quality– Q20 optics deployment – Q20 beam transfer, including injection into LHC– Longitudinal instabilities in a double RF system– Split tunes (20, 26), coupling correction– Instabilities (TMCI, ECI)– Space charge and working point studies– PS-SPS transfer studies– High bandwidth feedback (close feedback loop and damp head-tail modes)– Impedance identification

• Emittance preservation (across injector complex and LHC)• Some optimisation of MD time proposed with respect to 2011

– MD follow-up meetings and prioritisations in frame of SPSU-BD WG– More frequent (shorter) MD blocks more continuous effort on Q20 optimization– 5 day dedicated block for scrubbing studies

Expected performance potential

• Longitudinal instabilities & beam loading: after upgrade, expect factor 2 intensity possible w.r.t. 2011– 2.3×1011 p+/b for 25 ns, and >3.4×1011 p+/b for 50 ns– Main unknown is beam stability with high intensity (combination of single- and

coupled-bunch effects)• ecloud: should be solved after LS2 with aC coating of main magnets

– HBW feedback could help fight against vertical ECI• Heating of extraction kickers: should be solved after LS1

– Expect limit to be at least twice present beam power (2.3×1011 p+/b for 25 ns)• Outgassing of dump and impact on injection kickers MKP vacuum

– Effect mainly limitation for scrubbing and setting up, rather than LHC filling• TMCI

– Measured to be above about 3.5×1011 for single bunch on Q20 optics– HBW damper as possible additional mitigation

• Space charge limits– Expect to be able to exceed DQv of -0.15: 3.5×1011 p+ in 2.8 mm emittance

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Expected situation after upgrade• If all upgrades work as planned, SPS fairly well matched to

requirements– SPS should not be a limit for 25 ns beam for HL-LHC– Need to increase DQv above -0.15 towards -0.2 for 50 ns beam

Upgrade impact on other users

• Mandate is to “not reduce performance for other users”• No negative impact on any other users identified to date• Many positive effects expected:

– Extra RF 200 MHz power – New/upgraded beam instrumentation (other beams being considered in

specifications)– Vacuum sectorisation– Impedance reduction– HBW feedback and damper upgrade– Possibly also Q20 or split-tune optics

Risks and concerns

• ZS sparking (LSS2 electrostatic septum)– Interference with slow extracted FT beams;– Difficult to solve – ‘ppm’ main voltage modulation being studied;– Test ZS tank in LSS6 – now equipped with extra impedance shielding;

measurements to make in 2012;– Last resort would be ZS off and retracted during LHC beam, which strongly

impacts beam to North Area.• Dynamic vacuum behaviour of aC coating

– 16 m test chambers just installed; studies in 2012 to answer this• Unexpected problems with heating of other elements

– New study/analysis to be made in 2012 using updated beam parameters• Planning of LS2 ‘big bang II’ shutdown

– Already concern about accumulation of activities (e.g. magnet coating and LSS3 RF 200 MHz) – planning starting

• Project resources – securing manpower– Large ramp-up in activity and spending needed from 2013 onwards

Key 2012 LIU-SPS activities • 200 MHz upgrade

– Civil engineering studies: in progress– Amplifier market survey: launched– New main coupler: to start

• ecloud: prepare for aC coating in LS1 (4 half-cells)– Industrialisation of aC on MBA chambers: continuing– Answer question of dynamic pressure rise: in progress

• Kicker impedance reduction/ beam induced heating– Preparation (serigraphy) of final 1 MKE: in progress– Impedance/heating review and benefit analysis: to do

• High bandwidth feedback– Closed-loop damping studies and design report: to complete (LARP)

• Existing transverse feedback upgrade– Technical specification on new pickups: to define

• BI upgrades– Specifications with BI group and experts: to finalise following specification review, to have

clear milestones for LS1 and LS2– Implementation: to start

• Transfer line protection systems upgrade– Design study: in progress

• Other design studies– New scraper: in progress– Beam dump, new MKE/extraction: to start

• 2012 MD

Ions

• Production scheme moved away from original ‘bunchlet’ baseline– IBS and space charge effects less serious than anticipated

• Focus is now on increasing number of bunches for Pb-Pb– 50 ns bunch spacing– Rise time of SPS injection kicker MKP to be minimised – possible upgrade?

• Issues in SPS also include RF Noise, IBS & DQ on flat bottom– First batch suffers 40 more seconds on flat bottom: lower intensity/bunch,

transverse emittance blowup• Ions also being considered explicitly in all BI upgrades• New ion species also to be considered: Ar, deuterium

– LLRF may require some upgrade

Conclusions

• LIU-SPS upgrade baseline well defined for p+– Majority of work in tunnel for LS2– Implementation started for RF 200 MHz system– Other technical aspects progressing reasonably well

• Co-existence with other activities and consolidation work to organise and manage carefully– LS2 shutdown planning a key aspect: possible bottlenecks like transport

to investigate• Main planning defined to 2019

– Some changes inevitable as progress/delays/design choices occur– 2012 key activities identified

• Performance potential from upgrade– For LHC, approaches HL-LHC requirements but does not yet meet them– For other users, will be positive in many respects

• Risks and concerns– ZS sparking, understanding of aC coating vacuum behaviour, beam

induced heating, LS2 planning, adequate manpower

the end

Known limitations

E.Shaposhnikova, Chamonix 2011

ecloud mitigation• HC sputtering to deposit amorphous carbon (aC) layer

– Large reduction of SEY below ecloud threshold– Coating in dedicated workshop (ECX5) 4-6 magnets per day

SPS longitudinal instabilities

• Longitudinal stability: 25 ns beam unstable at 2-3e10 p+/b– Presently mitigated with long. emittance blowup (0.6 eVs) and 800 MHz

• Need 0.9 eVs for 25 ns stability with twice nominal Ib (Q26)– Maybe gain from lower impedance (200 MHz and kickers), x2 800 MHz V– Would be very beneficial to transfer longer (e.g. 1.8 ns) bunches to LHC (but

need to mitigate capture losses in LHC) -> MD studies needed– Q20: instability thresholds higher, but need smaller el to get same bunch length

for given VRF

• After upgrade, expect factor 2 intensity possible wrt 2011– 2.3×1011 p+/b for 25 ns, and >3.4×1011 p+/b for 50 ns– Main unknown is beam stability with high intensity (combination of single- and

coupled-bunch effects)

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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). – With larger emittance more VRF needed for same bunch length – Will anyway have 10% longer bunches for 2x nominal I, with 10 MV

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RF 200 MHz reorganisation• Increase power to 6 MW into 6 shorter cavities (from present 4) to

give 10 MV required at ultimate intensity – Needed for longitudinal stability (increase emittance from 0.6 eVs)– Reduces impedance by 20%– Big job: new BC3 building, new LSS3 layout, 26.5 MCHF over 7 years