CLIC Staged Design October 2012 D. Schulte for the CLIC collaboration.

CLIC Staged Design October 2012

D. Schulte for the CLIC collaboration

2

CDR Accelerator Volume: 3TeVDrive Beam Generation Complex

Main Beam Generation Complex

CLIC staging, LCWS October 2012D. Schulte

Conceptual design andfeasibility of 3TeV CLIC

3

CDR Accelerator Volume: 500GeVDrive Beam Generation Complex

Main Beam Generation Complex


A parameter set for 500GeVSome first studies

4CLIC staging, LCWS October 2012

Timeline

D. Schulte

From Steinar


Motivation

D. Schulte

Can operate 3TeV CLIC easilydown to 1TeV using full linac

But below 1TeV need bypasses to extract beam early or modify BDS

In this case seems a waste to not use most of the main linac

A staged approach has many advantages•Allows to have first physics earlier• Allows to optimise for each stage better• Stretches the budget• Can take into account lessons of earlier stages

Total cost might increase or mightIn practice decrease


CDRVolume 3Staging Scenarios

• Illustrate stages with two cases– 0.5, ~1.5 and 3 TeV– Energy choices we will be

updated based on further LHC findings

– Design based on 3TeV technology

• The examples are:– Scenario A is optimised for

the luminosity at 500GeV– Scenario B is is cost

optimised for the total project cost

D. Schulte


Parameter Drivers

D. Schulte

Based on usual luminosity formula:


Parameter Drivers

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Upper limit fromLuminosity spectrum(classical regime)

At 3TeV maximum luminosity:L0.01/L>0.3 =>nγ=O(2)N/σx≈1x108/nm (for σz=44μm)

At 500GeV comparable to ISR:L0.01/L≈0.6 =>nγ=O(1)N/σx≈2.5x108/nm


Parameter Drivers

D. Schulte

Lower limit from all systems

Upper limit frommain linac lattice and structure

Lower limit from Damping ringBDSRTML


Parameter Drivers

D. Schulte

Lower limit from all systems

Upper limit frommain linac lattice and structure

Easier to get N/σx at high energy Ratio of 3TeV to 500GeV is sqrt(1/6)

Just what we need

Lower limit from Damping ringBDSRTML

For fixed structure the charge is independent of energy (almost)

Beamsizes roughly scale assqrt(1/E)


Scenario B

Scenario is chosen to reduce cost at 500GeV and the total cost of all stages• Some main beam injector complex for all stages• BDS can be one decelerator sector shorter at 500GeV, fits in 3TeV tunnel•12 sectors powered in second stage is maximum with one drive beam generation complex• Scaled 3TeV BDS design used for stage 2• Can re-use all structures up to 3TeV

D. Schulte


Scenario A

Scenario is chosen for luminosity at 500GeV, L=2.3x1034m-2s-1

•Special structure for 500GeV leads to N=6.8x109 vs. 3.7 x109, G=80MV/m vs. 100MV/m, L=2.3x1034m-2s-1vs.L=1.3x1034m-2s-1

•Main beam RF pulse lengths are the same and power is comparable => can use the same drive beam generation complex• Main beam injector at stage 1 needs some additional RF power•Can use 80MV/m structure with the train for CLIC_G (the nominal 3TeV structure) => lose a bit of energy for stage 2

D. Schulte

13

Parameter Comparisonunit Scenario A Scenario B

Ecms TeV 0.5 1.4 3.0 0.5 1.5 3.0G MV/m 80 80/

100100 100 100 100

N 109 6.8 3.7 3.7 3.7 3.7 3.7Nsect 5 12 24 4 12 24

L 1034cm-2s-1 2.3 3.2 5.9 1.3 1.7 5.9L1% 1034cm-2s-1 1.4 1.3 2.0 0.7 1.4 2.0

Pbeam MW 9.6 12.9 27.7 4.6 13.7 27.7Pwall MW 272 364 589 235 364 589η % 3.6 3.6 4.7 2.0 3.8 4.7

D. Schulte CLIC staging, LCWS October 2012


Operation Scenarios

Stage Year 1 Year 2 Year 3 Year 4 Year 5

1 5% 25% 50% 75% 100%

2 and 3 25% 50% 100% 100% 100%

Assume 200 days/year50% useful luminosityi.e. 0.864x107s/year

D. Schulte


Operation Scenarios

First stages takes two years longer in scenario BBut second stage is one year shorter in BTotal difference is only one year

Ecms Int(L) goal

0.5 TeV 500 fb-1

1.4/1.5 TeV 1500 fb-1

3 TeV 2000 fb-1

D. Schulte


Luminosity Operating at Lower Energies

• Use 500GeV scenario A design

• Energy changed by gradient scaling

• Have to adjust bunch charge

• Can increase pulse length at certain energies

• More luminosity possible using extraction lines

D. Schulte


Construction Schedule Scenario A

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Construction Schedule Scenario A

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Power Consumption 3TeV

D. Schulte

We optimised thispart• Largest contribution• Strongest dependence on structure design• Best understood at the time


Power Consumption 500GeV (A)

D. Schulte

We considered thispart, which is now a much smaller fraction

• Need to review power consumption in many places• Options for savings exist


Cost of the 500GeV StageSwiss francs of December 2010

Incremental cost for B:4MCHF/GeV-> Step to 1.5TeV is less than first stage

D. Schulte


Goals for Next Phase• Iterate on energy choices

– 375GeV for the first stage to cover top– 1-2TeV depending on physics findings– 3TeV as current ultimate energy

• Focus on first energy stage– Consider upgrades

• Identify and review cost and power/energy saving options– Identify and carry out required R&D

• Re-optimise parameters– Develop an improved cost and power/energy consumption model– Iterations needed with saving options

• Study alternatives– E.g. first stage with klystrons

• Re-optimise the design

• Need to remain flexible, since we are waiting for LHC findings– But have some robustness of specific solutions and can anticipate this to some

extentD. Schulte

Simplified Parameter Diagram

Drive Beam Generation ComplexPklystron, Nklystron, LDBA, …

Main Beam Generation ComplexPklystron, …

Two-Beam Acceleration ComplexLmodule, Δstructure, …

Idrive

Edrive

τRF

Nsector

Ncombine

fr

Nnb

ncycle

E0

fr

Parameter RoutineLuminosity, …

Ecms, G, Lstructure

Variable Meaning Current value

Idrive Drive beam current 101A

Edrive Drive beam energy 2.37GeV

τRF Mainlianc RF pulse length 244ns

Nsector Number of drive beam sectors per linac

4

Ncombine Combination number 24

fr Repetition rate 50Hz

N Main beam bunch charge in linac

3.72e9

nb MB bunches per pulse 312

ncycle Spacing between MB bunches

6 cycles

E0 MB energy at linac entrance

9GeV

Ecms Centre-of-mass energy 500GeV

G Main linac gradient 100MV/m


Some Examples of Saving Options for Current Design

• Cost– Alternative structure fabrication– Longer main linacmodules– Maybe do not need electron pre-damping ring– CVS overdesigned for 500GeV– Main beam sources RF power quite high– Shorter drive beam pulses in first stage can reduce cost of

modulator (modular design)– Combining pairs of drive beam accelerator klystrons– …

• Power– Permanent drive beam turn-around magnets– …

D. Schulte


Exploration of Klystron-based First Stage

• The drive beam is necessary to reach high energies– Substantial improvement in scalability compared topreviousX-band designs

• At low energies klystronsmightbe competitive– Easier to qualify components

• No need of 100A beam for module reception tests

– Need klystrons for structure testing– And they are needed for the application of the technology at other

facilities (e.g. medical and light sources)

• Hence started to study a klystron-based first energy stage– As an alternative to a drive-beam based first energy stage– Currently at 500GeV

D. Schulte


RF Unit DesignNLC RF unitChr. Adolphsen et al.

For the first exploration a copy of the NLC/GLC design

D. Schulte


Structure Optimisation

50 60 70 80 90 1003000

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000Klystron based 500 GeV CLIC

<Eacc

> [MV/m]

Cost

[a.u

.]

2/3: N

s=free, L

s>200mm, t

p=free

2/3: Ns=6, L

s=230mm, t

p=242ns

2/3: Ns=6, L

s=480mm, t

p=242ns

2/3: Ns=6, L

s=480mm, t

p=483ns

CLIC_G, tp=242ns

CLIC_G, tp=483ns

5/6: Ns=free, L

s>200mm, t

p=free

5/6: Ns=6, L

s=230mm, t

p=242ns

5/6: Ns=6, L

s=480mm, t

p=242ns

5/6: Ns=6, L

s=480mm, t

p=483ns

Selected structures from optimisation fordrive beam case

We use a simple cost modelFixed cost per• klystron/modulator/pulse compressor• unit length of linac

D. Schulte


Cost vs. Figure of Merit

1 2 3 4 53000

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000Klystron based 500 GeV CLIC

FoM

Cost

[a.u

.]

2/3: N

s=free, L

s>200mm, t

p=free

2/3: Ns=6, L

s=230mm, t

p=242ns

2/3: Ns=6, L

s=480mm, t

p=242ns

2/3: Ns=6, L

s=480mm, t

p=483ns

CLIC_G, tp=242ns

CLIC_G, tp=483ns

5/6: Ns=free, L

s>200mm, t

p=free

5/6: Ns=6, L

s=230mm, t

p=242ns

5/6: Ns=6, L

s=480mm, t

p=242ns

5/6: Ns=6, L

s=480mm, t

p=483ns

Good compromise structuresare marked by arrows

D. Schulte

F.o.M.: L/Imain [arb. units] 1 5

Cost

[arb

. uni

ts]

3000

8000

29

Potential Klystron-based CLIC 500GeV Parameters

D. Schulte CLIC staging, LCWS October 2012

Case 2 3 5 Sc. A CLIC_G NLC

G (loaded) [MV/m] 57 67 57 80 100 52Str. Length: [mm] 480 480 480 229 229 600Δz[RF cycles] 6 6 6 6 6 16Bunch population: N [109] 5.49 4.95 7.01 6.8 3.72 7

Bunches per train:nb 382 335 337 354 312 190Pulse length: τp [ns] 244 244 244 244 244 400Input power: Pin [MW] 76 84 89 74.2 61.3 54Structure efficiency: η [%] 49.5 41.9 48 39.6 28.5 ~31

Est. rel. lumi in peak @ 50 Hz 1.81 1.44 2.04 2.08 1.0 (1.15?)

Klystrons per linac 2454 2292 2850 3520 2359 2232Linac cost [arb. units] 2528 2150 2528 1801 1441 (2771?

)Power / two linacs [MW] 76.5 71.4 88.8 109.7 73.5 (167?)

Linac cost [arb. units] 4982 4442 5378 5321 3800 (5003?)


Conclusion on Klystrons-based Stage

• Worthwhile to review– Could be somewhat cheaper solution at low energies– Easier to do full hardware prototyping, since no 100A

beam is needed

• Further steps are necessary to move from an exploration to a realistic design– E.g. do we need a second tunnel, or even more?– Will iterate on the design– Can profit from past studies

• Mightstart some technical developments if useful– High level of synergy with other applications

D. Schulte


Conclusion• Have robust staged scenarios for CLIC

– Two examples, since input from physics is missing• Have to wait for LHC and other results

– Based on the feasibility demonstration for 3TeV• Lower energy stages are equally feasible

– Can adjust energy stages to different physics needs• This is the largest uncertainty in the concept

– But concept is not yet fully optimised

• Will further improve the design– Further development of the technical basis

• Adjust design to technical limitations to be neither too aggressive nor to leave too much margin

– More focus on first energy stage• Including alternative technological solution

– Investigation of cost and power/energy reduction options• Re-optimisation of parameters and design

– Systematic optimisation of the design– First results for the CLIC workshop January 2012

D. Schulte


Reserve

D. Schulte


Klystron-based 500GeV Parameters

D. Schulte


Scenario A

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Scenario B

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36

Higgs at 125GeV

CLIC staging, LCWS October 2012

~250GeV

D. Schulte

37

Example of Potential SUSY Scenario

CLIC staging, LCWS October 2012

Have to wait for further LHC results before a decision can be made

A strategy process is active in Europe to define future directions

Consistent with current LHC resultsD. Schulte


Parameter Choice

D. Schulte

Luminosity can be expressed as

For the classical regime For the quantum regime

Limitation arises from beamstrahlung


Luminosity Spectrum Choice

D. Schulte

At 3TeV:L0.01/L>0.3 =>nγ=O(2)For maximum luminosity

At 500GeV:L0.01/L≈0.6 =>nγ=O(1)To be comparable to ISR


Comments

• Use BDS and post collision line designs for 500GeV and 3TeV– 500GeV design is shorter by one drive beam sector length– Both can be installed in the same tunnel (slightly different crossing angle)– 1.4/1.5 TeV is using the 3TeV design with magnet strengths scaled down

• Could be improved

• Use the same linac lattice, just shortened– Structure in scenario A is different from 3TeV, in scenario B it is the same

• Do not modify drive beam generation complex– Use only one for both linacs below 1.5 TeV– Shorten pulse length at 500GeV

• Main beam injectors, damping rings and RTML have the same layout– More RF power required at 500GeV in scenario A– Horizontal emittance relaxed in this scenario

D. Schulte

41

Conclusion (for SPC)

Drive beam scheme

Luminosity

OperationMachine Protection

Main linac gradient – Ongoing test close to or on target– Uncertainty from beam loading

– Generation tested, used to accelerate test beam, deceleration as expected

– Improvements on operation, reliability, losses, more deceleration (more PETS) to come

– Damping ring like an ambitious light source, no show stopper

– Alignment system principle demonstrated– Stabilisation system developed, benchmarked,

better system in pipeline– Simulations seem on or close to the target

– Start-up sequence defined– Most critical failure studied– First reliability studies– Low energy operation developed

We are ready for the next phase


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CLIC Staged Design October 2012 D. Schulte for the CLIC collaboration.

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