Readiness of plasma linacs for a HALHF collider application - PowerPoint Presentation

1. Readiness of plasma linacs for a HALHF collider applicationErik Adli, Carl A. Lindstrøm,University of Oslo, Norwayin collaboration with :Gevy J. Cao, Ben Chen, Ole Gunnar Finnerud (University of Oslo, Norway),with input from the communityEAAC2023 - The European Advanced Accelerator Concepts WorkshopElba Island, ItalySeptember 21, 2023

2. HALHF A Hybrid Asymmetric Linear Higgs FactoryEarlier progress for a PWFA-LC impeded by lack of credible overall concepts, partly due to the positron problem.Finally, we have a way forward, with a well-defined starting parameter set for the collider,and for the PWFA collider linac.And can ask the question: where do we stand with respect to what is required? HALHF: a Game Changer!Friday: C. A. Lindstrøm,The HALHF concept.2B. Foster, R. D’Arcy and C. A. Lindstrøm,  New J. Phys. 25, 093037 (2023)

3. WP No.Workpackage1.1Overall collider concepts (Higgs Factory)1.2Beam driven electron linac – integrated simulations1.3Laser driven electron linac1.4Positron acceleration1.5Spin preservation1.6Final focus system1.7Sustainability analysis2.1High-repetition rate laser-driven plasma module (coordination)2.2High rep-rate laser drivers 2.3High rep-rate targetry2.4LPA-experimental facility design (EPAC, CALA, ELI)3.1Electron-beam driven PWFA – experiment (FLASHForward/CLARA)3.2Proton-driven PWFA (at AWAKE)4.1Early High energy physics experimentsFrom July Community meeting,Accelerator R&D roadmap in the European Strategy for Particle Physics.3

4. The HALHF e- plasma linacI have split work to be done / challenges up as follows:Single plasma stageInterstage Multi-stage effectsDrive beam distribution e- driven e- acceleration in the blow-out regimeExernal injection of 5 GeV RF-produced e- beamHigh charge e- driver produced by an RF linac5-500 GeV linac: 16 stagesThe e- blow-out regime: high-gradient, high-efficiency, low emittance growth, low energy spread shown on paper, and experimentally demonstrated to increasingly good levels.4

5. Single stageWe need to demonstrate HALHF linac parameters in PWFA experiments. HALF LINAC TABLE (planned to be a shared google doc, currently not official, but open for reading)5

6. FACETFLASHForwardSingle stage – key PWFA 2-B experimental resultsLindstøm et al, PRL 126, 014801 (2021)Litos et al., PPCF 58, 034017

7. Single stage – beam parameters7HALHF reqsUnitCommentExperiments (2-B PWFA)FacilityReferencesMain beamCharge1.00E+10# particles7.18E+08FACETLitos et al., PPCF 58, 034017Emittance, norm, x160μmEmittance, norm, y0.56μm2.8FlashFORWARDTalk EAAC23Energy spread0.15%0.2FlashFORWARDLindstøm et al, PRL 126, 014801 (2021)Bunch length18μm50FACETLitos et al., PPCF 58, 034017Peak beam current10.6kA0.3FACETLitos et al., PPCF 58, 034017Avg. beam current16μAMin. energy in plasma5GeV1-20FACET, FlashFORWARDFinal energy in plasma500GeV30FACETLitos et al., PPCF 58, 034017Min beam size (in last plasma stage), y0.23μmGradient, efficiency and transformer ratioGradient6.4GV/m6.9FACETLitos et al., PPCF 58, 034017Total energy gain per stage:31.9GeV9FACETLitos et al., PPCF 58, 034017Driver-to-wake efficiency72%50FlashFORWARDLindstøm et al, PRL 126, 014801 (2021)Wake-to-beam efficiency53%42FlashFORWARDLindstøm et al, PRL 126, 014801 (2021)Driver-to-main efficiency38%21FlashFORWARDLindstøm et al, PRL 126, 014801 (2021)Transformer ratio1> 1

8. AC to DB : 141/255 = 55% DB to rf wake : (28+86)/141 = 81% Rf wake to MB : 28/141 = 25% -> DB to MB = 28/141 = 20% -> AC to MB : 28/255 = 11% AC to DB : (n/a) DB to plasma wake : 50% Plasma wake to MB : 42% -> DB to MB = 21% -> AC to MB : (n/a)CLIC:PWFA one-stage,experiement: AC to DB : (n/a) DB to plasma wake : 90% Plasma wake to MB : 90% -> DB to MB = 80% -> AC to MB : (n/a)PWFA one-stage,simulation:100%Before the plasma interactionDBdump29%PLASMA After the plasma interaction38%34%DBMBHALHFSingle stage - efficiency8

9. Single stage – dimensionless parameters9Derived dimensionless parametersHALHF REQNormalized main beam charge (ref)5.58-0.34FACETLitos et al., PPCF 58, 0340170.32FlashFORWARDLindstøm et al, PRL 126, 014801 (2021)Dimensionless main beam emittance (ref)0.15-0.26FlashFORWARDAssuming 100 mm x 2.8 mm mrad emittanceDimensionless luminosity per power (ref)19.83-0.51FlashFORWARDAssuming 100 mm x 2.8 mm mrad emittanceDimensionless drive beam charge15.05-Rosenzweig et al. PR STAB 7, 061302 (2004)G. J. Cao et al. arXiv:2309.10495G. J. Cao et al. arXiv:2309.10495

10. Single stage – plasma source, rep. rate, lifetimeJ. Garland et al., Rev. Sci. Instrum. 92, 013505 (2021)R. D’Arcy et al., Nature 603, 58 (2022)10Plasma cell lifetime requirement:CLIC 380 GeV: 20,000 acc. structures - lifetime = machine life.HALHF: 16 structures – replaced more frequently?Plasma cell operational requirement:12.5 MHz rep. rate within pulse10 kHz average rep. rate. Plasma sourceHALHF REQPlasma density7.00E+15/cm3large rangeSeveralLength5m1.3 m, 10 mFACET, AWAKELitos et al., PPCF 58, 034017, E. Oz, P. Muggli, NIM A 740 197 (2013)Uniformity and stabilityt.b.calc.0.2 % uniformityAWAKEE. Oz, P. Muggli, NIM A 740 197 (2013)Bunch separation80ns< 80 nsFlashFORWARDR. D’Arcy et al., Nature 603, 58 (2022)Bunches per train100#12@ 1 MHz, EAAC 23 talk (G. Loisch)Pulse (train) length8μs11J. Garland et al., Rev. Sci. Instrum. 92, 013505 (2021)Train rep. rate100Hz10FlashFORWARDLindstøm et al, PRL 126, 014801 (2021)Avg. bunch rep. rate10kHzLifetime collider1.00E+09pulsesAssuming 10 years running, at 1/3 up-timeLifetime plasma cell ?1.00E+07pulsesEasy replaceability?1.00E+06FlashFORWARDFF regular operationBreak-down / malfunction ratet.b.calcC.f. RF break-down rate

11. Avg. DB power 21.4 MW29% to 16 DB: dumps: 388 kW power into dump34% to 16 plasma cells, 5 m: 91 kW/m into plasma100%Before the plasma interactionDBdump29%PLASMA After the plasma interaction38%34%DBMBHALHFSingle stage – power and cooling11CLIC Conceptual Design Report (2012)CLIC: 540 kWto dumpCooling of plasma cell a large challenge!Energy recovery mechanisms?

12. InterstagingInterstage design requirements :Main beam emittance preservation - matching - dispersion cancelationIsochronocityTolerancesSynchronizationTransverse misalignmentSynchrotron radiationEffective gradient (interstage length)Technology choice: conventional or novelC. A. Lindstrøm, Phys. Rev. Accel. Beams 24, 014801 (2021)Current approach for HALHF (under study): conventional magnets + tapered plasma lens- average linac gradient 1.2 GV/mSelf-correcting longitudinal phase-spaceC. A. Lindstrøm, arXiv:2104.14460 12C. A. Lindstrøm, PhD thesis, University of Oslo.

13. Multi-stage effectsExamples: instabilities building up in the linac, total effect of jitter on luminosityNeeds integrated start-to-end simulations, including dynamics of interstages. Mixture of tracking, PIC and specialized codes.13

14. Multi-stage effects – transverse instabilitiesInstability along linac currently being studied for the current HALHF parameters.V. Lebedev, A. Burov, S. NagaitsevPhys. Rev. Accel. Beams 20, 121301 (2023)Instability models as part of integrated simulations.POSTER TUESDAYPOSTER TUESDAY14

15. Multi-stage effects – stability and uniformityStability and uniformity requirements not yet calculcated for HALHF. Requires a first freeze of the lattice to be done consistently.Integrated simulations, with luminosity as metric, to be performed. Tolerances fortransverse beam shot-to-shot jitterlongitudinal beam shot-to-shot jitterplasma source uniformityplasma source shot-to-shot stability...stability of other components and beam parametersNumbers can then be compared to state-of-the art results (e.g. AWAKE, LUX...). May already anticipate :Plasma source stability/uniformity may already be sufficient, e.g. AWAKE 0.1% uniformity.Beam jitter tolerances will be very challenging; earlier numbers in nm / nrad range, D. Schulte, Rev. Accl. Sci. Tech. 9, 209 (2016)Needs to be redone with HALHF parameters, plasma ramps and self-correcting interstaging.15

16. 16Multi-stage effects – tolerancingStatic and dynamic tolerances can be found with HALHF integrated simulations. Tedious but necessary work. Done for CLIC, ILC and other machines. HALHF can follow similar techniques, once a linac lattice is available.CLIC Conceptual Design Report (2012)Random examples from CLIC

17. Multi-stage effects – otherRadiation reactionScatteringIon motionSpin-transport...Studied by integrated linac simulation using appropriate modelling. When possible, each effect should be quantified and understood separately, in addition to be combined in full simulations.17

18. Drive beam distributionSome general ideas on the table, needs to be re-studied for HALHF, and detailed.J. Pfingstner er al., IPAC 2016 :General ideas, from 18

19. 19Simulation and design studiesExperiments and test-facilitiesSingle stageHigh-res, full PIC simulations of first and last plasma stageSimilar results from LWFA also usefulDemonstrate PWFA/LWFA with combined HALHF parametersDemonstrate high-rep rate, long lifetime plasma sourceDemonstrate cooling of plasma stage, energy recovery?Precise InstrumentationInterstageLattice designComponent designAny LWFA/PWFA staging preservering charge!Demonstrate novel components (non-linear plasma lens)Demonstrate staging with HALHF-like parameters and interstage designMulti-stage effectsMulti-stage beam dynamics (self-correction)Ensure sufficient surpression of transverse instabilitiesEstablish beam and component jitter tolerancesInclude other relevant physics in integrated simulatons: betatron radiation, ion motion, scattering, spinDemonstrate stability/jitter of acceleraion process in single stageBenchmark physics models in single stageDrive-beam distributionInvent appropriate conceptLattice designDemonstrate specialized magnets/kickcersOutstanding work/challenges (v0.1)This table for the HALHF linac only

20. SummaryWe have a path towards a plasma collider, HALHF. This is new.Not ready yet, but can now define “ready”. Clear linac requirements for PWFA- and plasma source performance,Large parts of the community in position to contribute. Examples:detailed single stage high-res, full simulations of first and last plasma stagedevelopment of MHz / avg kHz plasma cells, with long lifetime, and coolingstaging experiments at any levelgradual experimental single stage progress towards Lp ~ 20Integrated simulations a necessary tool, including for tolerancingMuch to be learned from the CLIC/ILC community; need their contributions Time scale: urgent to demonstrate the viability of a plasma collider to the HEP community – HALHF is currently our best hope20

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24. The ideal test facilityTo be defined...24

25. 100%Before the plasma interactionDBdump23%PLASMA After the plasma interaction50%27%DBMB100%Before the two-beam moduleDBdump19.1%ACC walland dumpAfter the two-beam module20%61%DBMBCLIC 3 TeV2013 SnowmassAdli, Delahaye et al., snowmasss 2013CLIC CDR100%Before the plasma interactionDBdump29%PLASMA After the plasma interaction38%34%DBMBHALHFFoster, D`Archy, Lindstrøm, HALHF 202325