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Accelerators and Photons .

Accelerators and Photons . Trends, challenges, opportunities Reinhard Brinkmann, DESY. Synchrotron radiation storage rings – the flagships . ESRF. SPring 8. PETRA III. APS. PETRA III. Storage rings – basic parameters. The future : Ultimate storage ring .

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Accelerators and Photons .

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  1. Accelerators and Photons. Trends, challenges, opportunities Reinhard Brinkmann, DESY

  2. Synchrotron radiation storage rings – the flagships ESRF SPring 8 PETRA III APS PETRA III

  3. Storage rings – basic parameters

  4. The future: Ultimate storage ring Invitedpaperat EPAC2000, Vienna: Intensive worktowardsultimateperformancestarted > 10years agowiththe ESRF groupand Pascal Elleaume† being a strong drivingforce

  5. Ultimate storage ring – emittancechallenge • Ultimate performancerequires e-beam emittancecomparabletophoton beam emittance („diffractionlimit“) e  ph = ph/4 • Beam emittance 10pm*radfor 1Å wavelength! • TME multi-bendachromatlatticewith large # ofdipolemagnets • Compromisefordynamicaperture • Relax focusing,  ~ factor 3 above theoreticallimit M. Borland et al, 2010

  6. Strong sextupoles – smalldynamicacceptance Analytical scalingestimate : Ax ~ x2/3 …. x

  7. Intrabeam – effects:  roundbeams • Forextremelydensebunches, Touscheklifetimedropsstrongly & emittancegrows due to IBS  don‘taimfory << x • Operate on x-y couplingresonancey = x • Gain a factoralmost 2 in zero-current xandreducegrowth due to IBS A. Xiao, IBS calculationsfor USR7 (2009)

  8. U.S.R.‘scont‘d • Storage ring near ~10pm*radverychallenging, but not impossiblewithstate-of-the-art technology • Top-upmodewithaccumulationofsmall Portionsof beam unlikelytowork fast on-axis kickerconcept Very large rings advantageous: practicalities (manymagnets!), effectiveuseofdamping Wigglers, forgivenlattice type acceptance proportional tocircumference ( usageofexistinginfrastructure PEP, PETRA, HERA) • USR withevensomewhat relaxed parameters (~50pm) hasnormalisedemittances <1mm*mradcompetitivewithlinac-drivensources !? • Longitudinal emittancemuchtoo large/peakcurrentmuchtoolow (factor ~100) todrivehard x-ray SASE FEL • Partial lasingconceivable: Lg ~100m forIpk = 50A – useK-J Kim et al. XFEL-oscillatorconcept?? (proposedfor an ERL!) Top-upoperation in PETRA-III

  9. Storage rings advanced-I: round-beam insertion skew triplet s.c. solenoid & undulator skew triplet • Consider „conventional“ ring with e.g. 2GeV, x = 1nm, y = 0.01nm, wantdiffraction limited beam at 1nm wavelength • Insteadofcouplingresonancewhere, x +y = const, usetransformation flat-to-round beam in an undulatorinsertionwherexy = const = 2,  = 0.1nm(R.B. EPAC 2002) • Possiblewithskewquadtransformation + solenoidfield (in practice: s.c. solenoid + helicalundulator in onedevice) (transformationconceptoriginallyproposedby Y. Derbenevfor e-cooling 1998) • Couldprovidediffraction limited 1nm soft X-rays in an (almost) existing ring • Has not madeitintopractice…(yet?): solenoid/undulatordevice not easy to design & build, concernskeepingthe flat-round-flat transformationperfectlyclosed, cost. schedule, userinterest…

  10. Storage rings advanced-II: fspulses/slicing Selectionofshortphoton pulse byenergymodulation + transversedisplacement idea: A. Zholents, M. Zolotorev, PRL 76 (1996), 912 firstexperiment (ALS): R. W. Schoenlein et al., Science 287 (2000), 2237 Courtesy Shaukat Khan, TU Dortmund Recentideaat DELTA/Dortmund: useseedingforcoherentgeneration & possibly EEHG schemetoproduce VUV radiationpulses

  11. Storage rings advanced-III: pspulses/rfdeflection Photon pulse shorteningbylong.-verticalcorrelationwithdeflectingmodecavity idea: A. Zholentset al. NIM A425 (1999), 385 (From K. Harkay et al., PAC2005)

  12. FELs – operational & underconstruction/commissioning LCLS-2009 FLASH-2005 2011 EU-XFEL-2015 … + FEL projects in Italy, Korea, Switzerland, …

  13. FEL parameters – SASE operation

  14. t=50 fsec t=100 fsec Neutze, Wouts,van der Spoerl, Weckert, Hajdu: Nature 406 (2000) 752-757 Peak brilliance in entirelynewregime

  15. Remarkableagreementofperformancewithpredictions • Excellentinjectorperformanceandverysmallemittancedilution in linac & bunchcompressors • Built-in safetymargins not reallynecessary – saturationreachedover ~half of total undulatorlength •  LCLS (& EU-XFEL) canreachperformncewellbeyond design specs •  forgivenwavelength design goal, beam energycanbelower LCLS commissioning April 2009: From P. Emma, PAC2009

  16. Parameter scaling – beam energy, emittance (parametrisationofstudiesby Saldin, Schneidmiller, Yurkov) • Not gainlength, but coherence (andpeakbrilliance ~Ebeam) stronglydependendent on energy (via absoluteemittance) • Injectorperformanceisthecrucialelementfor FEL facilitycost (Energy!) & performance

  17. Injector R&D – example PITZ @ DESY-Zeuthen

  18. “core” emittance for different bunch charges • Idea: Cut lowintensityregionof MEASURED phasespace (nolasing) 100% of 1nC:εx = 0.92 mm mrad, εy = 0.84 mm mrad preliminary yy´ xx´ Why not startwithhigherchargeandcollimatethebunch? (lookslikecouldgainfactor 2…3 in emittance, but: wakefields, radiationprotection, …) *LCLS results: projected emittance, 95% RMS values. D. Dowell + P. Emma, priv. commun. + FEL2009

  19. Towardssinglespikeswithlow-charge, shortbunches 150 pC 500 pC FLASH 2011 Bandwidth 1.3% Bandwidth 1.8 % ph ~ 15fs LCLS simulationat 1.5nm, 20pC bunchcharge (from Y. Ding et al., PAC09) FEL operation @20pC successfullydemonstrated

  20. Alternative to SASE FEL: seedingconcepts • HGHG: modulationwithopticallaser amplificationofhigherharmonics in severalstages • HHG: modulationwith high harmonicsofopticallasergeneratedbyinteractionwith a gas (orcombinationofboth)

  21. New idea: echo-enabledharmonicgeneration - proposed: G. Stupakov, PRL 102 (2009), 074801 - 1st experimental resultsat SLAC, D. Xiang et al. IPAC10 simulations by D. Xiang and G. Stupakov (2009) radiator laser 1 l1 laser 2 l2 modulator 2 modulator 1 Courtesy Shaukat Khan, TU Dortmund VUV pulse l/n

  22. Energyrecoverylinacs • 1st idea (forsuperconducting linear collider) by M. Tigner, NuovoCimento 1965 • Rapidlygrowinginterest in ERL concepts & projectsoverpast ~10 years (JLAB, Cornell, BNL, BINP, KEK, HZB, DESY, …) !: Cornell injector prototype achieved: 4mA, 0.4 – 1.5mm*mrad (I. Bazarov et al. PAC09)

  23. R&D on CW-injectorscrucial – synergywiths.c. FELs (Examples, not exhaustive) Trend forfutures.c. FELs (orupgrades) goestowardscw-operation – overlapwithdevelopmentprogrammefor ERLs

  24. Option for ERLs (ors.c. FELs): XFEL oscillator R. Colella, A. Luccio, OpticsComm. 50 (1984), K.-J. Kim, Y. Schvydk‘ovand S. Reiche, Phys. Rev. Lett. 100 (2008) CourtesyJohann Zemella, Univ. Hamburg Build-upof FEL radiationtowardssteady-stateoverseverals 10s ofpulses Extremelynarrowline 10-5 – 10-6/high spectralbrightness

  25. Photon sourceswithplasmaacceleration? 0 p/p  Emittance from LPWA withm sourcesizeandmradrmsdivergencecanbeof same orderasfromconventional beam source: L = focal length Chromaticemittancedilutionis not negligible!

  26. Synergiesandopportunities • Acceleratorphysicsandtechnologydevelopedforphotonsourcesaswellasavailableinfrastructurehave overlapwithdevelopmentsofplasmaacceleration – opportunitiestousesynergiesandjointlyadvancethisfieldofacceleratorresearch • Generation & dynamicsoffs-beams • Fs-synchronisation & diagnostics • Usageoftestfacilities & acceleratorinfrastructuresforplasmaaccelerationexperiments • …

  27. temperature controlled birefringent crystal motorized rotationstage OSS signal (UV) Will, Klemz, Optics Express 16 (2008) , 4922-14935 Example: using PITZ for plasma-wakefieldexperiment (similartoideaofcomb-beam by M. Ferrario et al.) Pulse shaperlaserby MBI Bunchstructurewith e.g. 5 or 6 spikesandapproximately linear increase in bunchchargeshouldbepossible Compressionofthisstructuretomatchplasmawavelength Demonstration of large transformerratiowithplasmawakefieldexperimentconceivable

  28. Example: using FLASH (II) totest LPWA withexternallyinjected beam Civilconstructionfor FLASH-II startsthisyear Useonebunch per linac pulse ofextracted FLASH-II beam forplasmaaccexperiments

  29. Thankyouforyourattention!

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