PLASMA WAKEFIELD ACCELERATION

Transcription

1 DESY Summer Student School Hamburg August 3 rd, 7 PLASMA WAKEFIELD ACCELERATION An introduction to laser- (and beam-driven concepts Jens Osterhoff FLASHFORWARD Project Leader Head, Research Group for Plasma Wakefield Accelerators Deutsches Elektronen-Synchrotron DESY, Particle Physics Division, Hamburg, Germany Accelerator Research and Development, Matter and Technology Helmholtz Association of German Research Centres, Berlin, Germany

2 Outline > Introduction to laser-driven plasma wakefield accelerators: why do we care? > Properties of plasma wakefields > (Some controlled beam injection techniques > Energy limit of acceleration process > Annex: beam-driven plasma wakefield acceleration (and FLASHForward project Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page

3 Accelerators are at heart of high-energy photon sources and particle colliders CUTTING-EDGE, HIGH-END SLOW-MOTION-CAMERAS AND MICROSCOPES TO STUDY THE STRUCTURE OF MATTER Particle colliders investigation of fundamental forces and constituents of matter DESY Hamburg Simulation of decay of a Higgs Boson (LHC, CERN 3 Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page

4 Accelerators are at heart of high-energy photon sources and particle colliders CUTTING-EDGE, HIGH-END SLOW-MOTION-CAMERAS AND MICROSCOPES TO STUDY THE STRUCTURE OF MATTER Synchrotron photon sources, e.g. Free-Electron Lasers (FELs investigation of processes on atomic and molecular scales Particle colliders investigation of fundamental forces and constituents of matter Anton Barty, CFEL/DESY Hamburg Illustration of an FEL-pulse diffracting off a protein (XFEL, DESY Applications beyond matter - medical accelerators (e.g. cancer rapy - material processing (e.g. food sterilization, welding - accelerator-driven reactors - cargo scanning (e.g. for nuclear fuel DESY Hamburg Simulation of decay of a Higgs Boson (LHC, CERN 4 Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page

5 Earth 7 km

6 European XFEL 3.4 km FLASH 35 m PETRA III.3 km

7 FLASH FEL facility 35 m long with ~ m. GeV SRF accelerator

8 What defines scale length of accelerator? LIMITS OF CONVENTIONAL TECHNOLOGY Working principle of an RF-cavity Electron bunch To be added here: Working principle of RF cavities, focus on electron accelerators ~ m long TESLA-type superconducting structure Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 9

9 What defines scale length of accelerator? LIMITS OF CONVENTIONAL TECHNOLOGY Working principle of an RF-cavity Electron bunch Alternating longitudinal electric field Ez To be added here: Working principle of RF cavities, focus on electron accelerators Standing microwave (.3 GHz ~ m long TESLA-type superconducting structure The goal: electrons with well defined energy gain Kinetic energy gain: W kin ee z d Accelerating field strength limited to ~5 MV/m by electrical breakdown Energy increase can only be achieved by longer acceleration distances! Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 9

10 What defines scale length of accelerator? LIMITS OF CONVENTIONAL TECHNOLOGY Ring accelerators for electrons? Advantage: same (short acceleration section may be used multiple times Disadvantage: energy loss by synchrotron radiation limits maximum energy (and achievable beam quality: insufficient for X-ray FELs Example: utilize LEP/LHC ring (7 km circumference for electrons Acceleration section e - Energy loss to radiation per circulation (GeV Electron energy (GeV W syn / r W 4 kin (m e c 4 Electron energy (GeV Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page

11 FLASH FEL facility 35 m long with ~ m. GeV SRF accelerator

12 Plasma wakefield accelerator.7 m delivers ~ GeV, a similar energy as FLASH Leemans et al., Nature Physics, 696 (6

13 Plasma wakefield acceleration in a nutshell Laser-pulse driven Laser wakefield acceleration LWFA Plasma target Witness Driver e - ~cm scale length Particle-beam driven Plasma wakefield acceleration PWFA vs. LWFA - average power of up to MW (vs. ~ W - wall-plug efficiency of ~% (vs. <.% beam-driven wakes (currently only viable solution for high-average-power applications Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 4

14 Plasma wakefield acceleration in a nutshell Laser-pulse driven Laser wakefield acceleration LWFA Plasma target Witness Driver e - ~cm scale length Particle-beam driven Plasma wakefield acceleration PWFA Hydrogen plasma: a soup of electrons and protons Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 5

15 Plasma wakefield acceleration in a nutshell Laser-pulse driven Laser wakefield acceleration LWFA Plasma target Witness Driver e - ~cm scale length Particle-beam driven Plasma wakefield acceleration PWFA Protons are ~ heavier than electrons, move slowly Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 6

16 Plasma wakefield acceleration in a nutshell Laser-pulse driven Laser wakefield acceleration LWFA Plasma target Witness Driver e - ~cm scale length Particle-beam driven Plasma wakefield acceleration PWFA Driver acts as electron snow plow, static protons pull back electrons Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 7

17 Plasma wakefield acceleration in a nutshell Laser-pulse driven Laser wakefield acceleration LWFA Plasma target Witness Driver e~cm scale length Particle-beam driven Plasma wakefield acceleration PWFA Driver acts as electron snow plow, static protons pull back electrons 7 Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page

18 Laser wakefield acceleration of electrons Plasma wakefield acceleration in a nutshell µm Laser-pulse driven FSUacceleration Jena, Gruppe M. Kaluza Laser wakefield µm LWFA ne.7 9 cm-3,!plasma 9 µm Witness Plasma target Driver µm e~cm scale length Particle-beam driven Plasma wakefield acceleration PWFA High-resolution (µm and fs visualization µm M. Schnell et al., Nat. Comm. 4, 4 (3 Driver acts as electron snow plow, static protonswave pull back of plasma andelectrons its evolution Also high-sensitivity measurement of pulse front tilt! M. Schwab et al., Applied Physics Jens Letters 98 (3 8 Osterhoff3, plasma.desy.de Summer Student Programme DESY August 3, 7 Page

19 Plasma wakefield acceleration in a nutshell Laser-pulse driven Laser wakefield acceleration LWFA Plasma target ~cm scale length Interesting for applications ~GeV energy ~fs duration Witness e - < µm emittance ~ka current Driver Particle-beam driven Plasma wakefield acceleration PWFA Bunch duration: fs O. Lundh et al., Nature Physics 7, 9 ( A. Buck et al., Nature Physics 7, 543 ( GeV energy gain over cm W.P. Leemans et al., Nature Physics, 696 (6 Size of structure p c! p (33 km q n e [cm 3 ] typically λp 33 µm (for ne 8 cm -3 Electric field strength E mc! p e (96 V/m q typically E GV/m (for ne 8 cm -3 n e [cm 3 ] Co-propagating, strong fields for acceleration c c Witness Driver Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 9 λp

20 Basics of plasma-based particle acceleration Wake excitation Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page

21 Basics of plasma-based particle acceleration Wake excitation Particle injection Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page

22 equation can(.4. be introduced: x Similar to eq., electric and magnetic fields can be expressed also in this case by scalar e(e + vthis Bz explicit on with respect to x-axis, hence ( ( y xdoes appearexpression in expression allows towith y not for solve (.4.5 for x : / n g e dt and vector potentials with Ex ( ( x+ c and(nbez x ( A ( x, respectively. Here it is y x ( g.4.6 x Consequently, temporal integration t of (.4. x gives a relation for py assuming ax g assumed that A, which will be justified retroactively with application of Coulomb g x (.4., electric and magnetic fields can be expressed also in this case byx scalar Similar to eq. ble initial transverse drift: used Electro-magnetic wave equation. The propagating electro-magnetic modes may be forg to eliminate That result may be Coordinate transformation into a co-moving frame x from (.4. d in space gauge later in derivation. The longitudinal Lorentz equation can be furr transformed and vector potentials with Ex py ( ( x and B ( A ( x, respectively. Here it is That result may be used to eliminate from (.4.6 to obtain sought-after exp z y x ea (.4.3 y malized by expressing electric and magnetic fields through potentials (.. as done before, 3d inobtain momentum That result may be used to eliminate from (.4.6 to sought-after x by making use of (.4.3 and by substituting quantities A, and v with ir normalized y x The just presented expressions of for Coulomb longitudinal momentum (.4.5, electro assumed that Ax, which will be justified retroactively with application n g g which n are combined with Ampere s law under consideration of Coulomb gauge A fr malized measures, this corresponds to: counterparts: nuity (.4.6, electro-magnetic modes (.4.7, potentials originating n g g g gauge later in derivation. The longitudinal Lorentz equation can be furr transformed n g g g d separation a (compare to eqs...: (.4.8 and factor (.4.9 constitute a closed set of equations c ( c (.4.5 x bytransverse making electron use of momentum (.4.3 and by quantities A ir normalized solution and discussion of resu y, and vx withnumerical A y dt substituting x x a (.4.4 Transformation into aresults co-movingitframe with magnetic and plasma waves. For furr progress is convenient to apply a c y A µ en v Numerical solution and discussion of equation of motion V counterparts: Laser(from propagation in underdense plasma y e y Numerical solution and discussion of leads results c t Finally, this to se aquasi-static set relations, of di erential equation and approximation formation of form t and x v t to which conve Continuity equation. The total charge contained inside fluid-like plasma medium is g d aleads Longitudinal electron momentum Finally, this to a set of di erential equations, which details temporal a evolution of electron density and electric potential ( Finally, this leads to a set of di erential equations, which details tempor c (.4.5 tudinal equation. Lorentz used longitudinal electronhere, momentum identity The A x equation A do frame Afor was and, as noted above, and velocity vg. Then spati co-moving withhence light wave at A itsx group preserved asvector long as ionization and recombination not play a role. a continuity (from equation of motion dt x of x evolution electron densitydensity and electric potentials in a in laser-driven plasma wake. ned from Poisson s equation: scalar potential is determined by Poisson s equatio evolution of electron and electric potentials a laser-driven plasma wa derivatives become: ntum component in laser propagation direction p yields: ( ( y equal zero. This expression can be rewritten in normalized units when considering x equation can be introduced: scalar potential is determined by plasma Poisson s equation (is.4.8(,.4.8 which can can be written as scalar potential is determined by Poisson s equation, which be written Continuity equation. The total charge contained inside fluid-like medium Resulting differential equation for scalar potential n and vg e e eq. (.4.3 andcontinuity definition of plasma frequency in unperturbed system: p equation p (n + c (.4.6 x t e x (Zn n (n dpx i e do not play a role. Hence preserved as long as ionization and recombination a continuity t x p p c e (Ex + vy Bz (nis of(n As may be seen, transformation Eulerian type and not Lorentz inva dt for c Electro-magnetic wave equation. propagating electro-magnetic modes may be equation can be introduced: c athe a n a ( Electro-magnetic wave equation transformation would be applicable as well, but leads to more complicated form g p c (.4.7 through p g ne normalized units this transmutes into: malized by expressing electric and magnetic fields potentials (.. as done before, t y c be(nexpressed also in this (.4.6 pin r to eq. (.4., electric and magnetic fields+can case by scalar p laboratory c + [McKinstrie frame e xareinterpretation g ( g ( + of results and ( +D g g t x law under of Coulomb gauge c +a +a which n are combined with Ampere s consideration A c ctor potentials with Ex ( ( x and Bpz ( Ay ( x, identity respectively. Here itsolved is for ( + : ( +a Now, (.4.9 can be ( g g with electron density normalized to initial electron background density n n (Zn. Electro-magnetic wave equation.the (n propagating electro-magnetic modes may bei for e(.4.8 Poisson s equation (compare..:will be justified retroactively This is a nonlinear ordinary di erential equation and ed that Axtoeqs., which with application of Coulomb x c done Poisson s Local charge separation sets up electric potentials, which can be obmalized byequation. expressing electric and magnetic fields through potentials (.. as before, A a and numerically. This is a nonlinear ordinary di erential equation and can be, solved W y xgsolved This is a nonlinear ordinary di erential equation can be Whe with QSA for case of.4.9 transforms (numerically. x Ay equation µ ene vcan later in derivation. The longitudinal Lorentz be furr transformed y x QSA for case of, (.4.9 transforms into: c Ampere s texpressed which n are -factor. combined with law under ofof A into: he relativistic can be more conveniently by substituting (.4.4 consideration QSA for case,g (.4.9gauge eq. transforms g Coulomb king use of (.4.3 and by substituting quantities Ay, and vx with ir normalized p + to eqs... : A A A This Ax and (compare transverse velocity: Here, vector identity was will usedsoon and,turn as noted above, + a out to be on l useful for applying p + a c transformation ( + rparts: p Ay c ( +eq. (.4.5 yields: mentum + a ( ( y equal zero. This expression can be rewritten in normalized units when considering equation. In new coordinate system A µ en v c d a ( + y e y (.4.9 cc t Once is determined, x and n are easily calcu ( (.4.5 x x p in unperturbed system: eq. (.4.3 and definition dt of plasma xfrequency Once is determined, and n are easily calculated with help of (.4.7 x y x x An example of a relativistic laser-driven plasma w d a Once is determined, and n are easily calculated with help.4.7 a of ( x Here, vector identity A A An A example was Jens used and, as noted above, A and ( plasma.desy.de ( xis August vg Student +plasma cxprogramme c 3, 7in Page.4. Osterhoff Summer DESY x x of a relativistic laser-driven wake depicted figure nuity equation. The total charge contained inside fluid-like plasma medium is dt y plasma is, ndepicted figure.4.. wakefield quantities normalized long and in An example of a relativistic laser-driven wake en, light amplitude a constitutes only influence on electron velocity normal a a n a Simple fluid model for plasma-wave excitation

23 Numerical solution for scalar wake potential for a Gaussian laser-pulse envelope d in space 3d in momentum a.5 λ p n p -/ Scalar potential Intensity profile Linear regime p c +a (+ Temporal laser-pulse shape in intensity Longitudinal electric field Electron density a. Nonlinear regime # E ~ mcω p % $ e Accelerating field strength & ( ' a ( + a / 96V/m ( n [cm -3 ] a ( + a / e.g. E GV/m (for n 8 cm -3, a Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 3

24 Numerical solution for scalar wake potential for a Gaussian laser-pulse envelope d in space 3d in momentum a.5 λ p n p -/ Scalar potential Intensity profile Linear regime p c +a (+ Temporal laser-pulse shape in intensity Longitudinal electric field Electron density a. µm Nonlinear regime µm n e.7 9 cm -3,! plasma 9 µm # E ~ mcω & p % ( $ e ' Accelerating field strength a ( + a / 96V/m ( n [cm -3 ] µm a ( + a / e.g. E GV/m (for n 8 cm -3, a M. Schnell et al., Nat. Comm. 4, 4 (3 Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 3

25 5 Wakefield properties in transverse dimensions 3d in space 3d in momentum 5 4 Laser envelope Accelerating phase Focusing phase Electron density modification Longitudinal electric field y [c / ω p ] z [c / ω p ] E z E y [c / ω p ] z [c / ω p ] Figure.5 nent of a E y E Longitudinal fields of a quasi-linear plasma wave Transverse fields Figure.6: of y-z a quasi-linear slice plane of plasma E y field wave component of a 3D PIC-simulation with a.5 Figure.7 nent of a Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 4

26 Wakefield properties in transverse dimensions 3d in space 3d in momentum Quasi-linear regime Non-linear regime from C.B.Schroeder et al., PRSTAB 3, 3 ( Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 5

27 The LWFA process can be complex - laser self-focussing - laser self-compression - wave breaking - beam hosing - beam loading - 3D particle-in-cell (PIC simulation Cold, non-relativistic wave breaking limit E cm e! p e Cold, relativistic wave breaking limit E wb E q( Temperature and transverse dynamics require furr modifications Initial laser pulse a λc 8 nm Δτ 5 fs FWHM w 3 μm FWHM Plasma density np 5 8 cm -3

28 Longitudinal phase space for test particles in wakefield Hamiltonian: â confer T. Esirkepov et al., Phys. Rev. Lett. 96, 483 (6 Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 7

29 Longitudinal phase space for test particles in wakefield Hamiltonian: â confer T. Esirkepov et al., Phys. Rev. Lett. 96, 483 (6 Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 7

30 Ionization for injection control > ionization of dopant gas near laser-pulse peak intensity > dopant concentration to tune injected charge and beam loading idea: demonstration: D.Umstadter et al., Phys. Rev. Lett. 76, 73 (996 A.Pak et al., Phys. Rev. Lett. 4, 53 ( C.McGuffey et al., Phys. Rev. Lett. 4, 54 ( 8 Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page

31 Colliding lasers for injection control > colliding lasers create strong ponderomotive kick > control laser parameters (pol., λ, a and overlap position for injection control idea: demonstration: E.Esarey et al., Phys. Rev. Lett. 79, 68 (997 J.Faure et al., Nature 444, 737 (6 Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 9

32 Colliding lasers for injection control > colliding lasers create strong ponderomotive kick > control laser parameters (pol., λ, a and overlap position for injection control idea: demonstration: E.Esarey et al., Phys. Rev. Lett. 79, 68 (997 J.Faure et al., Nature 444, 737 (6 Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 9

33 Density slopes for injection control reduced phase velocity v c dn e n e dz acceleration > phase velocity of plasma wake reduced on density down-slope > velocity of electrons may exceed vφ, leads to trapping > trapping in multiple buckets possible idea: demonstration: S.Bulanov et al., Phys. Rev. E 58, R557 (998 C.G.R.Geddes et al., Phys. Rev. Lett., 54 (8 Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 3

34 Energy gain scalings and single-stage limitations LASER DIFFRACTION: MITIGATED BY TRANSVERSE PLASMA DENSITY TAILORING (PLASMA CHANNEL Laser z R Plasma waveguide Capillary discharge plasma waveguides - Plasma fully ionized for t > 5 ns - After t ~ 8 ns plasma is in quasi-equilibrium: Ohmic heating is balanced by conduction of heat to wall - Ablation rate small: cap. lasts for > 6 shots - np 7-9 cm -3 Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 3

35 Energy gain scalings and single-stage limitations LASER DIFFRACTION: MITIGATED BY TRANSVERSE PLASMA DENSITY TAILORING (PLASMA CHANNEL Laser z R Plasma waveguide Capillary discharge plasma waveguides - Plasma fully ionized for t > 5 ns - After t ~ 8 ns plasma is in quasi-equilibrium: Ohmic heating is balanced by conduction of heat to wall - Ablation rate small: cap. lasts for > 6 shots - np 7-9 cm -3 In this example: ZR mm, guiding over 6 mm, guiding efficiency > 9 % Karsch, Osterhoff et al., New J. Phys. 9, 45 (7 D.J. Spence et al., J. Phys. B 34, 43 ( Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 3

36 Energy gain scalings and single-stage limitations ELECTRON-LASER DEPHASING: MITIGATED BY LONGITUDINAL PLASMA DENSITY TAILORING (PLASMA TAPER Constant density plasma Laser pulse, plasma wave travel with vφ vg < c Electrons travel with ve c > vφ y outrun accelerating field structure Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 3

37 Energy gain γ Energy gain scalings and single-stage limitations ELECTRON-LASER DEPHASING: MITIGATED BY LONGITUDINAL PLASMA DENSITY TAILORING (PLASMA TAPER 8 6 Ideal taper Linear taper No taper Normalized propagation distance Constant density plasma Laser pulse, plasma wave travel with vφ vg < c Electrons travel with ve c > vφ y outrun accelerating field structure Rising density plasma Plasma wave phase velocity vφ may be set to ve electrons can be phase locked Rittershofer et al., Phys. Plasmas 7, 634 ( Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 3

38 Energy gain scalings and single-stage limitations E (GV/m LASER DEPLETION: ENERGY LOSS INTO PLASMA WAVE EXCITATION U L (J 4 Single-stage laser energy PW class U L / n 3 p Accelerating gradient E / n p Coefficients determined from PIC simulations in quasi-linear regime (a.5. 5 TW class np (cm -3 np (cm -3 L (m Single-stage length L depl / n 3 p W / n p W (GeV PW class 5 TW class Single-stage energy gain Staging required for higher electron energies np (cm -3 Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 33 np (cm -3 confer C.B.Schroeder et al., PRSTAB 3, 3 (

39 Straw-man design of a TeV-class LWFA-based linear collider Design based on Challenges / required R&D > x GeV stages driven by a PW laser at ne 7 cm -3 W.P. Leemans and E. Esarey, Physics Today (March 9 > Laser system high peak power, high average power + efficiency > Single acceleration module deliver consistent beam quality emittance, energy, energy spread, charge efficient energy transfer of driver to witness > Heat management > Coupling of two plasma stages electron beam extraction and injection beam quality preservation > Laser in-coupling accelerator length > Positron acceleration > Final focus system > Positron beam generation (with low emittance > Electron beam generation (with low emittance Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 38

40 Efficiency and average-power requirements demand a quantum leap in laser technology Required power per particle beam Pb 5 MW Maximum power from grid PAC MW confer C.B. Schroeder et al., Phys. Rev. STAB 3, 3 ( Need 5% wallplug efficiency > Efficiency laser to plasma wave 5% > Efficiency plasma wave to beam 3% confer B. Shadwick et al., Phys. Plasmas 6, 5674 (9 from simulations Expected laser-to-beam efficiency of 5% Requires wallplug-to-laser efficiency of 33% With GeV modules 5 and total energy per beam ~3 J 6 J energy gain per module 4 J laser energy per module at ~7 khz repetition rate 68 kw average laser power required Modern PW lasers: % wallplug efficiency, ~ W average power Current roadblock for LWFA colliders. Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 39

41 Efficiency and average-power requirements demand a quantum leap in laser technology Required power per particle beam Pb 5 MW Maximum power from grid PAC MW confer C.B. Schroeder et al., Phys. Rev. STAB 3, 3 ( Need 5% wallplug efficiency > Efficiency laser to plasma wave 5% > Efficiency plasma wave to beam 3% confer B. Shadwick et al., Phys. Plasmas 6, 5674 (9 from simulations Expected laser-to-beam efficiency of 5% Requires wallplug-to-laser efficiency of 33% With GeV modules 5 and total energy per beam ~3 J 6 J energy gain per module 4 J laser energy per module at ~7 khz repetition rate 68 kw average laser power required ICAN Project G. Mourou et al., Nature Photonics 7, 58 (3 High-peak and high-average power, high-efficiency lasers based on fibers Modern PW lasers: % wallplug efficiency, ~ W average power Current roadblock for LWFA colliders. Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 39

42 The next-generation plasma wakefield accelerator - FLASHForward at DESY FLASHForward is Scientific mission > an extension to FLASH. GeV superconducting RF FEL facility > a new experiment for beam-driven plasma wakefield accelerator research > to demonstrate beam quality from a plasma-based wakefield accelerator suitable for first applications in photon science as a stepping stone towards high-energy physics applications FLASH FEL PHASE I (7- PHASE II (+ FLASH accelerator Extraction FLASH FEL Differential pumping Plasma cell Laser/plasma photon diagnostics Undulator Witness dump Witness dump Driver dump X-TCAV 4 fs, µj + 5 TW Beam matching and focussing section Beam diagnostics section X-ray diagnostics Probe/ionization/injection lasers - boost FLASH to ~ GeV with high efficiency (3%, conserve emittance and energy spread - generate usable beams in plasma with low emittance ( nm at >.5 GeV Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 4

43 Summary > Accelerators are at heart of most photon science and particle physics experiments, but are large installations > Plasma wakefield technology offers a promising path to compact accelerators with > GV/m fields > Two alternative driver technologies: laser- and beam-excited plasma wakes > Common goal: - plasma accelerator research usable plasma accelerators > Hope: miniaturization of accelerators leads to - significant cost reduction - widespread proliferation of compact accelerator technology - beams with new and extreme properties > Plasmas may have a revolutionary influence on accelerator applications Jens Osterhoff plasma.desy.de Summer Student Programme DESY August 3, 7 Page 4