Patric Muggli, HEEAUP05, 06/08/05 1 Beam Plasma Acceleration Patric Muggli University of Southern California Los Angeles, California USA

Patric Muggli, HEEAUP05, 06/08/05 2 Introduction to PWFA Short bunch PWFA results Conclusions Long bunch PWFA results Short bunch production O UTLINE Future Motivation - Propagation of e - and e + beams in long plasmas - Acceleration of e - and e + - Acceleration of e - - Betatron radiation

Patric Muggli, HEEAUP05, 06/08/05 3 T HANK Y OU! E-162-E164-E164X Collaborations: UCLA C. Barnes, F.-J. Decker, P. Emma, M. J. Hogan, R. Iverson, P. Krejcik, C. O’Connell, H. Schlarb, R.H. Siemann, D. Walz Stanford Linear Accelerator Center B.E. Blue, C. E. Clayton, C. Huang, C. Joshi, D. Johnson, W. Lu, K. A. Marsh, W. B. Mori, S. Wang, M. Zhou University of California, Los Angeles S. Deng, T. Katsouleas, S. Lee, P. Muggli, E. Oz University of Southern California

Patric Muggli, HEEAUP05, 06/08/05 4 Could a beam-driven plasma accelerator (PWFA) with ≈10 GeV/m accelerating gradient be used to double the energy of a linear collider? M OTIVATION Plasmas can sustain very large accelerating gradients: GeV/m (laser or particle beam driven plasma accelerators) Limited by rf surface breakdown ≤200 MV/m (?) SLAC: ≈200, 70 MW Klystrons ≈50 GeV e - /e + in ≈3 km Average gradient ≈17 MV/m 3 km Next linear collider (ILC): ≈35 MV/m (?), 15 km for 500 GeV?

Patric Muggli, HEEAUP05, 06/08/05 5 P LASMA W AKEFIELD ( e - ) Plasma wave/wake excited by a relativistic particle bunch Plasma e - expelled by space charge forces => energy loss (ion channel formation r c ≈(n b /n e ) 1/2  r + focusing Plasma e - rush back on axis => energy gain Plasma Wakefield Accelerator (PWFA) = Transformer Booster for high energy accelerator Linear scaling: ≈ 1/  z k pe  z ≈√2 or n e ≈10 14 cm -3 (with k pe  z <<1) U C L A

Patric Muggli, HEEAUP05, 06/08/05 6 P LASMA W AKEFIELD A CCELERATOR Driver bunch: high-charge (3N), modest emittance, shaped? Witness bunch: low charge (N), good emittance ion column focusing preserves emittance beam loading for ∆E/E<<1 Typical PWFA parameters: n e ≈10 16 cm -3, f pe ≈900 GHz, f pe ≈300 µm G ≈10-20 GeV/m N ≈1.5  e -  D ≈60 µm,  W ≈30 µm, ∆t≈150 µm Accelerating Decelerating (E z ) Focusing (E r ) Defocusing Driver Bunch: E 0 => ≈0 Witness Bunch: E 0 => ≥2E 0 Plasma provides focusing and acceleration

Patric Muggli, HEEAUP05, 06/08/05 7 P LASMA W AKEFIELD E XISTENCE

Patric Muggli, HEEAUP05, 06/08/05 8 P LASMA W AKEFIELD E SLAC 3 km e - /e + LINAC Final Focus Test Beam 3 km for 50 GeV e - and e + add 1 GeV over <1 m?

Patric Muggli, HEEAUP05, 06/08/05 9 E XPERIMENTAL S ET U P Optical Transition Radiation (OTR) y x y x - 1:1 imaging, spatial resolution <9 µm e -, e + N=2   z =0.7 mm E=28.5 GeV Ionizing Laser Pulse (193 nm) Li Plasma n e ≈2  cm -3 L≈1.4 m Cherenkov Radiator Streak Camera (1ps resolution) Bending Magnets X-Ray Diagnostic Optical Transition Radiators Dump ∫Cdt Quadrupoles Imaging Spectrometer 25 m IP0: IP2: x z y Plasma: Laser-ionized lithium vapor

Patric Muggli, HEEAUP05, 06/08/05 10 Long e - - beam: E28.5 GeV N<2  e -  z 0.63 mm (2.1 ps)  x =  y ≤70 µm n b ≥4  cm -3  xN 5  m-rad  yN 0.5  m-rad P LASMA W AKEFIELD F IELDS (E-162, e - ) Plasma: n e 0-2  cm -3 L1.4 m, laser ionized 2-D PIC Simulation OSIRIS n e =1.5  cm -3 Experiment: n b >n e => non linear, blow-out regime Front Blow-Out.  r Energy Gain Energy Loss Uniform focusing field (r,z) Typical parameters:

Patric Muggli, HEEAUP05, 06/08/05 11 P LASMA F OCUSING OF e - Beam Envelope Model for Plasma Focusing Multiple foci (betatron oscillation) within the plasma  x,y (z) at fixed n e =>  x,y (n e ) at fixed z Plasma Focusing Force > Beam “Emittance Force” (  beam =1/K>  plasma )  OTR In an ion channel: Envelope equation: with a focusing strength: =6 n e =2  cm -3 Plasma

Patric Muggli, HEEAUP05, 06/08/05 12 F OCUSING OF e - OTR Images ≈1m downstream from plasma Focusing of the beam well described by a simple model (n b >n e ): Plasma = Ideal Thick Lens No emittance growth observed as n e is increased Stable propagation over L=1.4 m up to as n e =1.8  cm -3 K≥1/  0 K≤1/  0 Channeling of the beam over 1.4 m or >12      Matched Propagation over long distance! n e, matched =  cm -3   ≈K PRL 88(13), (2002)PRL 93, (2004)

Patric Muggli, HEEAUP05, 06/08/05 13 W AKEFIELD F IELDS for e - & e + e-e- e+e+ Blow-Out Accelerating “Spike” Fields vary along r, stronger Less Acceleration, “linear-like” n e =1.5  cm -3 homogeneous, QUICKPIC  r =35 µm  r =700 µm  =1.8  d=2 mm

Patric Muggli, HEEAUP05, 06/08/05 14 e - & e + F OCUSING F IELDS* E x (GV/m) x (µm) z (µm) e-e- E x (GV/m) x (µm) z (µm) e+e+ e-e- e+e+  x0 =  y0 =25 µm  z =730 µm N=1.9  e + /e - n e =1.5  cm -3 *QuickPIC Linear, no abberations Non-linear, abberations

Patric Muggli, HEEAUP05, 06/08/05 15 F OCUSING OF e - / e + e-e- e+e+ n e =0n e ≈10 14 cm -3 2mm Ideal Plasma Lens in Blow-Out Regime Plasma Lens with Aberrations OTR images ≈1m from plasma exit (  x ≠  y ) Qualitative differences

Patric Muggli, HEEAUP05, 06/08/05 16 E XPERIMENT / S IMULATIONS  x0 =  y0 =25µm,  Nx =390  10 -6,  Ny =80  m-rad, N=1.9  e +, L=1.4 m Downstream OTR Excellent experimental/simulation results agreement! Simulations Experiment UV Energy (mJ) No  -tron oscillations

Patric Muggli, HEEAUP05, 06/08/05 17 E MITTANCE / S IMULATIONS  x0 =  y0 =25µm,  Nx =390  10 -6,  Ny =80  m-rad, N=1.9  e +, L=1.4 m Possible solution: hollow plasma channel for e + Slice emittance growth for e + e - core emittance preserved, phase mixing Front Back e-e- e+e+ n e =1.5x10 14 cm -3

Patric Muggli, HEEAUP05, 06/08/05 18 U C L A Introduction to PWFA Short bunch PWFA results Conclusions Long bunch PWFA results Short bunch production O UTLINE Future Motivation - Propagation of e - and e + beams in long plasmas - Acceleration of e - and e + - Acceleration of e - - Betatron radiation

Patric Muggli, HEEAUP05, 06/08/05 19 P LASMA W AKEFIELD F IELDS (E-162, e - ) Plasma: n e 0-2  cm -3 L1.4 m, laser ionized 2-D PIC Simulation OSIRIS n e =1.5  cm -3 Experiment: n b >n e => non linear, blow-out regime e - - beam: E28.5 GeV N2  e -  z 0.63 mm (2.1 ps)  x =  y 70 µm n b 4  cm -3  xN 5  m-rad  yN 0.5  m-rad Front Blow-Out. Focusing Energy Gain Energy Loss Uniform focusing field (r,z) Large decelerating/accelerating fields Typical parameters:

Patric Muggli, HEEAUP05, 06/08/05 20 CHERENKOV (aerogel) - Spatial resolution ≈100 µm - Energy resolution ≈30 MeV - Time resolution: ≈1 ps E XPERIMENTAL S ET U P y,E x E-162: e -, e + N=2   z =0.7 mm E=28.5 GeV Ionizing Laser Pulse (193 nm) Li Plasma n e ≈2  cm -3 L≈1.4 m Cherenkov Radiator Streak Camera (1ps resolution) Bending Magnets X-Ray Diagnostic Optical Transition Radiators Dump ∫Cdt Quadrupoles Imaging Spectrometer 25 m IP0: IP2: x z y Plasma: Laser-ionized lithium vapor

Patric Muggli, HEEAUP05, 06/08/05 21 e - A CCELERATION P RE-IONIZED, L ONG B UNCH Time resolution needed, but shows the physics Energy gain smaller than, hidden by, incoming energy spread Peak energy gain: 279 MeV, L=1.4 m, ≈200 MeV/m PRL 93, (2004)  z ≈730 µm N=1.2  e + k p  z ≈√2

Patric Muggli, HEEAUP05, 06/08/05 22 E NERGY L OSS/ G AIN e + Excellent agreement! Plasma Off Front Back n e =1.8  cm -3 Loss Gain Front Back n e =1.8  cm -3 Experiment 2-D Simulation  z ≈730 µm N=1.2  e + Loss ≈ 70 MeV Gain ≈ 75 MeV Loss ≈ 45 MeV/m  1.4 m=63 MeV Gain ≈ 60 MeV/m  1.4 m=84 MeV PRL 90, , (2003) (over 1.4 m) B.E Blue, UCLA

Patric Muggli, HEEAUP05, 06/08/05 23 N UMERICAL S IMULATIONS: E-164/X, e - E-164X:  z =20-10 µm: >10 GV/m gradient! (  r dependent! k p  r ≈1) 0.2 GeV/m f p =2.8 THz, n e =10 17 cm -3 Gradient Increases with 1/  z (N=cst) N=10 10 e -, k p  z ≈√2 n e ≈1.4x10 17 cm -3 for k p  z ≈√2 and  z =20 µm

Patric Muggli, HEEAUP05, 06/08/05 24 U C L A Introduction to PWFA Short bunch PWFA results Conclusions Long bunch PWFA results Short bunch production O UTLINE Future Motivation - Propagation of e - and e + beams in long plasmas - Acceleration of e - and e + - Acceleration of e - - Betatron radiation

Patric Muggli, HEEAUP05, 06/08/ GeV Existing bends compress to <100 fsec ~1 Å Add 12-meter chicane compressor in linac at 1/3-point (9 GeV) Damping Ring 9 ps 0.4 ps <100 fs 50 ps SLAC Linac 1 GeV GeV FFTB RTL 30 kA 80 fsec FWHM 1.5% Short Bunch Generation In The SLAC Linac Courtesy of SPPS Bunch length/current profile is the convolution of an incoming energy spectrum and the magnetic compression ChirpingCompression

Patric Muggli, HEEAUP05, 06/08/05 26 e - B UNCH M ANIPULATION Energy spectrum phase space current profile PWFA: accelerate e - in the back of the bunch Front Back Accelerated electrons Front Back Accelerated electrons LiTrack: K. Bane, P. Emma SLAC

Patric Muggli, HEEAUP05, 06/08/05 27 Accelerated e - originate from ≥0.9 GeV below the bunch max. energy! PWFA: accelerate e - in the back of the bunch A CCELERATED e - ≈0.9 GeV Accelerated electrons Front Back

Patric Muggli, HEEAUP05, 06/08/05 28 Short bunches can field-ionize their own plasma and create their own accelerating structure (E-164X, after-burner?) r/  r z/  z Li Vapor Plasma ∫Wdt≈0 ∫ Wdt=1 N=1.8  10 10,  r =10 µm,  z =20 µm in Li E r.max ≈47 GV/m  I = ionization potential = 5.45 eV for LiI E(t)= electric field in GV/m n*=effective quantum number =3.68Z/  I 1/2 see for example D. Bruhweiler et al., Phys. of Plasmas to be published, and P.Muggli et al, AAC-2002 Proceedings e - - B EAM F IELD- I ONIZATION Tunneling ionization rate (ADK model) : Threshold process

Patric Muggli, HEEAUP05, 06/08/05 29 “P LASMA S OURCE ” Lithium vapor in a heat-pipe oven Tunnel-ionization: n e =n o, Li P. Muggli et al., IEEE TPS (1999) Li He Pressure L Boundary Layers n 0 =  cm -3 T= °C L=10-20 cm P He ≈1-40 T e-e- Heater Wick Cooling Jackets Be Window Plasma Light Diagnostic : removes laser-related variations

Patric Muggli, HEEAUP05, 06/08/05 30 Coherent Transition Radiation (CTR) - CTR Energy≈I peak ≈1/  z Cherenkov (aerogel) - Spatial resolution ≈100 µm - Energy resolution ≈30 MeV E XPERIMENTAL S ET U P y,E x e-e- N=1.8   z =20-12µm E=28.5 GeV Optical Transition Radiators IP0: Li Plasma n e ≈0-3x10 17 cm -3 L≈10-20 cm Plasma light X-Ray Diagnostic, e-/e + Production Cherenkov Radiator Dump ∫Cdt Imaging Spectrometer IP2: x z y Energy Spectrum “X-ray” 25m Coherent Transition Radiation and Interferometer X-ray Chicane -Energy resolution ≈60 MeV E Energy Spectrum before … Energy Spectrum after… … the plasma Peak Current Bunch length

Patric Muggli, HEEAUP05, 06/08/05 31 N≈1.8  e - /bunch Accelerated charge >7% or >220 pC Energy loss is peak current or bunch length dependent n e ≈2.55  cm -3, L≈10 cm X (mm) Relative Energy (GeV) X (mm) X (mm) 7.9 GeV CTR=247CTR=299 CTR=283 CTR=318 n e =0 Gain Loss X (mm) ≈3 GeV! Energy gain reaches ≈3+1 GeV

Patric Muggli, HEEAUP05, 06/08/05 32 Details of the incoming energy spectra are visible Matching of incoming energy spectra with LITrack will allow for the unfolding of the effects n e ≈2.55  cm -3 I NCOMING S PECTRA Energy Spectra before the Plasma x-ray chicane) L≈10 cm, N≈ 1.8  Front Back

Patric Muggli, HEEAUP05, 06/08/05 33 Identical incoming energy spectra/events “Identical” outgoing energy spectra/events E x ≈10 GeV SIMILAR IN, SIMILAR OUT IN OUT

Patric Muggli, HEEAUP05, 06/08/05 34 Very consistent acceleration, varies with incoming bunch parameters Gain n e ≈2.8  cm -3, L≈10 cm N≈ 1.8  e - /bunch, arranged by CTR E x Energy (GeV) E x Energy Gain Energy Gain

Patric Muggli, HEEAUP05, 06/08/05 35 Betatron X-rays X-ray synchrotron radiation from electrons betarton oscillations e - beam X-rays Plasma ion column acts as a “Plasma Wiggler” lead to X-ray synchrotron radiation. n e =3e17 cm -3,  =56000, r 0 =10 µm, B  /r= 9 MT/m,  = 2cm Wiggler strength: Critical frequency on-axis (K>>1): Particle energy loss:

Patric Muggli, HEEAUP05, 06/08/05 36 Positron Production Experimental Setup Collimators e - Extraction e-e- z x Plasm a 40 m10 cm Bending Magnet hνhν Target 8mm Devon Johnson, UCLA Plasma length: L p =10 cm, N electrons =9.6x10 9 Plasma-conversion target distance: 40 m! Photon beam target ≈ 35 cm, collimated to r≈8 mm e + detection using magnetic spectrometer and 100 µm surface barrier detectors (SBDs), phospor screen and intensified camera Detector e+e+ Sector Magnet

Patric Muggli, HEEAUP05, 06/08/05 37 Simulation Results Simulated Positron DetectedSimulated Radiated Photon Spectrum L p =10 cm, N electrons =9.6x10 9, 8 mm dia n e = cm -3 => 2.4x10 6 e + n e =2x10 17 cm -3 => 6.9x10 6 e + n e =3x10 17 cm -3 => 1.2x10 7 e X 0 titanium target ≈4% photons collected # e + between 0-40 MeV 3x10 8 e + with L≈10 cm plasma (100% collection) Plasma wiggler as e + source?

Patric Muggli, HEEAUP05, 06/08/05 38 C ONCLUSIONS Plasmas can transport and accelerate multi-GeV particle bunches Particle energy gain measured: ≈4 GeV over 10 cm! Accelerating gradient ≈40 GeV/m over ≈10 cm! Acceleration very consistent and repeatable. Field-ionized PWFA => Long, dense plasmas Numerical tools are availabe to support experimentals results and project PWFA into the future No physics limitations observed so far Single Bunch Only!

Patric Muggli, HEEAUP05, 06/08/05 39 e - and e + : Driver bunches:  z =63 µm,  r =5 µm, N=3  e - /e +, 50 -> 0 GeV Witness bunches:  z =32 µm,  r =5 µm, N=1  e - /e +, 50 -> GeV Delay: d=200 µm Plasma: n e =1.8  cm -3, L=7, 21 m Accelerating gradient: 8, 3 GV/m, ∆E/E <10% P LASMA A FTERBURNER ( E XAMPLE) S. Lee et al., PRST-AB (2001) 3 km IP 50 GeV e - 50 GeV e + e - PWFA e + PWFA LENSES 7m21m GeV, e - /e + Collider

Patric Muggli, HEEAUP05, 06/08/05 40 Simulations by C. Huang, UCLA S IMULATION C HALLENGE DriverWitness Doubling the energy of a 500 GeV bunch possible! … … in only ≈30 m (≈17 GeV/m)! (simulation) Driver Witness >0.5 TeV N D =3x10 10, N w =10 10,  Nx =  Ny =2230x10 -6 m-rad,  x =  y =15 µm, (beam matched to the plasma)  zD =145 µm,  zW =10 µm, ∆z=100 µm N e =5.66x10 16 cm -3, L p =30 m L≈30 m

Patric Muggli, HEEAUP05, 06/08/05 41 Driver Witness >0.5 TeV L=0 mL≈10 m L≈20 mL≈30 m Simulations by C. Huang UCLA S IMULATION C HALLENGE Doubling the energy of 500 GeV bunch possible! … … in only ≈30 m! (simulation) N D =3x10 10, N w =10 10,  Nx =  Ny =2230x10 -6 m-rad,  x =  y =15 µm, (beam matched to the plasma)  zD =145 µm,  zW =10 µm, ∆z=100 µm N e =5.66x10 16 cm -3, L p =30 m, pre-ionized, Gradient>17 GeV/m

Patric Muggli, HEEAUP05, 06/08/05 42 S IMULATION C HALLENGE … CPU time 1 week on 16 proc. to 2 weeks on 32 proc.! ∆E/E≈5% FWHM Head erosion Wake loading evolution Stability with real beam parameters (  x,y,  x,y ) Narrow energy spread, could be improved with optimization …

Patric Muggli, HEEAUP05, 06/08/05 43 F UTURE Longer plasma (≈30 cm) for 10 GeV energy gain Two-bunch experiments for beam acceleration Doubling the energy of the 28.5 GeV SLAC beam in ≈70 cm Explore application of PWFA to a real HEC … Adjust afterburner concept parameters to a NLC, and optimize them Develop numerical tools Current (kA) Z (mm) ∆z≈145 µm Q≈11% (not optimized!) Identify key experiments to be performed towards an afterburner

Patric Muggli, HEEAUP05, 06/08/05 44

Patric Muggli, HEEAUP05, 06/08/05 45 O THER PWFA S Argone National Laboratory: -propagation, energy gain, two-bunch experiments, simulations Brookhaven National Laboratory: -linear wakefields, and PWFA driven by a train of bunches Yerevan Physics Institute, Armenia: -Acceleration of a single bunch in a multi-bunch driven wake Budker Institute, Novosibirsk, Russia: -e - and e + PWFAs, simulations

Patric Muggli, HEEAUP05, 06/08/05 46 H ALO F ORMATION  x0 ≈  y0 ≈25 µm,  Nx ≈390  10 -6,  Ny ≈80  m-rad, N=1.9  e +, L≈1.4 m Very nice agreement ExperimentSimulation

Patric Muggli, HEEAUP05, 06/08/05 47 Energy [GeV] No Plasma 2.8x10 17 cm -3 a) b) 1% 95% D ETAILED A NALYSIS Energy gain = energy of 1% charge point Energy loss = energy of 95% charge point >2.7 GeV PRL (2005)

Patric Muggli, HEEAUP05, 06/08/05 48 D ETAILED A NALYSIS n e = 1.0  cm -3 Energy loss, but no gain ( p >  z ) n e = 2.5  cm -3 Energy loss and gain n e = 3.5  cm -3 More, earlier loss and gain Empty symbols: plasma OUT Filled symbols: plasma IN Outcome depends on bunch “length”, peak current, profile Recover current profiles ≈1.7 GeV ≈4 GeV CTR Energy (a.u.) ≈I peak ≈ 1/  z

Patric Muggli, HEEAUP05, 06/08/05 49 n e ≈2.51  cm -3, L≈10 cm, N≈1.8  Confirm: e + gain energy from below the head energy Find similar incoming bunches with  2 on incoming spectra. O RIGIN OF A CCELERATED e - Retrieve energy of accelerated e + from incoming spectra and LITrack simulations ON OFF ≈10 GeV E x

Patric Muggli, HEEAUP05, 06/08/05 50 N≈1.8  e - /bunch Accelerated charge >7% or 220 pC Energy gain depends on the details of the incoming beam (x,y,z) n e ≈2.55  cm -3, L≈10 cm R ESULTS X (mm) Relative Energy (GeV) X (mm) X (mm) 7.9 GeV Pyro=247Pyro=299 Pyro=283 Pyro=318 n e =0 Gain Loss X (mm) ≈3 GeV! Energy gain reaches ≈4 GeV

Patric Muggli, HEEAUP05, 06/08/05 51 Charge Fraction at E>0: % of total charge or ≈220 pC! n e ≈3.5  cm -3 E NERGY S PECTRA L≈10 cm, N≈ 1.8  Energy Gain Energy Loss Energy Spectra after the Plasma Cherenkov) Peak energy gain above the beam head: ≈1.5 GeV total gain: ≈2.5 GeV Variations from incoming energy spectrum variations

Patric Muggli, HEEAUP05, 06/08/ % 70%  E/E=6% L=0L≈1m L≈2mL≈3m c/  p Driver Witness 50 GeV energy gain in 3 meters ! Simulations by C. Huang, UCLA S IMULATION C HALLENGE 2-bunch experiments, for beam acceleration! ≈10 GeV acceleration in long plasma Next experiments:

Patric Muggli, HEEAUP05, 06/08/05 53 Laser Wake Field Accelerator(LWFA) A single short-pulse of photons Trapped particles evolves to Self Modulated Laser Wake Field Accelerator(SMLWFA) Raman forward scattering instability Trapped particles Plasma Beat Wave Accelerator(PBWA) Two-frequencies, i.e., a train of pulses Injected particles Plasma Wake Field Accelerator(PWFA) A high energy particle bunch Injected particles 4 P LASMA A CCELERATORS * * Pioneered by J.M. Dawson at UCLA

Patric Muggli, HEEAUP05, 06/08/05 54 e - B UNCH M ANIPULATION Energy spectrum phase space current profile PWFA: accelerate e - in the back of the bunch Front Back Accelerated electrons Front Back Accelerated electrons LiTrack: K. Bane, P. Emma SLAC

Patric Muggli, HEEAUP05, 06/08/05 55 Accelerated e - originate from GeV below the bunch max. energy! PWFA: accelerate e - in the back of the bunch A CCELERATED e - ≈1.4 GeV ≈0.9 GeV Accelerated electrons Quote energy above the bunch head/front energy, analysis will reveal real energy gain Front Back

Patric Muggli, HEEAUP05, 06/08/05 56 L≈3 m 50 GeV energy gain in 3 meters ! 30% 70%  E/E=6% Simulations by C. Huang, UCLA JP1.126 Wednesday afternoon! S IMULATION C HALLENGE Driver Witness 2-bunch experiments, for beam acceleration! ≈10 GeV acceleration in long plasma Next experiments:

Patric Muggli, HEEAUP05, 06/08/05 57 P LASMA W AKEFIELD F IELDS (e - ) Plasma: n e =n  cm -3 L≈10 cm 3-D PIC Simulation OSIRIS N=10 10 e -, n e =2.1  cm -3, L=3 cm Much larger accelerating field e - - beam: E28.5 GeV N1.8  e -  z 20 µm (70 fs)  x =  y 15 µm n b 2.5  cm -3  xN 5  m-rad  yN 0.5  m-rad Front Focusing (r=  r ) Energy Gain Energy Loss Typical parameters: c Reach k p  r ≈1, (≈”linear” theory)

Patric Muggli, HEEAUP05, 06/08/05 58 N EAR F UTURE Long plasma => Large energy gain (2  E o in 70 cm?) Short positron bunches? Notch in the LI10 chicane => 2-bunch experiment!?! Beam acceleration with finite energy spectrum (XFEL beams? SLAC, DESY?)

Patric Muggli, HEEAUP05, 06/08/  m 12  m 1.5 % 6 mm 6 mm 0.08 % 6 mm 6 mm 1.2 % 1.2 mm 1.2 mm 1.1 % 1.2 mm 1.2 mm 1.6 % 50  m 50  m 1.6 % 50  m 50  m 1.5 % energy profile phasespace temporal profile 1.19 GeV 9 GeV 28 GeV Particle tracking in 2D… Courtesy of SPPS

Patric Muggli, HEEAUP05, 06/08/05 60 Energy loss ≈ peak current ≈ CTR energy ≈ 1/  z n e ≈2.55  cm -3, E NERGY L OSS Peak energy loss gradient ≥3.4 GeV/10 cm! L≈10 cm, N≈ 1.8  e - /bunch ≈I peak ≈1/  z Peak Energy Loss ≈I peak ≈1/  z Mean Energy Loss Relative Mean Energy (GeV) Relative Min. Energy (GeV)

Patric Muggli, HEEAUP05, 06/08/05 61 E NERGY S PECTROMETER (NON-INVASIVE, UPSTREAM OF PLASMA) Plasma e-e- Measure incoming bunch spectrum C.D. Barnes PhD. Thesis Stanford 2004

Patric Muggli, HEEAUP05, 06/08/05 62 e - : n e0 =2  cm -3, c/  p =375 µme + : n e0 =2  cm -3, c/  p =3750 µm  r =35 µm  r =700 µm Uniform focusing force (r,z)  =1.8  Non-uniform focusing force (r,z) d=2 mm Blow Out 3   beam Front Back 3  0 beam Front Back 3-D QuickPIC simulations, plasma e - density: e - & e + B EAM N EUTRALIZATION e-e- e+e+

Patric Muggli, HEEAUP05, 06/08/05 63 Optical Transition Radiation (OTR) Cherenkov (aerogel) - Spatial resolution ≈100 µm - Energy resolution ≈30 MeV E XPERIMENTAL S ET U P -1:1 imaging, spatial resolution ≈9 µm y,E x Since E-162: U C L A e-e- N=1.8   z =20-12µm E=28.5 GeV Optical Transition Radiators IP0: Li Plasma Gas Cell: H 2, Xe, NO n e ≈ cm -3 L≈ cm Plasma light X-Ray Diagnostic, e-/e + Production Cherenkov Radiator Dump ∫Cdt Imaging Spectrometer IP2: x z y Energy Spectrum “X-ray” 25m Coherent Transition Radiation and Interferometer y x Upstream y x Downstream X-ray Chicane -Energy resolution ≈60 MeV Plasma Light E

Patric Muggli, HEEAUP05, 06/08/05 64 L≈10 cm, N≈ 1.8  n e ≈3.5  cm -3 R ESULTS Pyro=358Pyro= X (mm) Relative Energy (GeV) Pyro= X (mm) X (mm) X (mm) Pyro= X (mm) Pyro=466 n e =0 Min. Gain Min. Loss +1.5 GeV Many similar events in a data set Acceleration with significant charge: ≈1.5+1 GeV Lower gain 3.5  cm -3

Patric Muggli, HEEAUP05, 06/08/05 65 A NALYSIS E XAMPLE Retrieve bunch energy distribution/current profile for energy gain events Event with GainIncoming Spectrum PLASMA ONPLASMA OFF Incoming Spectrum Incoming Energy Distribution Incoming Energy Distribution M.J. Hogan E x E

Patric Muggli, HEEAUP05, 06/08/05 66 T RAPPING OF P LASMA e - No Trapping Trapping Wavelength (nm) 610 nm Plasma Light Spectrum Continuum Evidence for plasma e - trapping: Excess charge after the plasma Trapping Threshold? Excess light from OTR screen Continuum light emission on plasma light spectrum Trapping mechanism? Dark current limit for the PWFA?

Patric Muggli, HEEAUP05, 06/08/05 67 AAC’04 AB I NTEGRATION P. Muggli and J.S.T. Ng, AAC’04 AIP Proceedings

Patric Muggli, HEEAUP05, 06/08/05 68 Based on upgrade of proposed next linear collider “Warm”=11.4 GHz “Cold”=1.3 GHz AAC’04 AB I NTEGRATION Courtesy of T. Raubenheimer, SLAC

Patric Muggli, HEEAUP05, 06/08/05 69 D ETAILED A NALYSIS: PRELIMINARY CTR Pyro signal Litrack peak Current (kA) “Confirm” expected dependency (M.J. Hogan)

Patric Muggli, HEEAUP05, 06/08/05 70 N EAR F UTURE (II) Notch in the LI10 chicane => 2 bunches Acceleration with finite energy spectrum Long plasma => Large energy gain (2  E o in 70 cm?) Acceleration with finite energy spectrum

Patric Muggli, HEEAUP05, 06/08/05 71 M ODUS O PERANDI Choose n e and LINAC beam parameters (N, …) At a given density vary/optimize acceleration signal - Incoming energy spectrum (phase ramp) - FFTB R 56 - beam waist location Match incoming spectra with LITrack -> Incoming bunch current profile -> Input into PWFA theory/simulations Acquire data with inherent variations - Energy spectra IN and OUT - Beam images b/a plasma - Standard beam parameters (N, position, …) K p  z ≈√2 -> n e ≈1.4  cm -3 for  z =20 µm Compare events with same incoming energy spectra

Patric Muggli, HEEAUP05, 06/08/05 72 S LICE A NALYSIS R ESULTS S INGLE E VENT n e =0.7  cm -3 Front E  n e =1.8  cm -3 Front E  Use low n e events as “plasma off” Select events by n e, and by position on the streak camera slit ≈3  z ≈500 MeV ∆E≈-170 MeV

Patric Muggli, HEEAUP05, 06/08/05 73 e - E NERGY G AIN/ L OSS Average energy gain (slice average) : 156 ±40 MeV (≈3  10 7 e - ) Average energy loss (slice average) : 159±40 MeV n e =1.8  cm -3 ) ps slice analysis results Energy gain by particles ≈279 MeV in the last (-6 ps) 1 ps slice Peak accelerating gradient ≈200 MeV/m (L=1.4 m) (with incoming energy chirp subtracted)  =-6 ps

Patric Muggli, HEEAUP05, 06/08/05 74 E XPERIMENTAL S ET U P e-e- N=1.8   z =20-12µm E=28.5 GeV Optical Transition Radiators IP0: Li Plasma Gas Cell: H 2, Xe, NO n e ≈ cm -3 L≈ cm Plasma light X-Ray Diagnostic, e-/e + Production Cherenkov Radiator Dump ∫Cdt Imaging Spectrometer IP2: x z y Energy Spectrum “X-ray” 25m Coherent Transition Radiation and Interferometer X-ray Chicane -Energy resolution ≈60 MeV E Coherent Transition Radiation (CTR) - CTR Energy≈I peak ≈1/  z

Patric Muggli, HEEAUP05, 06/08/05 75 e - & e + F OCUSING F IELDS r=  r r=3  r r=  r QuickPIC  x0 ≈  y0 ≈25 µm,  Nx ≈390  10 -6,  Ny ≈80  m-rad, N=1.9  e +,  z ≈730 µm, n e =1.5  10 -6, L≈1.1 cm Uniform focusing force (r,z) Non-uniform focusing force (r,z) Weaker focusing force Stronger focusing force FrontBackFrontBack e + : focusing fields vary along r and z!

Patric Muggli, HEEAUP05, 06/08/ D Relativistic Plasma Wave: Fields in rf cavities Limited by rf surface breakdown ≤200 MV/m (?) SLAC: ≈200, 70 MW Klystrons ≈50 GeV e - /e + in ≈3 km Average gradient ≈17 MV/m LARGE Collective response! High gradient, high-energy plasma accelerator? A CCELERATING F n e =10 14 cm -3 (f pe ≈100 GHz) 3 km Next linear collider (ILC): ≈35 MV/m (?), 15 km for 500 GeV? EzEz p c