1. Coulomb09, Senigallia, 18-06-2009 Ultra-High Brightness electron beams from laser driven plasma accelerators Luca Serafini, INFN-Milano Brightness Degradation due to Chromaticity blow-out in ultra-focused beams (  p/p> 1% is a danger) 6D Phase Space Density of beams produced by self-injection mechanisms (Brightness, Brilliance) Ultra-high brightness in step density gradient plasma injectors (A look at the particle beam beyond the source) Fs to As pulses of Coherent X-rays (the AOFEL)

2. Coulomb09, Senigallia, 18-06-2009 Vittoria Petrillo Università degli Studi, Milano (Italy) Alberto Bacci, Andrea R. Rossi, Luca Serafini, Paolo Tomassini INFN, Milano (Italy) Carlo Benedetti, Pasquale Londrillo, Andrea Sgattoni, Giorgio Turchetti Università and INFN Bologna (Italy)

3. Coulomb09, Senigallia, 18-06-2009 Brightness and Brilliance 5D and 6D phase space density Figures of Merit for Particle Beams

4. Coulomb09, Senigallia, 18-06-2009  n [  m] 10 13 10 14 10 15 10 16 10 17 I [kA] 10 18 AOFEL SPARX SPARC X-ray FEL @ 1 pC The Brightness Chart [A/(m. rad) 2 ] Self-Inj

5. Coulomb09, Senigallia, 18-06-2009  [  ] 10 14 10 15 10 16 10 17 BnBn SPARX SPARC The 6D Brilliance Chart [A/((m. rad) 2 0.1%)] Self-Inj Ext-Inj AOFEL X-ray FEL @ 1 pC

6. Coulomb09, Senigallia, 18-06-2009 Rapidity

7. Coulomb09, Senigallia, 18-06-2009 electron beam -- - - - ---- - - -- Physical Principles of the Plasma Wakefield Accelerator Space charge of drive beam displaces plasma electrons Transformer ratio Wake Phase Velocity = Beam Velocity (like wake on a boat) Plasma ions exert restoring force => Space charge oscillations Wake amplitude + + + + + + + + + + + + ++ ++ + + + + + + + + + + + + + + --- - - - - - - -- - - - -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - -- - - - - - - - - -- - - - - - - - - - - - - - - -- - - - ---- - - - - - - - --- - - - - - - - - - - - - - - - - -- - - - - - - - - - - +++++++++++ +++++++++++++++ +++++++++++++++ +++++++++++++++ - - - - - Ez Courtesy of T. Katsouleas Plasma acceleration experiments with SPARC/X e - beams

8. Coulomb09, Senigallia, 18-06-2009 Self-Injection beams seem to have low phase space density but high rapidity (suited for relativistic piston applications)

9. LNF – 29/05/2009 C. Benedetti

10. x envelope and emittance free diffraction in vacuum RETAR (A. Rossi) no description of plasma vacuum interface

11. Bunch length and average current

12. Energy spread

13. Transverse and longitudinal phase and configuration spaces @ 1 cm

14. Transverse and longitudinal phase and configuration spaces @ 92 cm

15. LNF – 29/05/2009 SPARC  n =1 mm. mrad,  0 = 200  m,  =300,  =0.6%, d=10 m  n =0.005 mm. mrad Self-Inj  n =2 mm. mrad,  0 = 1  m,  =2000,  =2%, d=1 m  n =40 mm. mrad Emittance Dilution due to Chromatic Effects on a beam emerging from a focus of spot size  0, drifting to a distance d

16. LNF – 29/05/2009 ASTRA (A. Bacci) : matching with a triplet

17. LNF – 29/05/2009 Space charge energy spread No Space charge energy spread

18. LNF – 29/05/2009 No Space charge No energy spread SPARC beam Space charge energy spread

19. Coulomb09, Senigallia, 18-06-2009 How to measure this emittance blow-up? No trace on beam envelope… energy selection?

20. LNF – 29/05/2009 SPARC 640  m AOFEL 3  m SPARX 580  m acceleration focusing beam plasma emittance laminarity parameter Beam-plasma wavelength betatron length transition spot-size Bubble-self.inj. 80-150  m

21. Coulomb09, Senigallia, 18-06-2009 Coherence and Time Duration

22. Coulomb09, Senigallia, 18-06-2009 CO 2 envelope TiSa envelope e - beam TiSa pulse plasma L sat =10L G =1.3 mm (  =0.002) CO 2 focus Z [m] r  m]

23. AOFEL injection by longitudinal nonlinear breaking of the wave at a density downramp looks one of the most promising since it can produce e-beams having both low energy spread and low transverse emittance. electromagnetic undulator made by a laser pulse counter propagating respect to the electron beam

24. First stage:LWFA with a gas jet modulated in areas of different densities with sharp density gradients. Energy (J)2 Waist (  m) 20 Intensity (W/cm 2 )7 10 18 Duration (fs)20 n 01 (cm -3 )1 10 19 L R (  m) 10 n 02 (cm -3 )0.6 10 19 p (  m) 13

26. Coulomb09, Senigallia, 18-06-2009  <><> <><> Selection of best part in the bunch: 40 pC in 2 fs (600 nm) Longitudinal phase space and density profile projected rms  n = 0.7  m

27. VORPAL C. Nieter J. R. Cary J.Comp.Phys. 196 448 (2004) New results by ALADYN Numerical Modelling Formation of the plasma Formation of the bunch Acceleration stage Astra Retar Beam-CO2 laser Interaction FEL instability Genesis 1.3 EURA Transition Plasma-undulator First stage Second stage Third stage

28. Second stage: Transition from the plasma to the interaction area with the e.m. undulator (analysis by ASTRA) With space charge Without space charge

29. FEL interaction with a e.m. undulator Pierce Parameter I A =17 10 3 Amp L g1d = u /(  Ideal 1d model L g  u     Three-dimensional model E rad =  E beam = 1.35nm

30. , <1

31. Generalized Pellegrini criterion Requirements for the growth

32. 50 20 kA  X 10 -6 m 1.15 10 6 m -1 1.3  =3 10 -3

33. L g1d =76  m  z =0.2  m L g =200  m

34. Transverse coherence d= L sat * /  x = 10*L g * /  x = 10*200 10 -6 *10 -9 /5 10 -6 =0.4  m Longitudinal coherence L c = /(  (1+  ) =0.04  m 1 spike each 10 L c

35. Third stage: FEL radiation = u (1+a w 2 )/4  2 by uploading the particles by VORPAL Superradiant structure 0.1  m=330 as Single spike structure Monochromatic pulse

36. First peakSaturation P max (W)2 10 8 1.5 10 8 E (  J) 0.050.12 L R  m) 0.050.5 L sat  mm) 1.4.5 R (nm) 1.35 d R/ R 0.81% 25 micron Laser requirements: 250 GW for 5 mm R=30  m E=4.16J

37. Coulomb09, Senigallia, 18-06-2009

38. I=31 KA  z =1.5  m  x =0.6 um  n =0.1  m  =45  E/E=0.3% a 0 =0.8  =0.162 nm

39. Conclusions All optical free-electron laser are possible with e-beam produced by LWFA in density downramp + electromagnetic undulators Characteristics of radiation: small energy/pulse, quasi transverse coherent, very short pulse, longitudinal coherence, monochromaticity Injection of the beam, control of the exit from the plasma, requirements of power and structure of the e. m. undulator

40. Coulomb09, Senigallia, 18-06-2009 Conclusions Beams produced by Self-Injection in the bubble regime look affected by strong chromaticity: serious emittance dilution after the source, loss of beam brightness Possible cures: prompt focusing in mm (plasma lenses?), energy selection (charge loss), emittance compensation schemes? Maximum brightness with step downramp density injection (1D mech., localized injection) Needs new targets, shock wave gas jets AOFEL: table top X-FEL delivering fs to as quasi-coherent bright X-ray pulses

41. Coulomb09, Senigallia, 18-06-2009

42. Scattered photons in collision  Scattered flux  Luminosity as in HEP collisions  Many photons, electrons  Focus tightly  Short laser pulse; <few psec (depth of focus) Thomson X-section Coulomb09, Senigallia, 18-06-2009

43. Rapidity

44. Coulomb09, Senigallia, 18-06-2009

45. This last group tries to realize the scheme proposed by Gruener et al. (1.74 GeV, 160 kA, 1mm mrad,  E/E=0.1%,  x =30  m) where an electron beam generated by LWFA in the bubble regime is driven in a static undulator  u =5 mm, =0.25nm, L sat =5m, L rad =4fs,P sat =58 GW,

46. The technology of ultra short, high power lasers has permitted the production and the study of high- brightness, stable, low divergence, quasi mono- energetic electron beams by LWFA. These beams are now an experimental reality ( for instance: Faure et al.,Leemans et al., Jaroszinski et. al, Geddes et al., ecc.) and can be used in applications for driving Free- electron lasers Last experimental results, see, for instance: J.Osterhoff et al. PRL 101 085002 (2008) (mono-energetic fraction: 10 pC@200 MeV, divergence=2.1 mrad FWHM) Koyama, Hosokai 20 pC @ 100 MeV and density downramp N. Hafz, Jongmin Lee, Nature photonics THCAU05 FEL Conf 2008

47. electron beam Ti:Sa pulse Ti:Sa envelope Gas jet Lsat≈10 Lg CO 2 envelope AOFEL Lg=10.1 x (  x 2/3 /I 1/3 )x( w /K 0 /JJ 2 ) 1/3

48. Coulomb09, Senigallia, 18-06-2009 Simulation with real bunch GENESIS Simulations starting from actual phase space from VORPAL (with oversampling)  =2.5  m (CO 2 laser focus closer to plasma) After 1 mm : 0.2 GW in 200 attoseconds L beff < 2 L c

49. Coulomb09, Senigallia, 18-06-2009 GENESIS Simulations for laser undulator at 1  m to radiate at 1 Angstrom Simulation with real bunch  =3.5  m Average power (L sat ~500  m, P sat ~10 MW) Peak power 100 MW in 100 attoseconds Field Coherence Time duration

50. Coulomb09, Senigallia, 18-06-2009

51. Slice 8, I=25 kA Equivalent Cathode