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P. Muggli, 5 th GLS, 10/02/10 The Plasma Wakefield Accelerator as a Light Source Driver Patric Muggli University of Southern California, Los Angeles

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Presentation on theme: "P. Muggli, 5 th GLS, 10/02/10 The Plasma Wakefield Accelerator as a Light Source Driver Patric Muggli University of Southern California, Los Angeles"— Presentation transcript:

1 P. Muggli, 5 th GLS, 10/02/10 The Plasma Wakefield Accelerator as a Light Source Driver Patric Muggli University of Southern California, Los Angeles Work supported by US DoE

2 P. Muggli, 5 th GLS, 10/02/10 O UTLINE Introduction to the PWFA PWFA Milestones PWFA challenges Drive/witness bunch generation PWFA experiments at SLAC Conclusions

3 P. Muggli, 5 th GLS, 10/02/10 3 Plasma wave/wake excited by a relativistic particle bunch Plasma e - expelled by space charge forces => energy loss + focusing Plasma e - rush back on axis=> energy gain Can be optimized for acceleration, focusing, radiation, … Plasma Wakefield Accelerator (PWFA): high-frequency, high-gradient, strong focusing beam-driven, colinear accelerator PWFA

4 P. Muggli, 5 th GLS, 10/02/10 PWFA C HARACTERISTICS Relativistic, short, dense bunch(es): Accelerating gradient:withand Typically for 1GV/m: in Blowout, nonlinear regime: Pure ion column focusing: free of geometric aberrations Combination of large transverse focusing gradient and large accelerating field leads to large energy gain All the beam particles and the wake are ultra-relativistic no dephasing! High energy (per particle) drive bunch Wavebreaking field: (max., single bunch, lin.)

5 P. Muggli, 5 th GLS, 10/02/10 Rosenzweig, PRL 61, 98–101 (1988) Q=2.1nC E 0 =21-15MeV  z =2.4mm n e = cm -3 L p =20-35cm PWFA M ILESTONES The demonstration! PWFA proposed: Chen, PRL 54 (1985)

6 P. Muggli, 5 th GLS, 10/02/10 Muggli PRL 93, (2004) Rosenzweig, PRL 61, 98–101 (1988) Q=3nC E 0 =28.5GeV  z =700µm n e =10 14 cm -3 L p =1.4m PWFA M ILESTONES e-e- e+e+ Blue PRL90, (2003).

7 P. Muggli, 5 th GLS, 10/02/10 Hogan PRL 95, (2005) Muggli PRL 93, (2004) Rosenzweig, PRL 61, 98–101 (1988) Q=3nC E 0 =28.5GeV  z =20µm n e =2.7x10 17 cm -3 L p =10cm PWFA M ILESTONES e-e-

8 P. Muggli, 5 th GLS, 10/02/10 Hogan PRL 95, (2005) Muggli PRL 93, (2004) Rosenzweig, PRL 61, 98–101 (1988) PWFA M ILESTONES e-e- Significant progress Large energy gain with a single bunch, particle acceleration L p =0,13,22,31 cm Muggli et al., NJP 12, (2010) Scaling with length!

9 P. Muggli, 5 th GLS, 10/02/10 Hogan PRL 95, (2005) Muggli PRL 93, (2004) Rosenzweig, PRL 61, 98–101 (1988) PWFA M ILESTONES e-e- 42 to 84GeV in 85cm of plasma! L p =0,13,22,31 cm Muggli et al., NJP 12, (2010) Scaling with length! Q=3nC E 0 =42GeV  z =20µm n e =2.7x10 17 cm -3 L p =85cm Energy doubling of an FEL drive bunch?

10 P. Muggli, 5 th GLS, 10/02/10 10 Focusing (E r ) Plasma wave/wake excited by a relativistic particle bunch Plasma e - expelled by space charge forces => energy loss + focusing Plasma e - rush back on axis => energy gain Optimize for acceleration and/or focusing (plasma lens) Plasma Wakefield Accelerator (PWFA): high-frequency, high-gradient, strong focusing beam-driven accelerator PWFA N EXT S TEP electron beam Accelerating Decelerating (E z ) Focusing (E r ) Defocusing Bunch train (D+W) for bunch acceleration (∆E/E<<1) Single bunch for particle acceleration (∆E/E~1)

11 P. Muggli, 5 th GLS, 10/02/10 PWFA C HALLENGES Long plasma source for energy doubling (m-scale, n e ≈ cm -3 range?) Low energy spread, careful beam loading, longitudinal bunch shaping? Low emittance, preserved over m-scale plasma (linear focusing, low scattering) Demonstration of bunch acceleration (FACET) Generation of drive/witness bunch train (ATF, FACET) Beam-plasma matching for low emittance beams

12 P. Muggli, 5 th GLS, 10/02/10 12 Correlated energy chirp from linac To Plasma Choose microbunches spacing and widths with mask and beam parameters: N, ∆z,  z, Q Emittance selection e-e- Detector PLD ∆z=434 µm ∆z=226 µm Muggli et al., PRL 2008 D RIVE/WITNEES B UNCH T RAIN G ENERATION

13 P. Muggli, 5 th GLS, 10/02/10 D RIVE/WITNEES B UNCH T RAIN G SLAC FACET Train for proof-of-principle experiments only, n e ≈10 16 cm -3 plasma Use the same masking method Witness N=3.3x10 9 e -  z =13µm Drive N=6.7x10 9 e -  z =44µm Need independent control of D and W bunch parameters

14 P. Muggli, 5 th GLS, 10/02/10 14 Drive Bunch Witness Bunch Drive Bunch Witness Bunch Ion Bubble Ion Bubble Beam 37GV/m (z=0) Wake evolution due to bunch head erosion, but no dephasing QuickPIC simulation, D:  z =30µm, N=3x10 10 e - W:  z =10µm, N=1x10 10 e -,  r0 =3µm SLAC: B UNCH A CCELERATION z=0 ∆z=115µm, n e =10 17 cm -3 Hogan, New J. Phys. 12, (2010) z= cm

15 P. Muggli, 5 th GLS, 10/02/10 15 QuickPIC simulation, D:  z =30µm, N=3x10 10 e - W:  z =10µm, N=1x10 10 e -,  r0 =3µm ∆z=115µm, n e =10 17 cm -3, E 0 =25GeV L p =80cm, gain 25GeV, ∆E/E 0 ≈3%, BUNCH ACCELERATION! D to W energy transfer efficiency ≈30% Witness Bunch Drive Bunch Wake evolution “bends” energy gain SLAC: B UNCH A CCELERATION E0E0 Hogan, New J. Phys. 12, (2010) e - /e - W No bunch shaping, bunches carved out of a single SLAC bunch

16 P. Muggli, 5 th GLS, 10/02/10 Tzoufras, Phys. Rev. Lett 2008 N ARROW E NERGY S PREAD Effective beam loading with bunch shaping No W bunch Witness bunch with linear density ramp perfect beam loading! Very narrow energy spread with linear ramp in witness bunch charge.

17 P. Muggli, 5 th GLS, 10/02/10 C ONCLUSION High gradient PWFA is a good candidate as a compact light source driver Physical parameters have been reached in proof of principle experiments Energy doubler (or more) concept attractive Challenges to produce required bunch quality (energy spread, …)


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