C.Joshi Electrical Engineering Department UCLA

1. Plasma Acceleration Research at SLAC: An OHEP Funded University-Laboratory Collaborative Research C.Joshi Electrical Engineering Department UCLA “Putting Beam Physics at the Forefront of Science” Work supported by DOE

2. WHO ARE WE? Management and Review Each institution has a PI: R.Siemann SLAC C.Joshi UCLA T.Katsouleas USC M.Hogan SLAC C.Joshi UCLA P.Muggli USC Experimenter Spokesperson Proposals for experiments reviewed by SLAC EPAC Proposals from UCLA and USC then submitted to DOE HEP for supplemental funding to existing multi year grants. Progress monitored through yearly reviews by DoE program Manager. .

3. Goals and Relevance To address critical issues for realizing a plasma-based accelerator at the energy frontier in the next decade. Our goals are strongly endorsed by the Marx subpanel “The challenge is to undertake and sustain the difficult and complex R&D needed to enable a feasible,cost and energy effective technology on the several decade horizon. Achieving these goals will require creativity and the development and maturation of new accelerator approaches and technologies.”

4. 14 TeV CM pp LHC at CERN -27 km -$6 Billion+? Can Plasmas Play A Role in Future High-Energy Particle Accelerators? -Smaller? -Cheaper?

5. Plasma Wake Field Accelerator • A high energy electron bunch Why Plasma Based Accelerators Vgr • Laser Wake Field Accelerator • A single short-pulse of photons • Drive beam • Trailing beam • Wake: phase velocity = driver velocity Large wake for a laser amplitude ao=eEo/mwoc ~ 1 or a beam density nb~ no Accelerating Field= 30GeV/m(1017/no)1/2 T.Tajima and J.M.Dawson PRL(1979) P.Chen et.al.PRL(1983)

6. Plasma Accelerator Progress “Accelerator Moore’s Law” ILC Working Machines Doing physics Max.Energy in Laser Experiments UCLA

7. UCLA Making of a collaboration: SLAC (ARDB) / USC / UCLA 6/96Snowmass ‘96, Chan Joshi and Tom Katsouleas discuss the possibility of a 1 GeV in 1 Meter PWFA experiment at SLAC 7/96-7/97 Collaboration E157 (SLAC/USC/LBNL/UCLA) formed, Proposal submitted and approved: Experiment scheduled for 1999 99-06SLAC/UCLA/USC collaboration carries out 5 highly successful experiments at FFTB Marx subpanel (2006) “An example of this basic science and the long timescale needed for such exploratory research to reach fruition is the work on plasma acceleration that has led to the wakefield acceleration experiment carried out at the SLAC ..(FFTB) by a collaboration from universities and national laboratories…National laboratories provide the infrastructure and expertise in the operation and use of such major facilities while the participant universities bring innovation and human resources..”

8. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + + + - - - - - - - - - drive beam + - - + + + + + - + + + + + - + + + + + + + - - - - + + + + + + + + + + + + + + + - - - - - - - - - - - - - - - - - - - - - - - + + + + + + + + + + + + + + + - - - - - - + + + + + + + + + + + + - - - - - - - + + + + + + + + + + + + + + + - - - - - - - - - - - - - - - - - - + + + + + + + + - - - - - - - - - Ez Beam-Driven Wakefield Accelerators (Blowout Regime) Rosenzweig et. 1990 Pukhov and Meyer-te-vehn 2002 (Bubble) • Space charge of the beam displaces plasma electrons • Plasma ion channel exerts restoring force => space charge oscillations • Linear focusing force on beams (F/r=2pne2/m) UCLA,USC,SLAC,ANL,FNAL,KEK,BNL

9. Beam-Driven PWFA@ SLAC Located in the FFTB 25 m FFTB

10. Acceleration Gradient Obeys Inverse Square Law E-164X: z = 20 - 10 µm > 10 GeV/m gradient! (r dependent! kpr ≈ 1) fp=2 .8 THz, W=3MT/m @ ne=1017 cm-3

11. Electron Beam Refraction at the Gas–Plasma Boundary Matching e- Wakefield Acceleration e+ qµ1/sinf q≈f o BPM Data – Model Phase Advance  ne1/2L Nature411, 43 (3 May 2001) E-157/162 Results with 600 micron electron bunches Focusing e- X-ray Generation Wakefield Acceleration e- Phase Advance  ne1/2L Phys. Rev. Lett.93, 014802 (2004) Phys. Rev. Lett.88, 154801 (2002) Phys. Rev. Lett.88, 135004 (2002) Phys. Rev. Lett.90, 214801 (2003) Phys. Rev. Lett.93, 014802 (2004)

12. BREAKING THE 1 GeV BARRIER With 15 micron long bunches ne≈3.51017 cm-3L≈10 cm, N≈ 1.81010 Charge Fraction at E>0: 8% of total charge!

13. U C L A ENERGY GAIN SCALING with PLASMA LENGTH 14GeV Energy Gain in less than 30cm !

14. E-167: Energy Doubling with aPlasma Wakefield Accelerator in the FFTB U C L A Some electrons increase their energy in 84cm! X Linac running all out to deliver compressed 42GeV Electron Bunches to the plasma Record Energy Gain Highest Energy Electrons Ever Produced @ SLAC Significant Advance in Demonstrating Potential of Plasma Accelerators Accepted for publication in Nature

15. Plasma Accelerator Progress “Accelerator Moore’s Law” ILC Working Machines Doing physics E167 E164X LBNL RAL LBL Osaka Max.Energy in Plasma Experiments UCLA

16. Manpower Graduate Students Engineers Postdoc Research Staff Faculty 1 2 ? 1 2 SLAC 2 2 1 1 3 UCLA 1 1 2 USC Note:Both UCLA and USC have both a theory/simulations and Experimental effort.

17. Quality Quality reviewed through publications,invited talks,fellowships and Prizes. Statistics since 2000 Total journal publications 24 PhD s Graduated 8 (5 expts ,3theory) Publications in Phys Rev.Lett 10 Publications in Nature 2 Physics Today,Scientific American 2 Total conference publications 50 Best thesis award (Comp.Physics) 1 1 Fellow of APS 1 Prizes (Maxwell Prize 2006) 1

18. JOURNAL PAPERS • M. J. Hogan et al., “E-157: A 1.4 Meter-Long Plasma Wakefield Acceleration Experiment Using A 30 GeV Electron Beam From The Stanford Linear Accelerator Center Linac”, Physics of Plasmas7, 2241 (2000). • 2) P. Muggli et al., “Collective Refraction Of A Beam Of Electrons At A Plasma-Gas Interface”, Nature411, 43 (3 May 2001) • 3) P. Catravas et al., “Measurements Of Radiation Near An Atomic Spectral Line From The Interaction Of A 30 GeV Electron Beam And A Long Plasma”, Physical Review E64 046502 (2001). • 4) P. Muggli et al., “Collective Refraction Of A Beam Of Electrons At A Plasma-Gas Interface”, Physical Review Special Topics - Accelerators and Beams4, 091301 (2001). • 6) S. Lee et al., “Energy Doubler For A Linear Collider”, Physical Review Special Topics - Accelerators and Beams5, 011001 (2002). • 7) Shouqin Wang et al., “X-Ray Emission From Betatron Motion In A Plasma Wiggler”, Physical Review Letters88, 135004 (2002) • 8) C. E. Clayton et al., “Transverse Envelope Dynamics Of A 28.5 GeV Electron Beam In A Long Plasma”, Physical Review Letters88, 154801 (2002) • 9) C. Joshi et al., ”High Energy Density Plasma Science With An Ultra-Relativistic Electron Beam”, Physics of Plasmas9, 1845 (2002). • 10) C. O'Connell et al., “Dynamic Focusing Of An Electron Beam Through A Long Plasma”, Physical Review Special Topics – Accelerators and Beams5, 1121301 (2002) • 12) M. J. Hogan et al., “Ultrarelativistic-Positron-Beam Transport through Meter-Scale Plasmas”, Physical Review Letters90, 205002 (2003). • 13) B. Blue et al., “Plasma Wakefield Acceleration of an Intense Positron Beam”, Physical Review Letters90, 214801 (2003). • 14) C. Joshi and T. Katsouleas, “Plasma Accelerators at the Energy Frontier and on Tabletops”, Physics Today, 47 (June 2003). • 15) P. Muggli et al., “Meter-Scale Plasma-Wakefield Accelerator Driven by a Matched Electron Beam”, Physical Review Letters93, 014802 (2004). 16) R. Maeda et al., "On the Possibility of a Multi-bunch Afterburner for Linear Colliders", Phys. Rev. ST Accel. Beams 7, 111301 (2004). 17) M. J. Hogan et al., “Multi-GeV Energy Gain in a Plasma-Wakefield Accelerator”, Physical Review Letters95 054802 (2005). 18) T. Katsouleas, “Plasma Accelerators Race to 10 GeV and Beyond,” Physics of Plasmas 13, 05503 (2006). 19) S. Deng, C. D. Barnes, C. E. Clayton, C. O’Connell, F.-J. Decker, R.A. Fonseca, C. Huang, M. J. Hogan, R. Iverson, D.K. Johnson, C. Joshi, T. Katsouleas, P. Krejcik, W. Lu, W. B. Mori, P. Muggli, E. Oz, F. Tsung, D. Walz, and M. Zhou, “Hose Instability and Wake Generation by an Intense Electron Beam in a Self-Ionized Gas,” Physical Review Letters, Vol. 96, 045001 (2006). 20) D. K. Johnson, D. Auerbach, I. Blumenfeld, C. D. Barnes, C. E. Clayton, J.J. Decker, S. Deng, P. Emma, M. J. Hogan, C. Huang, R. Ischebeck, R. Iverson, C. Joshi, T. C. Katsouleas, N. Kirby, P. Krejcik, W. Lu, K. A. Marsh, W. B. Mori, P. Muggli, C. L. O’Connell, E. Oz, R. H. Siemann, D. Walz, and M. Zhou, “Positron production by x rays emitted by betatron motion in a plasma wiggler,” Physical Review Letters97, 175003: 1-4 (2006). 21) I. Blumenfeld, C. E. Clayton, F-J. Decker, M.J. Hogan, C. Huang, R. Ischebeck, R. Iverson, C. Joshi, T. Katsouleas, N. Kirby, W. Lu, K. A. Marsh, W. B. Mori, P. Muggli, E. Oz, R. H. Siemann, D. Walz, and M. Zhou, “Energy Doubling of 42 GeV Electrons in a Meter Scale Plasma Wakefield Accelerator,” accepted by Nature, 2006. 22) E. Oz, S. Deng, T. Katsouleas, P. Muggli, C. D. Barnes, I. Blumenfeld, F. J. Decker, P. Emma, M. J. Hogan, R. Ischebeck, R. H. Iverson, N. Kirby, P. Krejcik, C. O’Connell, R. H. Siemann, D. Walz, and D. Auerbach, C. E. Clayton, C. Huang, D. K. Johnson, C. Joshi, W. Lu, K. A. Marsh, W. B. Mori, M. Zhou, “Ionization Induced Electron Trapping in Ultra-relativistic Plasma Wakes,” accepted by Physical Review Letters (2006) 23) C. Joshi, “Plasma Accelerators,” Scientific American, Vol. 294, 41-47 (Feb. 2006). 24) W. Lu, et al., “Nonlinear Theory for Relativistic Plasma Wakefields in the Blowout Regime,” Physical Review Letters96 165002 (2006).

19. Scientific Progress Requires a Sustained Effort

20. What is SABER? 2 3 1 SABER: South Arc Beam Experiment Region • A proposed facility for experiments requiring compressed, focused, high-energy beams of electrons or positrons. • To be built in the Instrument Section in the SLC South Arc tunnel. • SABER consists of three main components: • Experimental area with final focus and beam dump in SLC South Arc tunnel. • Linac Pulse Compressor upgrade to compress positron bunches. • Bypass Line to deliver e- or e+ beams to SABER for operational independence from the LCLS.

21. PWFA Mechanism Different For A Positron Beam e- Z Z Blow-out electron Flow-in positron e+ Positrons are the frontier – This research can only happen at SLAC A Compelling Question: Can the large amplitude wakes measured for electrons be created and sustained for a positron drive beam? 5.7GeV in 39cm  Evolution of a positron beam/wakefield and final energy gain in a self-ionized plasma

22. Impact Forefront work in beam and plasma physics Advanced Accelerator scheme that has demonstrated energy gains of interest to HEP Arguably the best group (among 30+ groups) in the world doing advanced accelerator work. . Attracts talented pool of graduate students. But Low salaries in HEP combined with opportunities in industry means retention is a problem for the field.

23. state-of-the-artfacilities The ingredients of a successful accelerator research program Facilities and Opportunities Compelling scientific questions University/national lab collaboration Rapid scientific progress follows naturally from these three

24. Conclusion:Marx Panel Again “OHEP should accept proposals from the laboratories to pursue longer term accelerator R&D that has the potential for significant impact and to invest in appropriate research and funding infrastructure” More specifically it recommends “FFTB has been shut down in order to proceed with the construction of a new light source.A successor,called SABER, has been proposed, but not yet funded.We encourage an early review of this project in order not to hinder further progress in this critical area”