Bob Siemann SLAC HEPAP Subpanel on Accelerator Research Plasma Wakefield Acceleration Facilities and Opportunities Concluding Remarks Dec 21, 2005 HEPAP Accel Research Subpanel 1 Plasma Wakefield Acceleration Presented by: Bob Siemann On behalf of: The E157, E162, E-164, E-164X, E167 Collaborations S. Deng,* T. Katsouleas, S. Lee,* R. Maeda, P. Muggli, E. Oz* and W. Quillinan University of Southern California B. Blue,* C. E. Clayton, E. Dodd, R. A. Fonseca, R. Hemker,* C. Huang,* D.K. Johnson,* C. Joshi, W. Lu,* K.A. Marsh, W. B. Mori, C. Ren, F. Tsung, S. Wang* and M. Zhou* University of California, Los Angeles R. Assmann, C. D. Barnes,* I. Blumenfeld,* F.-J. Decker, P. Emma, M.J. Hogan, R. Ischebeck, R.H. Iverson, N.A. Kirby,* P. Krejcik, C. O'Connell,* P. Raimondi, S.Rokni, R.H. Siemann, D. Walz and D. Whittum Stanford Linear Accelerator Center P. Catravas, S. Chattopadhyay, E. Esarey and W. P. Leemans Lawrence Berkeley National Laboratory The authors of at least one of our peer-reviewed papers * = the 14 students in these collaborations 1
Plasma Accelerators Showing Great Promise Scientific Question: Accelerating Gradients > 100 GeV/m have been measured in laser-plasma interactions. Can one make & sustain such high gradients for lengths that give significant energy gain? We are studying the underlying beam/plasma physics and looking at issues associated with applying the large focusing (MT/m) and accelerating (GeV/m) gradients in plasmas to high energy physics and colliders Unique SLAC Facilities The SLAC Linac & FFTB which have High Beam Energy Short Bunch Length High Peak Current Power Density e-& e+ Dec 21, 2005 HEPAP Accel Research Subpanel 3 PWFA Accelerator Concept - - -- -- -- - - -------- -- --- + -- - - - - + + + + + + + + + + + + -- + - -- + + + + + + + + + + + + + + + + + + + ------ - --- + --- -- - --- - Ez Accelerating Decelerating E z,linear N σ z 2 Ions Short bunch! Fully relativistic plasma simulations agree with σ z dependence Plasma Wakefield Acceleration - I Plasma e - electron beam E z : accelerating field N: # e - /bunch σ z : gaussian bunch length k p : plasma wave number n p : plasma density n b : beam density Dec 21, 2005 HEPAP Accel Research Subpanel 4 2
Plasma Wakefield Acceleration - II Closer to Reality - - -- -- -- - - -------- -- --- + -- - - - - + + + + + + + + + + + + -- + - -- + + + + + + + + + + + + + + + + + + + ------ - --- + --- -- - --- - Ez Accelerating Decelerating Plasma e - electron beam In most of the experiments a single bunch from the linac drives a large amplitude plasma wave which focus and accelerates particles AND the tail of that bunch is used to measure the accelerating field. σ z ~ λplasma π 2 When combined with E ~ N σ z z n p 1 σ 2 z Dec 21, 2005 HEPAP Accel Research Subpanel 5 Reality Plasma Wakefield Acceleration - III Dec 21, 2005 HEPAP Accel Research Subpanel 6 3
PWFA Experiments Located in the FFTB North Damping Ring Positron Return Line Beam Switch Yard (BSY) Positron Source PEP II End Station A (ESA) e-gun Linac FFTB South Damping Ring 3 km FFTB e - N=1.8 10 10 σ z =20-12µm E=28.5 GeV Energy Spectrum X-ray Coherent Transition Radiation and Interferometer Li Plasma Gas Cell: H 2, Xe, NO n e 0-10 18 cm -3 L 2.5-20 cm Plasma light Optical Transition Radiators Imaging Spectrometer 25m Cherenkov Radiator X-Ray Diagnostic, e-/e + Production FFTB Dec 21, 2005 HEPAP Accel Research Subpanel 7 y x z Cdt Dump Evolution of One Part Of the Apparatus The SLAC linac and FFTB: A stable yet flexible resource and facility Develop experience & expertise Explore physics 2x10 10 σ z = 600 μm Upstream OTR ArF laser (193 nm) to photoionize Li vapor Li plasma 1x10 14 cm -3 1.4 m water jacket Be window Early Experiments The Present Run 2x10 10 σ z = 15 μm Downstream OTR 3x10 17.3 m OTR, CTR, plasma light (spectrograph & gated camera) Magnet Cherenkov cell Toroid long λ autocorrelator filter wheels Cherenkov & OTR Dec 21, 2005 HEPAP Accel Research Subpanel 8 4
3 Highlights of Early Experimental Results (σ z = 600 μm) Electron Beam Refraction at the Gas impulse model BPM data Plasma Boundary 0.3 θ 1/sinφ 05190cec+m2.txt 8:26:53 PM 6/21/00 Positron Acceleration 0.2 0.1 θ (mrad) 0-0.1-0.2 θ φ o BPM Data Model -0.3-8 -4 0 4 8 φ (mrad) Nature 411, 43 (3 May 2001) σ x (µm) 600 500 400 300 200 Matching e - L=1.4 m σ 0 =14 µm ε N =18 10-5 m-rad β 0 =6.1 cm α 0 =-0.6 Plasma OFF Plasma ON Envelope Phys. Rev. Lett. 90, 214801 (2003) 100 0 BetatronFitShortBetaXPSI.graph 0 2 4 6 8 10 12 14 Phase Advance Ψ Ψ n 1/2 e L Phys. Rev. Lett. 93, 014802 (2004) Dec 21, 2005 HEPAP Accel Research Subpanel 9 Short Bunches 2 E N σ ( z z ) RTL 50 ps Damping Ring SLAC Linac 1 GeV 9 ps 0.4 ps 20-50 GeV FFTB <100 fs Add Add 12-meter chicane compressor in in linac linac at at 1/3-point (9 (9 GeV) Plasma Production by Tunnel Ionization 4 σ E / E =1.51% (FWHM: 4.33%) E = 28.493 GeV, N = 2.133 10 10 ppb e 4 No ionization Complete ionization ΔE/ E /% 2 0 2 1.5% 0 0.5 1 1.5 2 n/10 3 30 ka 80 fsec FWHM 28 GeV 5 Dec 21, 2005 HEPAP Accel Research Subpanel 10 0 Increasing Bunch Length Phys. Rev. Lett. 93, 014802 (2004) ΔE/ E /% I /ka 2 0 2 σ z = 28.0 μm (FWHM: 24.6 μm, Gauss: 11.0 μm) 30 25 20 15 10 0.1 0.2 0.3 z /mm I pk = 30.631 ka 0.1 0.2 0.3 z /mm Energy Spectrum 5
Summer 2004: Accelerating Gradient > 27 GeV/m! (Sustained Over 10cm)* Electrons have gained > 2.7 GeV over maximum incoming energy in 10cm Confirmation of predicted dramatic increase in gradient with short bunches No Plasma n p = 2.8x10 17 cm -3 First time a PWFA has gained more than 1 GeV & two orders of magnitude larger than previous beam-driven results * Large energy spread after the plasma is an artifact of doing single bunch experiments Dec 21, 2005 HEPAP Accel Research Subpanel 11 Summer 2005: Next PRL Cover?? Increased Beamline apertures Increased plasma length to 30 cm Electrons have gained > 10 GeV Large amplitude plasma waves are sustained for at least 30 cm! Dec 21, 2005 HEPAP Accel Research Subpanel 12 6
Always New Things to Look At! Trapped Particles Narrow Energy Spread Coherent (at λ ~ 500 nm) Cherenkov Radiation Next Step = 2-bunches produced by collimation ~ 80 MeV Either > 500 MeV or bunching of the 28.5 GeV beam Dec 21, 2005 HEPAP Accel Research Subpanel 13 Three different time horizons I. The remainder of the lifetime of the FFTB two bunch experiment understanding of the trapped particles from the plasma the energy doubling experiment 2x10 10 σ z = 15 μm Li plasma 3x10 17 cm -3 1.0 m Future Plasma Acceleration Research Incident Energy Dipole Dump Magnet II. The Intermediate term experiments at the NLC Test Accelerator III. Long term - high energy experiments with short bunch e + at SABER Return to these in a few minutes Dec 21, 2005 HEPAP Accel Research Subpanel 14 7
Facilities and Opportunities Dec 21, 2005 HEPAP Accel Research Subpanel 15 Facilities and Opportunities The plasma acceleration program at the FFTB provides an excellent example of the ingredients of a successful accelerator research program Compelling scientific questions University/national lab collaboration both benefit state-of-the-art facilities Experienced experimentalists, powerful scientific apparatus and rapid scientific progress follow naturally from these three Dec 21, 2005 HEPAP Accel Research Subpanel 16 8
Potential of plasma acceleration (USC/UCLA/SLAC) Positron Acceleration Scientific Questions & Collaborations The photonics revolution & particle acceleration (Stanford/SLAC) Limits of high gradient acceleration (ANL/LBNL/Maryland/MIT/NRL/SLAC) Dec 21, 2005 HEPAP Accel Research Subpanel 17 State-of-the Art Facilities: The NLCTA The NLCTA is located in End Station B, which is the location of some ILC & LARP R&D, high gradient research, and the laser acceleration experiment (E163) Significant investment in the past for the warm ILC 300 MeV X-band linac Augmented with an S-band photoinjector for E- 163 Additional X-band and L-band RF power is being developed or is available Ti:Sapphire laser system installed Space for experiments at 60 MeV and at 300 MeV NLCTA Dec 21, 2005 HEPAP Accel Research Subpanel 18 9
Accelerator Research at the NLCTA Use of the NLCTA for ILC related R&D continues and this R&D relies on some of the same systems as the non-ilc accelerator research Concentrate on non-ilc accelerator R&D at the NLCTA for this subpanel High gradient RF studies Sami Tantawi s talk Laser acceleration Bob Byer s talk Plasma acceleration Experiments at the NLCTA in the intermediate term NLCTA Laser Room An example - Drive-witness configuration with variable delay E163 Hall 60 MeV beam 300 MeV beam Plasma Experiment Location Dec 21, 2005 HEPAP Accel Research Subpanel 19 State-of-the Art Facilities: SABER The FFTB has been a gold mine for science Plasma acceleration (E157, E162, E164, E164X, E167) Plasma focusing (E150) Positron production (E166) Short Bunches High energy cosmic rays (FLASH (E165)) Short pulse x-ray physics (SPPS) The LCLS will be constructed in the straight-ahead line presently occupied by the FFTB, and SABER has been proposed as a replacement. Dec 21, 2005 HEPAP Accel Research Subpanel 20 10
Science at SABER The SABER white paper includes science in Plasma Wakefield Acceleration and Beam-Plasma Physics Inverse Compton Scattering An Intense THz Light Source for Surface Chemistry Magnetism and Solid State Physics Laboratory Astrophysics Experiments Energy Up to 30 GeV nominal Charge per pulse 3 nc e - or e + per pulse with full compression; 5 nc without full compression. Pulse length at IP 30 μm with 4 % momentum spread; 42 μm with 1.5 % momentum spread. Spot size at IP 10 μm nominal (η = η = 0) Momentum spread Drift space available for experimental apparatus 4 % full width with full compression; < 0.5 % full width without compression. 2 m from last quadrupole to focal point. Approximately 23 m from the focal point to the Arc 3 magnets Dec 21, 2005 HEPAP Accel Research Subpanel 21 Short Pulse e+ Are the Frontier Plasma Experiments at SABER Evolution of a positron beam/wakefield and final energy gain in a self-ionized plasma 5.7 GeV in 39cm N = 8.8x10 9 σ r = 11 μm σ z = 19.6 μm n p = 1.8x10 17 cm -3 Dec 21, 2005 HEPAP Accel Research Subpanel 22 11
Concluding Remarks Dec 21, 2005 HEPAP Accel Research Subpanel 23 Accelerator Research at SLAC Accelerator research at SLAC is relevant to high energy physics with research Supporting operating accelerators Designing the International Linear Collider Exploring the technology and physics for accelerators in the future Past accomplishments have been crucial in defining high energy physics today - storage rings and linear collider The research includes theory, simulation, experiment, and technology development. The results support accelerators that are centerpieces for other sciences. For example the LCLS. Collaboration and education are vital aspects of our work. We work hand-in-hand with scientists from other labs and universities Education of students from collaborating institutions and from Stanford Caolionn O Connell Dec 21, 2005 HEPAP Accel Research Subpanel 24 Chris Barnes Sho Wang & Chris Clayton 12