1. BELLA and laser-driven e-/e+ collider concept C.G.R. Geddes, E. Cormier-Michel, E. Esarey, C.B. Schroeder, C. Toth, W.P. Leemans LOASIS program, LBNL, http://loasis.lbl.gov Jean-Luc Vay, LBNL D.L. Bruhwiler, J.R. Cary, B.M. Cowan, C. Nieter, K. Paul Tech-X COMPASS meeting, 2009 1 1 *cgrgeddes@lbl.gov NA-22/Nonproliferation R&D

2. LOASIS team Staff E. Esarey (T) C. Geddes (S+E) A. Gonsalves (E) W.Leemans(E) N. Matlis (E) C. Schroeder (T) C. Toth (E) J. Van Tilborg (E) Eng/Techs D. Syversrud N. Ybarraza K. Sihler Admin O. Wong M. Condon (0.5) G. Rogers (0.1) Postdocs E. Cormier-Michel (S) J. Osterhoff (E) Students M. Bakeman (PhD) B. Kessler D. Kim C. Lin (PhD) G. Plateau (PhD) S. Shiraishi (PhD) T. Le Corre (M) H. Vincente Collaborators include: LBNL : K. Barat, M. Battaglia, W. Byrne, J. Byrd, R. Duarte, W. Fawley. K. Robinson, D. Rodgers, R. Donahue et al. Tech-X: J. Cary, D. Bruhwiler, et al. SciDAC team Oxford: S. Hooker et al. MPQ: F. Krausz, F. Gruener et al. LOA: O. Albert, L. Canova GSI: T. Stoehlker, D. Thorn

3. DOE Scientific Discovery through Advanced Computing: UCLA:W.B. Mori, F.S. Tsung, C. Huang, M. Tzoufras, M. Zhou, W. Lu, S. Martins, M. Tzoufras, V. Dycek + collaborators at IST USC/Duke:T. Katsouleas, X. Wang Simulation Collaboration LOASIS: C.G.R. Geddes, E. Michel E. Esarey, C.B. Schroeder, W.P. Leemans Tech-X:D. Bruhwiler, B. Cowan, P. Messmer, P. Mullowney, K.Paul, V. Ranjbar Tech - X & U. Colorado J. Cary OxfordW. Andreas, S. Bajlekov, N. Bourgeois, T. Ibbotson, S.M. Hooker NERSC, visualization:W. Bethel, J. Jacobsen, Prabhat, O. Rubel, D. Ushizima, G. Weber LBNL AMAC, CBP: R. Ryne, J.L. Vay (LDRD), W. Fawley (LDRD) Nebraska, B.A. Shadwick et al.;

4. Simulating modules for BELLA PW laser and towards a conceptual future LPLC Simulation & Theory must address  Collider requirements & design Required suite of models  10 GeV meter-scale stages  Parameters for efficient stages  Wake load & shaping (Cormier- Michel)  Low emittance injector – (Cormier-Michel)  Low noise fluid simulations (Bruhwiler)  Guiding experiments (Bruhwiler)  Full scale stages & evolution Envelope (Cowan), Lorentz (Vay, Mori) Collider concept Leemans & Esarey, Phys. Today 2009 ~10 GeV stages p ~100µm at 10 17 /cc Laser Trapped particles

5. Conceptual design of an LPLC  Linac length set by tradeoff of gradient vs. staging  Required luminosity L[10 34 cm -2 s -2 ] ~ (E cm [TeV]) 2 because (cross section ~  -2 )  Beam power: P b = fNE cm  AC wall-plug power: ~ 200 MW  2% efficiency  ~10% laser to beam  ~20% wall-plug to laser  Additional options include gamma-gamma collider** N ~ 3x10 9 f ~ 15 kHz E cm ~ 1 TeV P b ~ 4 MW 5TeV LPA length vs stage density LPLC Concept at 10 17 /cc *Collider Details – Schroeder et al, AAC 2008; Leemans & Esarey Phys. Today 2009 **Schroeder et al, PAC 2009 10 GeV stage

6. Calculated synchrotron radiation and scattering emittance contributions tolerable Michel, Schroeder, Esarey, Leemans, Phys. Rev. E (2006)  Betatron motion in high transverse fields (O[E 0 ])  synchrotron radiation F x ~ 1 GV/m (for n e =10 17 cm -3, r ~ μm) Energy spread induced < 10 -4 for collider params betatron motion synchrotron radiation  Beam – beam interaction (beamstrahlung) favors short (micron) bunches e-e- ion Coulomb collisions flat beam ε x = 10 -6 2 TeV f= 10 kHz N=10 9 n=10 17 cm -3  Scattering between beam and background plasma ions: Coulomb scattering emittance growth <nm for collider parameters *Details – Schroeder et al, AAC 2008; Leemans & Esarey Phys. Today 2009

7. Simulation + theory required to model self consistent laser, wake, and bunch  Explicit particle in cell simulates required physics – resolves laser period  Mhours CPU time for cm-scale GeV simulations (VORPAL*)  Meter scale of 10 GeV stages – O[Ghours] explicit  scaling + new models  scaled simulation – change density, scale parameters  envelope & quasistatic – average fast laser osc.  see Ben Cowan’s talk  Lorentz boosted – moving calculation frame  Vay, Mori talks  Combination of models for full solution  Require improved accuracy for collider emittances  Cormier-Michel, Bruhwiler, Vay * Vorpal - Nieter & Cary, JCP 2004. Tajima & Dawson PRL 1979;l Esarey et al. TPS 1996; Leemans et al., IEEE Trans. Plasma Science (1996); Phys. Plasmas (1998) p ~100µm at 10 17 /cc Laser Trapped particles Energy gain ~ n -1 (10 GeV at 10 17 /cc) Length ~ n -3/2 (1m at 10 17 /cc) Gradient ~ n 1/2 (10 GV/m at 10 17 /cc) Laser w 0 &L ~ p (100fs at 10 17 /cc) Depletion ~ Dephasing for a 0 > 1 Energy gain ~ n -1 (10 GeV at 10 17 /cc) Length ~ n -3/2 (1m at 10 17 /cc) Gradient ~ n 1/2 (10 GV/m at 10 17 /cc) Laser w 0 &L ~ p (100fs at 10 17 /cc) Depletion ~ Dephasing for a 0 > 1 Simulations of past expt.’s : Geddes et al JPCS 2008; ScDAC Review 2009

8. 10 GeV stages in Quasilinear regime High gradient symmetric e+/e- acceleration 8 e- accel e- focus e+ focus e+ accel a 0 =4  Quasilinear - a 0 ~1-2  e+/e- nearly symmetric  high gradient  Laser mode controls beam matching to wake  Bubble regime  wake curvature  focuses e-  defocuses e+ Linear, nonlinear scalings are of same order e- accel e- focus e+ focus e+ accel a 0 =1 Accel. field Focus field Density

9. Wake scales with density Scaled simulations at a=1 Scaling with density predicts wake structure for 10 GeV 40 J BELLA Stages  Use and verify linear theory predictions  field ~ 1/ p @ const. a0, k p L laser, k p w 0  Predict 10 GeV performance using short simulations at high density  Wake amplitude scales accurately:  over 100-fold in density & 2D/3D  between explicit, envelope and quasistatic codes  Simulation + scaling with theory predict:  wake structure  wake and laser evolution (details-Cowan,Vay) * Cormier-Michel et al, Proc. AAC 2008 Field ~ 1/ p 10 19 cm -3 = 120 GV/m 10 18 cm -3 = 40 GV/m Wake contours VORPAL slab 10 19 /cc WAKE Quasistatic cylindrical 10 17 /cc 14 kpXkpX 0 -13 kpRkpR 13

10. Spot size ~ p optimizes quasilinear wake excitation and guiding  Small spot sizes  channel dispersion reduces L dephase  energy depleted to transverse field  Large spot sizes  self focusing pinches focus  nonlinear wake results  Operate near k p w 0 ~ 5 *Linear scaling: Esarey et al TPS 1996, simulations Geddes PAC 2009 Dephasing, focusing, efficiency versus laser spot size normalized simulations

11. Efficient stage obtained near k p L =1 Resolves laser depletion, broadening 0  0 2 laser spectrum at depletion Intensity (A.U.) Laser, Accelerating field evolution  Scan pulse length with fixed laser energy*  stay on threshold of self focusing/nonlinearity  Characterized 0.5 < k p L < 3  k p L=1 optimal – laser depleted at dephasing  Depletion, field scale with density  Numerically converged at percent level  Does not resolve focusing oscillations – requires envelope (Cowan), Lorentz (Vay) *Geddes PAC 2009 k p L=2 laser energy k p L=2 accelerating field k p L=1 laser & accelerating field deplete at dephasing

12. ne (1/cm^3)2.0e18 a01 lambda_p(um)24 kp*L_laser2 tau (fs)25 w0 (µm)20 kp*w05.3 P(TW)14 P/Pc0.9 40 J 10 GeV 300pC Px [GeV at 10 17 ] k p L=1 stage: 300pC scaled to 10 17 Px [MeV at 10 19 ] 12 Scalable design for HEP, GeV stages Efficient collider stages with 40 J/PW ne (1/cm^3)1.0E+17 a01.4 lambda_p(um)108 kp*L_laser1 tau (fs)57 w0 (µm)90 kp*w05.3 P(TW)563 P/Pc1.8 0.5 J 0.4 GeV 50pC 0120 Quasilinear designs* NOTE : Nonlinear** stages accessible with same laser 40 J laser focused to 41µm 3 (a 0 =2) at n e = 1.3e17 -> 10 GeV, 200pC range of regimes can be explored 012 k p L=1 stage: 300pC scaled to 10 17 ** Lu et al, PRL 96, 0165002 (2006). * Cormier-Michel et al, AAC2008, Geddes et al PAC 2009.

13. BELLA 40 J PW Laser – Components for a Laser Plasma Collider + Radiation Sources BELLA PW laser 40 J / 40 fs 10 GeV stages Injection + Staging Positron acceleration + PWFA expt.’s Energy spread & Emittance preservation Radiation sources  Efficient collider module stages are accessible for e+ e-  Combination of models is required  Wake load & shaping for high efficiency (Cormier- Michel)  Low emittance injectors – (Cormier-Michel)  Low noise fluid simulations for low emittance structures (Bruhwiler)  Full scale stages & evolution- Envelope (Cowan), Lorentz (Vay, Mori)

14. SciDAC plans for BELLA project and a laser – plasma collider  Low emittance injector  Downramp (Envelope,Explicit)  Colliding pulse (Explicit)  Model collider emittances  Accurate momentum advance, error accumulation (weighting, mesh refinement, high order models)  Noise control (fluids, EM dispersion, Cerenkov)  Scattering & radiation, bench BD codes  10 GeV m-scale (PW laser)+staging  Stage design for efficiency, emittance  Scaling & speed- 1000x problem size Reduced models(Envelope,QS,Lorentz)  Laser vgroup (EM dispersion)  Hydro sim. of capillaries, jets  Key model development  Explicit PIC, Fluid, hybrid Long stage scaling, EM dispersion, Momentum accuracy  Laser Envelope model, Quasistatic Resolve depletion/wavelength shift, Small bunch  Optimal Lorentz Frame Diagnostics (simultaneity), Noise control, Backward waves Accurately model experiments – interpret & guide (Bruhwiler, Cormier-Michel)

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