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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.govJean-Luc Vay, LBNL
D.L. Bruhwiler, J.R. Cary, B.M. Cowan, C. Nieter, K. Paul Tech-X
COMPASS meeting, 2009
11
*cgrgeddes@lbl.gov
NA-22/Nonproliferation R&D
LOASIS team
StaffE. 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/TechsD. SyversrudN. YbarrazaK. Sihler
AdminO. WongM. Condon (0.5)G. Rogers (0.1)
PostdocsE. Cormier-Michel (S)J. Osterhoff (E)
StudentsM. Bakeman (PhD)B. KesslerD. KimC. 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. CanovaGSI: T. Stoehlker, D. Thorn
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
Oxford W. 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.;
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 1017/cc
Laser
Trapped particles
Conceptual design of an LPLC
Linac length set by tradeoff of gradient vs. staging
Required luminosity L[1034 cm-2 s-2] ~ (Ecm[TeV])2 because (cross section ~g-2)
Beam power: Pb = fNEcm
AC wall-plug power: ~ 200 MW 2% efficiency
~10% laser to beam ~20% wall-plug to laser
Additional options include gamma-gamma collider**
N ~ 3x109
f ~ 15 kHzEcm~ 1 TeV
Pb ~ 4 MW
5TeV LPA length vs stage density
LPLC Concept at 1017 /cc
*Collider Details – Schroeder et al, AAC 2008; Leemans & Esarey Phys. Today 2009 **Schroeder et al, PAC 2009
10 GeVstage
Calculated synchrotron radiation and scattering emittance contributions tolerable
Michel, Schroeder, Esarey, Leemans, Phys. Rev. E (2006)
Betatron motion in high transverse fields (O[E0]) synchrotron radiation
Fx ~ 1 GV/m (for ne=1017 cm-3, r ~ μm)
Energy spread induced < 10-4 for collider params
betatron motion
€
Prad =2e2γ 2
3m2c 3F⊥
2 ∝ γ 2rβ2
synchrotron radiation
Beam – beam interaction
(beamstrahlung) favors
short (micron) bunches
e- ion
€
dεn
dz=
γ
2kβ
d
dzθ 2 =
Zkp2re
kβ γln
bmax
bmin
⎛
⎝ ⎜
⎞
⎠ ⎟
Coulomb collisions
flat beam εx= 10-6
2 TeVf= 10 kHzN=109
n=1017 cm-3
Scattering between beam and background plasma ions:
Coulomb scattering emittance growth <nm for collider parameters
€
bmax ~ λ D = T 4πne2( )
1/ 2
*Details – Schroeder et al, AAC 2008; Leemans & Esarey Phys. Today 2009
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 1017/cc
Laser
Trapped particles
Energy gain ~ n-1 (10 GeV at 1017/cc)Length ~ n-3/2 (1m at 1017/cc)Gradient ~ n1/2 (10 GV/m at 1017/cc)
Laser w0&L ~ lp (100fs at 1017/cc)
Depletion ~ Dephasing for a0 > 1
Simulations of past expt.’s : Geddes et al JPCS 2008; ScDAC Review 2009
10 GeV stages in Quasilinear regime High gradient symmetric e+/e- acceleration
8
e- accel
e- focus
e+ focus
e+ accel
a0=4 Quasilinear - a0 ~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
a0=1Accel. field
Focus field
Density
Wake scales with densityScaled 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, kpLlaser, kpw0
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
1019 cm-3 = 120 GV/m1018 cm-3 = 40 GV/m
Wake contoursVORPAL slab 1019/cc
WAKE Quasistatic cylindrical 1017/cc
14 kpX 0
-13
k pR
13
Spot size ~ lp optimizes quasilinear wake excitation and guiding
Small spot sizes
channel dispersion reduces Ldephase
energy depleted to transverse field
Large spot sizes
self focusing pinches focus
nonlinear wake results
Operate near kpw0 ~ 5
*Linear scaling: Esarey et al TPS 1996, simulations Geddes PAC 2009
Dephasing, focusing, efficiencyversus laser spot size
normalized simulations
Efficient stage obtained near kpL =1
Resolves laser depletion, broadening
0 /w w0 2
laser spectrum at depletion
Inte
nsity
(A
.U.)
Laser, Accelerating field evolution
Scan pulse length with fixed laser energy* stay on threshold of self focusing/nonlinearity
Characterized 0.5 < kpL < 3
kpL=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
kpL=2 laser energy
kpL=2 accelerating field
kpL=1 laser & accelerating fielddeplete at dephasing
ne (1/cm^3) 2.0e18a0 1lambda_p(um) 24kp*L_laser 2tau (fs) 25w0 (µm) 20kp*w0 5.3P(TW) 14P/Pc 0.9
40 J 10 GeV300pC
Px [GeV at 1017]
kpL=1 stage: 300pC scaled to 1017
Px [MeV at 1019]
12
Scalable design for HEP, GeV stagesEfficient collider stages with 40 J/PW
ne (1/cm^3) 1.0E+17a0 1.4lambda_p(um) 108kp*L_laser 1tau (fs) 57w0 (µm) 90kp*w0 5.3P(TW) 563P/Pc 1.8
0.5 J 0.4 GeV
50pC
0 120
Quasilinear designs*
NOTE : Nonlinear** stages accessible with same laser
•40 J laser focused to 41µm3 (a0=2) at ne = 1.3e17 -> 10 GeV, 200pC
•range of regimes can be explored
0 12
kpL=1 stage: 300pC scaled to 1017
** Lu et al, PRL 96, 0165002 (2006).
* Cormier-Michel et al, AAC2008, Geddes et al PAC 2009.
BELLA 40 J PW Laser – Components for aLaser Plasma Collider + Radiation Sources
BELLAPW 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)
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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