Beam-Plasma Working GroupSummary
Barnes, Christopher SLAC [email protected], David Tech-X [email protected], Chris UCLA [email protected], Dimitre Tech-X [email protected], Eric LBNL [email protected], gwenael LBL [email protected], Mark SLAC [email protected], Chan UCLA [email protected], Tom USC [email protected], Patrick USC [email protected], Caolionn SLAC [email protected], erdem USC [email protected], Muggli USC [email protected], Dieter SLAC [email protected]
Principal participants:
Prepared by C. O’Connell and C. Barnes
Presented by T. Katsouleas
9:20-9:45 "Particle-in-cell simulations of tunneling ionization effects in plasma-based accelerators” D. Bruhwiler
9:45-10:10 "Parameter Studies of Tunneling Ionization Effects in E- 164 with Cs and Li”, D. Dimitrov
10:35-11:00 “Recent non-linear beam loading studies”, Mori
11:15-12:15 Joint w/ Plasma Astro
1:15-2:15 Joint w/ Plasma Astro
2:30- 3:00 “Discussion of Proposed Plasma Experiments,” Hogan
3:00 Open forum for new experiments
4:15 Joint w/ Sources -- Gwenel and Jamie
Beam-Plasma Schedule Wednesday 2/19/03
9:00-9:20 Organizational meeting: Talk sign-ups
Beam-Plasma cont’d
Open forum for new experiments
Requirements for Beam-ionized plasmas and wakes
Brainstorm 1: plasma astrophysics expts (joint?)
Brainstorm 2: prioritized issues for plasma accelerators
Brainstorm 3: beam physics opportunities
Brainstorm 4: Real-time modeling ideas
Table 1: Anticipated Experimental Beam RequirementsExperiment Bunch Structure Energy
(MeV)Comments/Critical Parameters
Plasma WakefieldAcceleration
Drive bunch, 1 - 4 nCWitness bunch, 0.1 nC, variable
50 - 350 Drive bunch length 2 psec, rmsTime interval between bunchesadjustable over 0.1 - 1 psec
High DemagnificationPlasma Lens
Single bunch,Variable charge
350 Emittance 4 to 4010-6 m, rmsBrightness>0.1 nC/psec/mm-mrad
Laser Acceleration( = 1.6 - 2.5 m)
Single bunch,5 - 50 pC
50 - 350 Energy spread 10-3Bunch length 2 psec, rmsEmittance 310-6 m, rms
Ion Channel Laser Single bunch,0.25 - 1 nC
50 - 350 Bunch length 2 psec, rmsEmittance 3 - 5 mm-mrad
Electron Beam HoseInstability
Single bunch,Variable charge
60 Variable bunch length 2 psec
Electron Beam GuidingOf Lasers
Single bunch,Variable charge
50 - 350 Variable peak current 2 kA
High Brightness e-Sources,Emittance Compensation,Tailored Profiles
Single and notcheddistribution bunches,1 - 4 nC goal
5 - 70 Emittance 210-6 m, rms,Ramped profiles < 5 psec length,5 kA peak current goals
Proposed ORION Experiments Illustrate Flexibility of ORION Facility:
Workshop Goal: Augment this list
Priority for the Plasma-Beam Physics Workgroup: High Priority for the Plasma-Beam Physics Workgroup: High Quality Acceleration with Narrow Quality Acceleration with Narrow E to be achieved E to be achieved
through Drive and Witness Bunchesthrough Drive and Witness Bunches
Critical Parameters:Drive: < 2ps with > 1nCWitness: 0.2 ps with .1 nC (light beam loading but narrow width
limits E) OR 0.4 ps with .3 nC (beam loading allowing for monoenergetic
gain)Questions: * Given the beam optics what will the witness beam look like - z, etc? * We can tolerate high emittance (x10). What charge and bunch length can we get?
For the 60 MeV witness: * Can we compress the bunch in the bypass line by factors of 5-10? * Phase slippage an issue for the 60 MeV beam (needs detailed modeling) * Will the kicker for the 2nd bunch extraction be fast enough (20 ns)? * Beam jitter for the witness bunch such that both bunches align - r * What is the timing resolution for the low energy bunch? * Can the two energies be focused to the plasma entrance? * Are there better ways to make a witness bunch out of the single pulse via
the rf gun?
* Concern that NLCTA chicane is not compatible with our requirements
Non-linear wakes allow low energy spread acceleration.Plasma Density: 5.66E15 cm-31st Beam: Nb=3.0E10, Sigma_z=100µ, Sigma_r=25µ, E=28.5Gev2nd beam: Nb=1.0E10, Sigma_z=20µ, Sigma_r=25µ, E=28.5Gev
2nd beam charge density
1st beam charge density
Nonlinear wake
Modeling Short Pulse PWFA Scenarios: E-164 and Afterburners – W. Mori
Wake flattened
Intense drive beam can ionize gas AND excite wake
• 50 GeV E-164X e- drive beam is short – r=20 m & z=30 m, with 2x1010 e- in the bunch
• Variables r & z are normalized to e=282 m– neutral Li density is nLi=1.4x1016 cm-3, peak e- density is ne=nLi
– up to 27 Li+/e- pairs are created in each cell where ionization occurs• The fields are normalized to E0=11.4 GV/m
– first peak in Ez is greater than E0, which indicates a nonlinear response– the wake then rapidly loses coherence
D. Bruhwiler
OOPIC Simulations of Tunneling Ionization Effects in E-164TI of Cs (left column) vs Preionized Only (right column)
z=100 m; r=20 m; Nbeam=1x1010; ne=5x1015 cm-3; nCs=1.25x1017 cm-3
• Ez surface plot
Preionized plasma electrons
• Ez surface plot
• Preionized plasma electrons
Experiment DiscussionBasic PhysicsHeavy Beam Loading Can give lower energy spread of accelerated particles (via
wake flattening) and gives high efficiency.Beam ionized Sources Choose parameters such that the incoming beam can ionize
the plasma source with tunnel ionization:
Astrophysics Weibel/Filamentation Experiment - Basic plasma physics, produces magnetic turbulence leading to synchrotron radiation. A possible model for GRBs. Needs as much charge and as long a pulse as possible & LARGE (~mm) spot sizes.Levels:1.) 60 MeV: Detect Filaments on screen2.) 350 MeV: Detect Synch. Rad.3.) 350 MeV + variable witness: Detect B field Lifetime
New ORION Experiments:
QnC
1.6 r
20m
z
.2ps
B
Integrating Code into ORION Faster
Couple Codes: PARMELA for the rf Gun ELEGANT for the beamline QUICKPIC, OSIRIS, OOPIC for plasma GENESIS for FEL interactions
Couplers: SDDS utilities MATLAB Unix scripts
Management: code czar?, SLAC IT, SLC Control System, etc.
Possible local cluster of ~16 nodes or access to remote clusters (QUICKPIC from 2 hours to 5 minutes).
Dual use clusters.
Gigabit Connections to cluster from data collection computers
Real Time Modeling: Discussed possibility of integrating software and hardware into ORION facility such that users have capability to model gun to detector.
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