Beam-Plasma Working GroupSummary

Barnes, Christopher SLAC cbarnes@slac.stanford.eduBruhwiler, David Tech-X bruhwile@txcorp.comClayton, Chris UCLA cclayton@ucla.eduDimitrov, Dimitre Tech-X dad@txcorp.comEsarey, Eric LBNL EEsarey@lbl.govfubiani, gwenael LBL gjfubiani@lbl.govHogan, Mark SLAC hogan@slac.stanford.eduJoshi, Chan UCLA joshi@ee.ucla.eduKatsouleas, Tom USC katsoule@usc.eduMuggli, Patrick USC muggli@usc.eduOConnell, Caolionn SLAC caolionn@stanford.eduOz, erdem USC erdemoz@usc.eduPatrick, Muggli USC muggli@usc.eduWalz, Dieter SLAC dwalz@slac.stanford.edu

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.