Beam-Plasma Working Group Summary Barnes, Bruhwiler, DavidTech-X Clayton, Dimitrov, DimitreTech-X Esarey, fubiani, Hogan, Joshi, Chan Katsouleas, Muggli, OConnell, Oz, Patrick, Walz, 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

Proposed ORION Experiments Illustrate Flexibility of ORION Facility: Workshop Goal: Augment this list

Priority for the Plasma-Beam Physics Workgroup: High Quality Acceleration with Narrow  E to be achieved through Drive and Witness Bunches Critical Parameters: Drive: 1nC Witness: 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-3 1st Beam: Nb=3.0E10, Sigma_z=100µ, Sigma_r=25µ, E=28.5Gev 2nd 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 2x10 10 e- in the bunch Variables r & z are normalized to e =282  m –neutral Li density is n Li =1.4x10 16 cm -3, peak e- density is n e =n Li –up to 27 Li + /e - pairs are created in each cell where ionization occurs The fields are normalized to E 0 =11.4 GV/m –first peak in E z is greater than E 0, which indicates a nonlinear response –the wake then rapidly loses coherence D. Bruhwiler

OOPIC Simulations of Tunneling Ionization Effects in E-164 TI of Cs (left column) vs Preionized Only (right column)  z =100  m;  r =20  m; N beam =1x10 10 ; n e =5x10 15 cm -3 ; n Cs =1.25x10 17 cm -3 Ez surface plot Preionized plasma electrons Ez surface plot Preionized plasma electrons

ExperimentDiscussion Basic Physics Heavy Beam LoadingCan give lower energy spread of accelerated particles (via wake flattening) and gives high efficiency. Beam ionized SourcesChoose parameters such that the incoming beam can ionize the plasma source with tunnel ionization: AstrophysicsWeibel/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 screen 2.) 350 MeV: Detect Synch. Rad. 3.) 350 MeV + variable witness: Detect B field Lifetime New ORION Experiments: BB

Integrating Code into ORIONFaster 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.