FACET: A Facility for Advanced FACET: A Facility for Advanced Accelerator Research at SLAC Accelerator Research at SLAC U. Wienands, SLAC U. Wienands, SLAC presently at CERN on a LARP-sponsored presently at CERN on a LARP-sponsored Long Term Visit Long Term Visit Division Head for FACET Linac Division Head for FACET Linac I am indebted to Mark Hogan for providing material on plasma acceleration I am indebted to Mark Hogan for providing material on plasma acceleration U. Wienands, SLAC 1 LAL Orsay, 17-Sep-10
Outline Outline • Motivation Motivation • • The FACET Project The FACET Project • • The Experimental Program The Experimental Program • • Conclusion Conclusion • U. Wienands, SLAC 2 LAL Orsay, 17-Sep-10
Accelerator Evolution Accelerator Evolution • Primary tools to advance HEP • Primary tools to advance HEP • Reaching limits of support • Reaching limits of support – size, costs, time scales – Internationalization can buy time, but only a little • Advance can come from • Advance can come from fundamental research into new fundamental research into new accelerating mechanisms accelerating mechanisms – Different materials – Higher frequencies – … U. Wienands, SLAC 3 LAL Orsay, 17-Sep-10
High Gradient Acceleration High Gradient Acceleration • The fundamental parameter is the accelerating The fundamental parameter is the accelerating • gradient gradient – reduce size, thus costs, of new facilities – may help in increasing beam brightness as well • Candidate technologies for high gradients: Candidate technologies for high gradients: • – High-frequency metallic structures (=> CLIC) O(100) MV/m – Dielectric structures (beam or laser driven) O(1) GV/m – Plasma wakefields O(10) GV/m • FACET aims at plasma and dielectric acceleration FACET aims at plasma and dielectric acceleration • U. Wienands, SLAC 4 LAL Orsay, 17-Sep-10
World-wide interest in Plasma- World-wide interest in Plasma- Wakefield Acceleration Wakefield Acceleration T. Katsouleas U. Wienands, SLAC 5 LAL Orsay, 17-Sep-10
Overall Thrust of FACET Overall Thrust of FACET • The primary goal of FACET is proof in principle The primary goal of FACET is proof in principle • that plasma acceleration can accelerate a bunch that plasma acceleration can accelerate a bunch – characterize the mechanism under beam loading – estimate beam parameters (witness) – estimate the efficiency and gradient reachable in practice – demonstrate acceleration of a positron bunch • Beyond that, FACET will provide a facility to Beyond that, FACET will provide a facility to • explore other accelerator physics issues explore other accelerator physics issues – Wakefield measurements (ILC, CLIC) – Matter in extreme fields U. Wienands, SLAC 6 – new radiation sources using crystals LAL Orsay, 17-Sep-10
The FACET Facility The FACET Facility Driven by first 2/3 rd rd of the SLAC 2-mile linac • Driven by first 2/3 of the SLAC 2-mile linac • – new exp. area in Sec. 19-20. – new compressor chicane in Sec. 10 for e + – new compressor chicanes in Sec. 19. – e – and slightly later also e + U. Wienands, SLAC 7 LAL Orsay, 17-Sep-10
The FACET Facility The FACET Facility • Beam Parameters: Beam Parameters: • Energy 23 GeV Energy 23 GeV Charge 3 nC Charge 3 nC Sigma z 14 µm Sigma z 14 µm Sigma r 10 µm Sigma r 10 µm Peak Current 22 kAmps Peak Current 22 kAmps Species e - - & e & e + + Species e – many of these can be tuned to match requirements – 30 Hz repetition rate U. Wienands, SLAC 8 LAL Orsay, 17-Sep-10
Staged Bunch Compression Staged Bunch Compression U. Wienands, SLAC 9 LAL Orsay, 17-Sep-10
S10 Compressor Chicane S10 Compressor Chicane U. Wienands, SLAC 10 LAL Orsay, 17-Sep-10
“Sailboat Sailboat” ” Chicane (S20) Chicane (S20) “ • 3rd-stage bunch compression • 3rd-stage bunch compression + and – bunches wrt. each other • precision timing e e + and e e – bunches wrt. each other • precision timing – allow e + bunch to sample wake from e – bunch U. Wienands, SLAC 11 LAL Orsay, 17-Sep-10
U. Wienands, SLAC 12 LAL Orsay, 17-Sep-10
U. Wienands, SLAC 13 LAL Orsay, 17-Sep-10
Linac Removed from FACET Expt. Area Linac Removed from FACET Expt. Area U. Wienands, SLAC 14 LAL Orsay, 17-Sep-10
Some of the Beam Diagnostics Some of the Beam Diagnostics SLAC linac: FACET IP BPM’s, Toroids, Feedbacks, GADCs, triggers U. Wienands, SLAC 15 LAL Orsay, 17-Sep-10
FACET Status FACET Status • C Construction onstruction expected to finish in Spring 2011 expected to finish in Spring 2011 • – accelerator and beam commissioning soon after. • Experimental Experimental program program to to begin begin Summer Summer 2011 2011 • • First Users Workshop @ SLAC March 18-19, 2010 First Users Workshop @ SLAC March 18-19, 2010 • – http://www-conf.slac.stanford.edu/facetusers/spring2010/ – 40 people, 9 institutions • Argonne, Brookhaven, Euclid Techlabs, Fermilab, SLAC, Stanford, UCLA, USC, UT Austin – 4 Working groups considered ideas for first experiments: • Plasma Wakefield Acceleration • Dielectric Wakefield Acceleration • Materials in Extreme Conditions • Crystals & Novel Sources of Radiation • Beamtime allocated in Beamtime allocated in a a proposal driven proposal driven process process • U. Wienands, SLAC 16 LAL Orsay, 17-Sep-10
Checking out the Linac… … Checking out the Linac U. Wienands, SLAC 17 LAL Orsay, 17-Sep-10
PWFA: Particle to Beam PWFA: Particle to Beam Acceleration Acceleration • Collimation system to craft drive/witness bunch from single • Collimation system to craft drive/witness bunch from single bunch (similar to BNL ATF wire system) bunch (similar to BNL ATF wire system) Adjust final compression Disperse the beam in energy dp/p [%] Witness x ∝ Δ E / E ∝ t Bunch 80cm Plasma z [mm] dp/p [%] Drive x [mm] Bunch ...selectively collimate Vary charge ratio, bunch lengths, spacing by changing collimators and linac phase, R56 Study wake loading in the non-linear regime for the first time U. Wienands, SLAC 18 LAL Orsay, 17-Sep-10
Beam Loading & Wake Evolution Beam Loading & Wake Evolution QuickPIC simulation, D: σ z =30 µ m, N=3x10 10 e - , W: σ z =10 µ m, N=1x10 10 e - , σ r0 =3 µ m, ∆ z=115 µ m, n e =10 17 cm -3 Energy [GeV] Propagation Distance [cm] • Beam loading at 37GeV/m (z = 0) • Beam loading at 37GeV/m (z = 0) • • After 80 After 80 cm plasma, gain cm plasma, gain 25 25 GeV with GeV with 3% 3% δ δ E E / / E E • Wake evolution due to bunch head erosion, but no dephasing • Wake evolution due to bunch head erosion, but no dephasing • Wake evolution “ “bends bends” ” energy gain but preserves low energy gain but preserves low ∆ ∆ E/E E/E • Wake evolution • Drive to witness Energy transfer efficiency ~ 30% • Drive to witness Energy transfer efficiency ~ 30% U. Wienands, SLAC 19 LAL Orsay, 17-Sep-10
U. Wienands, SLAC 20 LAL Orsay, 17-Sep-10
PWFA Collider PWFA Collider • Concept for a beam-driven PWFA collider (1TeV) Concept for a beam-driven PWFA collider (1TeV) • – R&D: e + , emittance, efficiency U. Wienands, SLAC 21 LAL Orsay, 17-Sep-10
FACET Beam is Well Suited for Studying FACET Beam is Well Suited for Studying DWA DWA A ‘‘drive’’ beam excites wake-fields in the tube, while a subsequent witness beam (not shown) would be accelerated by the Ez component of the reflected wakefields (bands of color). For large wakes want high charge, short bunches and narrow tubes, e.g. 2E10 e-, σ z =20 µ m, Si with 200 µ m ID get 85GV/m surface fields! U. Wienands, SLAC 22 LAL Orsay, 17-Sep-10
U. Wienands, SLAC 23 LAL Orsay, 17-Sep-10
1 GeV 1.5 TeV U. Wienands, SLAC 24 LAL Orsay, 17-Sep-10
Other Proposed Research Other Proposed Research • Ultrafast processes in magnetic solids. Ultrafast processes in magnetic solids. • • Wakefield measurements of CLIC structures Wakefield measurements of CLIC structures • • Optical diffraction radiation tests Optical diffraction radiation tests • • Time profile of 50 fs bunches Time profile of 50 fs bunches • • Test of advanced Feedback Algorithms. Test of advanced Feedback Algorithms. • U. Wienands, SLAC 25 LAL Orsay, 17-Sep-10
U. Wienands, SLAC 26 LAL Orsay, 17-Sep-10
U. Wienands, SLAC 27 LAL Orsay, 17-Sep-10
Other Research Considered Other Research Considered • Crystal Accelerator: Crystal Accelerator: • – idea has been around for a while, inverse FEL process – at FACET could be done with high-energy photons • Crystal collimation and X-ray generation Crystal collimation and X-ray generation • – use the strong bending in channeling to make Xrays – tried at other facilities (mostly e – : not efficient) – at FACET can use e + & get to non-negligible intensities • Bragg diagnostics. Bragg diagnostics. • • Beam collimation studies Beam collimation studies • • High-gradient structure tests. High-gradient structure tests. • U. Wienands, SLAC 28 LAL Orsay, 17-Sep-10
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