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Beam Dynamics of Energy Recovering Linacs

Beam Dynamics of Energy Recovering Linacs. S.A. Bogacz , G.A. Krafft , S. DeSilva and R. Gamage Jefferson Lab and Old Dominion University. Outline. Principle of Energy Recovering Linacs Historical overview First ideas and tests Projects and facilities worldwide Applications of ERLs

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Beam Dynamics of Energy Recovering Linacs

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  1. Beam Dynamics of Energy Recovering Linacs S.A. Bogacz, G.A. Krafft, S. DeSilva and R. Gamage Jefferson Lab and Old Dominion University USPAS, Fort Collins, CO, June 13-24, 2016

  2. Outline • Principle of Energy Recovering Linacs • Historical overview • First ideas and tests • Projects and facilities worldwide • Applications of ERLs • Colliders • Light sources • Electron Cooling of Ions • Challenges • Transverse/Longitudinal Optics • Multi-pass ERL topologies • Beam Breakup Instability • Nonlinear Effects • Summary and Outlook • D. Douglas, Jefferson Lab, CASA, 2015 • A. Jankowiak, Humboldt University Berlin,CAS 2015. USPAS, Fort Collins, CO, June 13-24, 2016

  3. EOut = EInj EInj Energy recovery in RF-fields – braking the DC limit Energy Recovery – Fundamental Idea lRf L = n · l + l / 2 E = EInj + DE (b ~ 1) Energy Flow = Acceleration  Energy Storage in the beam (loss free)  Energy Recovery = Deceleration USPAS, Fort Collins, CO, June 13-24, 2016

  4. Principle of Energy Recovering Linac Edump ~ 10 MeV I ~ 10 mA – 1 A P ~ 100 kW - MW Dump Acceleration: energy transfer to the beam Experiments need high beam power (MW to GW) and Supply of ever ‘fresh’ beam E ↑ RF Linac (super conducting) Acceleration up to many GeV E ↓ EInj ~ 10 MeV I ~ 10 mA – 1 A P ~ 100 kW - MW Deceleration: energy recovery, to be used by freshly accelerated beam Injector USPAS, Fort Collins, CO, June 13-24, 2016

  5. History –First Idea Nuovo Cimento, 37, 1228 (1965) USPAS, Fort Collins, CO, June 13-24, 2016

  6. History – First Test The Chalk River Reflexotron Schriber, Funk, Hodge, Hucheon, PAC1977, 1061-1063 USPAS, Fort Collins, CO, June 13-24, 2016

  7. History – First Demonstration Stanford SCA/FEL, 07/1987 (sc-FEL driver) T. I. Smith, et al., NIM A259, 1 (1987) 50MeV 150mA 5MeV MIT Bates Recirculated Linac (2.857GHz, nc, pulsed), 1985 J.B. Flanz et al., IEEE Trans. Nucl. Sci., NS-32, No.5, p.3213 (1985) USPAS, Fort Collins, CO, June 13-24, 2016

  8. Storage Rings vs Linacs STORAGE ID IP RING X-Rays Driven by different mechanism of emittance evolution USPAS, Fort Collins, CO, June 13-24, 2016

  9. Photon it looses momentum (also transverse) electron emits a photon RF Cavity E longitudinal momentum restored by accelerating cavity angle and displacement reduced → transverse emittance reduced Radiation Damping STORAGE ID IP RING X-Rays USPAS, Fort Collins, CO, June 13-24, 2016

  10. reference orbit dispersion orbit for particle with energy deviation Radiation Heating emission of a photon at position with dispersion (e.g. in a dipole, where the transverse position is energy dependent) electron oscillates around reference orbit  emittance increase STORAGE ID IP RING X-Rays Transverse emittance is defined by an equilibrium between these two processes (damping and heating) USPAS, Fort Collins, CO, June 13-24, 2016

  11. RF Cavity E Adiabatic Damping electron has initial transverse momentum longitudinal component increases during acceleration LINEAR ACCELERATOR X-Rays e0 e ID Source IP angle reduces with acceleration, emittance shrinks: Beam quality is defined by the source, the rest is a proper acceleration and phase-space control. USPAS, Fort Collins, CO, June 13-24, 2016

  12. Storage Rings vs Linacs STORAGE ID IP RING X-Rays • beam parameters defined by equilibrium • many user stations • limited flexibility – multi-pass • high average beam power (A, multi GeV) • typically long bunches (20 ps – 200 ps) • beam parameters defined by source • low number of user stations • high flexibility – single pass • limited average beam power (<< mA) • possible short bunches (sub psec) USPAS, Fort Collins, CO, June 13-24, 2016

  13. ERLs – The best of both worlds LINEAR ACCELERATOR X-Rays ID Source STORAGE ID IP RING IP X-Rays ENERGY RECOVERY LINAC IP ID High average beam power (multi GeV @ some 100 mA) for single pass experiments, excellent beam parameters, high flexibility, multi user facility Main Linac X-Rays Source USPAS, Fort Collins, CO, June 13-24, 2016

  14. ERL as a Next Generation Light source dump electron source main linac: several GeV USPAS, Fort Collins, CO, June 13-24, 2016

  15. Light source ERLs – ‘The best of both worlds’ USPAS, Fort Collins, CO, June 13-24, 2016 • Combines the ‘amenities’ of storage rings and linacs • with energy recovery: some 100mA @ many GeV possible • always “fresh” electrons (no equilibrium) • small emittance (~ 0.1 mm rad norm. = 10 pm rad@6GeV) • high brilliance ( x 100 – 1000 compared to storage rings) • short pulses ( ps down to 10 – 100 fs) • flexible choice of polarization • 100% coherence up to hard X-rays • real multi-user operation at many beam lines • tailored optics at each insertion device • Flexible modes of operation (high brilliance, short pulse, different pulse patterns) adaptable to user requirements!

  16. ‘Electron Cooler’ for Ion Beams first devices in the 70ies ‘Electrostatic’,e.g. Van-de-Graaff , Peletron, ... e- - source, acceleration +4.3MV DC collector deceleration +4.3MV ‘Cold’ electron beam always ‘fresh’ electrons ‘Hot’ ion beam in storage ring vElectron = vIon e.g. FermiLab recycler ring (Tevatron) anti protons: E = 9 GeV  b = 0.994 electrons: E = 4.9 MeV  UCooler = 4.39 MV I = 0.5A (DC)  P = 2.2 MW USPAS, Fort Collins, CO, June 13-24, 2016

  17. ERL Configurations DE/2 DE Single Linac DE/2 ‘Racetrack’ USPAS, Fort Collins, CO, June 13-24, 2016

  18. CEBAF ERL USPAS, Fort Collins, CO, June 13-24, 2016

  19. CEBAF ERL Ds = l/2 USPAS, Fort Collins, CO, June 13-24, 2016

  20. CEBAF ERL 0.75 GeV/pass 0.75 GeV/pass 85 MeV Ds = l/2 7.585 GeV USPAS, Fort Collins, CO, June 13-24, 2016

  21. CEBAF ERL Ds = l/2 USPAS, Fort Collins, CO, June 13-24, 2016

  22. CEBAF ERL 90:1 98.9% ERL hERL = Einj/Efinal Ds = l/2 85 MeV USPAS, Fort Collins, CO, June 13-24, 2016

  23. 50 BETA_X&Y[m] 0 0 BETA_X BETA_Y DISP_X DISP_Y 245.24 50 BETA_X&Y[m] 0 0 BETA_X BETA_Y DISP_X DISP_Y 248.269 Linacs Optics – Lowest pass (750 MeV) NL Einj E1 (750 MeV) SL Einj E1 NL Einj E1 SL E1 Einj USPAS, Fort Collins, CO, June 13-24, 2016

  24. Multi-pass ER Optics Acceleration/Deceleration SL Einj Einj E1 E1 NL NL E1 E1 1200 FODO E2 E2 E2 E2 Arc 2,4,6,8,A Arc 1,3,5,7,9 Arc 2,4,6,8,A Arc 1,3,5,7,9 SL SL E2 E2 E1 E1 Einj Einj E1 E1 Acceleration/Deceleration NL 1200 FODO E10 E9 E8 E6 E4 E7 Einj E5 E3 E2 E1 E10 E9 E8 E6 E4 E7 Einj E5 E3 E2 E1 ×5 USPAS, Fort Collins, CO, June 13-24, 2016

  25. Linacs Optics – Optimization Criteria • The optimization of the linac optics aims at mitigating the impact of • imperfections and collective effects such as wake-fields driven by: Free parameters: Input optics functions (β function and its derivative) Quads Strength profile minimize • One should also consider the interaction of bunches at different passes, • resulting in the integrals: where the energy and the β functions need to be evaluated for the different pass numbers: i, j minimize Merit function (3-pass) USPAS, Fort Collins, CO, June 13-24, 2016

  26. Optimized Multi-pass ER Optics Acceleration/Deceleration ‘Drift Linac’ • The quadrupole strength profile needs to be optimized in order to minimize the impact of imperfections and collective effects such as wake-fields, driven by the following parameter E10 E9 E8 E6 E4 E7 Einj E5 E3 E2 E1 USPAS, Fort Collins, CO, June 13-24, 2016

  27. Optimized Multi-pass ER Optics Acceleration/Deceleration ‘Drift Linac’ 600 FODO E10 E10 E9 E9 E8 E8 E6 E6 E4 E4 E7 E7 Einj Einj E5 E5 E3 E3 E2 E2 E1 E1 USPAS, Fort Collins, CO, June 13-24, 2016

  28. Optimized Multi-pass ER Optics Acceleration/Deceleration ‘Drift Linac’ 300 FODO E10 E10 E9 E9 E8 E8 E6 E6 E4 E4 E7 E7 Einj Einj E5 E5 E3 E3 E2 E2 E1 E1 USPAS, Fort Collins, CO, June 13-24, 2016

  29. Optimized Multi-pass ER Optics Acceleration/Deceleration ‘Drift Linac’ 600 FODO E10 E10 E9 E9 E8 E8 E6 E6 E4 E4 E7 E7 Einj Einj E5 E5 E3 E3 E2 E2 E1 E1 USPAS, Fort Collins, CO, June 13-24, 2016

  30. 5 100 BETA_X&Y[m] DISP_X&Y[m] -5 0 0 BETA_X BETA_Y DISP_X DISP_Y 339.79 5-pass ‘up’ + 5-pass ‘down’ Optics INJ - NL 85 MeV 835 MeV USPAS, Fort Collins, CO, June 13-24, 2016

  31. 5 300 BETA_X&Y[m] DISP_X&Y[m] -5 0 0 BETA_X BETA_Y DISP_X DISP_Y 657.399 5 300 BETA_X&Y[m] DISP_X&Y[m] -5 0 0 BETA_X BETA_Y DISP_X DISP_Y 655.119 5-pass ‘up’ + 5-pass ‘down’ Optics ARC1 - SL 1585 MeV 835 MeV ARC2 - NL 85 MeV 1585 MeV 2335 MeV USPAS, Fort Collins, CO, June 13-24, 2016

  32. 5 300 BETA_X&Y[m] DISP_X&Y[m] -5 0 0 BETA_X BETA_Y DISP_X DISP_Y 656.793 5 600 BETA_X&Y[m] DISP_X&Y[m] -5 0 0 BETA_X BETA_Y DISP_X DISP_Y 654.704 5-pass ‘up’ + 5-pass ‘down’ Optics ARC3 - SL 3085 MeV 2335 MeV ARC4 - NL 3835 MeV 3085 MeV USPAS, Fort Collins, CO, June 13-24, 2016

  33. 5 400 BETA_X&Y[m] DISP_X&Y[m] -5 0 0 BETA_X BETA_Y DISP_X DISP_Y 656.392 5 400 BETA_X&Y[m] DISP_X&Y[m] -5 0 0 BETA_X BETA_Y DISP_X DISP_Y 654.505 5-pass ‘up’ + 5-pass ‘down’ Optics ARC9 - SL 7585 MeV 6835 MeV ARCA - NL Dl/2 7585 MeV 6835 MeV USPAS, Fort Collins, CO, June 13-24, 2016

  34. 5 600 BETA_X&Y[m] DISP_X&Y[m] -5 0 0 BETA_X BETA_Y DISP_X DISP_Y 654.704 5 300 BETA_X&Y[m] DISP_X&Y[m] -5 0 0 BETA_X BETA_Y DISP_X DISP_Y 656.793 5-pass ‘up’ + 5-pass ‘down’ Optics ARC4 - NL 3085 MeV 2335 MeV ARC3 - SL 2335 MeV 1585 MeV USPAS, Fort Collins, CO, June 13-24, 2016

  35. 5 300 BETA_X&Y[m] DISP_X&Y[m] -5 0 0 BETA_X BETA_Y DISP_X DISP_Y 655.119 5 300 BETA_X&Y[m] DISP_X&Y[m] -5 0 0 BETA_X BETA_Y DISP_X DISP_Y 657.399 5-pass ‘up’ + 5-pass ‘down’ Optics ARC2 - NL 1585 MeV 835 MeV ARC1 - SL 835 MeV 85 MeV USPAS, Fort Collins, CO, June 13-24, 2016

  36. RLA Topologies DE/2 ‘Racetrack’ DE/2 2 ×DE/2 ‘Dogbone’ DE USPAS, Fort Collins, CO, June 13-24, 2016

  37. ‘Racetrack’ vs ‘Dogbone’ RLA DE/2 1.5 DE DE/2 DE 3 DE Twice the acceleration efficiency – traversing the linac in both directions while accelerating USPAS, Fort Collins, CO, June 13-24, 2016

  38. ‘Dogbone’ vs ‘Racetrack’ – Arc-length 9×DE/2 9×DE/2 =n(p + 4a)R n× a a =2npR 2n× Net arc-length break even: if a = p/4 USPAS, Fort Collins, CO, June 13-24, 2016

  39. ‘Racetrack’ vs ‘Dogbone’ ERL 0.5 GeV 3-pass RLA ‘Racetrack’ 10 GeV 20 GeV 10 GeV linac 30 GeV 40 GeV 0.5 GeV 50 GeV 60 GeV IP 10 GeV linac 60 GeV 17 GeV 6 GeV 28 GeV 39 GeV 49 GeV 0.5 GeV 60 GeV ‘Dogbone’ 5.5-pass RLA IP 0.5 GeV 60 GeV 11 GeV linac USPAS, Fort Collins, CO, June 13-24, 2016

  40. Multi-pass Linac Optics – Bisected Linac 5 15 BETA_X&Y[m] DISP_X&Y[m] 0 0 0 BETA_X BETA_Y DISP_X DISP_Y 39.9103 5 15 BETA_X&Y[m] DISP_X&Y[m] 0 0 0 BETA_X BETA_Y DISP_X DISP_Y 78.9103 ‘half pass’ , 900-1200 MeV initial phase adv/cell 90 deg. scaling quads with energy 6 meter 90 deg. FODO cells 17 MV/m RF, 2 cell cavities quad gradient 1-pass, 1200-1800 MeV mirror symmetric quads in the linac quad gradient USPAS, Fort Collins, CO, June 13-24, 2016

  41. 5 30 BETA_X&Y[m] DISP_X&Y[m] 0 0 0 BETA_X BETA_Y DISP_X DISP_Y 389.302 Multi-pass Linac Optics - Acceleration Arc 5 Arc 3 Arc 1 Arc 4 Arc 2 quad grad. 3.0 GeV 0.9 GeV 1.2 GeV 1.8 GeV 2.4 GeV 3.6 GeV length USPAS, Fort Collins, CO, June 13-24, 2016

  42. 5 30 BETA_X&Y[m] DISP_X&Y[m] 0 0 0 BETA_X BETA_Y DISP_X DISP_Y 389.302 Multi-pass Linac Optics - Deceleration Arc 5 Arc 4 Arc 3 Arc 2 Arc 1 3.6 GeV 1.2 GeV 0.9 GeV 1.8 GeV 2.4 GeV 3.0 GeV quad grad. length USPAS, Fort Collins, CO, June 13-24, 2016

  43. Beam Breakup Instability (BBU) USPAS, Fort Collins, CO, June 13-24, 2016

  44. Beam Breakup Instability (BBU) Krafft, Bisognano, and Laubach, unpublished (1988) USPAS, Fort Collins, CO, June 13-24, 2016

  45. Beam Breakup Instability (BBU) USPAS, Fort Collins, CO, June 13-24, 2016

  46. Beam Breakup Instability (BBU) USPAS, Fort Collins, CO, June 13-24, 2016

  47. Nonlinear Beam Optics USPAS, Fort Collins, CO, June 13-24, 2016

  48. Nonlinear Beam Optics USPAS, Fort Collins, CO, June 13-24, 2016

  49. JLAB IR/UV FEL DC Gun IR Wiggler SRF Linac Bunching Chicane UV FEL Transport Line Dump USPAS, Fort Collins, CO, June 13-24, 2016

  50. E E E E f f f f E E f f Longitudinal Matching Scenario • High peak current (short bunch) at FEL • bunch length compression at wiggler using quads and sextupoles to adjust compactions • “Small” energy spread at dump • energy compress while energy recovering • “short” RF wavelength/long bunch, large exhaust dp/p (~10%) • get slope, curvature, and torsion right (quads, sextupoles, octupoles) USPAS, Fort Collins, CO, June 13-24, 2016

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