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Alex Bogacz

Recirculating Linac Acceleration - End-to-end Simulation. Alex Bogacz. 0.9 GeV. 244 MeV. 146 m. 79 m. 0.6 GeV/pass. 3.6 GeV. 264 m. 12.6 GeV. 2 GeV/pass. Linac and RLAs - Goals. IDS Goals: Define beamlines /lattices for all components

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Alex Bogacz

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  1. Recirculating Linac Acceleration - End-to-end Simulation Alex Bogacz NuFact'09, Chicago, IL, July 24, 2009

  2. 0.9 GeV 244 MeV 146 m 79 m 0.6 GeV/pass 3.6 GeV 264 m 12.6 GeV 2 GeV/pass Linac and RLAs - Goals • IDS Goals: • Define beamlines/lattices for all components • Resolve physical interferences, beamline crossings etc • Error sensitivity analysis • End-to-end simulation (machine acceptance) • Component count and costing NuFact'09, Chicago, IL, July 24, 2009

  3. RLA Acceleration - Status • Presently completed lattices • Linear pre-accelerator – solenoid focusing • 4.5 pass Dogbone RLA × 2 (RLA I + RLA II) • Optimized multi-pass linac optics (bisected - quad profile along the linac) • Droplet return arcs (4) matched to the linacs • Transfer lines between the components – injection chicanes • Droplet arcs crossing – Double achromat Optics design • Chromatic corrections with sextupoles at Spr/Rec junctions • Error analysis for the Arc lattices (proof-or-principle) • Magnet misalignment tolerance – DIMAD Monte Carlo Simulation • Focusing errors tolerance – betatron mismatch sensitivity • Piece-wise end-to-end simulation with OptiM (pre-accelerator + RLA I) NuFact'09, Chicago, IL, July 24, 2009

  4. Linac-RLA Acceptance Initial phase-space after the cooling channel at 220 MeV/c bx,y = 2.74 m ax,y = -0.356 bg = 2.08 NuFact'09, Chicago, IL, July 24, 2009

  5. Linear Pre-accelerator – 244 MeV to 909 MeV Transverse acceptance (normalized): (2.5)2eN = 30 mm rad Longitudinal acceptance: (2.5)2 sDpsz/mmc= 150 mm 8 medium cryos 17 MV/m 6 short cryos 15 MV/m 11 long cryos 17 MV/m 2.4 Tesla solenoid 1.4 Tesla solenoid 1.1 Tesla solenoid NuFact'09, Chicago, IL, July 24, 2009

  6. ‘Soft-edge’ Solenoid • Non-zero aperture - correction due to the finite length of the edge : • It introduces axially symmetric edge focusing at each solenoid end: • Hard edge solenoid: NuFact'09, Chicago, IL, July 24, 2009

  7. ‘Soft-edge’ Solenoid – Nonlinear Effects • Nonlinear focusing term DF ~ O(r2) follows from the scalar potential: • Solenoid B-fields • Nonlinear focusing included in particle tracking NuFact'09, Chicago, IL, July 24, 2009

  8. Linear Pre-accelerator – 244 MeV to 909 MeV Transverse acceptance (normalized): (2.5)2eN = 30 mm rad Longitudinal acceptance: (2.5)2 sDpsz/mmc= 150 mm NuFact'09, Chicago, IL, July 24, 2009

  9. Multi-pass Linac Optics – Bisected Linac ‘half pass’ , 900-1200 MeV initial phase adv/cell 90 deg. scaling quads with energy quad gradient 1-pass, 1200-1800 MeV mirror symmetric quads in the linac quad gradient NuFact'09, Chicago, IL, July 24, 2009

  10. m- m- m+ m+ Injection/Extraction Chicane m+ m- NuFact'09, Chicago, IL, July 24, 2009

  11. Pre-accelerator–Chicane–Linac Matching a = 2×10-5 NuFact'09, Chicago, IL, July 24, 2009

  12. Pre-accelerator–Chicane–Linac Matching a = 2×10-5 NuFact'09, Chicago, IL, July 24, 2009

  13. Injection-to–Linac – Chromatic Corrections Dfxy = 1800 Dfxy = 1800 Dfxy = 1800 Dfxy = 1800 two families of sextupoles one family of sextupoles uncorrected NuFact'09, Chicago, IL, July 24, 2009

  14. Linac ½-to-Arc1 – Beta Match E =1.2 GeV • Already matched ‘by design’ • 900 phase adv/cell maintained across the ‘junction’ • No chromatic corrections needed NuFact'09, Chicago, IL, July 24, 2009

  15. Linac1-to-Arc2 – Chromatic Compensation E =1.8 GeV • ‘Matching quads’ are invoked • No 900 phase adv/cell maintained across the ‘junction’ • Chromatic corrections needed – two pairs of sextupoles NuFact'09, Chicago, IL, July 24, 2009

  16. Linac1-to-Arc2 - Chromatic Corrections initial uncorrected two families of sextupoles NuFact'09, Chicago, IL, July 24, 2009

  17. Mirror-symmetric ‘Droplet’ Arc – Optics (bout = bin and aout = -ain , matched to the linacs) E =1.2 GeV 2 cells out transition 2 cells out transition 10 cells in NuFact'09, Chicago, IL, July 24, 2009

  18. Longitudinal Compression in the RLA • Adiabatic compression in the RLA - off-crest acceleration in the linac + non zero momentum compaction in the arcs (M56~6 m) NuFact'09, Chicago, IL, July 24, 2009

  19. Summary • Presently completed Lattices: • Pre-accelerator (244 MeV-0.9) + injection double chicane • RLA I (0.9-3.6 GeV) and RLA II (3.6-12.6 GeV) • 4.5 pass linac • Droplet Arcs1-4 • Chromaticity correction with sextupoles validated via tracking • Piece-wise end-to-end simulation with OptiM (transport code) • Solenoid linac • Injection chicane • RLA I • Still to do… end-to-end simulation with fringe fields (sol. & rf cav.) NuFact'09, Chicago, IL, July 24, 2009

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