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Alex Bogacz

Acceleration in RLAs – Design Choices. Alex Bogacz. ‘Racetrack’ vs ‘Dogbone’ configuration multi-pass linacs focusing orbit separation simultaneous acceleration of both m + m - species 10 GeV Two-step-Dogbone RLA Quadrupole focusing scheme – Triplet vs FODO lattices multi-pass linac

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Alex Bogacz

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  1. Acceleration in RLAs – Design Choices Alex Bogacz • ‘Racetrack’ vs ‘Dogbone’ configuration • multi-pass linacs focusing • orbit separation • simultaneous acceleration of both m+m- species • 10 GeV Two-step-Dogbone RLA • Quadrupole focusing scheme – Triplet vs FODO lattices • multi-pass linac • matching to the Arcs • vertical injection double-chicane ISS Workshop, UC Irvine, August 21, 2006.

  2. mis- focusing factor: 1 + (n-1) DE/E0 E0 n - 1 arcs n arcs E0 + n DE orbit separation factor: [E0 + n DE]/[E0 + (n-1) DE] ≃ n/n-1 n/2 droplets n/2 droplets mis- focusing factor: 1 + n DE/E0 E0 E0 + (n + ½) DE orbit separation factor: [E0 + (n+½) DE]/[E0 + (n-2+½) DE] ≃ n/n-2 ‘Racetrack’ vs ‘Dogbone’ RLA (n-pass) DE/2 total arc length: (2n - 1) pR DE/2 DE total arc length: 2n (7/6) pR ISS Workshop, UC Irvine, August 21, 2006.

  3. m+ m- m- m+ m+ m- m- m- m- m+ m+ m+ m+ m- m- m+ ‘Racetrack’ vs ‘Dogbone’ RLA (both m+ and m- species ) ISS Workshop, UC Irvine, August 21, 2006.

  4. m+ m- m- m- m+ m+ m+ m+ m- m- ‘Racetrack’ vs ‘Dogbone’ RLA (both m+ and m- species ) ISS Workshop, UC Irvine, August 21, 2006.

  5. 0.2 GeV 0.9 GeV 3 GeV 0.6 GeV/pass 10 GeV 2 GeV/pass 10 GeV Two-step-Dogbone RLA 3.33… ext/injenergy ratio 3.0 GeV to 10 GeV 0.9 GeV to 3.0 GeV 1.5 GeV to 5.0 GeV ISS Workshop, UC Irvine, August 21, 2006.

  6. 0.2 GeV 0.9 GeV 3 GeV 0.6 GeV/pass 10 GeV 2 GeV/pass 10 GeV Two-step-Dogbone RLA 3.33… ext/injenergy ratio 3.0 GeV to 10 GeV 0.9 GeV to 3.0 GeV 1.5 GeV to 5.0 GeV ISS Workshop, UC Irvine, August 21, 2006.

  7. m- m- m+ m+ Injection double-chicane m+ m- ISS Workshop, UC Irvine, August 21, 2006.

  8. FODO vs Triplet focusing structure • The same length • The same phase advance per cell (Dfx= 900 = Dfy) FODO Triplet • Advantages: • much weaker quads (~3 times) • shorter quads (total) • easier chromaticity correction • Advantages: • longer straight sections • smaller vertical beta-function • uniform variation of betas and dispersion ISS Workshop, UC Irvine, August 21, 2006.

  9. Multipass linac - Triplet vs FODO focusing (900 phase adv/cell) 1-pass 2-pass 3-pass ISS Workshop, UC Irvine, August 21, 2006.

  10. Straight-Arc - Periodic transition Triplet FODO ISS Workshop, UC Irvine, August 21, 2006.

  11. Summary • ‘Dogbone’ RLA – preferred configuration (compared to the ‘Racetrack’) • better orbir separation for higher passes • more efficient use of the rf (extra half-pass) • offers symmetric solution for simultaneous acceleration of m+ and m- • FODO lattice more favorable (compared to the triplet) to accommodate large number of passes • uniform phase advance decrease in both planes • smaller variation of Twiss function – easier match to the Arcs • allows to maintain 900 phase advance per cell for lowest passes • Proposed 10 GeV two-step-dogboneRLA (30 mm rad acceptance) • 3.0-10GeV ‘dogbone’ with 400MHz SRF? • Needed: front-to-end simulation, magnet error/misalignment sensitivities etc. ISS Workshop, UC Irvine, August 21, 2006.

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