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Separation Scheme Options in the LCLS-II Modified LTU Lattice Y. Nosochkov LCLS-II Physics Meeting, May 9, 2012. Goals. Compare HXR/SXR beam separation schemes in the modified LTU lattice: 1. Horizontal kicker with current sheet septum versus
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Separation Scheme Options in the LCLS-II Modified LTU Lattice Y. NosochkovLCLS-II Physics Meeting, May 9, 2012
Goals Compare HXR/SXR beam separation schemes in the modified LTU lattice: 1. Horizontal kicker with current sheet septum versus 2. Vertical kicker with Lambertson septum (less expensive) Compare the kicker strength, orbit amplitude, number of LTU magnets, R56, I5 (ISR emittance growth) Y. Nosochkov
Full lattice with modified LTU HXR Undulator Linac LTU Bypass gun sd sd sd sd L0 µ 11-1 sd sz sd L1 L3 L2 sz sz BC1 BC2 11-3 to 14-4 DL1 sd 14-7 to 20-4 DL2 HXR SXR sd Y. Nosochkov
Existing design of Lambertson septum for vertical separation scheme Dy = 7 mm at septum P. Emma Y. Nosochkov
First look at the current sheet septum design for horizontal separation (C. Spencer) SXR HXR More expensive Assume Dx = 10 mm at septum, B = 2.6 kG, L = 2 m. HXR correction may be required to compensate for residual field. Y. Nosochkov
LTU SXR lattice for horizontal separation Include the kicker orbit as part ofthe reference trajectory Adjust septum and SXR main bend field for correction Long drift to minimize wall interference septum kicker diagnostic C1 Low bx at bends Y. Nosochkov
Horizontal separation orbit from kicker septum BX42 QDL43 QDL45 QDL46 QDL44 kicker X = -10 mm at septum Off-axis through QDL44,45,46 and BX42 Y. Nosochkov
LTU SXR lattice for vertical separation 3 extra cells are included thus making the LTUS longer by 52.8 m Septum angle is reduced ~30% Kicker-1 Kicker-1 septum diagnostic C1 C2 C3 C4 by is reduced, butbx at bends is increased SXR geometry downstream of LTU may need to be adjusted Y. Nosochkov
Vertical separation orbit and dispersion Y. Nosochkov
Parameters * Part of bend field DgeISR = 4∙10-8 ∙ I5 ∙ E6= 0.0035 mm-radat I5 = 7.7e-9 and 15 GeV Y. Nosochkov
Some comparison • Lambertson septum: less expensive, lower R56, one extra kicker • Current sheet septum: fewer quads in LTU, lower emittance growth, correctors combined with dipoles Y. Nosochkov