SCUs for the LCLS-II HXR FEL P. Emma July 8, 2014

SCUs for the LCLS-II HXR FELP. EmmaJuly 8, 2014 • Soft X-Ray (SXR) FEL for LCLS-II must cover 0.2-1.3 keV (4-GeV) • Hard X-Ray (HXR) FEL for LCLS-II must cover 1-5 keV (4-GeV) • SASE to 5 keV is just possible (with no margin) • Self-seeding with PMU not possible beyond 4 keV • Radiation dose at 1 MHz threatens PMU fields (DK/K ~ 0.01%) • SCU can extend photon range toward 8 keV, and beyond, with much less sensitivity to radiation dose Pe 120 kW SXU 0.93 m LTUS 0.65 m LCLS-I Linac LH BC1 BC2 D2 L1 L2-Linac L3-Linac 2.50 m Sec. 21-30 D10 BC3 Lu 145 m Pe 250 kW LTUH HXU “kicker” m-wall Pe 120 kW

magnetic gap is 2.3 mm larger than vac. gap, g E = 4.0 GeV (nominal) PMU g = 5 mm NbTi Nb3Sn g = 4 mm g = 4 mm ~5 keV SASE 7.6 keV SASE 145 m 6.8 keV SASE gex,y= 0.40 mm Ipk = 1 kA sE = 500 keV b = 16 m 20% Lu margin 3.4-m seg’s 1.0-m breaks 1 und. missing 1.5 keV low-lim. lu = 25.6 mm, 18.4mm, 16.8mm K = 0.6-2.4, 1.1-3.0, 1.3-3.2 B = 0.2-1.0T, 0.6-1.8 T, 0.8-2.0 T

magnetic gap is 2.3 mm larger than vac. gap, g E = 4.2 GeV (stretch) PMU NbTi g = 5 mm Nb3Sn g = 4 mm g = 4 mm 145 m 8.2 keV SASE gex,y= 0.40 mm Ipk = 1 kA sE = 500 keV b = 16 m 20% Lu margin 3.4-m seg’s 1.0-m breaks 1 und. missing 1.65 keV low ~7 keV HXRSS limit

magnetic gap is 2.3 mm larger than vac. gap, g E = 4.8 GeV (20% upgrade) PMU g = 5 mm NbTi g = 4 mm 10 keV SASE 145 m Nb3Sn g = 4 mm 8.3 keV HXRSS limit

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E = 4.0 GeV (nominal) – all 5-mm vac. gaps PMU g = 5 mm NbTi Nb3Sn g = 5 mm g = 5 mm 145 m lu = 25.6 mm, 19.2mm, 17.6 mm

E = 4.2 GeV - all 5-mm vac. gaps PMU NbTi Nb3Sn g = 5 mm g = 5 mm g = 5 mm 145 m lu = 25.6 mm, 19.2mm, 17.6 mm

E = 4.8 GeV - all 5-mm vac. gaps PMU NbTi g = 5 mm g = 5 mm 145 m Nb3Sn g = 5 mm 7.9 keV HXRSS limit lu = 25.6 mm, 19.2mm, 17.6 mm

E = 3.4 GeV (drop 5 Cryo-Modules) NbTi g = 4 mm 145 m Nb3Sn g = 4 mm lu = 25.6 mm, 18.4mm, 16.8 mm

SCUs for the LCLS-II HXR FEL P. Emma July 8, 2014