Post-LH Diagnostic Line for LCLS-II P. Emma, M. Woodley, Y. Nosochkov, Feb. 26, 2014 Steal beam at Hz with y -kicker after LH (  y = 15 mm) Bend hor. 0.7 m with septum magnet and keep parallel to wall Suppress septum dispersion and add screen at x & y beam waist for easy emittance measurements (quad-scan or multi-screen) Final spectrometer (bend up) with screen and 3-W dump Hor. RF deflector provides time resolved y -emittance meas. Ver. RF deflector provides time resolved x -emittance (future) RF deflectors also provide absolute bunch length measurements Spectrometer to measure projected and sliced energy spread Panofsky-Wenzel energy spread needs to be <<5 keV CSR should not distort beam (easy in LH with long bunch) Chromatic effects need to be small (easy in LH, hard in BC1) Keep diagnostics beamline < 20 m (?)

e  dump (~3 W) RF deflectors screen mrad 0.8 m 0.70 m 6.0  y x z 6.7 m XDFXDF YDFYDF z (plan view) (elevation view) HLAM KICKER HBND 2.0 m wall 10.1 m m 20  12 mm 0.8 m 0.5 m 1.74 m 0.5 m screen-1 future Post-Laser-Heater Diagnostics Line Schematic (only very roughly to scale) 20.8 m  y = -6.3 mm to suppress  y Rolled by 9.65  to suppress  y 100 Hz  y = mm to suppress  y

Kicker – reduce inductance using several sections, each with a pulser Kicker core (left) and full magnet (right), with 10 sections shown. Each core is driven by a separate pulser, but for clarity only one is shown here. pulser (10-MHz capability?) Tony Beukers magnet one core

OTR2 TCAVY TCAVX  y = 540 mm spectrometer x-dogleg y-kicker x-septum 3 OTRs (120  ) Post-Laser-Heater Diagnostics Line Thanks M. Woodley & Y. Nosochkov

Floor Coordinates 21.5 cm clearance (center-to-center) 66

Resolution Requirements Resolve rms beam sizes of order ~30  m to < 5% Deflectors should slice 1-mm bunch length into at least 10 bins (300 fs) Must resolve  ½ of 5-keV heater energy spread (i.e., 2.5×10  5 ) Panofsky-Wenzel effect in TCAVX should be  ¼ of 5-keV Use short (< 1 m) S-band RF deflector(s) – X-band not needed here  x,y = 0.45  m  E = 5 keV  z = 1.0 mm E = 100 MeV Q = 100 pC  x,y = 0.45  m  E = 5 keV  z = 1.0 mm E = 100 MeV Q = 100 pC

2 TCAV’s OFF 37  m SCREEN-1 (OTRB) OTRB TCAVY TCAVX (  y  110  m) 377  m 37  m TCAVY ON (0.5 MV) future SCREEN-1 (OTRB) zz slice-  x proj-  x proj-  y 400  m slice-  y 37  m TCAVX ON (0.5 MV) SCREEN-1 (OTRB) zz

2 TCAVs OFF SCREEN-2 (OTR2) 34  m 118  m OTR2 TCAVY TCAVX  y = 540 mm spectr. TCAVX ON (0.2 MV) HEATER OFF (    ) SCREEN-2 (OTR2) 21  m 523  m 1.0 keV PW  y   21  m  TCAVX ON (0.2 MV) HEATER OFF (    5 keV ) SCREEN-2 (OTR2) 34  m 523  m  5.0 keV LH CSR causes no issues  5.0 keV LH

2 TCAVs OFF SCREEN-2 (OTR2)  5.0 keV LH TCAVX ON (0.2 MV) HEATER OFF (    5 keV ) SCREEN-2 (OTR2) 523  m 1.0 keV PW TCAVX ON (0.2 MV) HEATER OFF (    ) SCREEN-2 (OTR2) 523  m  119  m 1.0 keV PW  x = 110  m V = 0.2 MV f = 2856 MHz TCAVX ON 269  m

  m  (26  m)/  y = 4.8×10  5   m  (38  m)/  y = 7.0×10  5  y = 540 mm  y = 20   y = 540 mm  y = 20    = 1.0×10  5 (PW)   = 5.0×10  5 (LH)  y = 810 mm  y = 30   y = 810 mm  y = 30    = 1.0×10  5 (PW)   = 5.0×10  5 (LH)   m  (32  m)/  y = 4.0×10  5   m  (52  m)/  y = 6.4×10  5  y  y ) 1/2 = 20  m 38  m 26  m 52  m 32  m

 y = 810 mm  y = 30   y = 810 mm  y = 30    = 1.0×10  5 (PW)   = 5.0×10  5 (LH)   m  (16  m)/  y = 2.0×10  5   m  (45  m)/  y = 5.6×10  5  y  y ) 1/2 = 12  m Spectrometer at Low Charge (Q = 10 pC,  y =  x = 0.15  m)   45  m 16  m

Chromatic Errors 0.05% rms energy spread (nominal) 0.20% rms energy spread (worst?)

Post-Laser-Heater Energy Spread at 95 MeV is 0.05% rms

No CSR Effects (100 pC, 1 mm bunch length) (0.05% rms energy spread) Linear energy-position correlations (dispersion) removed 5×10  5  y = 30  6×10  5

ParametersymbolvalueUnit Kicker lengthLkLk 0.5m Kicker fieldBkBk T Kicker field regulation (7% jitter)  B k /B k  rms 0.01% Vert. e  pos. at face of septum yy 15mm Septum bend angle xx 6.0deg Septum fieldBsBs 0.043T Septum lengthLsLs 0.8m Septum roll angle ss 9.65deg Beam line hor. offset (wrt linac) xx 0.7m TCAVX (and TCAY) lengthsL xc,yc 0.8m Max. crest TCAV voltage (S-band)V x,y 0.5MV Spectrometer bend lengthLyLy 0.5m Spectrometer bend fieldByBy 0.23T Spectrometer bend angle yy 20 (30?)deg Quadrupole lengthsLQLQ 0.1m Quadrupole pole-tip radiusrprp 16mm Max. quadrupole pole-tip fieldBpBp 0.12T Beamline Parameters

9-page PRD ready

L yy Quad focal length: Chromatic aberration: Chromatic Limitation on Dog-Leg Length Dog-Leg length:  = 20 m,   = 0.2%,  /  0  1%, L ≥ 2.3 m  = 20 m,   = 2.0%,  /  0  1%, L ≥ 23 m Laser Heater: BC1: