Post-LH Diagnostic Line for LCLS-IIP. Emma, M. Woodley, Y. Nosochkov, Feb. 26, 2014

Steal beam at 1-100 Hz with y-kicker after LH (Dy = 15 mm)Bend hor. 0.7 m with septum magnet and keep parallel to wallSuppress 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 dumpHor. RF deflector provides time resolved y-emittance meas.Ver. RF deflector provides time resolved x-emittance (future)RF deflectors also provide absolute bunch length measurementsSpectrometer to measure projected and sliced energy spreadPanofsky-Wenzel energy spread needs to be <<5 keVCSR 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-2

9.4 mrad

0.8 m0.70 m

6.0

y

x

z

6.7 m

XDFYDF

z(plan view)

(elevation view)

HLAMKICKER HBND

2.0 m

wall

10.1 m

0.633 m

20

12 mm

0.8 m 0.5 m

1.74 m

0.5 m

screen-1future

Post-Laser-Heater Diagnostics Line Schematic(only very roughly to scale)

20.8 m

Dy = -6.3 mm to suppress hy

Rolled by 9.65 to suppress hy

100 Hz

Dy = -0.28 mm to suppress hy

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

Parameter Value Unit

Field 6.3 mT

Length 0.5 m

Kick angle 9.4 mrad

Pulsers & cores 5 -

Pulser voltage 500 V

Stability (rms) 0.01 %

magnetone core

OTR

2TCAVY

TCAVX

h y =

540

mm

spectrometer

x-dogleg

y-ki

cker

x-se

ptum

3 O

TRs

(120

)

Post-Laser-Heater Diagnostics Line

Thanks M. Woodley &Y. Nosochkov

Floor Coordinates

21.5 cm clearance (center-to-center)

6

Resolution Requirements

Resolve rms beam sizes of order ~30 mm 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

gex,y = 0.45 mmsE = 5 keVsz = 1.0 mmE = 100 MeVQ = 100 pC

2 TCAV’s OFF

37 mm

37 mm

SCREEN-1 (OTRB)

OTR

B

TCAVY

TCAVX (sy 110 mm) 377 mm

37 mm

TCAVY ON (0.5 MV)future

SCREEN-1 (OTRB)

sz

slice

-ge x

proj-gexpr

oj-ge y

400 mm

slice-gey 37 mm

TCAVX ON (0.5 MV)SCREEN-1 (OTRB)

sz

2 TCAVs OFFSCREEN-2 (OTR2)

34 mm

118 mm

OTR

2

TCAVY

TCAVX

h y =

540

mm

spectr.

TCAVX ON (0.2 MV)HEATER OFF (sE =0)

SCREEN-2 (OTR2)

21 mm

523 mm

1.0 keV PW syb 21 mm

sE

TCAVX ON (0.2 MV)HEATER OFF (sE =5 keV)

SCREEN-2 (OTR2)

34 mm

523 mm

sE

5.0 keV LH

CSR causes no issues

sE

5.0 keV LH

2 TCAVs OFFSCREEN-2 (OTR2)

sE

5.0 keV LH

TCAVX ON (0.2 MV)HEATER OFF (sE =5 keV)

SCREEN-2 (OTR2)523 mm

1.0 keV PW

TCAVX ON (0.2 MV)HEATER OFF (sE =0)

SCREEN-2 (OTR2)523 mm

sE

119 mm

1.0 keV PWsx = 110 mmV = 0.2 MV

f = 2856 MHz

TCAVX ON

269 mm 269 mm

269 mm

sdm (26 mm)/hy = 4.8×10-5 sdm (38 mm)/hy = 7.0×10-5

hy = 540 mmqy = 20

hy = 540 mmqy = 20

sd = 1.0×10-5 (PW) sd = 5.0×10-5 (LH)

hy = 810 mmqy = 30

hy = 810 mmqy = 30

sd = 1.0×10-5 (PW) sd = 5.0×10-5 (LH)

sdm (32 mm)/hy = 4.0×10-5 sdm (52 mm)/hy = 6.4×10-5

(eyby)1/2 = 20 mm

38 mm26 mm

52 mm32 mm

hy = 810 mmqy = 30

hy = 810 mmqy = 30

sd = 1.0×10-5 (PW) sd = 5.0×10-5 (LH)

sdm (16 mm)/hy = 2.0×10-5 sdm (45 mm)/hy = 5.6×10-5

(eyby)1/2 = 12 mm

Spectrometer at Low Charge (Q = 10 pC, gey = gex = 0.15 mm)

sE sE

45 mm16 mm

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

qy = 30

6×10-5

Parameter symbol value UnitKicker length Lk 0.5 mKicker field Bk 0.0063 TKicker field regulation (7% jitter) (DBk/Bk)rms 0.01 %Vert. e- pos. at face of septum Dy 15 mmSeptum bend angle qx 6.0 degSeptum field Bs 0.043 TSeptum length Ls 0.8 mSeptum roll angle js 9.65 degBeam line hor. offset (wrt linac) Dx 0.7 mTCAVX (and TCAY) lengths Lxc,yc 0.8 mMax. crest TCAV voltage (S-band) Vx,y 0.5 MVSpectrometer bend length Ly 0.5 mSpectrometer bend field By 0.23 TSpectrometer bend angle qy 20 (30?) degQuadrupole lengths LQ 0.1 mQuadrupole pole-tip radius rp 16 mmMax. quadrupole pole-tip field Bp 0.12 T

Beamline Parameters

9-page PRD ready

L

hy

Quad focal length:

Chromatic aberration:

𝑓 ≈ 𝐿 /8Δ 𝜀𝜀0

≈ 12 ( 𝛽𝑓 )

2

𝜎𝛿❑2

𝐿≈8 𝛽𝜎𝛿

❑

√2 ( Δ 𝜀 /𝜀 )

Chromatic Limitation on Dog-Leg Length

Dog-Leg length:

b = 20 m, sd = 0.2%, De/e0 1%, L ≥ 2.3 m

b = 20 m, sd = 2.0%, De/e0 1%, L ≥ 23 m

Laser Heater:

BC1: