1

HXRSS Design Status

P. Emma et alFeb. 25, 2011

2

3

Figure 1 of the paper…

Taper last 10 undulators for 100-GW power level

1-mm rms e- pulse length (3 fs)

“…introduces no path delay of x-rays”

Taper works better

4

HRXSS Physics Requirements Document:Electron & FEL parameters (e.g., 20 pC)Chicane parametersMagnet requirementsCrystal with position/angle controlsVacuum chamber requirementsBragg diagnostic requirementsAll tolerances

5

2.6 mm

60 cm 60 cm

New HXR Self-Seeding Chicane for the LCLS Undulator (~U12)

QUAD

QUAD

3.4 m

existing undulator segment

QUAD

QUAD

BFW

|B0| ≈ 3.34 kG, R56 = 12 mm, cDt = 6 mm, hmax = 2.6 mm, q = 2.67 mrad

ELEVATION VIEW

PLAN VIEW

QUAD

QUAD

Remove one segment and add chicane (1.5 Å, 13.64 GeV)

BFW

BPM

BPM

BPM

e-

BFW

0-80 mm

chicane raft

B3B1 B4B2

36cm

36cm

36cm

36cm

3.20 m

58 cm

Beam Finder Wire

e-

crystal

provides 0-40 fs delay

6

32 mm

alignment stage

chicane raft

motor

0 - 80 mm

80 mm

e- beam with dipoles ON & inserted e- & x-ray beam with

dipoles retracted

existing girder

356 mm

8 mm

alignment stage

chicane raft

existing girder

existing horizontal slider

cross-sectional view elevation view

x-ray beam with dipoles inserted

2.6 mm

7

vq

CCD camera

YAG screen (>0.3-mm thick?)

crystaltransmitted x-raysincident x-rays

Bragg reflected x-rays

0.1 mm

vacuum window

f

FEL Wavelength Range: lr = 1.4 to 1.7 Å (somewhat arbitrary)Bragg Crystal Angles : q = 51.7° (1.4 Å) to 72.4° (1.7 Å)Camera Viewing Angles : f = 2(p/2 - q) = 35.2° to 76.6° (>41°)*

* Compromise: Allow camera viewing only from 1.4 to 1.6 Å or f = 77.6° to 51.4° (~27° range)

8

HXRSS Chicane Dipole Magnet Design is ReadyD. Walz• 0-6 A• 576 main coil turns• ±1% trim coils (±6 A)• No water cooling• ~50 W/magnet• 0.02° C tunnel rise

9

Possible 4-Axis Diamond Positioning System

D. Shu (ANL)

10

Possible HXRSS Layout at U15 (or U16)

J. Amann (SLAC)D. Shu (ANL)

Sliding raft to move all 4 dipoles IN or OUT (8 cm)

Crystal chamber (ion pump must move)

11

Issues

Do we place it at U15 or U16 (need ~1 GW seed)?Will we lose power in SASE mode (25% so far)?Can the chicane be tweaked to fix the phase error?Is a 0-40 fs chicane OK (i.e., only 20-40 pC supported)OK to have 2.6-mm crystal-to-electron hor. clearance?Commissioning plan started, but needs more thought.Existing LCLS monochromator only measures 10-4 BW. This will have to suffice OK for now?What will go wrong and how do we avoid it?