Paul Emma, et. al.Sep. 18, 2013

Design Considerations for the NGLS (Next Generation Light Source)

NGLS

What are the new facility directions ?

High-rate and Continuous Wave (CW) operation

FEL seeding for narrow BW & full coherence

Femtosecond x-ray pulses (~ 10-15 sec)

Multiple FELs with independently tunable wavelengths

Pulse length and BW control at FT-limit

Two-Color pulses with variable relative timing & color

Expandable facility well into the future

A Next Generation Light Source (NGLS)

A High Repetition Rate CW X-Ray FEL ArrayCW Superconducting Linac

X-Ray Beamlines and End-stations

3-9 FELs

~10 ms

~100 ms 600 ms

1 ms (CW)

BC1 BC2 2.4 GeV1 MHz injector

An Array of Unique Free-Electron Lasers

FEL-1Self-Seeded(250-1250 eV)

FEL-3Two-Color(250-1000 eV)

FEL-22-Stage HGHG(100-600 eV)

NGLS Layout

1 MHz CW e- injector ( = 0.6 mm, Q = 300 pC)1.3-GHz CW SRF @ 15 MV/m (24 CM’s, 0.3 mA)Two bunch compressors + heater (500 A)Beam spreader using RF deflectors (9 FELs)Three (initial) very diverse FEL designsDiagnostics and collimation sections720-kW main beam stops (3)

injector linac spreaderFELs (1-9)

beam stops

compressorse- diagnostics

e- diagnostics

exp. halls

collimation

Parameter Value UnitRF frequency 1300 MHzOperating temperature 1.8 KNumber of cav. per CM 8 -Mean operating gradient 14 MV/mAverage Q0 per CM 2101

0-

Lorentz detuning 1.5 Hz/(MV/m)2

Peak detune allowance 15 HzQext 3107 -Min. RF power per cavity 5.4 kWTotal cavity dynamic load 12.5 WRF AC power 1.8 MWTotal cryo-plant AC power 3.6 MW

Parameters for the CW SC-Linac (2.4 GeV)

J. Corlett, L. Doolittle, A. Ratti, R. Wells, et al.

Linac V(MV)

(deg)

Grad.(MV/m)

N CM’s

L0 95 ~0 15.9 1L1 129 –20 8.2 2L2 604 –23 12.9 6L3 1630 0 14.0 15

Average current = 0.3 mA

Achieved:Successful CW operationExcellent RF design performance at full power (20 MV/m)E-beam design energy (0.75 MeV)< 10-10 gun vac. pressureCs2Te cathode generating 100’s of pC/bunch @ 1 MHz40 C in 4 days: QE goes from 10% to 4% (promising lifetime)

Next Steps:Test CsK2Sb cathodes (green laser)6D phase space characterization at gun energy (and later at 30 MeV)

NGLS Photo-Cathode Gun (APEX)

F. Sannibale, D. Filippetto, C. Papadopoulos, R. Wells

186MHz

e-

NGLS High-Rate Injector (R&D at APEX - LBNL)

RF Gun

0.8 MeVwarm

UV

Bunch charge 300 pC

Beam rate 1 MHzGun gradient 20 MV/mLaser pulse (flat top) 44 ps

7 A (45 A)

Final e-beam energy 94 MeV

Energy spread (rms) 20 keVDrive laser l (Cs2Te) 266 nmQuantum efficiency ~5 %

solenoids1.3-GHz buncher

8

x,y < 0.6 mm

Ipk 45 A

sE/E 20 keV

APEX Gun (1 MHz CW)

Cs2Te

F. Sannibale, D. Filippetto, C. Papadopoulos, R. Wellscold

94 MeV

Eight 9-cell TESLA cavities (1.3 GHz)

APEX Parameters (done):

first beam

Mar. 18 ’13

velocity bunching ( 1/6)

186MHz

650-MHz booster for the injector? Possible layout for injector and first linac section

moderate ( RF compression beam is close to parabolic.

at end of linacNo need for 3.9 GHz RF linearizer

1.5-2 kAM. Venturini

Removing Energy Chirp with a Wakefield

add 5-m long de-chirper(2a = 6 mm)

L3 on crest

…or 35-deg off crest

5-m long dechirper

NGLS Longitudinal Phase Space

K. Bane,P. Emma,H.-S. Kang,G. Stupakov,M. Venturini

point-charge wake

PAL-ITF Dechirper Simulationsdechirper off

a = 4-15 mmp = 0.5 mmh = 0.6 mmg = 0.3 mmL = 1 m

dechirper on

PAL-ITF (Korea)

corrugated pipe

Aug. ‘13 experiment

Linac and Compressor Layout for 4 GeV

(cathode to undulator)

CM01 CM2,3 CM04 CM08 CM09 CM34

BC1280 MeV

R56 = -85 mmIpk = 100 A

Lb = 0.75 mmsd = 0.62 %

BC2850 MeV

R56 = -80 mmIpk = 500 A

Lb = 0.13 mmsd = 0.50 %

GUN0.75 MeV

LH94 MeV

R56 = -5 mmIpk = 46 A

Lb = 1.5 mmsd = 0.02 %

L0 0

V0 94 MV

L1 = -17.0°

V0 = 195 MV

HL = 180°

V0 = 0

L2 = -18°

V0 = 600MV

L3 = 0

V0 = 3150 MV

Spreader4.0 GeVR56 = 0

Ipk = 500 ALb = 0.13 mmsd 0.008 %

300 pC; Machine layout 2013-08-27; Bunch length Lb is FWHM

3.9GHz

Linac eV(MeV)

(deg)

Acc. Grad. (MV/m)

N. Cryo Mod’s

Spare Cav’s

L0 94 ~0 15.9 1 1

L1 194/215 -17/-30 12.4/15.9 2 1

HL 0/-30 -180 15.2/15.9 1 (3.9GHz) 0

L2 600/630 -18/-25 15.2/15.9 5 2

L3 3150/3200 0/±10 15.5/15.7 26 12

t

V 186

139

139 MHz = 3/4186 MHz (7.2 ns)

zDC bendseptumseptum

Beam Spreader System

RFdeflector

Split again 3 times with 3 more deflectors at 151 MHz = 13/16186 MHz (6.6 ns)

y

x

y

x

y

x

x

RF gun frequency = 1300/7 MHz 186 MHz(5.4 ns)

end oflinac

Phase-I (3 FELs) needs only one

RF deflector

Keep l long (139 MHz)

Dt = 5.4 nscollide two x-ray pulses

distribute e- bunches to 3-9 FELsM. Placidi,C. Sun

5.4 ns

Pulse-Stealing Diagnostics (BC1, BC2, EOL)

250-W dump

1200-W dump

1 MHz Linac

Intercepting diagnostics used only at low rate

Measure at 1 kHz:• Energy• Proj. energy spread• Slice energy spread• Proj. emittance• Slice emittance• Bunch length• Charge…

1 kHz Kicker (<1 ms)

TCAV

Screens/wires

100-W dump

Superconducting Undulator Technology

LCLS

Nb 3Sn

Perm. Mag.

NbTiNGLS

S. Prestemon, D. Arbelaez80% of short sample limit

Use Nb3Sn SC-undulators for efficiency & rad. hardness

Magnetic gap = 7.5 mm. Vacuum chamber 5.5 mm

97 m

Lmag = 26.4 m, Nu = 8 Lmag = 36.3 m, Nu = 11 P 

35.2 m 52.8 m

8.8 m

mon

o.20

000

4.4 mFEL-1 (SASE/Self-Seeded)

1 MHz230-1250 eVTo 2 keV SASENear FT-limit

58 m

         P    

   

rad-1mod

-1

rad-2mod

-2

 

4.4 m

6.0 m66 6 6

Lmag = 26.4 m, Nu = 8

FEL-2 (2-Stage HGHG)

0.1 MHz100-600 eV + 3rd stage optionFT-limited pulses (7 - 70 fs)

    

 

123 m

Lmag = 33 m, Nu = 10 P   

4.4 m

mod

1

48.4 m

Lmag = 33 m, Nu = 10 P

48.4 m

mod

2

0.5 mr

3 m

mFEL-3 (Two-Color FEL)

0.1 MHz, 230-1000 eV, two 1-fs pulses, variable color, pol., & timing

Based on Fermi Results in Trieste

Based on SXRSS

Based on SPARC Chirp/Taper Results in Frascati

Chirped/Tapered 2-Color FEL

Two 1-fs pulses at 0.1 MHz, 250-1000 eV, var. color, pol., & timingPossible attosec. pulse with ESASE

Few cycle 2-5 mm laser pulse chirps very short section of e-beam

G. Marcus, A. Zholents

ΔtFWHM ≈ 1.7 fs

21010 at1.0 keV

addtaper

8 fs

chirpedSASE

e-

More LBNL Presentations Soon

Wed. Sep. 25 (13:30)G. Penn - Three Unique FEL’s for NGLSJ. Byrd - Longitudinal Feedback for SRF Linac

Thurs. Sep. 26 (09:00)M. Venturini – Bunch Compression and DynamicsF. Sannibale – High-Rate, High-Brightness Injector

Wed. Oct. 2 (13:30)?J. Corlett - Superconducting RF Linac Design

C. Steier - Collimation