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Paul Emma, et. al.Sep. 18, 2013
Paul Emma, et. al.Sep. 18, 2013
Design Considerations for the NGLS (Next Generation Light Source)
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 m, 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 21010 - 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 MHz
Gun gradient 20 MV/m
Laser pulse (flat top) 44 ps
7 A (45 A)
Final e-beam energy 94 MeV
Energy spread (rms) 20 keVDrive laser l (Cs2Te) 266 nm
Quantum efficiency ~5 %
solenoids1.3-GHz buncher
8
gex,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 %
L0j 0
V0 94 MV
L1j = -17.0°
V0 = 195 MV
HLj = 180°
V0 = 0
L2j = -18°
V0 = 600MV
L3j = 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)
j(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-1mo
d-1
rad-2mo
d-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