s2e in lcls linac m. borland, lyncean technologies, p. emma, c. limborg, slac
TRANSCRIPT
S2E in S2E in LCLSLCLS Linac Linac
M. Borland, M. Borland, Lyncean Technologies,Lyncean Technologies,P. Emma, C. Limborg, P. Emma, C. Limborg, SLACSLAC
L = 6 m L = 9 mrf = 38°
L = 330 mrf = 43°
L = 550 mrf = 10°
BC-1L = 6 m
R56= 36 mm
BC-2L = 22 m
R56= 22 mm DL-2R56 = 0
DL-1R56 0
undulatorL = 120 m
6 MeVz 0.83 mm 0.1 %
150 MeVz 0.83 mm 0.10 %
250 MeVz 0.19 mm 1.8 %
4.54 GeVz 0.022 mm 0.76 %
14.35 GeVz 0.022 mm 0.01 %
...existing linac
L0
rfgun
L3L1 X
LhL =0.6 mrf=
L2
LCLSLCLS
Nominal Nominal LCLSLCLS Optics… Optics…
LCLSLCLS Start-to-End Tracking Simulations Start-to-End Tracking Simulations
Track entire machine to evaluate beam Track entire machine to evaluate beam brightness & FELbrightness & FEL
Track machine many times with jitter to test Track machine many times with jitter to test stability budgetstability budget
See C. Limborg talk for injectorSee C. Limborg talk for injector See Fawley, Reiche talks for FELSee Fawley, Reiche talks for FEL
ParmelaParmelaParmelaParmela ElegantElegantElegantElegant GenesisGenesisGenesisGenesis
space-chargespace-charge compression, wakes, CSR, …compression, wakes, CSR, … SASE FEL with wakesSASE FEL with wakes
LCLSLCLS
Initial Beam from Initial Beam from ParmelaParmela Tracking Tracking
1 nC1 nC10-psec 10-psec FWHMFWHM0.7-ps rise/fall0.7-ps rise/fall120 MV/m gun120 MV/m gunthermtherm 0.3 0.3
mm150 MeV150 MeV22101055 to 2 to 2101066
macro-particlesmacro-particles
x, yx, y
xx,,yy < 1 < 1 mmxx
yy
z, z, E/EE/E
Sliced Sliced ee- Beam to Evaluate FEL (- Beam to Evaluate FEL (zz 0.7 0.7 mmm)m)
IIpkpkxx,,yy EE//EE
mismatch variationmismatch variation
slice 4D centroid osc. amplitudeslice 4D centroid osc. amplitude
centroid match FEL wavelength
see S. Reiche, B. Fawley talks…see S. Reiche, B. Fawley talks…
‘‘Ming Xie method’Ming Xie method’
FEL parameter gain length FEL power
X-bandX-band XX--
LCLS.LCLS.
LCLS Longitudinal Jitter Tolerance BudgetLCLS Longitudinal Jitter Tolerance Budget
note, note, ElegantElegant simulations simulations use 0.5 ps use 0.5 ps rmsrms
zz//zz00 12.5% 12.5%
// 0.1% 0.1%
//00 8.6% 8.6%
EE//EE 0.01% 0.01%
ttrmsrms 125 fs 125 fs
ttfwfw//ttfwfw 12.5% 12.5%
2D2D tracking tracking used to used to develop develop
tolerance tolerance budgetbudget
Now add component transverse misalignments…Now add component transverse misalignments…
Misaligned randomly in Misaligned randomly in xx and and yy:: All quadrupoles: All quadrupoles: 300 300 m rmsm rms All rf structures: All rf structures: 300 300 m rmsm rms All BPMs:All BPMs: 300 300 m rmsm rms
Misaligned randomly in Misaligned randomly in xx and and yy:: All quadrupoles: All quadrupoles: 300 300 m rmsm rms All rf structures: All rf structures: 300 300 m rmsm rms All BPMs:All BPMs: 300 300 m rmsm rms
Transverse wakefields induce projected emittance growth and couple charge jitter to
emittance jitter
xx--yy screen screen
trajectory trajectory beforebefore steering steering
Misaligned randomly in Misaligned randomly in xx and and yy:: All quadrupoles: All quadrupoles: 300 300 m rmsm rms All rf structures: All rf structures: 300 300 m rmsm rms All BPMs:All BPMs: 300 300 m rmsm rms
Misaligned randomly in Misaligned randomly in xx and and yy:: All quadrupoles: All quadrupoles: 300 300 m rmsm rms All rf structures: All rf structures: 300 300 m rmsm rms All BPMs:All BPMs: 300 300 m rmsm rms
xx 10000 10000 mm
afterafter
Steered using Steered using ElegantElegant’s ‘global’ ’s ‘global’ algorithmalgorithm
Steered using Steered using ElegantElegant’s ‘global’ ’s ‘global’ algorithmalgorithm
xx 5 5 mm
yy 2 2 mm
xx 5 5 mm
yy 2 2 mm
trajectory trajectory afterafter steering steering
afterafter
Now let Now let ElegantElegant optimize both optimize both xx and and yy emittances with emittances with two two x-x- and two and two y-y-steering coils steering coils (pairs separated (pairs separated by by /2)/2)
Now let Now let ElegantElegant optimize both optimize both xx and and yy emittances with emittances with two two x-x- and two and two y-y-steering coils steering coils (pairs separated (pairs separated by by /2)/2)
steering coilssteering coils
xx 1.02 1.02
mmyy 1.09 1.09
mm
xx 1.02 1.02
mmyy 1.09 1.09
mm
M. Borland optimized 100 random seeds…M. Borland optimized 100 random seeds…
// 20% (projected) 20% (projected)
xx ( (
m)
m)
xx-position of feedback set-point (-position of feedback set-point (m)m)
Real Emittance Minimization Using Trajectory ‘Bumps’ in SPPSReal Emittance Minimization Using Trajectory ‘Bumps’ in SPPS
~10 minutes~10 minutes
((NeNe 3.5 nC, 3.5 nC, zz 1 mm) 1 mm)
H. Schlarb, H. Schlarb, P. EmmaP. Emma
Now run 200 Now run 200 S2ES2E simulations, including simulations, including GenesisGenesis runs, runs, but with a distorted and ‘emittance-tuned’ trajectory… but with a distorted and ‘emittance-tuned’ trajectory…
M. Borland,M. Borland,PE,PE,
J. Lewellen,J. Lewellen,C. Limborg,C. Limborg,M. WoodleyM. Woodley
SC-wiggler SC-wiggler is ONis ON
II 3.91 kA, rms 3.91 kA, rms 10% 10% xx 2.29 2.29 m, rms m, rms 5% 5%
EE 14.36 GeV, rms 14.36 GeV, rms 0.04% 0.04% yy 0.93 0.93 m, rms m, rms 4% 4%
projected projected xx-emittance-emittance
ee energy energy
projected projected yy-emittance-emittance
peak currentpeak current
xxss 0.76 0.76 m, rms m, rms 2% 2%
yyss 0.67 0.67 m, rms m, rms 2% 2%
sliced sliced xx-emittance-emittance
sliced sliced yy-emittance-emittance
bunch arrival timebunch arrival timett 0, rms 0, rms 49 fs 49 fs
EEEE 7 7101055, rms , rms 0.8 0.8101055
sliced energy spreadsliced energy spread
xx-position-positionxx 0, rms 0, rms 9 9 m (30% m (30% xx))
yy 0, rms 0, rms 1.5 1.5 mmyy-position-position
xx-angle-anglexx 0, rms 0, rms 0.55 0.55 radrad
yy 0, rms 0, rms 0.21 0.21 radradyy-angle-angle
mean mean values values set to set to
zero for zero for Genesis Genesis
runsruns
wavelengthwavelength
rr 1.5 1.5 ÅÅ, rms , rms 0.09 0.09
gain lengthgain length
LLgg ? m, rms ? m, rms 5% 5% PP 4 GW, rms 4 GW, rms 25% ??? 25% ???
Gain lengthGain length
LLgg 4.1 m, rms 4.1 m, rms 5 5
Fairly realistic simulations with jitter demonstrate tight, but Fairly realistic simulations with jitter demonstrate tight, but achievable tolerances – achievable tolerances – SPPSSPPS experience very helpful experience very helpful
Transverse wakefields are correctable – not a major issue Transverse wakefields are correctable – not a major issue (lower charge, shorter linac, and shorter bunch vs. (lower charge, shorter linac, and shorter bunch vs. SLCSLC))
LCLSLCLS still deciding on SC-wiggler at BC2, or laser system at still deciding on SC-wiggler at BC2, or laser system at injector (as proposed at DESY for TTF-2; Saldin injector (as proposed at DESY for TTF-2; Saldin et al.et al.))
LCLSLCLS entering engineering stage – detailed design must be entering engineering stage – detailed design must be ‘nailed’ down very soon (CD-2b in March 2004)‘nailed’ down very soon (CD-2b in March 2004)
Final CommentsFinal Comments**
* Special thanks to M. Borland: working for free!* Special thanks to M. Borland: working for free!
initial modulation period prior to BC1initial modulation period prior to BC1
CSR gain (1D-model) in CSR gain (1D-model) in LCLSLCLS without wakefield or long. space-charge without wakefield or long. space-charge
SC-wig ONSC-wig ON
SC-wig OFFSC-wig OFF
see Z. Huang talk Tuesdaysee Z. Huang talk Tuesday