Download - Longitudinal Space Charge (LSC) modeling
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Simulation of Microbunching Instability in LCLS with Laser-HeaterJuhao Wu, M. Borland (ANL), P. Emma, Z. Huang, Juhao Wu, M. Borland (ANL), P. Emma, Z. Huang,
C. Limborg, G. Stupakov, J. WelchC. Limborg, G. Stupakov, J. Welch
Simulation of Microbunching Instability in LCLS with Laser-HeaterJuhao Wu, M. Borland (ANL), P. Emma, Z. Huang, Juhao Wu, M. Borland (ANL), P. Emma, Z. Huang,
C. Limborg, G. Stupakov, J. WelchC. Limborg, G. Stupakov, J. Welch
Longitudinal Space Charge (LSC) modelingLongitudinal Space Charge (LSC) modeling Drift space and Accelerator cavity as test-bed for a LSC Drift space and Accelerator cavity as test-bed for a LSC
modelmodel Implement of LSC model in ELEGANTImplement of LSC model in ELEGANT
Simulation of microbunching instability (ELEGANT)Simulation of microbunching instability (ELEGANT) Without laser-heaterWithout laser-heater With laser-heaterWith laser-heater
Longitudinal Space Charge (LSC) modelingLongitudinal Space Charge (LSC) modeling Drift space and Accelerator cavity as test-bed for a LSC Drift space and Accelerator cavity as test-bed for a LSC
modelmodel Implement of LSC model in ELEGANTImplement of LSC model in ELEGANT
Simulation of microbunching instability (ELEGANT)Simulation of microbunching instability (ELEGANT) Without laser-heaterWithout laser-heater With laser-heaterWith laser-heater
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
MotivationMotivationMotivationMotivation• What’s new? LSC important in photoinjector and
downstream beam line; (see Z. Huang’s talk)• PARMELA / ASTRA simulation time consuming for S2E;
difficult for high-frequency microbunching (numerical noise);
• Find simple, analytical LSC model, and implement it to ELEGANT for S2E instability study;
• Starting point –- free-space 1-D model; (justification)• Transverse variation of the impedance decoherence;
small? 2-D?• Pipe wall decoherence; small?
• Test LSC model in simple element
• Use such a LSC model for S2E instability study
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
LSC Model (1-D)LSC Model (1-D)• Free space 1-D model: transverse uniform coasting beam with
longitudinal density modulation (on-axis)
where, rb is the radius of the coasting beam;
• For more realistic distribution find an effective rb, and use the above impedance;
• Radial-dependence of the impedance will increase energy spread and enhance damping; small?
pancake beam
pencil beam
rb
λ
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Space Charge Oscillation in a Coasting BeamSpace Charge Oscillation in a Coasting BeamSpace Charge Oscillation in a Coasting BeamSpace Charge Oscillation in a Coasting Beam• Distinguish: low energy case high energy case; • Space charge oscillation becomes slow, when the electron
energy becomes high; the residual density modulation is then ‘frozen’ in the downstream beam line.
rb=0.5 mm, I0=100 A
E = 12 MeV
E = 6 MeV
freq. plasma 2
2/1
30
2/1
0030
pAb
LSCA
scI
I
r
ckZk
I
Ic
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Two QuantitiesTwo QuantitiesTwo QuantitiesTwo Quantities
• The quantities we concern are density modulation, and energy modulation
sfedN
skb ikz ;1
);( XX
Density modulation
s
AI
kbkZIds
00 ]);([]);([
)(
Energy modulation R56
Integral equation approach
Heifets-Stupakov-Krinsky(PRST,2002); Huang-Kim(PRST,2002) (CSR)
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Analytical integral equation approachAnalytical integral equation approachFind Find an effective radiusan effective radius for realistic transverse distributions and for realistic transverse distributions and use 1-D formula for LSC impedance; for parabolic & Gaussianuse 1-D formula for LSC impedance; for parabolic & Gaussian
GeneralizeGeneralize the momentum compaction function to treat the momentum compaction function to treat acceleration in LINAC, and for drift space as wellacceleration in LINAC, and for drift space as well
SimulationSimulationPARMELAPARMELAASTRAASTRAELEGANTELEGANT
Analytical integral equation approachAnalytical integral equation approachFind Find an effective radiusan effective radius for realistic transverse distributions and for realistic transverse distributions and use 1-D formula for LSC impedance; for parabolic & Gaussianuse 1-D formula for LSC impedance; for parabolic & Gaussian
GeneralizeGeneralize the momentum compaction function to treat the momentum compaction function to treat acceleration in LINAC, and for drift space as wellacceleration in LINAC, and for drift space as well
SimulationSimulationPARMELAPARMELAASTRAASTRAELEGANTELEGANT
Testing the LSC modelTesting the LSC modelTesting the LSC modelTesting the LSC model
s
xx
dxs
2356)(1)(
)(
xbr 7.1
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Integral EquationsIntegral EquationsIntegral EquationsIntegral Equations
s
kbsKdsskbsskb00 ]);([),(]);([]);([
Density modulation
Energy Modulation:
s
AI
kbkZIds
00 ]);([]);([
)(
AI
KZIssiksK
]);([)()()(),( 56
• Applicable for both accelerator cavity and drift space
• Impedance for LSC
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Analytical integral equation approach – two limitsAnalytical integral equation approach – two limitsDensity and energy modulation in a drift at distance Density and energy modulation in a drift at distance ss;;
At a very large At a very large , plasma phase advance , plasma phase advance ((s/c) << 1s/c) << 1, , “ “frozen,” energy modulation gets accumulatedfrozen,” energy modulation gets accumulated(Saldin-Schneidmiller-Yurkov, TESLA-FEL-2003-02)(Saldin-Schneidmiller-Yurkov, TESLA-FEL-2003-02)
Integral equation approach deals the general evolution of Integral equation approach deals the general evolution of the density and energy modulationthe density and energy modulation
Analytical integral equation approach – two limitsAnalytical integral equation approach – two limitsDensity and energy modulation in a drift at distance Density and energy modulation in a drift at distance ss;;
At a very large At a very large , plasma phase advance , plasma phase advance ((s/c) << 1s/c) << 1, , “ “frozen,” energy modulation gets accumulatedfrozen,” energy modulation gets accumulated(Saldin-Schneidmiller-Yurkov, TESLA-FEL-2003-02)(Saldin-Schneidmiller-Yurkov, TESLA-FEL-2003-02)
Integral equation approach deals the general evolution of Integral equation approach deals the general evolution of the density and energy modulationthe density and energy modulation
Analytical Approach – Two LimitsAnalytical Approach – Two LimitsAnalytical Approach – Two LimitsAnalytical Approach – Two Limits
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
• 3 meter drift without accelerationAnalytical vs. ASTRAAnalytical vs. ASTRA (energy modulation)Analytical vs. ASTRAAnalytical vs. ASTRA (energy modulation)
• In analytical approach:• Transverse beam size variation due to transverse space charge: included;• Slice energy spread increases: not included;
• 1 keV resolution? Coasting beam vs. bunched beam?
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Analytical vs. ASTRAAnalytical vs. ASTRA (density modulation)Analytical vs. ASTRAAnalytical vs. ASTRA (density modulation)
• 3 meter drift without acceleration
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
• Assume 10% initial density modulation at gun exit at 5.7 MeV;• After 67 cm drift + 2 accelerating structures (150 MeV in 7 m), LSC
induced energy modulation;
PARMELA simulation Analytical approach
Analytical vs. PARMELA Analytical vs. PARMELA (energy modulation)
Analytical vs. PARMELA Analytical vs. PARMELA (energy modulation)
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
S2E SimulationS2E SimulationS2E SimulationS2E Simulation• LSC model
• Analytical approach agrees with PARMELA / ASTRA simulation;
• Wall shielding effect is small as long as (typical in our study);
• Free space calculation overestimates the results (10 – 20%);• Radial-dependence and the shielding effect decoherence; (effect
looks to be small)
• Free space 1-D LSC impedance with effective radius has has been implementedbeen implemented in ELEGANT;
• S2E simulation• Injector simulation with PARMELA / ASTRA (see C. Limborg’s
talk);• downstream simulations ELEGANT with LSC model (CSR, ISR,
Wake etc. are all included)
pipeRk
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Comparison with ELEGANTComparison with ELEGANT• Free space 1-D LSC model with effective radius • Example with acceleration: current modulation at different
wavelength
Elegant tracking Analytical calculation--- 1 mm, --- 1 mm, --- 0.5 mm,--- 0.5 mm, --- 0.25 mm, --- 0.25 mm, --- 0.1 mm --- 0.1 mm
I=100 A, rI=100 A, rbb=0.5 mm, E=0.5 mm, E00=5.5 MeV, Gradient: =5.5 MeV, Gradient: 7.5 MV/m7.5 MV/m
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Halton sequence (quiet start) particle generatorHalton sequence (quiet start) particle generatorBased on PARMELA output file at E=135 MeV, with 200 k Based on PARMELA output file at E=135 MeV, with 200 k particlesparticlesLongitudinal phase space: keep correlation between t and p --- fit Longitudinal phase space: keep correlation between t and p --- fit p(t), and also local energy spread p(t), and also local energy spread pp(t)(t)
Multiply density modulation (Multiply density modulation ( 1 %) 1 %)Transverse phase space: keep projected emittanceTransverse phase space: keep projected emittance6-D Quiet start to regenerate 2 million particles6-D Quiet start to regenerate 2 million particles
Bins and Nyquist frequency --- typically choose bins to make the Bins and Nyquist frequency --- typically choose bins to make the wavelength we study to be larger than 5 Nyquist wavelengthwavelength we study to be larger than 5 Nyquist wavelength
2000 bins for initial 11.6 ps bunch2000 bins for initial 11.6 ps bunchNyquist wavelength is 3.48 Nyquist wavelength is 3.48 mmWe study wavelength longer than 20 We study wavelength longer than 20 mm
Halton sequence (quiet start) particle generatorHalton sequence (quiet start) particle generatorBased on PARMELA output file at E=135 MeV, with 200 k Based on PARMELA output file at E=135 MeV, with 200 k particlesparticlesLongitudinal phase space: keep correlation between t and p --- fit Longitudinal phase space: keep correlation between t and p --- fit p(t), and also local energy spread p(t), and also local energy spread pp(t)(t)
Multiply density modulation (Multiply density modulation ( 1 %) 1 %)Transverse phase space: keep projected emittanceTransverse phase space: keep projected emittance6-D Quiet start to regenerate 2 million particles6-D Quiet start to regenerate 2 million particles
Bins and Nyquist frequency --- typically choose bins to make the Bins and Nyquist frequency --- typically choose bins to make the wavelength we study to be larger than 5 Nyquist wavelengthwavelength we study to be larger than 5 Nyquist wavelength
2000 bins for initial 11.6 ps bunch2000 bins for initial 11.6 ps bunchNyquist wavelength is 3.48 Nyquist wavelength is 3.48 mmWe study wavelength longer than 20 We study wavelength longer than 20 mm
Simulation DetailsSimulation DetailsSimulation DetailsSimulation Details
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
WakeWake
Low-pass filter is essential to get stable resultsLow-pass filter is essential to get stable resultsSmoothing algorithms (e.g. Savitzky-Golay) is not helpfulSmoothing algorithms (e.g. Savitzky-Golay) is not helpful
Non-linear regionNon-linear regionSynchrotron oscillation Synchrotron oscillation rollover rollover harmonics harmonicsLow-pass filter is set to just Low-pass filter is set to just allowallow the second harmonic the second harmonic
WakeWake
Low-pass filter is essential to get stable resultsLow-pass filter is essential to get stable resultsSmoothing algorithms (e.g. Savitzky-Golay) is not helpfulSmoothing algorithms (e.g. Savitzky-Golay) is not helpful
Non-linear regionNon-linear regionSynchrotron oscillation Synchrotron oscillation rollover rollover harmonics harmonicsLow-pass filter is set to just Low-pass filter is set to just allowallow the second harmonic the second harmonic
Simulation DetailsSimulation DetailsSimulation DetailsSimulation Details
)]()()]([FFT[IFFT)( ZftItW
Low-pass filter
Current form-factor
Impedance
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Gain calculation (linear region)Gain calculation (linear region)Choose the central portion to do the analysisChoose the central portion to do the analysisUse polynomial fit to remove any gross variationUse polynomial fit to remove any gross variationUse NAFF to find the modulation wavelength and the amplitudeUse NAFF to find the modulation wavelength and the amplitude
Gain calculation (linear region)Gain calculation (linear region)Choose the central portion to do the analysisChoose the central portion to do the analysisUse polynomial fit to remove any gross variationUse polynomial fit to remove any gross variationUse NAFF to find the modulation wavelength and the amplitudeUse NAFF to find the modulation wavelength and the amplitude
Simulation DetailsSimulation DetailsSimulation DetailsSimulation Details
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Without laser-heater (Without laser-heater ( 1% initial density modulation at 30 1% initial density modulation at 30 m )m )Really badReally bad
With matched laser-heater (With matched laser-heater ( 1% initial density modulation at 30 1% initial density modulation at 30 m )m )Microbunching is effectively dampedMicrobunching is effectively damped
Without laser-heater (Without laser-heater ( 1% initial density modulation at 30 1% initial density modulation at 30 m )m )Really badReally bad
With matched laser-heater (With matched laser-heater ( 1% initial density modulation at 30 1% initial density modulation at 30 m )m )Microbunching is effectively dampedMicrobunching is effectively damped
Phase space evolution along the beam linePhase space evolution along the beam linePhase space evolution along the beam linePhase space evolution along the beam line
30 m
5105
EE
EE
time (sec)
injector output (135 MeV)
= 30 = 30 mm
5105
NO HEATERNO HEATER
1% LCLS
time (sec)
30 m
EE
EE
after DL1 dog-leg (135 MeV)
= 30 = 30 mm
5105
5105
NO HEATERNO HEATER
LCLS
time (sec)
time (sec)
30 m
EE
EE
before BC1 chicane (250 MeV)
= 30 = 30 mm
11031103
NO HEATERNO HEATER
LCLS
time (sec)
time (sec)
30/4.3 m
EE
EE
after BC1 chicane (250 MeV)
= 30 = 30 mm
1103
1103
NO HEATERNO HEATER
LCLS
time (sec)
time (sec)
30/4.3 m
EE
EE
before BC2 chicane (4.5 GeV)
= 30 = 30 mm
5104
5104
NO HEATERNO HEATER
LCLS
time (sec)
time (sec)
30/30 m
EE
EE
after BC2 chicane (4.5 GeV)
= 30 = 30 mm
21032103
NO HEATERNO HEATER
LCLS
time (sec)
time (sec)
30/30 m
EE
EE
before undulator (14 GeV)
= 30 = 30 mm
11031103
NO HEATERNO HEATER
0.09 % rms
LCLS
time (sec)
time (sec)
30 m
5105
EE
EE
injector output (135 MeV)
= 30 = 30 mm
5105
MATCHEDMATCHED HEATER HEATER
1% LCLS
time (sec)
time (sec)
30 m
EE
EE
just after heater (135 MeV)
= 30 = 30 mm
510455101044
MATCHEDMATCHED HEATER HEATER
LCLS
time (sec)
time (sec)
30 m
EE
EE
after DL1 dog-leg (135 MeV)
= 30 = 30 mm
510455101044
MATCHEDMATCHED HEATER HEATER
LCLS
time (sec)
time (sec)
30 m
EE
EE
before BC1 chicane (250 MeV)
= 30 = 30 mm
11031103
MATCHEDMATCHED HEATER HEATER
LCLS
time (sec)
time (sec)
30/4.3 m
EE
EE
after BC1 chicane (250 MeV)
= 30 = 30 mm
2103
MATCHEDMATCHED HEATER HEATER
2103
LCLS
time (sec)
time (sec)
30/4.3 m
EE
EE
before BC2 chicane (4.5 GeV)
= 30 = 30 mm
5104 5104
MATCHEDMATCHED HEATER HEATER
LCLS
time (sec)
time (sec)
30/30 m
EE
EE
after BC2 chicane (4.5 GeV)
= 30 = 30 mm
5104
5104
MATCHEDMATCHED HEATER HEATER
LCLS
time (sec)
time (sec)
30/30 m
EE
EE
before undulator (14 GeV)
= 30 = 30 mm
2104
2104
MATCHEDMATCHED HEATER HEATER
0.01% rms
LCLS
time (sec)
time (sec)
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
End of BC2
Undulator entrance
Nonlinear region / Saturation
LCLS gain and slice energy spreadLCLS gain and slice energy spreadLCLS gain and slice energy spreadLCLS gain and slice energy spread
1%, 301%, 30mm
Laser-Heater Physics Review, March 01, 2004Laser-Heater Physics Review, March 01, 2004 Juhao Wu, SLACJuhao Wu, SLAC
Simulation of Microbunching Instability in LCLS with Laser-Simulation of Microbunching Instability in LCLS with Laser-HeaterHeater
[email protected]@SLAC.Stanford.EDU
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Discussion and ConclusionDiscussion and ConclusionDiscussion and ConclusionDiscussion and Conclusion
Instability not tolerable without laser-heater for Instability not tolerable without laser-heater for < 200 -- < 200 -- 300 300 m with about m with about 1% density modulation after 1% density modulation after injector;injector;
Laser-heater is quite effective and a fairly simple and Laser-heater is quite effective and a fairly simple and prudent addition to LCLS;prudent addition to LCLS;
Injector modulation study also important, no large Injector modulation study also important, no large damping is found to confidently eliminate heater. (damping is found to confidently eliminate heater. (see C.
Limborg’s talk) )
Instability not tolerable without laser-heater for Instability not tolerable without laser-heater for < 200 -- < 200 -- 300 300 m with about m with about 1% density modulation after 1% density modulation after injector;injector;
Laser-heater is quite effective and a fairly simple and Laser-heater is quite effective and a fairly simple and prudent addition to LCLS;prudent addition to LCLS;
Injector modulation study also important, no large Injector modulation study also important, no large damping is found to confidently eliminate heater. (damping is found to confidently eliminate heater. (see C.
Limborg’s talk) )