LCLSII 5keV FEL SASE simulations
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LCLSII 5keV FEL SASE simulations
Y. Ding(SLAC)
LCLSII physics meeting 11/6/2013
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Ideal flat beam check
• 4 GeV, 1kA, 0.4µm emittance, 500keV energy spread;
• Undulator period 2.6cm, K = 0.585 (aw=0.414);• Each section 3.38m (N=130), break 1.17m (N=45). • Total undulator beamline including breaks and
U16( it is a drift in setup) is ~150m.• FEL 5keV (2.486 Angstrom)• Checked emittance, current and beta function
with Genesis simulations using a flat beam.
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Ideal flat beam: gain curve vs emittance
Gain vs. emittance (beta function 15m, 1kA, 500keV energy spread).
Gain vs. current (beta function 15m, 0.3µm, 500keV energy spread).
1kA
800A0.4µm
0.35µm0.3µm
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S2E beam from Paul4GeV, 100pC: ~1kA, 500keV energy spread, core slice emittance ~0.3µm.
0.3µm slice emittance
head
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Match and center the core part
t-x t-xp
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Match and center the Core part
Total pulse energy ~ 18µJ, ~ 35 fs (half of e-beam )
Average beta 20m
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Summary: 5keV, SASE
• Resistive wall wake field from undulator chamber is checked, and negligible at this beam condition.
• With the present S2Ebeam, it barely works at 5keV and the core 0.3um emittance helps.
• CSR limits higher currents. This might be further optimized.
• LSC and mircobunching not included in this S2E beam.