1. Tapering optimizations for TW level superconducting undulators:
summary of simulation results
Claudio Emma, Paul Emma, Claudio Pellegrini, Juhao Wu
SLAC
July 2014

2. Simulation parameters and tapering optimisation
Undulator
Radiation Beam
Electron Beam
λu = 1.9 cm
λr = nm
I0 = 4 kA
K = 3.45
Prad = 5 MW
εx,εy = 0.4/0.4 μm
Lu = 70.3 m
σrad,0 = 22 μm
σe = 12.6 μm
Nsec = 35
ZR,seed = 10 m
E = 7.3 GeV
lFODO = 4.14 m
σγ = 1.7*10-4
ρ=9.8535*10-4 Lg1D = 89 cm
Ming-Xie Parametrization
Kq,0 = 47.5 T/m
Lg3d = 0.99 m

3. Tapering Optimization Results
Time Independent
Simulations
Dashed-> NCU optimized for 200 m undulator
Solid-> SCU optimized for 70 m undulator

4. Planar vs. Helical (parabolic electron dist.)

5. Time Dependent Results (parabolic)
Time dependent effects do not spoil bunching
as they do after 200 m in NCU

6. Radiation and Coherence Properties
Coherence area
much larger than
radiation beam spot size

7. Comparison SCU vs. NCU time dependent sim’s
normalized to 3-D gain lengths
NCU
Lg1d = 1.85 m
Lg3d = 1.98 m
SCU
Lg1d = 0.89 m
Lg3d = 0.99 m