Here are the results for the LCLS Argonne workshop. I still have to do 
some minor runs and in the attached file I present only the output of 
the 'very long' Genesis runs. Note that the file is rather large (> 4 
MByte) due to the various profiles in power and bunching.

The plot should be easy to understand, but for clarification here are 
my plotting standard (I assume a flat profile with 3.4 kA, a emittance 
of 1.2 mm mrad and an energy spread of del_gamma=2.8):

In general the colors refers to:

green - 15 Angstrom
blue - 1.5 Angstrom
red - 1.0 Angstrom

For the bunching I plot also the higher harmonics as well with:
solid line - fundamental
dashed line - 2nd harmonic
dotted line - 3rd harmonic

The effect of wakefields is shown in the second plot. The degradation 
is rather large because there is a residual amplitude of the wake 
potential along the main part of the bunch. Theoretically you can 
compensate with a very small taper but it would be very sensitive to 
any fluctuation in the current profile (e.g. a spike which contains 
only 10% of the total charge at the head of the bunch makes the taper 
useless).


The last two plots are the results for an independent run at 1.5 
Angstrom. They are marked with the purple color.

The solid line is as in the plots before, with no wakefields, no energy 
loss due to spontaneous radiation, no taper to compensate that and a 
simpler undulator lattice for faster calculation.

The dotted line is the results of the simulation, including the energy 
loss, stepwise taper (light purple plot in the last graph) and a 
detailed undulator lattice with the superperiod.
The slight offset with respect to the solid line can be explained that 
the realistic lattice has more drift space than the simplified lattice. 
In total it is 1.5 m

The dashed line has the same parameters as the run for the dotted line 
except that an additional taper is introduced after saturation to 
increase the output power (dark purple in last plot).

Sve