Jean-Paul,

 

Take a look at the following web site.

 

http://www-ap.fnal.gov/~syoon/SC/FMI.html

 

Look at the top under microbunch injection at the section for input and the scenerio VIII with the dual harmonic... under VII he has an interesting annimation (except the 2nd harmonic has 300 kV and in VIII he reduced it to 200 kV to make a more uniform distribution).  As I mentioned earlier, these simulations DO NOT have broadband impedance it them. This will be added sometime in the future. I don’t think its a show stopper, it just needs to be addressed.

 

 

As you can see the microbunches are tiny compared to the MI bucket... some numbers

 

For PHASE:

Typical bunch length is +/- 20 mm or so -> +/-66ps  -> 0.13 ns bunch length

There are 0.0323 MI bucket degrees/ns

MI bucket length 18.9s ns -> 0.612 degrees

We want to inject in to the central +/-6ns of the bucket (12 ns total) this is about 4 325 Mhz buckets.

 

Due to harmonic number mismatch 325/53.2811400 = 6.15... we get longitudinal painting by chopping out 2 out of 6 bunches...

On one of his plots (in VIII, I think) he shows the micro bunches inside the bucket. The annimation in VI is instructive to watch...

 

So you see that even with 2degrees/2% the the bunch length looks to still fit within the bucket (goes form 40mm to say 160mm and this is only 0.52 ns which is still only 0.017 degrees in the MI bucket...

 

I don’t know how to put a limit on the phase jitter, I think a larg number needs to be simulated to see where it breaks.

 

For ENERGY:

 

Again , the energy spread in all TRACK cases  looks less than +/- 15 MeV. If  the phase is less 
than +/- 0.1 deg then the +/-15 MeV works , however if the particle is injected at +/- .2 degrees, 
then the tolerance on the energy is greatly reduced.  The acceptance looks to be .045 eV-sec. 

 

TRANSVERSE

 

In the transverse, from foil temperature considerations we want a spot sice of 
about 1.2 to 1.5 mm sigma (7.2mm to 9mm) which means the foil ahould be on the
 order of 6 times these values, maybe 6.25 times these numbers to reduce the foil misses and reduce 
the load on the absorber. 

 

The ILC no errors produces a spot size within this range. Looking at the .5% and 1% w/o collimation, 
they both seem to be within the range. The 2%2degrees would require significant collimation in the 
transport line... I hope things aren’t this bad... But I think this really dosen’t matter because beam 
is scraped in the LINAC early any way.

 

So I would say that we would be comfortable with 1%/1degree/10 units.errors.  

 We paint top 25 to 40 pi-mm-mr normalized 

 

I would asy maximum we could collimate would by 6% (that is 1% on each collimator individually 
(if it’s even possible... in real life)

 

I hope this helps. I’d upload something, even if it’s not ready, fairly soon, just to get place holder...

 

Thanks,

 

The poster looks good !!

 

Dave

 

QUESTION:  When I look at the parameters for each of the 4 cases, you write them at 1629.7m or at the foil... What does the emitx and emity mean? Are these numbers dependent on the beta at the foil?