Elegant users forum

Michael,
I use the attached file tracking the storaged beam's trajectory in the injection process.
When I use parkickU.wf as waveform file, I can get a orbit no distorted.
But When I use parkick.wf as waveform file, a very large distorted orbit was generated.
What's wrong with my kicker setting?
thanks!

Shancai,

I don't think there is anything wrong with your kicker settings. The problem is that you have strong sextupoles inside the bump.

As the kickers fire, they kick the stored beam a t=0, t=0.22 us, t=0.44us, etc. However, the bump is matched only for t=0.5 us (full amplitude), because of the sextupoles. For other times, the bump is mismatched and thus you end up with a large oscillation. APS has the same problem (though not was bad as your simulation).

The only solution is to design the ring so that there are no sextupoles inside the injection bump. You can also reduce the problem by making the kicker waveform as short as possible.

--Michael

Thanks a lots！

Hello Michael and all friends,

I wanted to see the effect of 4 horizontal bumps in my lattice. I didn't consider any error, but when I plotted Cx-s, I couldn't see a closed orbit. I checked the lattice in MAD-X and the results were totally different actually there is a closed orbit! Also, I removed bumps from my lattice to see if the problem is because of bumps but again I couldn't see any closed orbit. Can you help me to see what is wrong in my calculation?

Cheers,
Sara

Sara,

If I turn on computation of the closed orbit (which is different from computing the centroid position for transport, as you've done), then I see a closed orbit as shown. I modified both your .ele and .lte files; look for "!!!" in the files to see what I did. I noticed that the lattice functions look a bit off. In particular, alphax and alphay are not zero in the straight sections. This may be expected, but I thought I would point it out.

--Michael