Elegant users forum

The problem was that the first element in the lattice was a TWISS element. I had used that in the original design because we had several inputs to switch between and it was convenient. That element doesn't play well with &correct, I guess, because when I eliminate it (and move the twiss parameters t...

I move some of the MONIs closer to that second octupole to see if the problem was the size of the trajectory. Hoping that would fix the issue. Nope.

The trajectory not being corrected was due to me setting n_xy_cycles = 1 in my &correct statement. It didn't occur to me that this could be an issue, because it is the default setting but simply commenting that line out fixes the trajectory problem from my last post: x-diff.png y-diff.png The proble...

Another unexpected feature shows up in my last post. Why is the beam not on the x-axis near the end of the beamline? Isn't that what correction should be doing? If I look at the last ~10 meters of beam line in the trajectory file, it appears that the last kicker isn't properly zeroing the position o...

Another clue is that residual dispersion due to having kickers in an area with "natural" dispersion due to bends is pretty strongly correlated with the trajectory difference between the centroid and the value found by &correct, especially in the y-plane. x-diff.png y-diff.png I still don't understan...

Ok, I have a kinda-sorta functioning example. There are three parameters that interplay to cause wild behavior of the centroid. I think this is what I'm seeing in my simulations. I hacked the staticPlusDynamicErrors example to bits trying to reproduce the problem I was seeing. I cannot explain why t...

I think this issue is related to octupoles and &correct. Here is what happens when I set default_order differently in step A and step B: K3 = 1 K3 = 100000 A order B order x-Diff (mm) y-Diff (mm) x-Diff (mm) y-Diff (mm) 1 1 0 0 0 0 1 2 0.02 0.02 0.02 0.02 1 3 0.02 0.02 0.02 0.08 2 1 0.02 0.02 0.02 0...

Here is the picture of the beam at the exit:

I'm having an issue with getting the centroid trajectory (Cx, Cy in %s.cen) of a low energy beam (beta*gamma = 0.15) to match the trajectory given by &correct. I cannot post my lattice, so I'll have to settle for describing the problem as best I can and hope I trigger enough keywords to get some hel...

I'm not sure what to call this, bug or working as intended, but it appears that adding random multipoles to the elements that allow it (CCBEND,KQUAD, etc) doesn't play well with trajectory correction. I've created a minimum functioning examples of the issue and attached it. The example is based on s...