Search found 38 matches

by GPenn
18 May 2020, 16:35
Forum: Ring Tracking
Topic: Issue with moments_output for a very perturbed ring
Replies: 4
Views: 1462

Re: Issue with moments_output for a very perturbed ring

Thank you Michael, Separating the kicks out is straightforward, I will see what it does. To be clear, there is no bug with KQUAD elements, just KSEXT? The errors on the magnets in that lattice file are a little strange, I think there is supposed to be a combination of local and global corrections go...
by GPenn
17 Apr 2020, 17:30
Forum: Feature Requests
Topic: Uniform corrector fields in CSBEND element?
Replies: 2
Views: 6464

Uniform corrector fields in CSBEND element?

It would be convenient to include additional uniform dipole fields in bending elements such as CSBEND, to be used as correctors instead of affecting the nominal orbit. This is especially true for offset quadrupoles that are being labelled as CSBEND magnets (even though the CCBEND element would be a ...
by GPenn
30 Mar 2020, 20:25
Forum: Ring Tracking
Topic: Issue with moments_output for a very perturbed ring
Replies: 4
Views: 1462

Issue with moments_output for a very perturbed ring

Hi, I have been looking at the ALS-U ring with large errors that have been corrected with kicker magnets and other adjustments. The final beamline was converted from AT simulations. Although it looks like there is a closed orbit, moments_output produces the following error message: Warning: particle...
by GPenn
21 Feb 2020, 17:16
Forum: Ring Tracking
Topic: Question about having a fiducial bunch in a ring with bunches from sdds file
Replies: 3
Views: 4907

Re: Question about having a fiducial bunch in a ring with bunches from sdds file

Thank you, that helps a lot! I was definitely veering in the wrong direction.

-Gregg
by GPenn
06 Feb 2020, 13:23
Forum: Ring Tracking
Topic: Question about having a fiducial bunch in a ring with bunches from sdds file
Replies: 3
Views: 4907

Question about having a fiducial bunch in a ring with bunches from sdds file

Hi, I am doing ring simulations for long range wakes and ion effects. I would like to include a first fiducial bunch while using n_passes_fiducial=1 in the run_control command. The bunches are from an SDDS file, so I am using the sdds_beam command. This works fine if I follow the example from the fo...
by GPenn
28 Jan 2020, 19:50
Forum: Bugs
Topic: synch_rad losses in quad with nonzero kick
Replies: 1
Views: 4338

synch_rad losses in quad with nonzero kick

In a KQUAD element with |K1|>1, if either HKICK or VKICK is nonzero (it doesn't matter how small) then the radiation losses are oversized and scale quadratically with K1. An electron could lose more than an MeV in a modest-strength magnet. KSEXT elements have the same issue with the value of K2. In ...
by GPenn
09 Jan 2020, 18:57
Forum: Bugs
Topic: Tracking issues in CSBEND elements in the presence of errors
Replies: 9
Views: 9540

Re: Tracking issues in CSBEND elements in the presence of errors

Thanks Mike, That clarifies things a lot. I think the problem is simply that I'm comparing elegant to a model that is too simplistic. It's harder than I thought to account for the difference between the physical centerline of the magnet and the reference orbit when there is an error in the tilt. I'm...
by GPenn
07 Jan 2020, 19:27
Forum: Bugs
Topic: Tracking issues in CSBEND elements in the presence of errors
Replies: 9
Views: 9540

Re: Tracking issues in CSBEND elements in the presence of errors

The revised code works great. Now putting ETILT and TILT with the same sign gives completely consistent behavior including for off-momentum particles. I have one final question just to make sure I'm interpreting things correctly. It looks like in the CSBEND element, FSE and ETILT do not impact quadr...
by GPenn
06 Jan 2020, 18:25
Forum: Bugs
Topic: Tracking issues in CSBEND elements in the presence of errors
Replies: 9
Views: 9540

Re: Tracking issues in CSBEND elements in the presence of errors

I am attaching the set of files for the figures in the previous message. One thing in csbend.c that looks suspicious to me is there are a few places with the line ttilt = tilt + etilt; and I assume that ttilt is supposed to be the total tilt. But with the sign conventions as they are, maybe it shoul...
by GPenn
06 Jan 2020, 18:23
Forum: Bugs
Topic: Tracking issues in CSBEND elements in the presence of errors
Replies: 9
Views: 9540

Re: Tracking issues in CSBEND elements in the presence of errors

Thank you for looking into this, Mike. For the DX issue, the fact that a shift in x means different things at the entrance and exit makes sense. I hadn't taken that into account. The difference is very close to DX*(1-cos(angle)). Is that why there is also a change in the 't' coordinate? Because it c...