Search found 1924 matches

by michael_borland
26 Oct 2023, 10:43
Forum: Bugs
Topic: CWIGGLER generates vertical dispersion in helical mode
Replies: 6
Views: 1075

Re: CWIGGLER generates vertical dispersion in helical mode

Mikhail, Regarding the issue with helical devices, it is not so much a bug as an unavoidable limitation. In a planar device, if we want a wiggler to generate zero orbit offset and zero dispersion, we need to start and end with half-length poles. The field is assumed to have the peak value at the sta...
by michael_borland
26 Oct 2023, 10:38
Forum: General
Topic: Coupling in ibsEmittance
Replies: 4
Views: 910

Re: Coupling in ibsEmittance

Mikhail,

The "sum rule" is only correct when Jx=1. If Jx>1, the sum of the emittances is always greater than the natural emittance.

--Michael
by michael_borland
26 Oct 2023, 10:36
Forum: Linac Tracking
Topic: How does Elegant use input file for FTRFMODE?
Replies: 2
Views: 542

Re: How does Elegant use input file for FTRFMODE?

Wei-hou,

Yes, that sounds right. We usually get the data from an eigenmode solver that gives the quantities needed directly.

--Michael
by michael_borland
25 Oct 2023, 16:19
Forum: Bugs
Topic: CWIGGLER generates vertical dispersion in helical mode
Replies: 6
Views: 1075

Re: CWIGGLER generates vertical dispersion in helical mode

Mikhail, Thanks for the detailed examples. The issues with the HELICAL=0 case can be solved by some fine-tuning. In particular, for CWIGGLER devices the transport matrix is determined through particle tracking. That has limited accuracy. You can improve the results for case 2 by adding this command ...
by michael_borland
25 Oct 2023, 12:49
Forum: General
Topic: Coupling in ibsEmittance
Replies: 4
Views: 910

Re: Coupling in ibsEmittance

Mikhail,

The formula you quote is incorrect when the horizontal damping partition number Jx is not 1. The correct formula is ex=ex0/(1+K*Jy/Jx), ey=K*ex.

For example, for APS-U we have ex0=44.3 pm and Jx=2.21. With K=1, we get ex=ey=30.5 pm

--Michael
by michael_borland
25 Oct 2023, 12:23
Forum: Ring Tracking
Topic: Access to tracking_based_matrices
Replies: 2
Views: 605

Re: Access to tracking_based_matrices

Ryutaro,

You can get the matrices from the matrix_output command. It provides the option for a text file or an SDDS file.

--Michael
by michael_borland
25 Oct 2023, 12:23
Forum: Ring Tracking
Topic: Ring tracking with ciwggler element
Replies: 6
Views: 963

Re: Ring tracking with ciwggler element

Weijie, It is puzzling that they don't agree, then. The CWIGGLER element uses the code developed by Ying Wu for AT many years ago. If you are just using sinusoidal mode, you could check the vertical tune using tracking and compare that to the twiss parameter calculation. They should agree closely. -...
by michael_borland
25 Oct 2023, 12:18
Forum: General
Topic: Use of the function computeCBGGE
Replies: 2
Views: 921

Re: Use of the function computeCBGGE

Ryutaro, The problem is that the phi values are not sufficiently precise. Maybe they originated in a single-precision calculation or limited-precision printout. You can fix this using sddssnap2grid DIC_C17_cydrincalcood.sdds DIC_C17_cydrincalcood.snap -col=phi,max=3600 This command will look at the ...
by michael_borland
25 Oct 2023, 12:06
Forum: Ring Tracking
Topic: Gas Scattering lifetime
Replies: 8
Views: 3682

Re: Gas Scattering lifetime

Pradeep,

There's an up-to-date example in the examples file, which you can obtain from our software download page, or at https://ops.aps.anl.gov/cgi-bin/oagLog4 ... les.tar.gz

Look for PAR/elasticScatteringTracking and PAR/inelasticScatteringTracking.

--Michael
by michael_borland
18 Oct 2023, 18:32
Forum: General
Topic: orbit ocrrection
Replies: 2
Views: 843

Re: orbit ocrrection

I found a few problems in your files: * You had the WEIGHT parameter step to 0 on all the monitors. This causes them to be ignored. I set the value to 1. * You defined HC and VC as KICKER elements, then placed them one after the other in the lattice. Since these correct in both planes, it means you ...