Elegant users forum

After a little more looking, I've concluded that this isn't a bug, but rather a result of the presence of linear and nonlinear coupling, through tilted quadrupoles and sextupoles, respectively. Elegant alternates between correcting in the x and y planes. With n_xy_cycles=1, it corrects the x plane, ...

NuanYa, You need to ask for orbit correction in order to get amplification factors. Try adding &correct mode = "orbit" n_xy_cycles = 1 n_iterations = 100 &end (In this case, n_xy_cycles = 1 is required.) I'll add a check so it doesn't crash. Thanks for the report. --Michael

Joe,

That would be pretty easy to implement, but I'm not sure when I'll get to it.

Meanwhile, it is easy to do with a SCRIPT element, which allows you to transform the particle distribution using an external program or script.

--Michael

This seems to be a bug that appears when n_xy_cycles=1. Set n_xy_cycles to 2 or higher in &correct and you should see consistency.

Thanks for reporting the problem.

--Michael

Ryutaro, I would be suspicious of this result. First, the convergence warning indicates that the normal algorithm had a problem. Second, you have tracking_turns=1, which asks elegant to use a fall-back multi-turn tracking method; however, you only asked it to use 1 turn, which isn't reliable. It som...

Version 2023.4 has been released, with several feature and performance improvements. See the change log in the manual for details.

--Michael

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...

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

Wei-hou,

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

--Michael

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 ...