Elegant users forum

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 ...

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

Ryutaro,

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

--Michael

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. -...

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 ...

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

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 ...