Elegant users forum

Louis, This happens because twiss_output is a "setup/action" command. When output_at_each_step=0, it is in "action" mode: it does the calculation immediately. When output_at_each_step=1, twiss_output is in "setup" mode: it only sets up for twiss computations and output later. "Later" means when a ma...

Michele Joyce (JLab) wants to know if it is possible to scan a series of quadrupoles sequentially in elegant as part of an emittance measurement, instead of the common method of scanning several quads together. This can be done using the enumeration_file feature of vary_element, which allows enumera...

Louis, The problem here is that, while SDDS does file locking, a process can't lock files against itself. So even though the closed orbit calculation locks the file, the orbit correction calculation is allowed to access it because it is part of the same process. For now I think people just have to k...

Weiming, A very guru-like solution. It doesn't keep data like ElementName and s with the beta values, which might be a problem for some applications. I suspect that if the intermediate files are put on /tmp (or a local disk rather than a networked disk), then the speed of the two methods will be qui...

Weiming,

Here's how I'd do it:

sddsconvert input.twi input-x.twi -rename=column,betax=beta
sddsconvert input.twi input-y.twi -rename=column,betay=beta
sddscombine input-x.twi input-y.twi new.twi -merge -delete=col,betax,betay
rm input-x.twi input-y.twi

--Michael

Reported by Vadim Sajaev: When transmute_elements is used to turn a sextupole into a quadrupole, the following problems are seen: 1. Some parameters of the new quad are filled with garbage values. 2. When alter_elements is used to change parameter values, elegant crashes. 3. When save_lattice is use...

Jim,

Thanks for posting this. I've changed the software documentation page to point to this entry.

--Michael

I thought that for dynamic aperture the strongest effect comes from the field errors in bends. So if you have these SYSTEMATIC_MULTIPOLES and RANDOM_MULTIPOLES up to an arbitrary order in quadrupoles why not have them in dipoles? I'm quite new to dynamic aperture calculations. For electron machines...

petrenko wrote:Thanks for the example!

Do you have plans to include higher order components (Kn, n>4) in CSBEND element?

This is the first request I've had for this. I'll add it to my list of things to do. Out of curiousity, is there a particular motivation or application?

--Michael

The find_aperture command can be used for finding dynamic aperture. It uses various search methods to find the DA boundary. Another method is just to perform tracking with a beam that fills a large rectangle in x-y space. By using the losses parameter of the run_setup command, one can get a record o...