Elegant users forum

Hi there,

We are currently engaged in S2E jitter simulations, using ASTRA for photoinjector modelling and elegant for linac modelling. Currently we are focused on the arrival time jitter, and my question is regarding the interface between ASTRA and elegant. Our current approach is to look at the arrival time jitter at the end of our injector, and then convert that into a corresponding phase shift on cavities implemented in elegant. Is there a more elegant (excuse the pun) method for carrying the arrival time jitter forward into elegant simulations, while having cavities nominally set to the desired phase rather than manually phase shifted to emulate the effect of time-of-flight variation through the injector?

All the best,
Bill

Bill,

The recommended way is to run a fiducial beam before the beam with errors. You can have this beam in the first page of the input file you name with &sdds_beam. Be sure to give track_pages_separately=1 so elegant knows that each page is a separate case. For efficiency, I recommend having many beam files in the input file, with the first being the ideal case and the others being various jitter instances. I also don't recommend using a single-particle fiducial beam, since that will have different phasing (averaged over all the particles) than a real beam.

Also, give first_is_fiducial=1 on the &run_control command, so elegant knows not to add errors.

There are some examples in the on-line example set that illustrate some of these points, under the bunchCompression subdirectory.

--Michael