Question regarding a setting of CSRDRIFT "length"

[Seong-Yeol Kim]

Hi, I am currently running the elegant simulation along the chicane type bunch compressor, and noticed that the emittance after the BC is slightly different when using different CSRDRIFT length (e.g., between second and third dipole magnets while maintaining same distance between them together with "DRIF" element). I think that the discrepancy depends on the length, and in my case, it is about maximum 5% difference.

I was wondering if I should set the length of the CSRDRIFT to be always following a "overtaking length" based on https://journals.aps.org/prab/pdf/10.11 ... B.4.070701 (Otherwise I am wondering if the discrepancy of the emittance is over/underestimated result due to the setting of the CSRDRIFT).

I think I should set it following the overtaking length, as the bunch right along the exit of the bending angle is begin to propagate along the straight line. Thus, I think that the effective region where the radiation affects the bunch should be finite, not the entire straight line afterwards. Nevertheless, I would like to get some valuable comments from you, and I would very appreciate if you could provide them.

Thank you very much!
Seongyeol

[michael_borland]

Seongyeol,

Which mode are you using for CSRDRIFT? The recommended mode is Stupakov's mode, which is invoked by setting USE_STUPAKOV=1.

--Michael