Elegant users forum

Hi Michael, I am having trouble to calculate the momentum aperture and Touschek's lifetime in a two-energy storage ring. We have two rings connected through SRF cavities. Low energy ring (150 MeV) and High energy ring (1000 MeV) are connected by SRF cavities which first accelerates the beam and the...

Hi Michael, Thank you so much. And I think Dynamic aperture is OK with coupling section for a ring lattice because &find_aperture(as follow) is based on track. Is it right? Thank you again. guohui &find_aperture output = "%s-check.aper", mode = n-lines, n_lines = 41, xmin = -0.0015, xmax = 0.0015, y...

Thank you, Michael,

But even with emittances_from_twiss_command = 0, there is no output also.

Guohui

michael_borland wrote: ↑

15 Mar 2018, 15:49

Guohui,

Sorry, my mistake. Add

Code: Select all

emittances_from_twiss_command = 0

to the &coupled_twiss_output command.

--Michael

Hi Michael, I add the your suggested lines of &coupled_twiss_output to the .ele file as attached. But when I run it, it gives a error information as follow. emittances_from_twiss_command was set but twiss calculations not seen Thanks. Guohui Guohui, &twiss_output assumes that the lattice is uncoupl...

Hi Michael, I add the your suggested lines of &coupled_twiss_output to the .ele file as attached. But when I run it, it gives a emittances_from_twiss_command was set but twiss calculations not seen Thanks. Guohui Guohui, &twiss_output assumes that the lattice is uncoupled. The beta functions etc. ar...

Thank you very much, Michael. Guohui, &twiss_output assumes that the lattice is uncoupled. The beta functions etc. are computed from the 2x2 submatrices for the x and y planes. So stritly speaking they are not correct anywhere in the presence of coupling. You can compute the coupled twiss parameters...

Hi Michael, Thank you very much. By the way, how did you calculate tune in $twiss_output? And are beta_x, alfa_x right in the output of $twiss_output? Or in the output of $twiss_outputare, are beta_x, alfa_x right in decoupling section in the lattice, but wrong in the coupling section? As you know, ...

Michael,

I have email them to you.
Thank you.

Guohui

michael_borland wrote: ↑

14 Mar 2018, 16:25

Guohui,

I would need to see the lattice file to comment. Can you upload it?

--Michael

Hi Micheal,

I find a tune difference in a collider ring lattice between MADX and ELEGANT.
The collider ring has two decoupling section. This cause a different tune output from the two CODE.
It is right?

Thank you.

Guohui

Guohui, Thanks for sending the lattice. One problem is too few kicks for the quadrupoles. Some of your quadrupoles are quite long and not weak, so the lattice functions can change considerably inside them. This means you need more kicks to get a good model. I got tunes of 0.219 and 0.160 by increas...