include fast_ring generation from a list of machine parameters (tunes, chromaticities, ac, U0, etc)

[lfarv]

It's not very clear for me. Do you mean that given a list of machine parameters (to be defined), one could generate a fast ring from scratch ?

Not sure it's possible with a "simple" parameter list. Radiation, for instance: the radiated power is not enough, it depends where it occurs (dispersion, β …). Entering the diffusion matrix as a machine parameter is not easy…

However, if there is a simple solution, why not ?

[swhite2401]

@lfarv this is done in other collective effects codes using just damping times + equilibrium emittances (exponential decay + white noise which amplitude depends on the distance w.r.t the target)

For the rest I think it is straight forward as long as you assume uncoupled motion.

I have somewhere an implementation in matlab that I used before we introduced the fastring.

[lcarver]

So for some more information...

I want to make a function that can provide some simple longitudinal and transverse elements for a given list of global machine parameters i.e.

fring = gen_uncoupled_ring(beta_funcs, alpha_funcs, Disp_funcs, Qx, Qy, Qpx, Qpy, axx, axy, ayy, Vrf, phi_s, U0, alphac, emittances, damping_times)

And then fring would be composed of:

a 6x6 tracking element (uncoupled and without radiation damping) a nonlinear element (for chromaticity and amplitude detuning) an rf cavity element a damping element to include the radiation damping and equilibrium emittance (as Simon said, to see the pyheadtail implementation see here: https://github.com/PyCOMPLETE/PyHEADTAIL/blob/master/PyHEADTAIL/radiation/radiation.py)

If we have this, I can (for example) take a table of parameters for any other machine, and make some simulations. I don't need to have the full lattice model.

[lfarv]

This seems to be answered in #643. Can we close the issue?

[lcarver]

thanks to all.