modulate_elements

[fliller]

Here you go!

[michael_borland]

Thanks!

[fliller]

Michael,

I _may_ have found another bug in Modulate_elements. Attached is a demo which saws the possible bug. It is similar to the previous example except that now I turn on the RF system. When I turn on the RF, there are two things I see:
1) for modulate elements, I need to have negative times in my file which specifies the element values, othwerwise I get an error that the interpolation fails when it encounters a particle with negative times.
2) the phase space behaviour is _VERY_ different with the RF on. Some of this is expected, synchrotron oscillations etc, but the islands I get with no RF completely disappear. If I start the scan at settings which generate the islands, they appear, but if I try to move the islands with the scan, they do not move.

I believe this may be an error in the code, but I am not whole heartedly convinced, but it smells like a duck, and walks like a duck.

Ray

[michael_borland]

Ray,

I'm a bit swamped right now. One suggestion is to try the MODRF element, which allow imposing various modulations in an rf cavity. Also, RAMPRF allows specifying time-dependent waveforms for phase and amplitude.

--Michael

[fliller]

Michael,

The modulation is not on the RF, it is still on the quadrupoles. I am just adding in the RF to the dynamics.

Ray

[michael_borland]

Ray,

Ok, I'll try to have a look in the next few days. One thing you might check is whether it is the same with QUAD and KQUAD elements. It should be very similar.

--Michael

[fliller]

Michael,

It is pratically unchanged.

Ray

[michael_borland]

Ray,

Try setting change_t=0 on the RFCA. Otherwise, you are reseting the average particle coordinates to <t>=0, which is going to mess up the calculation of the modulation amplitude.

--Michael

[fliller]

Michael,

BINGO, worked like a charm. Thanks for your help.

Ray