Strategies for building magnet arc of storage ring?

Dear FLUKA forum,

I would like to ask for your input/advice concerning strategies for building a magnet arc of a storage ring (in this case the 2.3 km PETRA storage ring at DESY). I have already reconstructed each unique magnet in the arc from CAD models as a “prototype” and used LATTICE to duplicate and ROT-DEFI to transform the “replica” magnets to their proper positions within the storage ring tunnel.

Previously, it was enough for our studies to model a single arc and to use a cylindrical vacuum pipe of uniform thickness for the entire single arc. The next stage of our studies would require implementing the realistic (and often more complex) vacuum chambers and expanding the geometry to include multiple arcs.

In an effort to not build the complex vacuum chambers for each replica-magnet along the arc, I built the complex vacuum chamber also into my prototype-magnets. However, this leaves a small air gap between the replica-magnets within the tunnel. You can observe an example of this gap in the image below (top-view).

The question is: What is the clever(er) way to build such a geometry in order to bridge these gaps in order to have a continuous vacuum between different magnets and types of chambers?

Dear @ted.liang ,

Congratulations on the excellent geometry models!

We face a similar challenge when modelling LHC or other CERN beam lines.

Our approach is to model the vacuum chamber in the initial FLUKA file including the tunnel and then place the magnets (or other beam elements) as replicas, as you have done.
This ensures continuity between different vacuum sections while tolerating minor mismatches in the vacuum chamber, particularly in the interconnections and in the arcs.

To illustrate this, take a look at the attached image which shows LHC Insertion Region 7 with magnets and collimator as replicas superimposed on continuous vacuum pipes.

I hope this information is helpful.

Cheers, Luigi

1 Like