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2021-11-24.md 6.18 KiB

Minutes of #14 Remote E-Beam Meeting (draft)

The meeting was held on Zoom on 24/11/2021 - See indico

!!! info "Participants" Nicolo Biancacci, Jean Cenede, Roberto Corsini, Davide Gamba, Mikko Karppinen, Andrea Latina, Oliver Meusel (Frankfurt University), Laurette Ponce, Adriana Rossi, Kathrin Schulte-Urlichs (GSI), James Storey, Luke Von Freeden, Fredrik Wenander, Michail Zampetakis,

New AD e-cooler particle tracking in Opera (Luke Von Freeden)

Luke started with an introduction about e-cooling.

The simulations done with Opera take only magneto-static effects into account. No self field of the particles (e.g. space charge) nor interactions with walls (e.g. indirect-space charge) effects are taken into account by the solver presently used by Luke within Opera. By default, particle emitters can be defined only on a square grid with uniform spacing between emitter. Luke overcome this limitation by profiting of in-opera python console which allows to programmatically define a local coordinate system as as placing emitters at any desired location.

The magneto-static system is solved on a 3D triangular mesh. Grading of the mesh can be adjusted, and made more fine at location of interest, e.g. where the beam is supposed to pass. Typical mesh steps are of the order of 15 mm. (Note: in slide "Numerical sensitivity" says "0.30mm largest delta between meshes": what is this?)

Typical time to solve magneto-static system is of the order of 4 hours for the new AD e-cooler. This time can vary considerably depending on the level of complexity of the object (e.g. number of coils, ferromagnetic material) as well as mesh size at the location of interest.

After magneto-static system is solved, tracking of particles is fast (minutes time scale) and one can track particles with a step size smaller than the magnetic mesh size: in this case, fields are interpolated using non-linear interpolation at the particle location. A first study varying the magneto-static mesh size and track discretization (0.5 mm or 1 mm) did not show major variation of the tracked particles from the gun till the end of the e-cooler drift, suggesting that mesh size is probably good enough.