Spin Tracking for Plasma Staging #1154
Description
At EAAC25, we discussed needs for spin tracking in staging of (of e+/e-) plasma-based accelerators (LPA/PWFA). State-of-the-art simulations via ABEL (e.g., for HALHF or for the 10TeV CoM effort) use HiPACE++ for the plasma stage and ImpactX for inter-stage transport. HiPACE++ already added spin tracking, so it makes sense to to close the gap and for ImpactX document what elements are needed for the inter-stage transport -- thus this issue.
As a timeline, this could be needed at the end of 2025/early 2026, because @carlandreaslindstrom has a PhD student ready to study this. This aligns well with our new LDRD (PI @cemitch99), starting in Oct 2025, that besides other goals adds spin tracking #546 to ImpactX.
The elements needed for this effort would be:
- drift
- bend
- (quadruple)
- sextupole
- (ideal) tapered plasma lens
Besides the last bullet, this is anyway an essentials list, so likely highly synergistic.
Side note / assumption we discussed: At least for HALHF, the charge per beam is large but not extreme (currently at 0.3nC) and the beam beta function is >=100micron in the plasma lens. Thus, the modeling of the plasma lens via a map in ImpactX is currently sensible, as no dramatic wake should be driven in the plasma lens itself. (This assumption still needs verification in a plasma code like WarpX or HiPACE++.)