The OPAL Discussion Forum

[DAVID SU <qilesu AT g.ucla.edu>]

Dear all,

I am trying to understand how OPAL knows where to put the imagePotential:

1. ParallelTTracker::computeSpaceChargeFields(...) transforms all the particle positions from the reference frame to the beam frame before calling PartBunch::computeSelfFields(int binNumber)
2. PartBunch::computeSelfFields(int binNumber) computes a "zshift" and passes it to solver_m when computing "imagePotential"

How does PartBunch know the cathode is in -z direction without the information (i.e. CoordinateSystemTrafo) from ParallelTTracker? If either the beam frame or the reference frame are slightly misaligned in orientation from the lab frame, wouldn't PartBunch need more than just a "zshift" to find the image charges?

Thanks,

David