In the OM2p and OM3p simulation properties dialog box Solver tab, you may define both the shunt impedance path and the kick factor path. Each path is defined by its own pair of vectors, which indicate the start point and end point of the path. These paths serve two purposes:
In every OM simulation, these integration paths are used to resolve ambiguities in the mode solution. At least one of these paths should pass through a part of your geometry with nonzero fields. The direction of the path should roughly correspond to the expected direction of the fields. Every eigensolver result has a sign ambiguity, and results for periodic problems also have a phase ambiguity. The path is used to choose the sign and phase consistently between AMR steps. If the path does not encounter nonzero fields, the eigensolver will automatically choose the field sign and phase. The result may differ between AMR steps, leading to difficulties with convergence.
If you are modeling an RF accelerator cavity, the solver will use these integration paths, along with the particle beta, to determine the cavity's shunt impdance and kick factor as described in “Tables”.