In accelerator physics, the concept of impedance is popularly used to
describe the interactions of charged particles inside a bunch or between
bunches in a train. Standard formulations of impedance assume that the driving
charge has a constant velocity v=vizβ in the z direction of the
Cartesian coordinate system. For the case of driving charge moving along a
curved orbit, impedance can be formulated in the Frenet-Serret coordinate
system, but there seems to be a lack of systematic formulations. This note
presents an effort in this direction.Comment: 11 page