On the coupling impedance for particles with opposite velocitiesD. Davino1, G. Dôme2 and L. Verolino3
1 Università degli Studi del Sannio, Dipartimento di Ingegneria, Piazza Roma, 82100 Benevento, Italy
2 Retired from CERN, 1211 Geneva 23, Switzerland
3 Università Federico II di Napoli, Dipartimento di Ingegneria Elettrica, via Claudio 21, 80125 Napoli, Italy
(Received: 27 March 2002 / Revised version: 5 December 2002 / Published online: 26 February 2003 )
As already shown by several authors, the reciprocity theorem can be rewritten as a simple formula connecting the longitudinal coupling impedances of a particle travelling in the positive and negative directions of an infinitely long vacuum chamber crossing a scattering structure (cavity, step junction, iris, etc.) of general shape. The formula is valid for any particle velocity. As an example, we consider the case of two semi-infinite circular vacuum chambers with different radii; for this case we give the explicit difference between the coupling impedances and the wake potentials.
© Società Italiana di Fisica, Springer-Verlag 2003