Hertz potentials approach to the dynamical Casimir effect in cylindrical   cavities of arbitrary section
  We study the creation of photons in resonant cylindrical cavities with time dependent length. The physical degrees of freedom of the electromagnetic field are described using Hertz potentials. We describe the general formalism for cavities with arbitrary section. Then we compute explicitly the number of TE and TM motion-induced photons for cylindrical cavities with rectangular and circular sections. We also discuss the creation of TEM photons in non-simply connected cylindrical cavities. 
Martin Crocce, Diego A. R. Dalvit, Fernando C. Lombardo, Francisco D.   Mazzitelli