The fields in rectangular and circular waveguides are derived from Maxwell's
equations by superposition of plane waves. Subsequently the results are applied
to explain cavity modes. Interaction of the cavity modes with a charged
particle beam leads to the fundamental parameters used to describe the
performance of accelerating cavities. Finally an introduction to multi-gap
cavities is given by the example of travelling-wave structures.Comment: 17 pages, contribution to the CAS - CERN Accelerator School:
Specialised Course on RF for Accelerators; 8 - 17 Jun 2010, Ebeltoft, Denmar