Two Examples of "Confluence" in Periodic Slow Wave Structures

The properties that result from the elimination of a stop-band of a Iossless periodic slow wave structure are discussed. For two particular structures, it is shown that theory predicts a nonzero group velocity at the point of confluence of the two passbands. This confluence is desirable for linear accelerator structures operating at the /spl pi/-mode since it produces increased mode separation. Certain characteristics of zero and /spl pi/-mode confluence are also discussed.