The DA/spl Phi/NE 3/sup rd/ harmonic cavity

The installation of a passive 3/sup rd/ harmonic cavity in both the e/sup +/ and e/sup -/ rings of the Frascati /spl Phi/-factory DA/spl Phi/NE has been decided in order to improve the Touschek lifetime by increasing the bunch length. The implications of the RF harmonic system on the beam dynamics, in particular those related to the gap in the bunch filling pattern, have been carefully studied by means of analytical and numerical tools. A single-cell cavity incorporating a ferrite ring for the HOM damping has been designed through the extensive use of MAFIA and HFSS simulation codes. One cavity prototype has been built and extensively bench tested, while the fabrication of the two final cavities is almost completed. A description of the design and construction activities, and a set of experimental measurements are reported in this paper.