High Power Windows at DESY Operation Experiences, Development Work on TTF Input Couplers

There are many different types of rf high power couplers operated in the various existing accelerators at DESY. However the main effort of coupler development is actually done at the TTF activity. Consequently this report concentrates on TTF input couplers. The TESLA project needs for it's superconducting cavities input couplers with unusual features besides high performance and very high reliability. Reliability is a strict requirement because partial or complete exchange of a coupler after installation to a cryomodule might imply disassembling of more or less a whole module and danger of contamination to the cavities. In reference to this both coupler types which were developed for the first TTF module are considered as prototypes. First experiences with these couplers and hrther development work will be reported here.