Status of Superconducting Cavities in LEP

The upgrade of the Large Electron Positron collider (LEP) with superconducting cavities is nearing a successful completion. There are presently 240 superconducting cavities installed which, together with the original copper RF system, provide up to 2.6GV per turn. The majority of the superconducting cavities is of niobium sputtered on copper and runs at an operating gradient of 6MV/m. In 1997, LEP has operated routinely at an energy of 91.5GeV per beam and with a total current of over 5mA. The operation of the RF system has been very satisfactory, with only a few cavities limited in field. This paper will concentrate on describing the operation of this system during 1997, including new features, operational procedures and present limitations. Future plans, notably the work towards improving performance and the installation of the remaining cavities, will also be covered.