Superconducting Cavity Beam Test in CESR
The first use of a superconducting accelerating structure in a storage ring is described. Two 5-cell 1500 MHz ''muffin tin'' superconducting niobium cavities (1 m active length) were operated in the Cornell 8 GeV e/sup +/e/sup -/ storage ring, CESR. A 6.1 mA beam was captured and stored at 3.5 GeV using only the superconducting cavity. Up to 12.5 kW was transferred to the beam by the cavity. Single bunch currents up to 12 mA were reached in conjunction with the normal 500 MHz RF. Beam induced higher order mode (HOM) powers of 290 W were carried to room-temperature loads by four couplers and waveguides; no HOM-induced cryogenic dissipation was detectable. Q's of the 76 most prominent resonances were measured. Transverse and longitudinal beam instabilities were studied by mechanically sweeping the tune of the cavities; current thresholds are compared to theory. The cavity exhibited the ability to survive breakdown at high incident power without degradation.
Status of superconducting RF cavity development
The scope of accelerator applications of RF superconducting devices is briefly discussed from a historical perspective. Current high-velocity and low-velocity acceleration projects and development activity are outlined. Projects at CEBAF, CERN, DESY, KEK, Argonne, Stony Brook, JAERI, and Kansas State are considered. The development of high-T(i)c(ei) oxide RF superconductors is also discussed.<<ETX>>
First Results on a Superconducting RF-Test Cavity for LEP
In 1979 a feasibility study for the application of superconducting accelerator cavities to LEP was started at CERN. In a first series of measurements using a single cell test cavity (f= 500 MHz) quality factors of 2.1 × 109 and maximum acceleration fields of 4.6 MV/m were reached at 4.2 K. A short survey of the experimental layout and the results are given. For the measurements a chain of carbon resistors and solid state X-ray detectors was used for temperature and X-ray mapping of the cavity surface. Together with a visual inspection of the cavity interior during operation a better insight in field breakdowns mechanism and electron loading could be obtained.