A superconducting accelerating cavity in PETRA

Abstract To investigate the feasibility of superconducting accelerating cavities in electron-positron storage rings a single cell niobium cavity was constructed and tested in PETRA at DESY, Hamburg. The paper describes the experimental setup and summarizes the results obtained: Accelerating field gradients of the order of 3MV/m and Q -values of 10 9 can be obtained in an operating storage ring and maintained over many weeks. Synchrotron radiation impinging on the cavity surface does not affect the performance. Higher order modes excited by the beam were coupled out, their amplitudes were measured and agree with theory. PETRA could be operated at 5 GeV and 2 mA with the superconducting cavity alone.