CERN, Geneva
MPI-K, Heidelberg
Cockcroft Institute, Warrington, Cheshire
The surface resistance RS of superconducting cavities can be obtained by measuring the unloaded quality factor Q0. RS can vary strongly over the cavity surface but the value obtained is only an average over the whole surface. Furthermore surface analysis tools are difficult to apply inside a cavity. A more convenient way consists of investigating small samples. They can be cheaply manufactured and easily duplicated. RF cavities excited in the TE011 mode with a sample attached as the cover plate are often used for material characterization. However, there is the drawback of relatively large size at the frequencies of interest concerning accelerator applications. At CERN a compact Quadrupole Resonator has been developed for the RF characterization of superconducting materials at 400 MHz. In addition the resonator can also be excited at multiple integers of this frequency. Besides RS it enables determination of the critical RF magnetic field, the thermal conductivity and the penetration depth of the attached samples, at different temperatures. The features of the resonator will be compared with those of similar RF devices and first results will be presented.
CERN, Geneva
MPI-K, Heidelberg
Cockcroft Institute, Warrington, Cheshire
The Superconducting Proton Linac (SPL) at CERN is part of the planned injector upgrade of the LHC. Initially used at low duty cycle as LHC injector it has the potential to be upgraded as a high power proton driver for neutrino physics and/or radioactive ion beams. In this paper the influence of the beam parameters on the build-up of Higher Order Mode (HOM) voltages is studied together with their interaction on the beam. For this purpose we use bunch tracking simulations in the longitudinal and transverse plane in order to define Beam Break-Up (BBU) limits. These simulations take into account changing values for the HOM frequency spread and are carried out using various distances between the HOM frequencies and the main machine lines.
