UMAN, Manchester
CERN, Geneva
Instituut voor Kern- en Stralingsfysica, K. U. Leuven, Leuven
The upgrade of the ISOLDE machine at CERN foresees a superconducting linac based on two gap independently phased Nb sputtered Quarter Wave Resonators (QWRs) working at 101.28MHz and producing an accelerating field of 6MV/m on axis. A deep study of the fields in the cavity is fundamental in order to pin down the crucial e-m parameters of the structure such as peak fields, quality factor and e-m power dissipated on the cavity wall. Furthermore it is fundamental to provide for an efficient tuning system to the structure. In this paper the full list of the e-m cavity parameters will be reported. The tuning plate design and realization will be described. Finally the frequency measurements with and without tuner plate at room temperature will be presented.
UMAN, Manchester
CERN, Geneva
Instituut voor Kern- en Stralingsfysica, K. U. Leuven, Leuven
The first stage of the planned upgrade of the ISOLDE facility at CERN will provide a boost in beam energy from 3MeV/u up to 5.5MeV/u. In order to reach this goal, it is planned to install downstream the present structure, a superconducting linac based on two gap independently phased Nb sputtered Quarter Wave Resonators (QWRs) working at 101.28MHz. The cavity parameters foresee to have a power dissipated on the cavity wall of 7W with a Q0=6.6· 108 for an accelerating field of 6MV/m. The cavity will be fed via a moveable antenna that, in operating condition, is designed to reach a maximum overcoupled condition of a factor 200 (rms power flowing in the coupler line of 350W) in order to get a bandwidth at the resonant frequency of 30 Hz. It is also needed for this power coupler a wide dynamic range (Qext ranging from 104 to 109) for tests both at room temperature and in superconducting operating mode. Furthermore the sliding mechanism has to be “dust free”. In the following, starting from e-m cavity parameters, the attention will be focused on the power coupler design and line analysis.
UMAN, Manchester
CERN, Geneva
Instituut voor Kern- en Stralingsfysica, K. U. Leuven, Leuven
The superconducting upgrade of the REX-ISOLDE radioactive ion beam (RIB) post-accelerator at CERN will utilise a compact lattice comprising quarter-wave resonators (QWRs) and solenoids, accelerating beams in the mass range 2.5 < A/q < 4.5 to over 10 MeV/u. The short and independently phased quarter-wave structures allow for the acceleration of RIBs over a variable velocity profile and provide an unrivalled longitudinal acceptance when coupled with solenoid focusing. The incorporation of the solenoids into the cryomodule shortens the linac, whilst maximising the transverse acceptance, but the application of solenoid focusing in the presence of asymmetric QWR fields can have consequences for the beam quality. The rotation of an asymmetric beam produces an effective emittance growth in the laboratory reference system. We present modifications of the cavity geometry to optimise the symmetry of the transverse fields in the high-beta QWR. A racetrack shaped beam port is analysed and a modification made to the inner conductor with a geometry that will enable a niobium film to be effectively sputtered onto the cavity surface.
UMAN, Manchester
CERN, Geneva
Instituut voor Kern- en Stralingsfysica, K. U. Leuven, Leuven
The first stage of the planned upgrade of the ISOLDE facility at CERN will provide a boost in beam energy from 3MeV/u up to 5.5MeV/u. In order to reach this goal, it is planned to install downstream the present structure, a superconducting linac based on two gap independently phased Nb sputtered Quarter Wave Resonators (QWRs) working at 101.28MHz. The cavity parameters foresee to have a power dissipated on the cavity wall of 7W with a Q0=6.6· 108 for an accelerating field of 6MV/m. The cavity will be fed via a moveable antenna that, in operating condition, is designed to reach a maximum overcoupled condition of a factor 200 (rms power flowing in the coupler line of 350W) in order to get a bandwidth at the resonant frequency of 30 Hz. It is also needed for this power coupler a wide dynamic range (Qext ranging from 104 to 109) for tests both at room temperature and in superconducting operating mode. Furthermore the sliding mechanism has to be “dust free”. In the following, starting from e-m cavity parameters, the attention will be focused on the power coupler design and line analysis.