74 research outputs found
SPIRAL2 RFQ prototype - First results
JACoW web site MOPCH103International audienceThe SPIRAL2 RFQ is designed to accelerate either 5 mA deuteron beam (Q/A=1/2) or a 1 mA of q/A=1/3 particle up to 0.75 MeV/A at 88 MHz. It is a CW machine which has to show stable operation, provide the required availability and reduce losses to a minimum in order to minimize the activation constraints. Extensive modelisation was done to ensure a good vane position under RF. The prototype of this 4-vane RFQ was built and tested in INFN-LNS Catania and then in IN2P3-LPSC Grenoble. It allowed us to measure the vacuum quality, the RF field by X-ray measurements, the cavity displacement and the real vane displacement during the RF injection. Different techniques were used, including an innovative CCD measurement with a 0.8 ÎŒm precision. This paper outlines the different results
Theoretical study and experimental result of the RF coupler prototypes of Spiral2
JACoW web site THPCH160International audienceSpiral2 is a 40 MeV-5mA deuterons and a 14.5 MeV/u-1mA heavy ions superconducting linac under construction at GANIL. The RF couplers have to provide 12 kW CW power to the cavities at 88 MHz for an accelerating field of 6.5 MV/m. Two solutions corresponding to two different technologies have been designed and two prototypes have been built. We present the technical proposals ans issues as well as the results (manufacturing, test at low and high power, multipacting...) leading to the final choice
High intensity linac driver for the SPIRAL-2 project : Design of superconducting 88 MHz quarter wave resonators (beta 0.12), power couplers and cryomodules
ACCInternational audienceA Superconducting Linac Driver, delivering deuterons with energy up to 40 MeV (5 mA) and heavy ions with energy of 14.5 MeV/u (1 mA ), is proposed for the Spiral-2 radioactive beams facility. For the high energy section of the linac, a superconducting 88 MHz Quarter Wave Resonator (beta 0.12) has been designed and the optimisation of RF and mechanical performances will be presented. Based on the present state-of-art of the Superconducting RF technology, maximum electric surface field of 40 MV/m and magnetic surface field of 80 mT, have been adopted which should allow to reach an accelerating field of 7 MV/m (energy gain 3 MeV per resonator). A first complete prototype is under construction. The high intensity deuteron beam specifications have imposed the design of an original power coupler (maximum power 20 KW). The RF, mechanical, and thermal characteristics will be presented. The design of the cryomodule for this high energy section, integrating two QWR with its associated equipments (couplers, tuners, helium tanks), will be presented
Subsidence monitoring within the Athens Basin (Greece) using space radar interferometric techniques
Gravity-driven instabilities: interplay between state-and-velocity dependent frictional sliding and stress corrosion damage cracking
We model the progressive maturation of a heterogeneous mass towards a
gravity-driven instability, characterized by the competition between frictional
sliding and tension cracking, using array of slider blocks on an inclined basal
surface, which interact via elastic-brittle springs. A realistic state- and
rate-dependent friction law describes the block-surface interaction. The inner
material damage occurs via stress corrosion. Three regimes, controlling the
mass instability and its precursory behavior, are classified as a function of
the ratio of two characteristic time scales associated with internal
damage/creep and with frictional sliding. For , the whole mass
undergoes a series of internal stick and slip events, associated with an
initial slow average downward motion of the whole mass, and progressively
accelerates until a global coherent runaway is observed. For ,
creep/damage occurs sufficiently fast compared with nucleation of sliding,
causing bonds to break, and the bottom part of the mass undergoes a
fragmentation process with the creation of a heterogeneous population of
sliding blocks. For the intermediate regime , a macroscopic
crack nucleates and propagates along the location of the largest curvature
associated with the change of slope from the stable frictional state in the
upper part to the unstable frictional sliding state in the lower part. The
other important parameter is the Young modulus which controls the
correlation length of displacements in the system.Comment: 40 pages, 13 figure
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