DESY, Hamburg
INFN/LASA, Segrate (MI)
W.C. Heraeus GmbH COPY, Materials Technology Dept., Hanau
Few cavities of the 4th and 6th cavity generation treated accordingly the XFEL recipe have shown performance of ca. 15 MV/m caused by thermal break down without field emission. Effort to post purify some cavities with titanium, that was successfully applied for FLASH cavities, did not improve the performance. The T-map analysis detected the quench areas mainly close to the equator. Optical control by high resolution camera and non-destructive X-Ray radiography have been applied and allowed to monitor the defects in some cases with good correlation to T-map observation. In order to get more detailed information of defects some samples have been extracted from cavity and investigated by light microscope, SEM, EDX and Auger spectroscopy. The detected distinctions are discussed
IPN, Orsay
INFN/LASA, Segrate (MI)
GANIL, Caen
Accelerator Driven system (ADS) are being considered for their potential use in the transmutation of nuclear waste. Such a device typically requires a 600MeV to 1GeV accelerator delivering a beam of few mA intensity. Because of the induced thermal stress to the subcritical core, the high-power proton LINAC will have to fulfill stringent reliability requirements, with less than a dozen of unwanted beam trips per year. One working package of the EUROTRANS project* is dedicated to the design, realization and tests of a prototypical cryomodule for the LINAC high energy section equipped with a 5 cells superconducting cavity and its tuning system. Developed at INFN, this RF cryogenic device will be tested at IPNO, early 2010. We will describe the status of the R&D activities, regarding the cryogenic system, the cavity, the power coupler, the doorknob transition and the RF source developed by Thales Electron Devices. Then, we will review the foreseen experimental reliability characterization of the cryomodule with its RF control system in nominal operating conditions.
INFN/LASA, Segrate (MI)
In the cavity production process some defects may appear on the niobium surface, after the chemical and/or electrochemical processes, mainly in the region close to the equatorial weld and in the HAZ (Heat Affected Zone). We have produced defects on the Nb surface, with geometrical characteristics similar to the defects that may be produced during the mechanical machining of the cavity cells. We have investigated the evolution of these defects, during the usual chemical and electrochemical surface preparation stages.
INFN/LASA, Segrate (MI)
DESY, Hamburg
Three superconducting 3.9 GHz cavity prototypes have been fabricated for the XFEL linac injector, with minor modifications to the RF structures built by FNAL for the FLASH linac. This paper describes the production procedures and RF preparation experience, the chemical processing and the plans for the vertical tests at INFN Milano for the characterization of the structures.