A selection of point of view camcorders : Technical specifications, classroom trials, and potential applications

About 50 nine-cell cavities of the recent fine-grain niobium cavity productions have been analysed with respect to maximum and usable gradient in the first and last vertical RF acceptance test, respectively. Parameters of the analysis were the manufacturer of the cavities, the location of the Main EP (=> industry or in-house), the final surface treatment (=> final 40 μm EP or short 10 μm “Flash BCP) and the cavity preparation strategy (=> vertical acceptance test with or without He-tank welded). Moreover, the effect of a re-processing of field emission loaded cavities by an additional ultra pure high pressure water rinsing (HPR) has been investigated

Nitrogen infusion R&D at DESY a case study on cavity cut-outs

A first series of nitrogen infusion runs of 1.3 GHz single-cell cavities at DESY resulted in an unexpected and severe deterioration observed during the vertical cold test. To investigate the origin of the deterioration, one of the cavities underwent extensive radio-frequency measurements and a temperature- and magnetic field-mapping was performed in collaboration with the Helmholtz-Zentrum Berlin. After combining all results, regions of interests were identified and cut-out of the cavity. Subsequent surface analysis techniques (EBSD, PALS, PIXE, SEM/EDX, SIMS, XPS) were applied in order to identify the microscopic origin of the deterioration and especially the differences between hot and cold spots as well as quench spots. An excess of niobium carbides, reducing the thermal conductivity, was identified as the probable cause for the deterioration, and the size- and density-distributions were observed to be crucial for the resulting performance reduction. The origin for the local differences in the niobium carbide formation between hot and cold spots is an effect of preexisting variations of the crystal structure.BMBF, 05H18GURB1, Verbundprojekt 05H2018 - R&D BESCHLEUNIGER (STenCiL): Optimierung der Hochfrequenzeigenschaften supraleitender Resonatoren durch Oberflächenbehandlun

Recent Progress with EU-XFEL

The superconducting accelerator of the European XFEL consists of the injector part and the main linac. The injector includes one 1.3 GHz accelerator module and one 3.9 GHz third-harmonic module, while the main linac will consist of 100 accelerator modules, operating at an average design gradient of 23.6 MV/m. The fabrication and surface treatment by industry as well as RF acceptance tests of the required 808 superconducting 1.3 GHz cavities are close to an end by the time of SRF 2015. The accelerator module assembly, testing and installationin the tunnel is in full swing. First steps of commissioning have been made. The status and results of cavity and module RF tests at 1.3 GHz and 3.9 GHz are presented

Infrastructure, Methods and Test Results for the Testing of 800 Series Cavities for the European XFEL

The main linac of the European XFEL will consist of 100 accelerator modules, i.e. 800 superconductingaccelerator cavities operated at a design gradient of 23.6 MV/m. The fabrication and surface preparation of thecavities in industry is in full swing. This talk describes the infrastructure and procedures of the vertical acceptance test in the "Accelerator Module Test Facility AMTF" at DESY. The present status of the test results is given