SRF2013 - List of Authors (Ermakov, A.)

Paper

Title

Page

Statistic to Eddy-Current Scanning of Niobium Sheets for European XFEL

171

A. Brinkmann, S. Arnold, A. Ermakov, J. Iversen, M. Lengkeit, A. Poerschmann, L. Schaefer, W. Singer, X. Singer
DESY, Hamburg, Germany

The fabrication experiences of superconducting cavities for FLASH have shown that eddy-current scanning of the Nb-sheets foreseen for half-cells reduces the cavity failures. New eddy current devices have been developed and build together with the industry for the production of 800 pieces 1.3 GHz superconducting niobium cavities for European XFEL. More than 15.000 Nb-sheets provided by three companies have been tested by eddy-current scanning. The sheets that demonstrated local deviations of the signal have been subsequently non-destructively examined by 3d-microscope and X-Ray element analysis. The surface defects (dents, holes, scratches) are the mainly detected flaws. In addition several types of foreign material inclusions observed. Statistic concerning eddy-current signal deviation and rejection rates for each supplier will be presented.

TUP024

Unloaded Quality Factor Qo of Prototype European XFEL Cavities, Large Grain and Hydroformed Cavities

A. Ermakov, W. Singer, X. Singer
DESY, Hamburg, Germany

A statistical analysis of the unloaded quality factor Q0 of TESLA shape cavities at low accelerating field (up to 5 MV/m) and medium accelerating field (5-20 MV/m) was done on base of available RF data for test series: single-cell and 9-cell large grain cavities, single cell and multi-cell hydroformed at DESY cavities, fine grain cavities-prototypes for European XFEL. On the one hand the purpose of statistical analysis is done to find the relationship between the parameters describing the behavior between unloaded quality factor Q0 (as function of the accelerated field Eacc) and main treatment procedures (Buffered Chemical Polishing BCP, Electropolishing EP, 120°C baking). On the other hand the relationship between Q0 and different types of cavities (cavities with reduced number of grain boundaries, cavities without equator welding seam, cavities of standard fine grain material) was evaluated. The non - linearity of the surface resistance in low and medium field regions analyzed for these types of cavities and compared with the available theoretical models.

Paper	Title	Page
MOP032	Statistic to Eddy-Current Scanning of Niobium Sheets for European XFEL	171
	A. Brinkmann, S. Arnold, A. Ermakov, J. Iversen, M. Lengkeit, A. Poerschmann, L. Schaefer, W. Singer, X. Singer DESY, Hamburg, Germany
	The fabrication experiences of superconducting cavities for FLASH have shown that eddy-current scanning of the Nb-sheets foreseen for half-cells reduces the cavity failures. New eddy current devices have been developed and build together with the industry for the production of 800 pieces 1.3 GHz superconducting niobium cavities for European XFEL. More than 15.000 Nb-sheets provided by three companies have been tested by eddy-current scanning. The sheets that demonstrated local deviations of the signal have been subsequently non-destructively examined by 3d-microscope and X-Ray element analysis. The surface defects (dents, holes, scratches) are the mainly detected flaws. In addition several types of foreign material inclusions observed. Statistic concerning eddy-current signal deviation and rejection rates for each supplier will be presented.

TUP024	Unloaded Quality Factor Qo of Prototype European XFEL Cavities, Large Grain and Hydroformed Cavities
	A. Ermakov, W. Singer, X. Singer DESY, Hamburg, Germany
	A statistical analysis of the unloaded quality factor Q0 of TESLA shape cavities at low accelerating field (up to 5 MV/m) and medium accelerating field (5-20 MV/m) was done on base of available RF data for test series: single-cell and 9-cell large grain cavities, single cell and multi-cell hydroformed at DESY cavities, fine grain cavities-prototypes for European XFEL. On the one hand the purpose of statistical analysis is done to find the relationship between the parameters describing the behavior between unloaded quality factor Q0 (as function of the accelerated field Eacc) and main treatment procedures (Buffered Chemical Polishing BCP, Electropolishing EP, 120°C baking). On the other hand the relationship between Q0 and different types of cavities (cavities with reduced number of grain boundaries, cavities without equator welding seam, cavities of standard fine grain material) was evaluated. The non - linearity of the surface resistance in low and medium field regions analyzed for these types of cavities and compared with the available theoretical models.