SRF2011 - List of Authors (Ermakov, A.)

Paper

Title

Page

Nine - Cell Tesla Shape Cavities Produced From Hydroformed Cells

431

W. Singer, A. Ermakov, G. Kreps, A. Matheisen, X. Singer, K. Twarowski
DESY, Hamburg, Germany
R. Crooks
Black Laboratories, L.L.C., Newport News, USA
P. Kneisel
JLAB, Newport News, Virginia, USA
I.N. Zhelezov
RAS/INR, Moscow, Russia

Production of two types of seamless niobium tubes for hydroforming of RF cavities has been developed. The first type of tubes, developed at DESY, have been spun from sheets and flow formed. The second type of tubing was developed by Black Laboratories in collaboration with the company ATI Wah Chang. These longer length tubes were extruded from a heavily deformed billet, processed for a fine-grained microstructure and flow formed. Several seamless three cell units have been produced by hydroforming at DESY. Some of the units have been treated by buffered chemical polishing and RF tested at JLab. The accelerating gradient Eacc of the units exceeded in most cases 30 MV/m. Three of the 3-cell units from the first type of tubing were combined to three 9-cell niobium cavities at the company E. Zanon. The 3-cell units from extruded tubing are welded together to the fourth 9-cell cavity at JLab. All cavities are in preparation for the RF tests at DESY and JLab. Up to now two of the cavities are electropolished and tested at DESY. The first cavity reached an accelerating gradient of Eacc of ~30 MV/m, the second one ~35 MV/m.

Poster TUPO026 [2.664 MB]

TUPO036

Material for European XFEL Resonators

460

W. Singer, S. Arnold, A. Brinkmann, J.A. Dammann, A. Ermakov, J. Iversen, D. Klinke, M. Lengkeit, W.-D. Möller, P. Poerschmann, X. Singer
DESY, Hamburg, Germany

Twelve different types of semi-finished products will be provided by DESY to producers of European XFEL superconducting resonators. Work on material for XFEL cavities is divided into three phases (prototyping, pre-series and series production). Two new companies (Ningxia OTIC and Plansee Metal GmbH) have been qualified as XFEL suppliers. Material is contracted to 4 companies (Ningxia OTIC, Plansee Metal GmbH, Tokyo Denkai and W.C. Heraeus). Procurement of semi-finished products includes: acceptance on producer’s site, eddy current scanning of the sheets, testing for required parameters (RRR, interstitial impurity analysis, metallic impurities analysis, metallography, tensile test, hardness HV, dimensional check, surface roughness), documentation using the DESY EDM-System, marking, delivery to companies. Semi-finished products for pressure bearing sub-components of cavities have to be fabricated according Pressure Equipment Directive 97/23/EC. Qualification of material and the certification of the material producers were done by a “notified body”. Appropriate infrastructure and logistic for guiding through more than 20.000 of semi-finished products has been build up.

Poster TUPO036 [2.332 MB]

THPO055

Investigation of Samples Separated From Prototype Cavities of the European XFEL

855

X. Singer, S. Aderhold, A. Ermakov, D. Reschke, W. Singer, K. Twarowski
DESY, Hamburg, Germany
M. Hoss
W.C. Heraeus GmbH, Materials Technology Dept., Hanau, Germany

XFEL prototype cavities fabricated in industry and treated at DESY mainly meet the specification. Few cavities demonstrated low performance (13-20 MV/m) limited by thermal breakdown. The T-map analysis detected quench areas mainly close to the equator. Optical inspection by high resolution camera allowed tracking the several stages of preparation (as received, after the main electropolishing EP, after RF test) and in some cases makes possible monitoring the evolution of defects. In order to understand the nature of reduced performance and get more detailed information on the origin of defects, some samples have been extracted from four cavities and investigated by light microscope, 3D-microscope, SEM, EDX and Auger spectroscopy. Several surface flaws with sizes from a few μm to hundreds of μm have been detected. The defects can be grouped in four categories. The first category of defects indicates foreign elements (often with increased content of carbon). Deviation from smooth surface profile characterizes the second type of defects (holes, bumps). Damaged surface areas at high pressure water rinsing and etching pits belong to the third and fourth category of defects.

Poster THPO055 [3.802 MB]

Paper	Title	Page
TUPO026	Nine - Cell Tesla Shape Cavities Produced From Hydroformed Cells	431
	W. Singer, A. Ermakov, G. Kreps, A. Matheisen, X. Singer, K. Twarowski DESY, Hamburg, Germany R. Crooks Black Laboratories, L.L.C., Newport News, USA P. Kneisel JLAB, Newport News, Virginia, USA I.N. Zhelezov RAS/INR, Moscow, Russia
	Production of two types of seamless niobium tubes for hydroforming of RF cavities has been developed. The first type of tubes, developed at DESY, have been spun from sheets and flow formed. The second type of tubing was developed by Black Laboratories in collaboration with the company ATI Wah Chang. These longer length tubes were extruded from a heavily deformed billet, processed for a fine-grained microstructure and flow formed. Several seamless three cell units have been produced by hydroforming at DESY. Some of the units have been treated by buffered chemical polishing and RF tested at JLab. The accelerating gradient Eacc of the units exceeded in most cases 30 MV/m. Three of the 3-cell units from the first type of tubing were combined to three 9-cell niobium cavities at the company E. Zanon. The 3-cell units from extruded tubing are welded together to the fourth 9-cell cavity at JLab. All cavities are in preparation for the RF tests at DESY and JLab. Up to now two of the cavities are electropolished and tested at DESY. The first cavity reached an accelerating gradient of Eacc of ~30 MV/m, the second one ~35 MV/m.
	Poster TUPO026 [2.664 MB]

TUPO036	Material for European XFEL Resonators	460
	W. Singer, S. Arnold, A. Brinkmann, J.A. Dammann, A. Ermakov, J. Iversen, D. Klinke, M. Lengkeit, W.-D. Möller, P. Poerschmann, X. Singer DESY, Hamburg, Germany
	Twelve different types of semi-finished products will be provided by DESY to producers of European XFEL superconducting resonators. Work on material for XFEL cavities is divided into three phases (prototyping, pre-series and series production). Two new companies (Ningxia OTIC and Plansee Metal GmbH) have been qualified as XFEL suppliers. Material is contracted to 4 companies (Ningxia OTIC, Plansee Metal GmbH, Tokyo Denkai and W.C. Heraeus). Procurement of semi-finished products includes: acceptance on producer’s site, eddy current scanning of the sheets, testing for required parameters (RRR, interstitial impurity analysis, metallic impurities analysis, metallography, tensile test, hardness HV, dimensional check, surface roughness), documentation using the DESY EDM-System, marking, delivery to companies. Semi-finished products for pressure bearing sub-components of cavities have to be fabricated according Pressure Equipment Directive 97/23/EC. Qualification of material and the certification of the material producers were done by a “notified body”. Appropriate infrastructure and logistic for guiding through more than 20.000 of semi-finished products has been build up.
	Poster TUPO036 [2.332 MB]

THPO055	Investigation of Samples Separated From Prototype Cavities of the European XFEL	855
	X. Singer, S. Aderhold, A. Ermakov, D. Reschke, W. Singer, K. Twarowski DESY, Hamburg, Germany M. Hoss W.C. Heraeus GmbH, Materials Technology Dept., Hanau, Germany
	XFEL prototype cavities fabricated in industry and treated at DESY mainly meet the specification. Few cavities demonstrated low performance (13-20 MV/m) limited by thermal breakdown. The T-map analysis detected quench areas mainly close to the equator. Optical inspection by high resolution camera allowed tracking the several stages of preparation (as received, after the main electropolishing EP, after RF test) and in some cases makes possible monitoring the evolution of defects. In order to understand the nature of reduced performance and get more detailed information on the origin of defects, some samples have been extracted from four cavities and investigated by light microscope, 3D-microscope, SEM, EDX and Auger spectroscopy. Several surface flaws with sizes from a few μm to hundreds of μm have been detected. The defects can be grouped in four categories. The first category of defects indicates foreign elements (often with increased content of carbon). Deviation from smooth surface profile characterizes the second type of defects (holes, bumps). Damaged surface areas at high pressure water rinsing and etching pits belong to the third and fourth category of defects.
	Poster THPO055 [3.802 MB]