SRF2011 - List of Authors (Singer, W.)

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]

TUPO046

Results on Large Grain Nine-Cell Cavities at DESY: Gradients up to 45 MV/m after Electropolishing

490

D. Reschke, S. Aderhold, A. Gössel, J. Iversen, S. Karstensen, D. Kostin, G. Kreps, A. Matheisen, W.-D. Möller, F. Schlander, W. Singer, X. Singer, N. Steinhau Kühl, A.A. Sulimov, K. Twarowski
DESY, Hamburg, Germany

Since 2009 a series of eight nine-cell cavities (AC151 – AC158) of TESLA shape fabricated of large grain (LG) niobium material is under preparation and test at DESY. In a first step all cavities were tested after a BCP treatment. In a second step additional electro polishing is applied to all cavities. In this paper the treatment will be discussed and present results will be reported

WEIOB04

XFEL Cavity Procurement as an Example of Technology Transfer

606

W. Singer
DESY, Hamburg, Germany

Procurement of superconducting RF cavities for the European XFEL consists of two phases. The preparation phase for the European XFEL cavity production includes: qualification of high purity niobium vendors and potential cavity producers; accommodation of the TESLA cavity design to the XFEL demands; establishing the XFEL treatment process, work out and check the strategy of preparation for the vertical acceptance test; define the documentation and prompt data transfer, qualification of created infrastructure, cavity acceptance criteria and tests. A detailed specification has been worked out on the basis of ca. 50 prototype cavities. Production of 600 cavities is currently contracted on the principle “build to print”; the cavity material will be provided by DESY. DESY will supply vendors with machine for cavity tuning at room temperature and equipment for RF measurement of dumb bells and end groups. The cavity with helium tank has to be built as a component according Pressure Equipment Directive (PED) 97/23/EC. The contracted “notified body” will supervise the material qualification and procurement. Monitoring of the vendor’s work will be executed by DESY and INFN (Milano) team.

THPO053

Material for Fabrication of DESY Large Grain/Single Crystal Cavities

854

X. Singer, J. Iversen, W. Singer, K. Twarowski
DESY, Hamburg, Germany
H.G. Brokmeier
Technische Universität Clausthal, Institut für Nichtmetallische Werkstoffe, Clausthal-Zellerfeld, Germany
R. Grill
Plansee Metall GmbH, Reutte, Austria
F. Schölz, B. Spaniol
W.C. Heraeus GmbH, Materials Technology Dept., Hanau, Germany

Material for large grain LG and single crystal SC cavities of TESLA shape has been developed in collaboration with industry. One of the aspects of LG material was electron beam melting of the ingots with required structure. The second was slicing of the discs cost effectively with tight thickness tolerances, high surface quality and high purity. Surface and structural properties of SC on the LG discs are investigated. Measurements of the crystal orientation on the LG discs of three companies have been done by complete penetration using synchrotron radiation. Two LG material features have been stressed in cavity production: the influence of the LG crystal orientation on the anisotropic behavior during deep drawing and the impact of pronounced steps at grain boundaries on cavity behavior. 11 LG 9-cell cavities of XFEL-like shape are fabricated. The procedure of increasing the crystal size by rolling of LG discs and cut out of SC discs, followed by subsequent forming and welding without destroying of the SC structure, was developed. A method of fabrication of single crystal cavities was proposed. Several SC cavities with different crystal orientations were produced.

Poster THPO053 [2.201 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]

THPO059

Correlation of Microstructure, Chemical Composition and RRR-Value in High Purity Niobium (Nb-RRR))

863

R. Grill, W. Simader
Plansee Metall GmbH, Reutte, Austria
M. Heilmaier, D. Janda
TU Darmstadt, Darmstadt, Germany
W. Singer, X. Singer
DESY, Hamburg, Germany

For manufacturing of Nb-RRR sheet material a thorough understanding of material properties and niobium metallurgy is necessary to meet the required regarding material properties as specified for the XFEL project. Especially for the RRR value it is known, that residual stresses, and increased levels of vacancy and impurity concentrations, and dislocation densities after the final heat treatment can cause a severe degradation of the RRR value. Also, a comprehensive understanding of the influence of further microstructural properties (e.g. different textures due to rolling operations and annealing, dislocation substructures, etc.) on the RRR-value is lacking. For specimens having RRR-values in the range of 360 to 430, the crystallographic texture has been investigated and correlated with the measured RRR values. Furthermore, the possible influence of different impurity levels on the RRR value was calculated, compared with the measured values and discussed with regard to the current material specification for the XFEL project.

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]

TUPO046	Results on Large Grain Nine-Cell Cavities at DESY: Gradients up to 45 MV/m after Electropolishing	490
	D. Reschke, S. Aderhold, A. Gössel, J. Iversen, S. Karstensen, D. Kostin, G. Kreps, A. Matheisen, W.-D. Möller, F. Schlander, W. Singer, X. Singer, N. Steinhau Kühl, A.A. Sulimov, K. Twarowski DESY, Hamburg, Germany
	Since 2009 a series of eight nine-cell cavities (AC151 – AC158) of TESLA shape fabricated of large grain (LG) niobium material is under preparation and test at DESY. In a first step all cavities were tested after a BCP treatment. In a second step additional electro polishing is applied to all cavities. In this paper the treatment will be discussed and present results will be reported

WEIOB04	XFEL Cavity Procurement as an Example of Technology Transfer	606
	W. Singer DESY, Hamburg, Germany
	Procurement of superconducting RF cavities for the European XFEL consists of two phases. The preparation phase for the European XFEL cavity production includes: qualification of high purity niobium vendors and potential cavity producers; accommodation of the TESLA cavity design to the XFEL demands; establishing the XFEL treatment process, work out and check the strategy of preparation for the vertical acceptance test; define the documentation and prompt data transfer, qualification of created infrastructure, cavity acceptance criteria and tests. A detailed specification has been worked out on the basis of ca. 50 prototype cavities. Production of 600 cavities is currently contracted on the principle “build to print”; the cavity material will be provided by DESY. DESY will supply vendors with machine for cavity tuning at room temperature and equipment for RF measurement of dumb bells and end groups. The cavity with helium tank has to be built as a component according Pressure Equipment Directive (PED) 97/23/EC. The contracted “notified body” will supervise the material qualification and procurement. Monitoring of the vendor’s work will be executed by DESY and INFN (Milano) team.

THPO053	Material for Fabrication of DESY Large Grain/Single Crystal Cavities	854
	X. Singer, J. Iversen, W. Singer, K. Twarowski DESY, Hamburg, Germany H.G. Brokmeier Technische Universität Clausthal, Institut für Nichtmetallische Werkstoffe, Clausthal-Zellerfeld, Germany R. Grill Plansee Metall GmbH, Reutte, Austria F. Schölz, B. Spaniol W.C. Heraeus GmbH, Materials Technology Dept., Hanau, Germany
	Material for large grain LG and single crystal SC cavities of TESLA shape has been developed in collaboration with industry. One of the aspects of LG material was electron beam melting of the ingots with required structure. The second was slicing of the discs cost effectively with tight thickness tolerances, high surface quality and high purity. Surface and structural properties of SC on the LG discs are investigated. Measurements of the crystal orientation on the LG discs of three companies have been done by complete penetration using synchrotron radiation. Two LG material features have been stressed in cavity production: the influence of the LG crystal orientation on the anisotropic behavior during deep drawing and the impact of pronounced steps at grain boundaries on cavity behavior. 11 LG 9-cell cavities of XFEL-like shape are fabricated. The procedure of increasing the crystal size by rolling of LG discs and cut out of SC discs, followed by subsequent forming and welding without destroying of the SC structure, was developed. A method of fabrication of single crystal cavities was proposed. Several SC cavities with different crystal orientations were produced.
	Poster THPO053 [2.201 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]

THPO059	Correlation of Microstructure, Chemical Composition and RRR-Value in High Purity Niobium (Nb-RRR))	863
	R. Grill, W. Simader Plansee Metall GmbH, Reutte, Austria M. Heilmaier, D. Janda TU Darmstadt, Darmstadt, Germany W. Singer, X. Singer DESY, Hamburg, Germany
	For manufacturing of Nb-RRR sheet material a thorough understanding of material properties and niobium metallurgy is necessary to meet the required regarding material properties as specified for the XFEL project. Especially for the RRR value it is known, that residual stresses, and increased levels of vacancy and impurity concentrations, and dislocation densities after the final heat treatment can cause a severe degradation of the RRR value. Also, a comprehensive understanding of the influence of further microstructural properties (e.g. different textures due to rolling operations and annealing, dislocation substructures, etc.) on the RRR-value is lacking. For specimens having RRR-values in the range of 360 to 430, the crystallographic texture has been investigated and correlated with the measured RRR values. Furthermore, the possible influence of different impurity levels on the RRR value was calculated, compared with the measured values and discussed with regard to the current material specification for the XFEL project.