SRF2011 - List of Authors (Aderhold, S.)

Paper

Title

Page

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

TUPO066

Analysis of Recent Results from Second Sound, Temperature Mapping and Optical Inspection of 1.3 GHz Cavities at DESY

558

F. Schlander, S. Aderhold, D. Reschke, K. Twarowski
DESY, Hamburg, Germany

DESY is preparing for the delivery of some 600 superconducting 9-cell cavities for the European XFEL. Analysing the history and recorded data of recently tested cavities gives important evidence for proper treatment, preparation and handling of cavities. The experience given by temperature mapping, the Second Sound technique and optical inspection will be compared and an overview of the results obtained so far will be given in this report.

Poster TUPO066 [1.160 MB]

WEIOB05

Large Grain Cavities: Fabrication, RF Results and Optical Inspection

607

S. Aderhold
DESY, Hamburg, Germany

SRF cavities produced from large grain niobium material have been investigated as an alternative to the standard fine grain material in the past years. While many single cell cavities have been prepared and successfully tested, the number of large grain 9-cell cavities available at the laboratories worldwide is still small. The worldwide experience and results with fabrication, treatment and testing will be compared. At DESY, a batch of eight large grain 9-cell cavities has been processed and tested recently, in addition to three cavities that had been processed and tested earlier. The surface preparation process has been closely followed by optical inspection in-between all treatment steps that include surface removal. Several of the vertical RF tests have been done with T-mapping and/or second sound measurements for determination of the quench location. The results after a first treatment cycle with BCP and a second treatment cycle with EP will be presented.

Slides WEIOB05 [2.185 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
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

TUPO066	Analysis of Recent Results from Second Sound, Temperature Mapping and Optical Inspection of 1.3 GHz Cavities at DESY	558
	F. Schlander, S. Aderhold, D. Reschke, K. Twarowski DESY, Hamburg, Germany
	DESY is preparing for the delivery of some 600 superconducting 9-cell cavities for the European XFEL. Analysing the history and recorded data of recently tested cavities gives important evidence for proper treatment, preparation and handling of cavities. The experience given by temperature mapping, the Second Sound technique and optical inspection will be compared and an overview of the results obtained so far will be given in this report.
	Poster TUPO066 [1.160 MB]

WEIOB05	Large Grain Cavities: Fabrication, RF Results and Optical Inspection	607
	S. Aderhold DESY, Hamburg, Germany
	SRF cavities produced from large grain niobium material have been investigated as an alternative to the standard fine grain material in the past years. While many single cell cavities have been prepared and successfully tested, the number of large grain 9-cell cavities available at the laboratories worldwide is still small. The worldwide experience and results with fabrication, treatment and testing will be compared. At DESY, a batch of eight large grain 9-cell cavities has been processed and tested recently, in addition to three cavities that had been processed and tested earlier. The surface preparation process has been closely followed by optical inspection in-between all treatment steps that include surface removal. Several of the vertical RF tests have been done with T-mapping and/or second sound measurements for determination of the quench location. The results after a first treatment cycle with BCP and a second treatment cycle with EP will be presented.
	Slides WEIOB05 [2.185 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]