IPAC2017 - List of Authors (Grewe, R.)

Paper	Title	Page
MOPVA057	Structural Investigations of Nitrogen-Doped Niobium for Superconducting RF Cavities	996
	M. Major, L. Alff, M. Arnold, J. Conrad, S. Flege, R. Grewe, N. Pietralla TU Darmstadt, Darmstadt, Germany F. Hug IKP, Mainz, Germany
	Funding: Work supported by BMBF through 05H15RDRBA. Niobium is the standard material for superconducting RF (SRF) cavities. Superconducting materials with higher critical temperature or higher critical magnetic field allow cavities to work at higher operating temperatures or higher accelerating fields, respectively. Enhancing the surface properties of the superconducting material in the range of the penetration depth is also beneficial. One direction of search for new materials with better properties is the modification of bulk niobium by nitrogen doping. In the Nb-N phase diagram the cubic delta-phase of NbN has the highest critical temperature (16 K). Already slight nitrogen doping of the alpha-Nb phase results in higher quality factors.* Nb samples will be N-doped at the refurbished UHV furnace at IKP Darmstadt. The first results on the structural investigations of the processed Nb samples at the Materials Research Department of TU Darmstadt are presented. * Grassellino et al., Proc. SRF2015, MOBA06, 48.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA057
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TUPAB030	Construction and Status of the Thrice Recirculating S-DALINAC	1384
	M. Arnold, R. Grewe, J. Pforr, N. Pietralla TU Darmstadt, Darmstadt, Germany C. Eschelbach, M. Lösler Frankfurt University of Applied Sciences, Frankfurt am Main, Germany F. Hug IKP, Mainz, Germany T. Kürzeder HIM, Mainz, Germany
	Funding: Work supported by DFG through RTG 2128 and CRC 634. From 1991 until 2015 the S-DALINAC (Superconducting-DArmstadt-LINear-ACcelerator) was operated as a twice recirculating electron accelerator. Its design energy of 130 MeV in cw-operation was not reached so far due to a lower quality factor of the SRF cavities and thus a higher dissipated power to the helium bath. In 2015/2016 a third recirculation has been built. Enabling a fourth passage through the main linac, the accelerating gradients can be reduced to fit the resulting dissipated power to the available cooling power for running at design energy. The upgrade to a thrice recirculating accelerator required the reconstruction of main parts of the existing lattice as well as an installation of a new beam line. All magnets had to be aligned carefully in position and orientation using high-precision metrology sensors. This contribution will present an overview of the construction and the alignment process. A latest status of the commissioning will be given.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB030
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Structural Investigations of Nitrogen-Doped Niobium for Superconducting RF Cavities

996

M. Major, L. Alff, M. Arnold, J. Conrad, S. Flege, R. Grewe, N. Pietralla
TU Darmstadt, Darmstadt, Germany
F. Hug
IKP, Mainz, Germany

Funding: Work supported by BMBF through 05H15RDRBA.
Niobium is the standard material for superconducting RF (SRF) cavities. Superconducting materials with higher critical temperature or higher critical magnetic field allow cavities to work at higher operating temperatures or higher accelerating fields, respectively. Enhancing the surface properties of the superconducting material in the range of the penetration depth is also beneficial. One direction of search for new materials with better properties is the modification of bulk niobium by nitrogen doping. In the Nb-N phase diagram the cubic delta-phase of NbN has the highest critical temperature (16 K). Already slight nitrogen doping of the alpha-Nb phase results in higher quality factors.* Nb samples will be N-doped at the refurbished UHV furnace at IKP Darmstadt. The first results on the structural investigations of the processed Nb samples at the Materials Research Department of TU Darmstadt are presented.
* Grassellino et al., Proc. SRF2015, MOBA06, 48.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA057

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB030

Construction and Status of the Thrice Recirculating S-DALINAC

1384

M. Arnold, R. Grewe, J. Pforr, N. Pietralla
TU Darmstadt, Darmstadt, Germany
C. Eschelbach, M. Lösler
Frankfurt University of Applied Sciences, Frankfurt am Main, Germany
F. Hug
IKP, Mainz, Germany
T. Kürzeder
HIM, Mainz, Germany

Funding: Work supported by DFG through RTG 2128 and CRC 634.
From 1991 until 2015 the S-DALINAC (Superconducting-DArmstadt-LINear-ACcelerator) was operated as a twice recirculating electron accelerator. Its design energy of 130 MeV in cw-operation was not reached so far due to a lower quality factor of the SRF cavities and thus a higher dissipated power to the helium bath. In 2015/2016 a third recirculation has been built. Enabling a fourth passage through the main linac, the accelerating gradients can be reduced to fit the resulting dissipated power to the available cooling power for running at design energy. The upgrade to a thrice recirculating accelerator required the reconstruction of main parts of the existing lattice as well as an installation of a new beam line. All magnets had to be aligned carefully in position and orientation using high-precision metrology sensors. This contribution will present an overview of the construction and the alignment process. A latest status of the commissioning will be given.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB030

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)