IPAC2015 - List of Authors (Hall, D.L.)

Paper	Title	Page
WEPTY072	Update on Nitrogen-doped 9-cell Cavity Performance in the Cornell Horizontal Test Cryomodule	3446
	D. Gonnella, R.G. Eichhorn, F. Furuta, G.M. Ge, D.L. Hall, Y. He, K.M.V. Ho, G.H. Hoffstaetter, M. Liepe, J.T. Maniscalco, T.I. O'Connel, S. Posen, P. Quigley, J. Sears, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA A. Grassellino, C.J. Grimm, O.S. Melnychuk, A. Romanenko Fermilab, Batavia, Illinois, USA
	Funding: U.S. Department of Energy The Linac Coherent Light Source-II (LCLS-II) is a new x-ray source that is planned to be constructed in the existing SLAC tunnel. To meet the quality factor specifications (2.7x 10¹⁰ at 2.0 K and 16 MV/m), nitrogen-doping has been proposed as a preparation method for the SRF cavities. In order to demonstrate the feasibility of these goals, four 9-cell cavity tests have been completed in the Cornell Horizontal Test Cryomodule (HTC), which serves as a test bench for the full LCLS-II cryomodule. Here we report on the most recent two cavity tests in the HTC: one cavity nitrogen-doped at Cornell and tested with high Q input coupler and then again tested with high power LCLS-II input coupler. Transition to test in horizontal cryomodule resulted in no degradation in Q0 from vertical test. Additionally, increased dissipated power due to the high power input coupler was small and in good agreement with simulations. These results represent a crucial step on the way to demonstrating technical readiness for LCLS-II.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY072
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WEPTY074	Recent Studies on the Current Limitations of State-of-the-Art Nb3Sn Cavities	3454
	D.L. Hall, M. Liepe, J.T. Maniscalco, S. Posen Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA Th. Proslier ANL, Argonne, Illinois, USA
	Funding: NSF PHY-1305500 PHY-14116318 DOE ER41802 Recent advances in the study of Nb3Sn at Cornell University have yielded single-cell cavities that show excellent performance without the limiting Q-slope seen in previous work. This performance has been shown to be repeatable across multiple cavities. However, they are still limited by a quench field of approximately 16 MV/m, as well as residual resistance. In this work we present results quantifying the impact of ambient magnetic fields on Nb3Sn cavities, as well as discuss the impact of cavity cooldown procedures on cavity performance. Finally, we will briefly discuss XRD results that shed light on the composition of the Nb3Sn layer and how this relates to the current limits of these cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY074
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WEPTY075	Hc2 Measurements of Nb3Sn and Nitrogen-doped Niobium using Physical Property Measurement System	3458
	J.T. Maniscalco, D. Gonnella, D.L. Hall, M. Liepe, S. Posen Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The measurement of the upper critical field of a type-2 superconductor, Hc2, is an important step in determining its superconducting properties, and therefore its suitability as a material in SRF cavities. However, measuring Hc2 directly can be challenging, as performing electrical measurements causes changes in the very properties one seeks to measure. We present a method for extracting Hc2 from resistivity measurements made near the transition temperature for varied applied fields and excitation currents. We also present results of these measurements made on Nb3Sn and nitrogen-doped niobium.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY075
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WEPTY076	RF Performance Studies of Thin-Film Superconductors Using a Sample Host Cavity	3462
	J.T. Maniscalco, D.L. Hall, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Thin-film superconductors have the potential for reduced cost and for improved SRF performance over traditional bulk niobium superconducting cavities. Materials such as Nb3Sn, multilayer NbN/MgO, and thin-film Nb are currently under investigation for cost reduction or possible improvements in RF losses and accelerating gradients. Due to the complex geometries of traditional RF cavities, it is preferable to use a sample host cavity to study flat samples of the novel materials. The Cornell sample host cavity has been commissioned and has now reached peak magnetic surface fields of 100 mT. We present updates on the recent performance of the cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY076
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WEPTY078	High Q0 at Medium Fields in Nb3Sn SRF Cavities at 4.2 K	3467
	S. Posen, D.L. Hall, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA Th. Proslier ANL, Argonne, Illinois, USA
	Nb3Sn has proven itself to be a very promising alternative SRF material. With twice the critical temperature of niobium cavities, 1.3 GHz Nb3Sn cavities can achieve quality factors on the order of 10¹⁰ even at 4.2 K, significantly reducing cryogenic infrastructure and operational costs. In addition, its large predicted superheating field may allow for maximum accelerating gradients up to twice that of niobium for high energy applications. In this work, we report on new cavity results from the Cornell Nb3Sn SRF program demonstrating a significant improvement in the maximum field achieved with high Q0 in a Nb3Sn cavity. At 4.2 K, accelerating gradients above 16 MV/m were obtained with Q0 of 8x10⁹, showing the potential of this material for future applications. In addition to this result, current limitations are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY078
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Paper

Title

Page

Update on Nitrogen-doped 9-cell Cavity Performance in the Cornell Horizontal Test Cryomodule

3446

D. Gonnella, R.G. Eichhorn, F. Furuta, G.M. Ge, D.L. Hall, Y. He, K.M.V. Ho, G.H. Hoffstaetter, M. Liepe, J.T. Maniscalco, T.I. O'Connel, S. Posen, P. Quigley, J. Sears, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
A. Grassellino, C.J. Grimm, O.S. Melnychuk, A. Romanenko
Fermilab, Batavia, Illinois, USA

Funding: U.S. Department of Energy
The Linac Coherent Light Source-II (LCLS-II) is a new x-ray source that is planned to be constructed in the existing SLAC tunnel. To meet the quality factor specifications (2.7x 10¹⁰ at 2.0 K and 16 MV/m), nitrogen-doping has been proposed as a preparation method for the SRF cavities. In order to demonstrate the feasibility of these goals, four 9-cell cavity tests have been completed in the Cornell Horizontal Test Cryomodule (HTC), which serves as a test bench for the full LCLS-II cryomodule. Here we report on the most recent two cavity tests in the HTC: one cavity nitrogen-doped at Cornell and tested with high Q input coupler and then again tested with high power LCLS-II input coupler. Transition to test in horizontal cryomodule resulted in no degradation in Q0 from vertical test. Additionally, increased dissipated power due to the high power input coupler was small and in good agreement with simulations. These results represent a crucial step on the way to demonstrating technical readiness for LCLS-II.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY072

Export •

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WEPTY074

Recent Studies on the Current Limitations of State-of-the-Art Nb3Sn Cavities

3454

D.L. Hall, M. Liepe, J.T. Maniscalco, S. Posen
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
Th. Proslier
ANL, Argonne, Illinois, USA

Funding: NSF PHY-1305500 PHY-14116318 DOE ER41802
Recent advances in the study of Nb3Sn at Cornell University have yielded single-cell cavities that show excellent performance without the limiting Q-slope seen in previous work. This performance has been shown to be repeatable across multiple cavities. However, they are still limited by a quench field of approximately 16 MV/m, as well as residual resistance. In this work we present results quantifying the impact of ambient magnetic fields on Nb3Sn cavities, as well as discuss the impact of cavity cooldown procedures on cavity performance. Finally, we will briefly discuss XRD results that shed light on the composition of the Nb3Sn layer and how this relates to the current limits of these cavities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY074

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

WEPTY075

Hc2 Measurements of Nb3Sn and Nitrogen-doped Niobium using Physical Property Measurement System

3458

J.T. Maniscalco, D. Gonnella, D.L. Hall, M. Liepe, S. Posen
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The measurement of the upper critical field of a type-2 superconductor, Hc2, is an important step in determining its superconducting properties, and therefore its suitability as a material in SRF cavities. However, measuring Hc2 directly can be challenging, as performing electrical measurements causes changes in the very properties one seeks to measure. We present a method for extracting Hc2 from resistivity measurements made near the transition temperature for varied applied fields and excitation currents. We also present results of these measurements made on Nb3Sn and nitrogen-doped niobium.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY075

Export •

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

WEPTY076

RF Performance Studies of Thin-Film Superconductors Using a Sample Host Cavity

3462

J.T. Maniscalco, D.L. Hall, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Thin-film superconductors have the potential for reduced cost and for improved SRF performance over traditional bulk niobium superconducting cavities. Materials such as Nb3Sn, multilayer NbN/MgO, and thin-film Nb are currently under investigation for cost reduction or possible improvements in RF losses and accelerating gradients. Due to the complex geometries of traditional RF cavities, it is preferable to use a sample host cavity to study flat samples of the novel materials. The Cornell sample host cavity has been commissioned and has now reached peak magnetic surface fields of 100 mT. We present updates on the recent performance of the cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY076

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

WEPTY078

High Q0 at Medium Fields in Nb3Sn SRF Cavities at 4.2 K

3467

S. Posen, D.L. Hall, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
Th. Proslier
ANL, Argonne, Illinois, USA

Nb3Sn has proven itself to be a very promising alternative SRF material. With twice the critical temperature of niobium cavities, 1.3 GHz Nb3Sn cavities can achieve quality factors on the order of 10¹⁰ even at 4.2 K, significantly reducing cryogenic infrastructure and operational costs. In addition, its large predicted superheating field may allow for maximum accelerating gradients up to twice that of niobium for high energy applications. In this work, we report on new cavity results from the Cornell Nb3Sn SRF program demonstrating a significant improvement in the maximum field achieved with high Q0 in a Nb3Sn cavity. At 4.2 K, accelerating gradients above 16 MV/m were obtained with Q0 of 8x10⁹, showing the potential of this material for future applications. In addition to this result, current limitations are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY078

Export •

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