SRF2015 - List of Authors (Smith, E.N.)

Paper	Title	Page
MOBA08	Niobium Impurity-Doping Studies at Cornell and CM Cool-Down Dynamic Effect on Q0	55
	M. Liepe, B. Clasby, R.G. Eichhorn, B. Elmore, F. Furuta, G.M. Ge, D. Gonnella, T. Gruber, D.L. Hall, G.H. Hoffstaetter, J.J. Kaufman, P.N. Koufalis, J.T. Maniscalco, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	As part of a multi-laboratory research initiative on high Q0 niobium cavities for LCLS-II and other future CW SRF accelerators, Cornell has conducted an extensive research program during the last two years on impurity-doping of niobium cavities and related material characterization. Here we give an overview of these activities, and present results from single-cell studies, from vertical performance testing of nitrogen-doped nine-cell cavities, and from cryomodule testing of nitrogen-doped nine-cell cavities.
	Slides MOBA08 [8.983 MB]
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MOPB006	Hc2 Measurements of Superconductors	79
	J.T. Maniscalco, D. Gonnella, D.L. Hall, M. Liepe, E.N. Smith Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: NSF/DOE Recently, Cornell has improved a method for extracting the upper critical field Hc2 of a thin-film superconductor using four-point resistivity measurements. In the field of superconducting radio-frequency accelerators (SRF), novel materials and processes such as nitrogen-doped niobium and Nb3Sn may allow for improved SRF performance and cost efficiency over traditional niobium. In this paper we present updated results on Hc2 measurements for Nb3Sn, as well as results for niobium prepared with an 800 C bake. We also extract important material properties from these measurements, such as the Ginzburg Landau parameter, the mean free path, and coherence length, which are critical for determining SRF performance.
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MOPB041	Cryomodule Testing of Nitrogen-Doped Cavities	182
	D. Gonnella, B. Clasby, R.G. Eichhorn, B. Elmore, F. Furuta, G.M. Ge, D.L. Hall, Y. He, G.H. Hoffstaetter, J.J. Kaufman, P.N. Koufalis, M. Liepe, J.T. Maniscalco, T.I. O'Connell, P. Quigley, D.M. Sabol, E.N. Smith, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA A. Grassellino, C.J. Grimm, J.P. Holzbauer, O.S. Melnychuk, Y.M. Pischalnikov, A. Romanenko, W. Schappert, D.A. Sergatskov Fermilab, Batavia, Illinois, USA A.D. Palczewski, C.E. Reece JLab, Newport News, Virginia, USA
	Funding: DOE and the LCLS-II High Q Project The Linac Coherent Light Source-II (LCLS-II) is a new FEL x-ray source that is planned to be constructed in the existing SLAC tunnel. In order to meet the required high Q0 specification of 2.7x10¹⁰ at 2 K and 16 MV/m, nitrogen-doping has been proposed as a preparation method for the SRF cavities in the linac. In order to test the feasibility of these goals, four nitrogen-doped cavities have been tested at Cornell in the Horizontal Test Cryomodule (HTC) in five separate tests. The first three tests consisted of cavities assembled in the HTC with high Q input coupler. The fourth test used the same cavity as the third but with the prototype high power LCLS-II coupler installed. Finally, the fifth test used a high power LCLS-II coupler, cavity tuner, and HOM antennas. Here we report on the results from these tests along with a systematic analysis of change in performance due to the various steps in preparing and assembling LCLS-II cavities for cryomodule operation. These results represent one of the final steps to demonstrate readiness for full prototype cryomodule assembly for LCLS-II.
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MOPB084	Performance of Nitrogen-Doped 9-Cell SRF Cavities in Vertical Tests at Cornell University	328
	G.M. Ge, R.G. Eichhorn, B. Elmore, F. Furuta, D. Gonnella, T. Gruber, G.H. Hoffstaetter, J.J. Kaufman, M. Liepe, T.I. O'Connell, J. Sears, E.N. Smith Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Cornell University treated five LCLS-II 9-cell cavities by nitrogen-doping recipe. In this paper, we reported the performance of these 9-cell cavities. In the treatments, the nitrogen recipes are slightly different. The cavities have been firstly doped under high nitrogen pressure; after the vertical tests some of the cavities has been reset the surface and re-doped under light nitrogen pressure. The detail of the cavity preparation and test results will be shown. The comparison of the different recipes will be discussed.
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TUPB081	Multi-Cell Temperature Mapping and Conclusions	783
	F. Furuta, R.G. Eichhorn, G.M. Ge, D. Gonnella, D.L. Hartill, G.H. Hoffstaetter, J.J. Kaufman, M. Liepe, E.N. Smith Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Multi-cell temperature mapping (T-map) system has been developed and applied on SRF Nb cavities vertical tests (VT) at Cornell. It has nearly two thousand thermometers and achieved a 1mK resolution of niobium surface temperature rinsing in superfluid helium . We have upgraded the system to be capable of monitoring the temperature profiles of quench spot on cavity. The recent results of T-map during cavity tests and details will be reported.
	Poster TUPB081 [4.421 MB]
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THBA05	Higher Order Mode Absorbers for High Current SRF Applications	1036
	R.G. Eichhorn, J.V. Conway, T. Gruber, Y. He, G.H. Hoffstaetter, Y. Li, M. Liepe, T.I. O'Connell, P. Quigley, J. Sears, V.D. Shemelin, E.N. Smith, M. Tigner Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Efficient damping of the higher-order modes (HOMs) of the superconducting cavities is essential for any high current operation. The talk will provide an overview on the latest advances of HOM absorber development for high intensity SRF applications. As the ideal absorber does not exist, the different conceptual approaches will be presented and the associated issues are outlined. Design examples from various labs will be given that help explain the issues and resolutions. Some focus will be given to the Cornell HOM beamline absorber that was design for high current, short bunch operation with up to 400 W heating. The design will be reviewed and testing results will be reported.
	Slides THBA05 [4.022 MB]
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FRAA04	Performance of the Cornell ERL Main Linac Prototype Cryomodule	1437
	F. Furuta, B. Clasby, R.G. Eichhorn, B. Elmore, G.M. Ge, D. Gonnella, D.L. Hall, G.H. Hoffstaetter, R.P.K. Kaplan, J.J. Kaufman, M. Liepe, T.I. O'Connell, S. Posen, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Cornell has designed, fabricated, and tested (by the time of the conference) a high current (100 mA) CW SRF prototype cryomodule for the Cornell ERL. This talk will report on the design and performance of this very high Q0 CW cryomodule including design issues and mitigation strategies.
	Slides FRAA04 [4.614 MB]
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Paper

Title

Page

Niobium Impurity-Doping Studies at Cornell and CM Cool-Down Dynamic Effect on Q0

55

M. Liepe, B. Clasby, R.G. Eichhorn, B. Elmore, F. Furuta, G.M. Ge, D. Gonnella, T. Gruber, D.L. Hall, G.H. Hoffstaetter, J.J. Kaufman, P.N. Koufalis, J.T. Maniscalco, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

As part of a multi-laboratory research initiative on high Q0 niobium cavities for LCLS-II and other future CW SRF accelerators, Cornell has conducted an extensive research program during the last two years on impurity-doping of niobium cavities and related material characterization. Here we give an overview of these activities, and present results from single-cell studies, from vertical performance testing of nitrogen-doped nine-cell cavities, and from cryomodule testing of nitrogen-doped nine-cell cavities.

Slides MOBA08 [8.983 MB]

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MOPB006

Hc2 Measurements of Superconductors

79

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

Funding: NSF/DOE
Recently, Cornell has improved a method for extracting the upper critical field Hc2 of a thin-film superconductor using four-point resistivity measurements. In the field of superconducting radio-frequency accelerators (SRF), novel materials and processes such as nitrogen-doped niobium and Nb3Sn may allow for improved SRF performance and cost efficiency over traditional niobium. In this paper we present updated results on Hc2 measurements for Nb3Sn, as well as results for niobium prepared with an 800 C bake. We also extract important material properties from these measurements, such as the Ginzburg Landau parameter, the mean free path, and coherence length, which are critical for determining SRF performance.

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MOPB041

Cryomodule Testing of Nitrogen-Doped Cavities

182

D. Gonnella, B. Clasby, R.G. Eichhorn, B. Elmore, F. Furuta, G.M. Ge, D.L. Hall, Y. He, G.H. Hoffstaetter, J.J. Kaufman, P.N. Koufalis, M. Liepe, J.T. Maniscalco, T.I. O'Connell, P. Quigley, D.M. Sabol, E.N. Smith, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
A. Grassellino, C.J. Grimm, J.P. Holzbauer, O.S. Melnychuk, Y.M. Pischalnikov, A. Romanenko, W. Schappert, D.A. Sergatskov
Fermilab, Batavia, Illinois, USA
A.D. Palczewski, C.E. Reece
JLab, Newport News, Virginia, USA

Funding: DOE and the LCLS-II High Q Project
The Linac Coherent Light Source-II (LCLS-II) is a new FEL x-ray source that is planned to be constructed in the existing SLAC tunnel. In order to meet the required high Q0 specification of 2.7x10¹⁰ at 2 K and 16 MV/m, nitrogen-doping has been proposed as a preparation method for the SRF cavities in the linac. In order to test the feasibility of these goals, four nitrogen-doped cavities have been tested at Cornell in the Horizontal Test Cryomodule (HTC) in five separate tests. The first three tests consisted of cavities assembled in the HTC with high Q input coupler. The fourth test used the same cavity as the third but with the prototype high power LCLS-II coupler installed. Finally, the fifth test used a high power LCLS-II coupler, cavity tuner, and HOM antennas. Here we report on the results from these tests along with a systematic analysis of change in performance due to the various steps in preparing and assembling LCLS-II cavities for cryomodule operation. These results represent one of the final steps to demonstrate readiness for full prototype cryomodule assembly for LCLS-II.

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MOPB084

Performance of Nitrogen-Doped 9-Cell SRF Cavities in Vertical Tests at Cornell University

328

G.M. Ge, R.G. Eichhorn, B. Elmore, F. Furuta, D. Gonnella, T. Gruber, G.H. Hoffstaetter, J.J. Kaufman, M. Liepe, T.I. O'Connell, J. Sears, E.N. Smith
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Cornell University treated five LCLS-II 9-cell cavities by nitrogen-doping recipe. In this paper, we reported the performance of these 9-cell cavities. In the treatments, the nitrogen recipes are slightly different. The cavities have been firstly doped under high nitrogen pressure; after the vertical tests some of the cavities has been reset the surface and re-doped under light nitrogen pressure. The detail of the cavity preparation and test results will be shown. The comparison of the different recipes will be discussed.

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TUPB081

Multi-Cell Temperature Mapping and Conclusions

783

F. Furuta, R.G. Eichhorn, G.M. Ge, D. Gonnella, D.L. Hartill, G.H. Hoffstaetter, J.J. Kaufman, M. Liepe, E.N. Smith
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Multi-cell temperature mapping (T-map) system has been developed and applied on SRF Nb cavities vertical tests (VT) at Cornell. It has nearly two thousand thermometers and achieved a 1mK resolution of niobium surface temperature rinsing in superfluid helium . We have upgraded the system to be capable of monitoring the temperature profiles of quench spot on cavity. The recent results of T-map during cavity tests and details will be reported.

Poster TUPB081 [4.421 MB]

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THBA05

Higher Order Mode Absorbers for High Current SRF Applications

1036

R.G. Eichhorn, J.V. Conway, T. Gruber, Y. He, G.H. Hoffstaetter, Y. Li, M. Liepe, T.I. O'Connell, P. Quigley, J. Sears, V.D. Shemelin, E.N. Smith, M. Tigner
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Efficient damping of the higher-order modes (HOMs) of the superconducting cavities is essential for any high current operation. The talk will provide an overview on the latest advances of HOM absorber development for high intensity SRF applications. As the ideal absorber does not exist, the different conceptual approaches will be presented and the associated issues are outlined. Design examples from various labs will be given that help explain the issues and resolutions. Some focus will be given to the Cornell HOM beamline absorber that was design for high current, short bunch operation with up to 400 W heating. The design will be reviewed and testing results will be reported.

Slides THBA05 [4.022 MB]

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FRAA04

Performance of the Cornell ERL Main Linac Prototype Cryomodule

1437

F. Furuta, B. Clasby, R.G. Eichhorn, B. Elmore, G.M. Ge, D. Gonnella, D.L. Hall, G.H. Hoffstaetter, R.P.K. Kaplan, J.J. Kaufman, M. Liepe, T.I. O'Connell, S. Posen, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Cornell has designed, fabricated, and tested (by the time of the conference) a high current (100 mA) CW SRF prototype cryomodule for the Cornell ERL. This talk will report on the design and performance of this very high Q0 CW cryomodule including design issues and mitigation strategies.

Slides FRAA04 [4.614 MB]

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