SRF2015 - List of Keywords (ECR)

Paper	Title	Other Keywords	Page
MOAA05	Status of the RISP Superconducting Heavy Ion Accelerator	cryomodule, linac, ion, rfq	31
	D. Jeon IBS, Daejeon, Republic of Korea
	Funding: This work was supported by the the Institute for Basic Science funded by the Ministry of Science, ICT and Future Planning (MSIP) and the National Research Foundation (NRF) of Korea. Construction of the RISP heavy ion accelerator facility is in progress in Korea. The driver linac is a superconducting linac that can accelerate uranium to proton beams, delivering 400 kW beam power to various targets. Prototyping and test of the superconducting cavities and cryomodules are proceeding. Prototype superconducting cavities were fabricated through domestic vendors and their vertical tests were performed in collaboration with TRIUMF. Vertical tests showed good performance of the prototype cavities, which verified that there were no significant issues of the cavity design and fabrication. SRF Test Facility is under construction to be completed by early 2016. Progress report of the RAON accelerator systems is presented.
	Slides MOAA05 [5.587 MB]
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MOPB085	Efforts of the Improvement of Cavity Q-Value by Plasma Cleaning Technology: Plan and Results From Cornell University	plasma, cavity, experiment, SRF	333
	G.M. Ge, F. Furuta, G.H. Hoffstaetter, M. Liepe, J. Sears, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	We reported the plasma works at Cornell University. The plasma has been generated for 1) surface cleaning to reduce field emission; 2) the cavity quality factor improvement. The experiment design, including RF design, the gas type and pressure selection, the external DC magnetic field calculation, had been discussed. The plasma experiment set-up by using a 1.3GHz single-cell cavity is shown. Argon and helium plasma was successfully ignited in the cavity; the results of the plasma processing will be displayed.
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TUBA03	On the Understanding of Q-Slope of Niobium Thin Films	niobium, ion, SRF, cavity	494
	S. Aull, T. Junginger, A. Sublet, W. Venturini Delsolaro, P. Zhang CERN, Geneva, Switzerland J. Knobloch HZB, Berlin, Germany J. Knobloch University of Siegen, Siegen, Germany A-M. Valente-Feliciano JLab, Newport News, Virginia, USA
	The Q-slope of niobium coated copper cavities at medium fields is still the limiting factor for the application the Nb/Cu technology in accelerators. This paper presents a dedicated study of a niobium coating with bulk-like characteristics which shows a Q-slope comparable to bulk Nb at 400 MHz and 4 K. Combining the bulk like film with recent findings of the HIE Isolde indicates that the film microstructure and the Nb/Cu interface are the key aspects to understanding the Q-slope.
	Slides TUBA03 [3.414 MB]
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TUBA08	Growth and Characterization of Multi-Layer NbTiN Films	SRF, cavity, radio-frequency, lattice	516
	A-M. Valente-Feliciano, G.V. Eremeev, C.E. Reece, J.K. Spradlin JLab, Newport News, Virginia, USA M.C. Burton, R.A. Lukaszew The College of William and Mary, Williamsburg, Virginia, USA
	Significant theoretical interest has stimulated efforts to grow and characterize thin multi-layer superconductor/insulator/superconductor structures for their potential capability of supporting otherwise inaccessible surface magnetic fields in SRF cavities. The technological challenges include realization of high quality superconductors with sharp, clean, transition to high quality dielectric materials and back to superconductor, with careful thickness control of each layer. Choosing NbTiN as the first candidate material, we have developed the tools and techniques that produce such SIS film structures and have begun their characterization. Using DC magnetron sputtering and HiPIMS, NbTiN and AlN can be deposited with nominal superconducting and dielectric parameters. Hc1 enhancement is observed for NbTiN layers with a Tc of 16.9 K for a thickness less than 150 nm. The optimization of the thickness of each type of layer to reach optimum SRF performance is underway. This talk describes this work and the rf performance characteristics observed to date.
	Slides TUBA08 [8.536 MB]
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TUPB029	Material Quality & SRF Performance of Nb Films Grown on Cu via ECR Plasma Energetic Condensation	SRF, ion, plasma, interface	622
	A-M. Valente-Feliciano, G.V. Eremeev, C.E. Reece, J.K. Spradlin JLab, Newport News, Virginia, USA S. Aull CERN, Geneva, Switzerland Th. Proslier ANL, Argonne, Illinois, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The RF performance of bulk Nb cavities has continuously improved over the years and is approaching the intrinsic limit of the material. Although some margin seems still available with processes such as N surface doping, long term solutions for SRF surfaces efficiency enhancement need to be pursued. Over the years, Nb/Cu technology, despite its shortcomings, has positioned itself as an alternative route for the future of superconducting structures used in accelerators. Significant progress has been made in recent years in the development of energetic deposition techniques such as Electron Cyclotron Resonance (ECR) plasma deposition. Nb films with very high material quality have then been produced by varying the deposition energy alluding to the promise of performing SRF films. This paper presents RF measurements, correlated with surface and material properties, for Nb films showing how, by varying the film growth conditions, the Nb film quality and surface resistance can be altered and how the Q-slope can be eventually overcome.
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TUPB063	A Multi-Sample Residual Resistivity Ratio System for High Quality Superconductor Measurements	niobium, cavity, feedback, electron	726
	J.K. Spradlin, C.E. Reece, A-M. Valente-Feliciano JLab, Newport News, Virginia, USA
	Funding: This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR2317. For developing accelerator cavity materials, superconducting transition temperature (T_C), transition width (ΔTC), and residual resistivity ratio (RRR), are useful parameters to correlate with SRF performance and fabrication processes of bulk, thin film, and novel materials. The RRR gauges the purity and structure of the superconductor based on the temperature dependence of electron scattering in the normal conducting state. Combining a four point probe delta pulse setup with a switch allows multiplexing of the electrical measurements to 32 samples per cooldown cycle. The samples are measured inside of an isothermal setup in a liquid helium (LHe) dewar. The isothermal setup is required for a quasistatic warmup of the samples through TC. This contribution details the current setup for collecting RRR and TC data, the current standard of throughput, measurement quality of the setup, and the improvements underway to increase the system’s resolution and ease of use.
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Paper

Title

Other Keywords

Page

MOAA05

Status of the RISP Superconducting Heavy Ion Accelerator

cryomodule, linac, ion, rfq

31

D. Jeon
IBS, Daejeon, Republic of Korea

Funding: This work was supported by the the Institute for Basic Science funded by the Ministry of Science, ICT and Future Planning (MSIP) and the National Research Foundation (NRF) of Korea.
Construction of the RISP heavy ion accelerator facility is in progress in Korea. The driver linac is a superconducting linac that can accelerate uranium to proton beams, delivering 400 kW beam power to various targets. Prototyping and test of the superconducting cavities and cryomodules are proceeding. Prototype superconducting cavities were fabricated through domestic vendors and their vertical tests were performed in collaboration with TRIUMF. Vertical tests showed good performance of the prototype cavities, which verified that there were no significant issues of the cavity design and fabrication. SRF Test Facility is under construction to be completed by early 2016. Progress report of the RAON accelerator systems is presented.

Slides MOAA05 [5.587 MB]

Export •

reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)

MOPB085

Efforts of the Improvement of Cavity Q-Value by Plasma Cleaning Technology: Plan and Results From Cornell University

plasma, cavity, experiment, SRF

333

G.M. Ge, F. Furuta, G.H. Hoffstaetter, M. Liepe, J. Sears, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

We reported the plasma works at Cornell University. The plasma has been generated for 1) surface cleaning to reduce field emission; 2) the cavity quality factor improvement. The experiment design, including RF design, the gas type and pressure selection, the external DC magnetic field calculation, had been discussed. The plasma experiment set-up by using a 1.3GHz single-cell cavity is shown. Argon and helium plasma was successfully ignited in the cavity; the results of the plasma processing will be displayed.

Export •

reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)

TUBA03

On the Understanding of Q-Slope of Niobium Thin Films

niobium, ion, SRF, cavity

494

S. Aull, T. Junginger, A. Sublet, W. Venturini Delsolaro, P. Zhang
CERN, Geneva, Switzerland
J. Knobloch
HZB, Berlin, Germany
J. Knobloch
University of Siegen, Siegen, Germany
A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA

The Q-slope of niobium coated copper cavities at medium fields is still the limiting factor for the application the Nb/Cu technology in accelerators. This paper presents a dedicated study of a niobium coating with bulk-like characteristics which shows a Q-slope comparable to bulk Nb at 400 MHz and 4 K. Combining the bulk like film with recent findings of the HIE Isolde indicates that the film microstructure and the Nb/Cu interface are the key aspects to understanding the Q-slope.

Slides TUBA03 [3.414 MB]

Export •

reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)

TUBA08

Growth and Characterization of Multi-Layer NbTiN Films

SRF, cavity, radio-frequency, lattice

516

A-M. Valente-Feliciano, G.V. Eremeev, C.E. Reece, J.K. Spradlin
JLab, Newport News, Virginia, USA
M.C. Burton, R.A. Lukaszew
The College of William and Mary, Williamsburg, Virginia, USA

Significant theoretical interest has stimulated efforts to grow and characterize thin multi-layer superconductor/insulator/superconductor structures for their potential capability of supporting otherwise inaccessible surface magnetic fields in SRF cavities. The technological challenges include realization of high quality superconductors with sharp, clean, transition to high quality dielectric materials and back to superconductor, with careful thickness control of each layer. Choosing NbTiN as the first candidate material, we have developed the tools and techniques that produce such SIS film structures and have begun their characterization. Using DC magnetron sputtering and HiPIMS, NbTiN and AlN can be deposited with nominal superconducting and dielectric parameters. Hc1 enhancement is observed for NbTiN layers with a Tc of 16.9 K for a thickness less than 150 nm. The optimization of the thickness of each type of layer to reach optimum SRF performance is underway. This talk describes this work and the rf performance characteristics observed to date.

Slides TUBA08 [8.536 MB]

Export •

reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)

TUPB029

Material Quality & SRF Performance of Nb Films Grown on Cu via ECR Plasma Energetic Condensation

SRF, ion, plasma, interface

622

A-M. Valente-Feliciano, G.V. Eremeev, C.E. Reece, J.K. Spradlin
JLab, Newport News, Virginia, USA
S. Aull
CERN, Geneva, Switzerland
Th. Proslier
ANL, Argonne, Illinois, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The RF performance of bulk Nb cavities has continuously improved over the years and is approaching the intrinsic limit of the material. Although some margin seems still available with processes such as N surface doping, long term solutions for SRF surfaces efficiency enhancement need to be pursued. Over the years, Nb/Cu technology, despite its shortcomings, has positioned itself as an alternative route for the future of superconducting structures used in accelerators. Significant progress has been made in recent years in the development of energetic deposition techniques such as Electron Cyclotron Resonance (ECR) plasma deposition. Nb films with very high material quality have then been produced by varying the deposition energy alluding to the promise of performing SRF films. This paper presents RF measurements, correlated with surface and material properties, for Nb films showing how, by varying the film growth conditions, the Nb film quality and surface resistance can be altered and how the Q-slope can be eventually overcome.

Export •

reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)

TUPB063

A Multi-Sample Residual Resistivity Ratio System for High Quality Superconductor Measurements

niobium, cavity, feedback, electron

726

J.K. Spradlin, C.E. Reece, A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA

Funding: This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR2317.
For developing accelerator cavity materials, superconducting transition temperature (T_C), transition width (ΔTC), and residual resistivity ratio (RRR), are useful parameters to correlate with SRF performance and fabrication processes of bulk, thin film, and novel materials. The RRR gauges the purity and structure of the superconductor based on the temperature dependence of electron scattering in the normal conducting state. Combining a four point probe delta pulse setup with a switch allows multiplexing of the electrical measurements to 32 samples per cooldown cycle. The samples are measured inside of an isothermal setup in a liquid helium (LHe) dewar. The isothermal setup is required for a quasistatic warmup of the samples through TC. This contribution details the current setup for collecting RRR and TC data, the current standard of throughput, measurement quality of the setup, and the improvements underway to increase the system’s resolution and ease of use.

Export •

reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)