SRF2019 - List of Keywords (injection)

Paper	Title	Other Keywords	Page
MOP027	Study on Nitrogen Infusion using KEK New Furnace	cavity, SRF, accelerating-gradient, vacuum	95
	K. Umemori, E. Kako, T. Konomi, S. Michizono, H. Sakai KEK, Ibaraki, Japan T. Okada Sokendai, Ibaraki, Japan J. Tamura JAEA/J-PARC, Tokai-mura, Japan
	KEK has been carried out high-Q/high-G R&D, to realize high performance of SRF cavities toward ILC. KEK constructed a new furnace, which is dedicated for N-infusion studies. We performed more than 10 times of N-infusion trials using 1.3 GHz single-cell cavities. Some results showed better Q-values up to high field, however, some results showed degraded Q-E slopes probably due to contamination. Improvement of accelerating gradient is not observed at moment. We have tried to clean the furnace and Nitrogen injection line to reduce the effect of contamination. Details of procedures of N-infusion, results of vertical tests, condition of the furnace including RGA spectrum and Nb sample analysis results are shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP027
About •	paper received ※ 04 July 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019
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TUFUA5	Recent Development on Nitrogen Infusion Work Towards High Q and High Gradient	cavity, SRF, niobium, radio-frequency	355
	P. Dhakal JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. A quality factor as high as 2 × 10¹⁰ at 1.5 GHz was achieved at a gradient of 35 MV/m by 800 °C annealing and N-infusion at 140 °C. A comparison of the field dependence of the surface resistance after N-infusion with a recent theoretical model that extends the calculation of the BCS surface resistance to high rf fields suggests an increase in the quasiparticles¿ relaxation time with increasing infusion temperature, which could be due to a decreasing density of subgap states. Nb coupons treated similarly showed the formation of thicker oxynitride layer on the surface beneath thin dielectric Nb₂O₅ layer. A plausible explanation for the improved Q₀ is that the oxynitride layer on the Nb surface adds additional electron scattering within RF penetration depth.
	Slides TUFUA5 [6.077 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUFUA5
About •	paper received ※ 19 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THP031	Operation Experience with the LHC ACS RF System	cavity, cryomodule, operation, MMI	911
	K. Turaj, L. Arnaudon, P. Baudrenghien, O. Brunner, A.C. Butterworth, F. Gerigk, M. Karppinen, P. Maesen, E. Montesinos, F. Peauger, G.J. Rosaz, E.N. Shaposhnikova, D. Smekens, M. Taborelli, M. Therasse, H. Timko, D. Valuch, N. Valverde Alonso, W. Venturini Delsolaro CERN, Meyrin, Switzerland
	The LHC accelerating RF system consists of two cryomodules per beam, each containing four single-cell niobium sputtered 400.8 MHz superconducting cavities working at 4.5 K and an average accelerating voltage of 2 MV. The paper summarises the experience, availability and evolution of the system within 10 years of operation. The lessons learned from the successful replacement and re-commissioning of one cryomodule with a spare module, and the recent re-test of the originally installed module on the test stand are also included. Finally, a review of currently launched spare cavity production and long-term developments are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP031
About •	paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOP027

Study on Nitrogen Infusion using KEK New Furnace

cavity, SRF, accelerating-gradient, vacuum

95

K. Umemori, E. Kako, T. Konomi, S. Michizono, H. Sakai
KEK, Ibaraki, Japan
T. Okada
Sokendai, Ibaraki, Japan
J. Tamura
JAEA/J-PARC, Tokai-mura, Japan

KEK has been carried out high-Q/high-G R&D, to realize high performance of SRF cavities toward ILC. KEK constructed a new furnace, which is dedicated for N-infusion studies. We performed more than 10 times of N-infusion trials using 1.3 GHz single-cell cavities. Some results showed better Q-values up to high field, however, some results showed degraded Q-E slopes probably due to contamination. Improvement of accelerating gradient is not observed at moment. We have tried to clean the furnace and Nitrogen injection line to reduce the effect of contamination. Details of procedures of N-infusion, results of vertical tests, condition of the furnace including RGA spectrum and Nb sample analysis results are shown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP027

About •

paper received ※ 04 July 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019

Export •

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

TUFUA5

Recent Development on Nitrogen Infusion Work Towards High Q and High Gradient

cavity, SRF, niobium, radio-frequency

355

P. Dhakal
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A quality factor as high as 2 × 10¹⁰ at 1.5 GHz was achieved at a gradient of 35 MV/m by 800 °C annealing and N-infusion at 140 °C. A comparison of the field dependence of the surface resistance after N-infusion with a recent theoretical model that extends the calculation of the BCS surface resistance to high rf fields suggests an increase in the quasiparticles¿ relaxation time with increasing infusion temperature, which could be due to a decreasing density of subgap states. Nb coupons treated similarly showed the formation of thicker oxynitride layer on the surface beneath thin dielectric Nb₂O₅ layer. A plausible explanation for the improved Q₀ is that the oxynitride layer on the Nb surface adds additional electron scattering within RF penetration depth.

Slides TUFUA5 [6.077 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUFUA5

About •

paper received ※ 19 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

Export •

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

THP031

Operation Experience with the LHC ACS RF System

cavity, cryomodule, operation, MMI

911

K. Turaj, L. Arnaudon, P. Baudrenghien, O. Brunner, A.C. Butterworth, F. Gerigk, M. Karppinen, P. Maesen, E. Montesinos, F. Peauger, G.J. Rosaz, E.N. Shaposhnikova, D. Smekens, M. Taborelli, M. Therasse, H. Timko, D. Valuch, N. Valverde Alonso, W. Venturini Delsolaro
CERN, Meyrin, Switzerland

The LHC accelerating RF system consists of two cryomodules per beam, each containing four single-cell niobium sputtered 400.8 MHz superconducting cavities working at 4.5 K and an average accelerating voltage of 2 MV. The paper summarises the experience, availability and evolution of the system within 10 years of operation. The lessons learned from the successful replacement and re-commissioning of one cryomodule with a spare module, and the recent re-test of the originally installed module on the test stand are also included. Finally, a review of currently launched spare cavity production and long-term developments are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP031

About •

paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

Export •

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