IPAC2022 - List of Keywords (radio-frequency)

Paper	Title	Other Keywords	Page
TUOXSP2	Analysis of Low RRR SRF Cavities	cavity, SRF, niobium, accelerating-gradient	783
	K. Howard, Y.K. Kim University of Chicago, Chicago, Illinois, USA D. Bafia, A. Grassellino Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. This work was supported by the University of Chicago. Recent findings in the superconducting radio-frequency (SRF) community have shown that introducing certain impurities into high-purity niobium can improve quality factors and accelerating gradients. Success has been found in nitrogen-doping, diffusion of the native oxide into the niobium surface, and thin films of alternate superconductors atop a niobium bulk cavity. We question why some impurities improve RF performance while others hinder it. The purpose of this study is to characterize the impurity profile of niobium with a low residual resistance ratio (RRR) and correlate these impurities with the RF performance of low RRR cavities so that the mechanism of recent impurity-based improvements can be better understood and improved upon. Additionally, we perform a low temperature bake on the low RRR cavity to evaluate how the intentional addition of oxygen to the RF layer affects performance. We have found that low RRR cavities experience low temperature-dependent BCS resistance behavior more prominently than their high RRR counterparts. The results of this study have the potential to unlock a new understanding on SRF materials.
	Slides TUOXSP2 [1.495 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOXSP2
About •	Received ※ 08 June 2022 — Accepted ※ 11 June 2022 — Issue date ※ 25 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUOXSP3	Evaluation of Geometrical Precision and Surface Roughness Quality for the Additively Manufactured Radio Frequency Quadrupole Prototype	rfq, laser, operation, radio-frequency-quadrupole	787
	T. Torims, D. Krogere, G. Pikurs, A. Ratkus Riga Technical University, Riga, Latvia A. Cherif, M. Vretenar CERN, Meyrin, Switzerland N. Delerue Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France M. Foppa Pedretti, M. Pozzi Rösler Italiana s.r.l., Concorezzo, Italy S. Gruber, E. Lopez Fraunhofer IWS, Dresden, Germany T. Otto TalTech, Tallinn, Estonia M. Thielmann, P. Wagenblast TRUMPF, Ditzingen, Germany M. Vedani POLIMI, Milano, Italy
	A multidisciplinary collaboration within the I.FAST project teamed-up to develop additive manufacturing (AM) technology solutions for accelerators. The first prototype of an AM pure-copper radio frequency quadrupole (RFQ) has been produced, corresponding to 1/4 of a 4-vane RFQ. It was optimised for production with state-of-the-art laser powder bed fusion technology. Geometrical precision and roughness of the critical surfaces were measured. Alt-hough the obtained values were beyond standard RFQ specifications, these first results are promising and con-firmed the feasibility of AM manufactured complex cop-per accelerator cavities. Therefore, further post-processing trials have been conducted with the sample RFQ to im-prove surface roughness. Algorithms for the AM techno-logical processes have also been improved, allowing for higher geometrical precision. This resulted in the design of a full 4-vane RFQ prototype. At the time of the paper submission the full-size RFQ is being manufactured and will undergo through the stringent surface quality meas-urements. This paper is discussing novel technological developments, is providing an evaluation of the obtained surface roughness and geometrical precision as well as outlining the potential post-processing scenarios along with future tests plans. Torims T, et al. First Proof-of-Concept Prototype of an Additive Manufactured Radio Frequency Quadrupole. Instruments. 2021; 5(4):35. https://doi.org/10.3390/instruments5040035
	Slides TUOXSP3 [10.031 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOXSP3
About •	Received ※ 20 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 12 June 2022 — Issue date ※ 10 July 2022
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TUPOTK010	Nitric Acid Soaking after Imperfect Furnace Treatments	cavity, niobium, SRF, linac	1211
	R. Ghanbari, A. Dangwal Pandey DESY, Hamburg, Germany C. Bate University of Hamburg, Hamburg, Germany W. Hillert, M. Wenskat University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	Annealings of niobium cavities in UHV or nitrogen atmospheres are crucial for the performance in the later cryogenic tests and operation. Recovery methods for imperfect annealing conditions have been discussed, and a more recent proposal, the so-called "nitric acid soak" has been studied here in detail. It shows surprising recovery potential, albeit the unclear origin of this improvement. We present our investigation on the several potential origins. For this, we used SEM, SIMS and XPS measurements of niobium samples to study the surface morphology and contaminations. We can reject the favored hypothesis on the origin of the improvement, and propose an alternative origin.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK010
About •	Received ※ 10 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 18 June 2022
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TUPOTK035	CVD Nb₃Sn-on-Copper SRF Accelerator Cavities	cavity, SRF, niobium, factory	1291
	G. Gaitan, P.N. Koufalis, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA V.M. Arrieta, S.R. McNeal Ultramet, Pacoima, California, USA M. Liepe Cornell University, Ithaca, New York, USA
	Funding: This work is supported by the US Department of Energy SBIR program under grant number DE-SC0017902. Gabriel Gaitan is supported by the National Science Foundation under Grant No. PHY-1549132. Nb₃Sn is the most promising alternative material for achieving superior performance in Superconducting Radio-Frequency (SRF) cavities, compared to conventional bulk Nb cavities now used in accelerators. Chemical vapor deposition (CVD) is an alternative to the vapor diffusion-based Nb₃Sn growth technique predominantly used on bulk niobium cavities and may enable reaching superior RF performance at reduced cost. In collaboration with Cornell, Ultramet has developed CVD process capabilities and reactor designs to coat copper SRF cavities with thick and thin films of Nb and Nb₃Sn. In this paper, we present our latest research efforts on CVD Nb₃Sn-on-copper SRF cavities, including RF performance test results from two 1.3 GHz SRF cavities coated by Ultramet.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK035
About •	Received ※ 15 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 21 June 2022
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TUPOTK036	Study of Chemical Treatments to Optimize Niobium-3 Tin Growth in the Nucleation Phase	niobium, cavity, SRF, site	1295
	L. Shpani, S.G. Arnold, G. Gaitan, M. Liepe, Z. Sun Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA T. Arias, M.M. Kelley, N. Sitaraman Cornell University, Ithaca, New York, USA
	Funding: This research is funded by the National Science Foundation under Grant No. PHY-1549132, the Center for Bright Beams. Niobium-3 Tin (Nb₃Sn) is a high-potential material for next-generation Superconducting Radiofrequency (SRF) cavities in particle accelerators. The most promising growth method to date is based on vapor diffusion of tin into a niobium substrate with nucleating agent Tin Chloride (SnCl₂). Still, the current vapor diffusion recipe has significant room for realizing further performance improvement. We are investigating how different chemical treatments on the niobium substrate before coating influence the growth of a smooth and uniform Nb₃Sn layer. More specifically, this study focuses on the interaction between the SnCl₂ nucleating agent and the niobium surface oxides. We compare the effect of different chemical treatments with different pH values on the tin droplet distribution on niobium after the nucleation stage of coating. We also look at the effect that the nucleation temperature has on the smoothness and uniformity of the tin distribution, with the ultimate goal of optimizing the recipe to coat smooth Nb₃Sn cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK036
About •	Received ※ 12 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022
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TUPOTK037	Status Update on Cornell’s SRF Compact Conduction Cooled Cryomodule	cavity, cryomodule, SRF, operation	1299
	N.A. Stilin, A.T. Holic, M. Liepe, T.I. O’Connell, J. Sears, V.D. Shemelin, J. Turco Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	A new frontier in Superconducting RF (SRF) development is increasing the accessibility of SRF technology to small-scale accelerator operations which are used in various industrial or research applications. This is made possible by using commercial cryocoolers as a cooling source, which removes the need for expensive liquid cryogenics and their supporting infrastructure. Cornell University is currently developing a new cryomodule based on a conduction cooling scheme. This cryomodule will use two pulse tube cryocoolers in place of liquid cryogenics in order to cool the system. A new 1.3 GHz cavity has been designed with a set of four niobium rings welded at the equator and irises which allow for a direct thermal link between the cavity and cryocooler cold heads. The cavity will use two coaxial RF input couplers capable of delivering up to 100 kW total RF power for high-current beam operation. This coupler design was modified from the Cornell ERL injector couplers, including simplifications such as removing the cold RF window and most outer bellows, while retaining inner bellows for adjustable coupling.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK037
About •	Received ※ 12 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 16 June 2022
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TUPOTK038	Next Generation SRF Cavities at Cornell University	cavity, SRF, simulation, accelerating-gradient	1303
	N.M. Verboncoeur, M. Liepe, R.D. Porter, L. Shpani Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Our goal is to develop new materials and protocols for the growth and preparation of thin-film and layered superconductors for next generation SRF cavities with higher performance for future accelerators. We are working primarily with Nb₃Sn to achieve this goal, as well as other materials which aim to optimize the RF field penetration layer of the cavity. This contribution gives a general update on our most recent cavity test results. A deeper insight into RF loss distribution and dynamics during cavity testing is gained using a new global high-speed temperature mapping system (T-Map).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK038
About •	Received ※ 11 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 22 June 2022
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TUPOTK044	Preliminary Results of a Magnetic and Temperature Map System for 3 GHz Superconducting Radio Frequency Cavities	cavity, SRF, MMI, niobium	1315
	I.P. Parajuli, G. Ciovati, J.R. Delayen, A.V. Gurevich, B.D. Khanal ODU, Norfolk, Virginia, USA G. Ciovati, J.R. Delayen JLab, Newport News, Virginia, USA
	Funding: Work supported by NSF Grant 100614-010. Jlab work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Superconducting radio frequency (SRF) cavities are fundamental building blocks of modern particle accelerators. A surface resistance in the tens of nanoOhm range is achieved when cooling these cavities to liquid helium temperature, ~2 - 4 K. One of the leading sources of residual losses in SRF cavities is trapped magnetic flux. Flux trapping mechanism depends on different surface preparations and cool-down conditions. We have designed, developed and commissioned a combined magnetic and temperature mapping system using anisotropic magneto-resistance sensors and carbon resistors, respectively, to study the flux trap mechanism in 3 GHz single-cell niobium cavities. In this contribution, we will describe the experimental apparatus and present preliminary test results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK044
About •	Received ※ 02 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 24 June 2022 — Issue date ※ 25 June 2022
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TUPOTK045	Magnetic Field Mapping of 1.3 GHz Superconducting Radio Frequency Niobium Cavities	cavity, SRF, niobium, MMI	1319
	I.P. Parajuli, G. Ciovati, J.R. Delayen, A.V. Gurevich ODU, Norfolk, Virginia, USA G. Ciovati, J.R. Delayen JLab, Newport News, Virginia, USA
	Funding: Work supported by NSF Grant 100614-010. Jlab work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Niobium is the material of choice to build superconducting radio frequency (SRF) cavities, which are fundamental building blocks of modern particle accelerators. These cavities require a cryogenic cool-down to ~2 - 4 K for optimum performance minimizing RF losses on the inner cavity surface. However, temperature-independent residual losses in SRF cavities cannot be prevented entirely. One of the significant contributor to residual losses is trapped magnetic flux. The flux trapping mechanism depends on different factors, such as surface preparations and cool-down conditions. We have developed a diagnostic magnetic field scanning system (MFSS) using Hall probes and anisotropic magneto-resistance sensors to study the spatial distribution of trapped flux in 1.3 GHz single-cell cavities. The first result from this newly commissioned system revealed that the trapped flux on the cavity surface might redistribute with increasing RF power. The MFSS was also able to capture significant magnetic field enhancement at specific cavity locations after a quench.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK045
About •	Received ※ 02 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 20 June 2022 — Issue date ※ 27 June 2022
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TUPOTK059	Modeling O and N Alloying in Nb for SRF Applications	cavity, SRF, niobium, vacuum	1354
	E.M. Lechner, M.J. Kelley, A.D. Palczewski, C.E. Reece JLab, Newport News, Virginia, USA J.W. Angle, M.J. Kelley Virginia Polytechnic Institute and State University, Blacksburg, USA F.A. Stevie NCSU AIF, Raleigh, North Carolina, USA
	Funding: This work was coauthored by Jefferson Science Associates LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and grant No. DE-SC-0014475 to Virginia Tech for the support of J. Angle. N and O-alloyed superconducting radio frequency cavities exhibit extraordinary quality factors. Developing diffusion models that describe interstitial N and O in Nb is important for optimizing alloyed cavity quality factors and accelerating gradients. N and O-alloyed Nb samples are examined with SEM AND SIMS and their diffusion profiles modeled.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK059
About •	Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 17 June 2022
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TUPOMS062	Overall Performance of 26 Power Stations at 400 kW - 352 MHz	cavity, ion-source, controls, linac	1573
	C. Pasotti, A. Cuttin Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The spoke cavities section of the European Spallation Source (ESS) Linac will be powered by 26 Radio Frequency Power Stations (RFPSs). Each RFPS delivers 400 kW of Radio Frequency (RF) power at 352.21 MHz in pulsed mode at a repetition rate up to 14 Hz and a 5 % duty cycle, thanks to a twin tetrodes RF power sources integration. This equipment belongs to the Italian In-Kind Contributions (IKCs) to ESS. Elettra Sincrotrone Trieste S.C.p.A (Elettra) is responsible for the development, manufacturing and commissioning of the RFPSs and is managing the RFPS manufacturing contract awarded to European Science Solutions s.r.l (ESS-It). So far, 24 units have been delivered and, by mid 2022, the entire contribution, plus a complete spare unit, will be delivered to ESS. The overall performance of the RFPSs, the lessons learned, and the optimizations adopted along the manufacturing process and the difficulties that the COVID-19 pandemic has posed along the way are presented in this contribution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS062
About •	Received ※ 07 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 04 July 2022
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WEPOMS049	ESS RFQ Electromagnetic Simulations Using CST Studio Suite	rfq, simulation, cavity, radio-frequency-quadrupole	2365
	E. Trachanas, A. Bignami, N. Gazis, B. Jones, R. Zeng ESS, Lund, Sweden G. Fikioris, E.N. Gazis, A. Kladas National Technical University of Athens, Zografou, Greece P. Hamel, O. Piquet CEA-IRFU, Gif-sur-Yvette, France
	The Radio Frequency Quadrupole (RFQ) of the European Spallation Source (ESS), operates at 352.21 MHz with an RF pulse length of 3.2 ms and repetition rate of 14 Hz. The RFQ focuses, bunches and accelerates the 62.5 mA proton beam from 75 keV up to 3.6 MeV. In an effort to study and compare the results from 3D electromagnetic codes, different models of the RFQ were simulated with CST Studio suite. This paper presents the selection of optimal parameters for simulation of the RFQ cavity voltage and comparison of the results with the RFQ design code Toutatis.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS049
About •	Received ※ 08 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 17 June 2022
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THPOTK051	Corrosion of Copper Components in the Deionized Water Cooling System of ALBA Synchrotron Light Source: Current Research Status and Challenges	operation, synchrotron, cavity, experiment	2891
	M. Quispe, E. Ayas, J.J. Casas, C. Colldelram, Ll. Fuentes, J. Iglesias ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain A. Garcia La Romanica, Barberà del Vallès, Sabadell, Spain
	Currently, the ALBA Synchrotron Light Source is carrying out studies on corrosion in copper components of the deionized water cooling circuit. The preliminary studies, based on Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), and X-Ray Diffraction (XRD) have shown the presence of intergranular, pitting, and generalized corrosion in the analyzed copper samples. The purpose of this paper is to present new advances in the field of this research, such as: the study of the influence of low velocity water flow in the cooling circuit on the current high dissolved oxygen content (> 6500 ppb), the results of corrosion products found in the cooling circuit, the description of the improper operation of the cooling circuit as a closed loop, and FEA studies of copper components in order to redefine the water flow velocity design criteria to values lower than 3 m/s and thus minimize corrosion by erosion. Finally, in order to attenuate the corrosion rate, preventive solutions are presented such as the viability to install an oxygen content degassing plant, new instrumentation for water quality monitorization, and installation of degassing equipment at strategic positions of the cooling circuit.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK051
About •	Received ※ 07 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 17 June 2022
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Paper

Title

Other Keywords

Page

TUOXSP2

Analysis of Low RRR SRF Cavities

cavity, SRF, niobium, accelerating-gradient

783

K. Howard, Y.K. Kim
University of Chicago, Chicago, Illinois, USA
D. Bafia, A. Grassellino
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. This work was supported by the University of Chicago.
Recent findings in the superconducting radio-frequency (SRF) community have shown that introducing certain impurities into high-purity niobium can improve quality factors and accelerating gradients. Success has been found in nitrogen-doping, diffusion of the native oxide into the niobium surface, and thin films of alternate superconductors atop a niobium bulk cavity. We question why some impurities improve RF performance while others hinder it. The purpose of this study is to characterize the impurity profile of niobium with a low residual resistance ratio (RRR) and correlate these impurities with the RF performance of low RRR cavities so that the mechanism of recent impurity-based improvements can be better understood and improved upon. Additionally, we perform a low temperature bake on the low RRR cavity to evaluate how the intentional addition of oxygen to the RF layer affects performance. We have found that low RRR cavities experience low temperature-dependent BCS resistance behavior more prominently than their high RRR counterparts. The results of this study have the potential to unlock a new understanding on SRF materials.

Slides TUOXSP2 [1.495 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOXSP2

About •

Received ※ 08 June 2022 — Accepted ※ 11 June 2022 — Issue date ※ 25 June 2022

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

TUOXSP3

Evaluation of Geometrical Precision and Surface Roughness Quality for the Additively Manufactured Radio Frequency Quadrupole Prototype

rfq, laser, operation, radio-frequency-quadrupole

787

T. Torims, D. Krogere, G. Pikurs, A. Ratkus
Riga Technical University, Riga, Latvia
A. Cherif, M. Vretenar
CERN, Meyrin, Switzerland
N. Delerue
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
M. Foppa Pedretti, M. Pozzi
Rösler Italiana s.r.l., Concorezzo, Italy
S. Gruber, E. Lopez
Fraunhofer IWS, Dresden, Germany
T. Otto
TalTech, Tallinn, Estonia
M. Thielmann, P. Wagenblast
TRUMPF, Ditzingen, Germany
M. Vedani
POLIMI, Milano, Italy

A multidisciplinary collaboration within the I.FAST project teamed-up to develop additive manufacturing (AM) technology solutions for accelerators. The first prototype of an AM pure-copper radio frequency quadrupole (RFQ) has been produced, corresponding to 1/4 of a 4-vane RFQ*. It was optimised for production with state-of-the-art laser powder bed fusion technology. Geometrical precision and roughness of the critical surfaces were measured. Alt-hough the obtained values were beyond standard RFQ specifications, these first results are promising and con-firmed the feasibility of AM manufactured complex cop-per accelerator cavities. Therefore, further post-processing trials have been conducted with the sample RFQ to im-prove surface roughness. Algorithms for the AM techno-logical processes have also been improved, allowing for higher geometrical precision. This resulted in the design of a full 4-vane RFQ prototype. At the time of the paper submission the full-size RFQ is being manufactured and will undergo through the stringent surface quality meas-urements. This paper is discussing novel technological developments, is providing an evaluation of the obtained surface roughness and geometrical precision as well as outlining the potential post-processing scenarios along with future tests plans.
* Torims T, et al. First Proof-of-Concept Prototype of an Additive Manufactured Radio Frequency Quadrupole. Instruments. 2021; 5(4):35. https://doi.org/10.3390/instruments5040035

Slides TUOXSP3 [10.031 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOXSP3

About •

Received ※ 20 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 12 June 2022 — Issue date ※ 10 July 2022

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TUPOTK010

Nitric Acid Soaking after Imperfect Furnace Treatments

cavity, niobium, SRF, linac

1211

R. Ghanbari, A. Dangwal Pandey
DESY, Hamburg, Germany
C. Bate
University of Hamburg, Hamburg, Germany
W. Hillert, M. Wenskat
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Annealings of niobium cavities in UHV or nitrogen atmospheres are crucial for the performance in the later cryogenic tests and operation. Recovery methods for imperfect annealing conditions have been discussed, and a more recent proposal, the so-called "nitric acid soak" has been studied here in detail. It shows surprising recovery potential, albeit the unclear origin of this improvement. We present our investigation on the several potential origins. For this, we used SEM, SIMS and XPS measurements of niobium samples to study the surface morphology and contaminations. We can reject the favored hypothesis on the origin of the improvement, and propose an alternative origin.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK010

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Received ※ 10 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 18 June 2022

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TUPOTK035

CVD Nb₃Sn-on-Copper SRF Accelerator Cavities

cavity, SRF, niobium, factory

1291

G. Gaitan, P.N. Koufalis, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
V.M. Arrieta, S.R. McNeal
Ultramet, Pacoima, California, USA
M. Liepe
Cornell University, Ithaca, New York, USA

Funding: This work is supported by the US Department of Energy SBIR program under grant number DE-SC0017902. Gabriel Gaitan is supported by the National Science Foundation under Grant No. PHY-1549132.
Nb₃Sn is the most promising alternative material for achieving superior performance in Superconducting Radio-Frequency (SRF) cavities, compared to conventional bulk Nb cavities now used in accelerators. Chemical vapor deposition (CVD) is an alternative to the vapor diffusion-based Nb₃Sn growth technique predominantly used on bulk niobium cavities and may enable reaching superior RF performance at reduced cost. In collaboration with Cornell, Ultramet has developed CVD process capabilities and reactor designs to coat copper SRF cavities with thick and thin films of Nb and Nb₃Sn. In this paper, we present our latest research efforts on CVD Nb₃Sn-on-copper SRF cavities, including RF performance test results from two 1.3 GHz SRF cavities coated by Ultramet.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK035

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Received ※ 15 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 21 June 2022

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TUPOTK036

Study of Chemical Treatments to Optimize Niobium-3 Tin Growth in the Nucleation Phase

niobium, cavity, SRF, site

1295

L. Shpani, S.G. Arnold, G. Gaitan, M. Liepe, Z. Sun
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
T. Arias, M.M. Kelley, N. Sitaraman
Cornell University, Ithaca, New York, USA

Funding: This research is funded by the National Science Foundation under Grant No. PHY-1549132, the Center for Bright Beams.
Niobium-3 Tin (Nb₃Sn) is a high-potential material for next-generation Superconducting Radiofrequency (SRF) cavities in particle accelerators. The most promising growth method to date is based on vapor diffusion of tin into a niobium substrate with nucleating agent Tin Chloride (SnCl₂). Still, the current vapor diffusion recipe has significant room for realizing further performance improvement. We are investigating how different chemical treatments on the niobium substrate before coating influence the growth of a smooth and uniform Nb₃Sn layer. More specifically, this study focuses on the interaction between the SnCl₂ nucleating agent and the niobium surface oxides. We compare the effect of different chemical treatments with different pH values on the tin droplet distribution on niobium after the nucleation stage of coating. We also look at the effect that the nucleation temperature has on the smoothness and uniformity of the tin distribution, with the ultimate goal of optimizing the recipe to coat smooth Nb₃Sn cavities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK036

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Received ※ 12 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022

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TUPOTK037

Status Update on Cornell’s SRF Compact Conduction Cooled Cryomodule

cavity, cryomodule, SRF, operation

1299

N.A. Stilin, A.T. Holic, M. Liepe, T.I. O’Connell, J. Sears, V.D. Shemelin, J. Turco
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

A new frontier in Superconducting RF (SRF) development is increasing the accessibility of SRF technology to small-scale accelerator operations which are used in various industrial or research applications. This is made possible by using commercial cryocoolers as a cooling source, which removes the need for expensive liquid cryogenics and their supporting infrastructure. Cornell University is currently developing a new cryomodule based on a conduction cooling scheme. This cryomodule will use two pulse tube cryocoolers in place of liquid cryogenics in order to cool the system. A new 1.3 GHz cavity has been designed with a set of four niobium rings welded at the equator and irises which allow for a direct thermal link between the cavity and cryocooler cold heads. The cavity will use two coaxial RF input couplers capable of delivering up to 100 kW total RF power for high-current beam operation. This coupler design was modified from the Cornell ERL injector couplers, including simplifications such as removing the cold RF window and most outer bellows, while retaining inner bellows for adjustable coupling.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK037

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Received ※ 12 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 16 June 2022

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TUPOTK038

Next Generation SRF Cavities at Cornell University

cavity, SRF, simulation, accelerating-gradient

1303

N.M. Verboncoeur, M. Liepe, R.D. Porter, L. Shpani
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Our goal is to develop new materials and protocols for the growth and preparation of thin-film and layered superconductors for next generation SRF cavities with higher performance for future accelerators. We are working primarily with Nb₃Sn to achieve this goal, as well as other materials which aim to optimize the RF field penetration layer of the cavity. This contribution gives a general update on our most recent cavity test results. A deeper insight into RF loss distribution and dynamics during cavity testing is gained using a new global high-speed temperature mapping system (T-Map).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK038

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Received ※ 11 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 22 June 2022

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TUPOTK044

Preliminary Results of a Magnetic and Temperature Map System for 3 GHz Superconducting Radio Frequency Cavities

cavity, SRF, MMI, niobium

1315

I.P. Parajuli, G. Ciovati, J.R. Delayen, A.V. Gurevich, B.D. Khanal
ODU, Norfolk, Virginia, USA
G. Ciovati, J.R. Delayen
JLab, Newport News, Virginia, USA

Funding: Work supported by NSF Grant 100614-010. Jlab work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Superconducting radio frequency (SRF) cavities are fundamental building blocks of modern particle accelerators. A surface resistance in the tens of nanoOhm range is achieved when cooling these cavities to liquid helium temperature, ~2 - 4 K. One of the leading sources of residual losses in SRF cavities is trapped magnetic flux. Flux trapping mechanism depends on different surface preparations and cool-down conditions. We have designed, developed and commissioned a combined magnetic and temperature mapping system using anisotropic magneto-resistance sensors and carbon resistors, respectively, to study the flux trap mechanism in 3 GHz single-cell niobium cavities. In this contribution, we will describe the experimental apparatus and present preliminary test results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK044

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Received ※ 02 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 24 June 2022 — Issue date ※ 25 June 2022

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TUPOTK045

Magnetic Field Mapping of 1.3 GHz Superconducting Radio Frequency Niobium Cavities

cavity, SRF, niobium, MMI

1319

I.P. Parajuli, G. Ciovati, J.R. Delayen, A.V. Gurevich
ODU, Norfolk, Virginia, USA
G. Ciovati, J.R. Delayen
JLab, Newport News, Virginia, USA

Funding: Work supported by NSF Grant 100614-010. Jlab work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Niobium is the material of choice to build superconducting radio frequency (SRF) cavities, which are fundamental building blocks of modern particle accelerators. These cavities require a cryogenic cool-down to ~2 - 4 K for optimum performance minimizing RF losses on the inner cavity surface. However, temperature-independent residual losses in SRF cavities cannot be prevented entirely. One of the significant contributor to residual losses is trapped magnetic flux. The flux trapping mechanism depends on different factors, such as surface preparations and cool-down conditions. We have developed a diagnostic magnetic field scanning system (MFSS) using Hall probes and anisotropic magneto-resistance sensors to study the spatial distribution of trapped flux in 1.3 GHz single-cell cavities. The first result from this newly commissioned system revealed that the trapped flux on the cavity surface might redistribute with increasing RF power. The MFSS was also able to capture significant magnetic field enhancement at specific cavity locations after a quench.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK045

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Received ※ 02 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 20 June 2022 — Issue date ※ 27 June 2022

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TUPOTK059

Modeling O and N Alloying in Nb for SRF Applications

cavity, SRF, niobium, vacuum

1354

E.M. Lechner, M.J. Kelley, A.D. Palczewski, C.E. Reece
JLab, Newport News, Virginia, USA
J.W. Angle, M.J. Kelley
Virginia Polytechnic Institute and State University, Blacksburg, USA
F.A. Stevie
NCSU AIF, Raleigh, North Carolina, USA

Funding: This work was coauthored by Jefferson Science Associates LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and grant No. DE-SC-0014475 to Virginia Tech for the support of J. Angle.
N and O-alloyed superconducting radio frequency cavities exhibit extraordinary quality factors. Developing diffusion models that describe interstitial N and O in Nb is important for optimizing alloyed cavity quality factors and accelerating gradients. N and O-alloyed Nb samples are examined with SEM AND SIMS and their diffusion profiles modeled.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK059

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Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 17 June 2022

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TUPOMS062

Overall Performance of 26 Power Stations at 400 kW - 352 MHz

cavity, ion-source, controls, linac

1573

C. Pasotti, A. Cuttin
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The spoke cavities section of the European Spallation Source (ESS) Linac will be powered by 26 Radio Frequency Power Stations (RFPSs). Each RFPS delivers 400 kW of Radio Frequency (RF) power at 352.21 MHz in pulsed mode at a repetition rate up to 14 Hz and a 5 % duty cycle, thanks to a twin tetrodes RF power sources integration. This equipment belongs to the Italian In-Kind Contributions (IKCs) to ESS. Elettra Sincrotrone Trieste S.C.p.A (Elettra) is responsible for the development, manufacturing and commissioning of the RFPSs and is managing the RFPS manufacturing contract awarded to European Science Solutions s.r.l (ESS-It). So far, 24 units have been delivered and, by mid 2022, the entire contribution, plus a complete spare unit, will be delivered to ESS. The overall performance of the RFPSs, the lessons learned, and the optimizations adopted along the manufacturing process and the difficulties that the COVID-19 pandemic has posed along the way are presented in this contribution.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS062

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Received ※ 07 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 04 July 2022

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WEPOMS049

ESS RFQ Electromagnetic Simulations Using CST Studio Suite

rfq, simulation, cavity, radio-frequency-quadrupole

2365

E. Trachanas, A. Bignami, N. Gazis, B. Jones, R. Zeng
ESS, Lund, Sweden
G. Fikioris, E.N. Gazis, A. Kladas
National Technical University of Athens, Zografou, Greece
P. Hamel, O. Piquet
CEA-IRFU, Gif-sur-Yvette, France

The Radio Frequency Quadrupole (RFQ) of the European Spallation Source (ESS), operates at 352.21 MHz with an RF pulse length of 3.2 ms and repetition rate of 14 Hz. The RFQ focuses, bunches and accelerates the 62.5 mA proton beam from 75 keV up to 3.6 MeV. In an effort to study and compare the results from 3D electromagnetic codes, different models of the RFQ were simulated with CST Studio suite. This paper presents the selection of optimal parameters for simulation of the RFQ cavity voltage and comparison of the results with the RFQ design code Toutatis.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS049

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Received ※ 08 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 17 June 2022

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THPOTK051

Corrosion of Copper Components in the Deionized Water Cooling System of ALBA Synchrotron Light Source: Current Research Status and Challenges

operation, synchrotron, cavity, experiment

2891

M. Quispe, E. Ayas, J.J. Casas, C. Colldelram, Ll. Fuentes, J. Iglesias
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
A. Garcia
La Romanica, Barberà del Vallès, Sabadell, Spain

Currently, the ALBA Synchrotron Light Source is carrying out studies on corrosion in copper components of the deionized water cooling circuit. The preliminary studies, based on Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), and X-Ray Diffraction (XRD) have shown the presence of intergranular, pitting, and generalized corrosion in the analyzed copper samples. The purpose of this paper is to present new advances in the field of this research, such as: the study of the influence of low velocity water flow in the cooling circuit on the current high dissolved oxygen content (> 6500 ppb), the results of corrosion products found in the cooling circuit, the description of the improper operation of the cooling circuit as a closed loop, and FEA studies of copper components in order to redefine the water flow velocity design criteria to values lower than 3 m/s and thus minimize corrosion by erosion. Finally, in order to attenuate the corrosion rate, preventive solutions are presented such as the viability to install an oxygen content degassing plant, new instrumentation for water quality monitorization, and installation of degassing equipment at strategic positions of the cooling circuit.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK051

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Received ※ 07 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 17 June 2022

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