LINAC2022 - Table of Session: THPOGE (Poster Session)

Paper	Title	Page
THPOGE01	Study on the Multipactor Barriers of the SARAF-Phase 2 Low-Beta and High-Beta Superconducting Cavities	802
	G. Ferrand, L. Maurice CEA-IRFU, Gif-sur-Yvette, France M. Baudrier, N. Pichoffpresenter CEA-DRF-IRFU, France
	CEA is committed to delivering a Medium Energy Beam Transfer line and a superconducting linac (SCL) for SARAF accelerator in order to accelerate 5 mA beam of either protons from 1.3 MeV to 35 MeV or deuterons from 2.6 MeV to 40 MeV. The SCL contains 13 half-wave resonator (HWR) low beta cavities (β= 0.09) at 176 MHz and 14 HWR high-beta cavities (β = 0.18) at 176 MHz. The low-beta and high-beta series were qualified in 2021 and 2022 respectively. This contribution will focus on the observation of the multipactor barriers for all cavi-ties. It will present series of data obtained during the conditioning of these cavities
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE01
About •	Received ※ 27 July 2022 — Revised ※ 23 August 2022 — Accepted ※ 07 September 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOGE02	Investigation of HiPIMS-Coated S(I)S Structures for SRF Cavities	805
SUPCPA02	use link to see paper's listing under its alternate paper code
	A.Ö. Sezgin, X. Jiang, M. Vogel University Siegen, Siegen, Germany C.Z. Antoine CEA-IRFU, Gif-sur-Yvette, France S. Keckert, J. Knobloch, O. Kugeler, D.B. Tikhonov HZB, Berlin, Germany J. Knobloch University of Siegen, Siegen, Germany O.B. Malyshev STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R. Ries, E. Seiler Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic L.G.P. Smith STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	The sustainable next generation particle accelerators require innovative solutions to overcome the current technological challenges set by existing bulk niobium superconducting radio-frequency (SRF) cavities. Thin film-based multilayer structures in the form of superconductor-insulator-superconductor (SIS) may be the long-sought-after breakthrough for higher performance SRF cavities by enhancing both accelerating gradients and quality factors. In order to understand better the underlying mechanisms of SIS structures to be coated onto (S)RF cavities, we study various material properties with the resultant superconducting properties of high-power im-pulse magnetron sputtering (HiPIMS)-coated S(I)S structures of Nb-(AlN)-NbN with different thicknesses which are designed to be coated mainly on OFHC copper (Cu) samples for more efficient SRF cavities. This contribution presents materials properties of the aforementioned HiPIMS-coated S(I)S structures as well as the superconducting and RF behaviours of these multilayers which are assessed comparatively via DC and AC magnetization techniques.
	Poster THPOGE02 [0.747 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE02
About •	Received ※ 25 August 2022 — Revised ※ 30 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 02 September 2022
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THPOGE03	Design & Multiphysics Analysis of Three-cell, 1.3 GHz Superconducting RF Cavity for Electron Beam Accelerator to Treat Wastewater	809
SUPCGE04	use link to see paper's listing under its alternate paper code
	P. Kumar, A. Pathak, R. Varma IIT Mumbai, Mumbai, India
	To treat industrial effluents including contaminants of emerging concern (CECs), Irradiation treatment by electron beam accelerator has shown promising results. Our aim is to design and develop a superconducting linear electron accelerator. A 1.3 GHz, three cell conduction cooled, TM class superconducting cavity has been proposed to accelerate a 100 mA electron beam from 100 keV to 4.5 MeV. The main aim of the design is to optimize the cavity for low heat loss and high accelerating gradient. The optimized ratio of peak surface electric and magnetic field to accelerating field for cavity are Epk/E_acc= 2.72 and Hpk/E_acc= 4.11 mT/(MV/m). The optimized Geometry factor (G) and R/Q values for this cavity are 246.7 and 306.4 ohms respectively. Here we also addressed other multiphysics issues such as Lorentz force detuning (LFD), Higher order modes (HOMs) and Multipacting. The multiphysics analysis helps to estimate the degree of these challenges. The final Lorentz detuning factor of the cavity has been reduced to 0.12 Hz/(MV/m)2, HOMs of 2.18 and 2.9 GHz modes are dominating except the main mode and Multipacting phenomena is not found at 15 MV/m of accelerating gradient.
	Poster THPOGE03 [1.121 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE03
About •	Received ※ 22 August 2022 — Revised ※ 25 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 14 October 2022
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THPOGE05	Some Interesting Observations During Vertical Test on ESS-HB-704 SRF Cavities	812
	K.D. Dumbell, A.E.T. Akintola, R.K. Buckley, M.J. Ellis, S. Hitchen, P.C. Hornickel, C.R. Jenkins, J. Lewis, A.J. May, P.A. McIntosh, K.J. Middleman, A.J. Moss, S.M. Pattalwar, M.D. Pendleton, P.A. Smith, A.E. Wheelhouse, S. Wilde STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom M.D. Hancock, J. Hathaway, C. Hodgkinson, G. Jones, M. Lowe, D.A. Mason, G. Miller, J. Mutch, A. Oates, J.T.G. Wilson STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	The vertical test stand in use at Daresbury has three cavities loaded horizontally at different heights. The jacketed cavities are supplied with liquid helium from a header tank at the top of the configuration. A few cavities have been tested in different positions and the results have been analysed. The pressure of the helium inside the jacketed cavities is affected by the height of the liquid helium column above the jacket and using results from earlier analysis during cool-down enables the pressure of the cavity to be determined from the frequency of operation. Analysis of the effects may allow for corrections to the frequency to be made. In addition to the above observations there have also been some challenges in the operation at higher power as the phase of the self-excited loop driving the system, has been seen to change. This paper discusses some of the observation, analysis of those observations and challenges that are being addressed in the continuing use of this facility.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE05
About •	Received ※ 10 August 2022 — Revised ※ 13 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 15 September 2022
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THPOGE09	Split Thin Film SRF 6 GHz Cavities	814
	B.S. Sian, G. Burt, D.J. Seal Lancaster University, Lancaster, United Kingdom G. Burt, O.B. Malyshev, D.J. Seal, R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom O.B. Malyshev, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom H.S. Marks Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	Many current accelerators use cavities that are manufactured as two half cells that are electron beam welded together, the weld is across the peak surface current of the cavity. This weld can lead to large increases in surface resistance and limit the performance of thin film coated cavities. Many problems with the coating process for thin film Superconducting Radio Frequency (SRF) cavities are also due to this weld. Thin film SRF cavities can perform as well as bulk niobium cavities if the cavity is manufactured seamlessly, without any weld, as they have a more uniform surface, however, they are much more difficult and expensive to manufacture. A cavity with a split longitudinally, parallel to the direction of the electric field, would not need to be welded. These seamless cavities are easier to manufacture and coat. This opens the possibilities to coat with new materials and multilayer coatings. These cavities may allow SRF cavities to operate at significantly better parameters (higher quality factor and maximum accelerating field) than current state of the art cavities. This work discusses development and testing of longitudinally split seamless cavities at Daresbury Laboratory.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE09
About •	Received ※ 25 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 12 September 2022 — Issue date ※ 15 October 2022
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THPOGE10	RF Characterisation of Bulk Niobium and Thin Film Coated Planar Samples at 7.8 GHz	818
SUPCPA04	use link to see paper's listing under its alternate paper code
	D.J. Seal, G. Burt, O.B. Malyshev, B.S. Sian, R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom G. Burt, D.J. Seal, B.S. Sian Lancaster University, Lancaster, United Kingdom E. Chyhyrynets, C. Pira INFN/LNL, Legnaro (PD), Italy O. Hryhorenko, D. Longuevergne Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France O.B. Malyshev, E.A. Marshall, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom H.S. Marks Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	Research is ongoing into the use of superconducting thin films to replace bulk niobium for future radio frequency (RF) cavities. A key part of this research requires measuring the RF properties of candidate films. However, coating and testing thin films on full-sized cavities is both costly and time-consuming. Instead, films are typically deposited on small, flat samples and characterised using a test cavity. A cost-effective facility for testing such samples has recently been built and commissioned at Daresbury Laboratory. The facility allows for low power surface resistance measurements at a resonant frequency of 7.8 GHz, temperatures down to 4 K and sample surface magnetic fields up to 1 mT. A brief overview of this facility as well as recent results from measurements of both bulk Nb and thin film coated samples will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE10
About •	Received ※ 11 August 2022 — Revised ※ 19 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 16 September 2022
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THPOGE13	Design of Production PIP-II SSR1 Cavities	822
	C.S. Narug, J. Bernardinipresenter, M. Parise, D. Passarelli Fermilab, Batavia, Illinois, USA
	Funding: Work supported by the Fermi National Accelerator Laboratory, managed and operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. The testing and manufacturing process of the PIP-II Single Spoke Resonators Type 1 (SSR1) prototype jacketed cavity presented opportunities for refinement of the production series. Experience from the prototype cavity and the design of other cavities at Fermilab were used. The mechanical design of the production jacketed cavity has been modified from the prototype design to allow for improvements in overall performance, structural behavior, and manufacturability of the weld joints.
	Poster THPOGE13 [1.199 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE13
About •	Received ※ 14 August 2022 — Revised ※ 23 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 02 September 2022
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THPOGE15	Measuring the Seebeck Coefficient at Cryogenic Temperatures for LCLS-II-HE Project	825
SUPCPA01	use link to see paper's listing under its alternate paper code
	L. Shpani, M. Ge, A.T. Holic, M. Liepe, J. Sears, N.M. Verboncoeur Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work is supported by the DOE LCLS-II HE Project. The Seebeck effect plays a crucial role during the cooldown procedure in SRF based accelerators, like LCLS-II at SLAC. The temperature-dependent Seebeck coefficient quantitatively measures the strength of electric potential induced by thermal gradients in metals. This effect is present in cryomodules and drives thermoelectric currents generating magnetic fields. These fields can get trapped in cavities and cause additional dissipation in RF fields. We have therefore designed and commissioned an experimental setup that does continuous measurements of the Seebeck coefficient for cryogenic temperatures ranging from 200K down to below 10K. We present results of the measurements of this coefficient for materials commonly used in cryomodules, such as niobium, titanium, niobium-titanium, silicon bronze, and stainless steel.
	Poster THPOGE15 [0.959 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE15
About •	Received ※ 27 August 2022 — Revised ※ 04 September 2022 — Accepted ※ 26 September 2022 — Issue date ※ 29 September 2022
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THPOGE16	Evaluation of Single-Cell Cavities Made of Forged Ingot Niobium at Jefferson Lab	828
	P. Dhakal, G. Ciovati, G.R. Myneni JLab, Newport News, Virginia, USA G. Ciovati, B.D. Khanal ODU, Norfolk, Virginia, USA G.R. Myneni BSCE, Yorktown, Virginia, USA
	Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Currently, fine grain niobium (Nb) (grain size ~ 50 um) and large grain Nb (grain size of a few cm) are being used for the fabrication of superconducting radio frequency (SRF) cavities. Medium grain forged ingot with grain size of a few hundred um may be beneficial for cost-effectiveness as well as providing better performance for future SRF-based accelerators. Forged ingot Nb with medium grain size is a novel production method to obtain Nb discs used for the fabrication of superconducting radio frequency cavities. We have fabricated two 1.5 GHz single cell cavities made from forged Nb ingot with a residual resistivity ratio of ~100. The cavities were chemically and mechanically polished and heat-treated in the temperature range of 650-1000 C before the rf test. One of the cavities reached an accelerating gradient of 34 MV/m with a quality factor Q > 1e10, while the second cavity was limited at 14 MV/m, likely due to a weld defect at the equator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE16
About •	Received ※ 22 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 03 September 2022 — Issue date ※ 15 September 2022
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THPOGE18	Design of a 1.3 GHz RF-Dipole Crabbing Cavity for International Linear Collider	832
	S.U. De Silva, J.R. Delayen ODU, Norfolk, Virginia, USA R.A. Rimmer JLab, Newport News, Virginia, USA
	The International Liner Collider (ILC) requires crabbing systems to increase the luminosity of the colliding electron and positron bunches. There are several frequency options for the crabbing cavity. We have designed a 1.3 GHz compact 1-cell and 2-cell rf-dipole crabbing cavity to compensate for luminosity degradation due to large crossing angle. This paper presents the 1-cell and 2-cell cavities designed to meet the current specifications including the fundamental power coupler and higher order mode couplers.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE18
About •	Received ※ 11 August 2022 — Revised ※ 26 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 16 September 2022
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THPOGE19	Field Shielding of NbTiN Based Multilayer Structure for Accelerating Cavities	836
SUPCRI06	use link to see paper's listing under its alternate paper code
	I.H. Senevirathne, J.R. Delayen, A.V. Gurevich ODU, Norfolk, Virginia, USA D.R. Beverstock The College of William and Mary, Williamsburg, Virginia, USA D.R. Beverstock, J.R. Delayen, A-M. Valente-Feliciano JLab, Newport News, Virginia, USA
	Funding: NSF Grants PHY-1734075 and PHY-1416051, and DOE Awards DE-SC0010081 and DE-SC0019399 Over the past few decades, bulk niobium (Nb) has been the material of choice for superconducting radio frequen-cy (SRF) cavities used in particle accelerators to achieve higher accelerating gradients and lower RF losses. Multi-layer (SIS) structures consisting of alternating thin layers of superconductor(S) and insulator(I) deposited on a bulk Nb have been proposed to enhance the peak surface magnetic field and sustain a higher accelerating gradient. In this study, multilayers based NbTiN and AlN deposited on bulk Nb are used to test the proposed enhancement using the DC magnetic Hall probe technique. The tech-nique detects a penetrating magnetic field through the multilayer sample as it is placed under an external mag-netic field produced by a magnetic coil. This work re-ports the characterization and measurements of the mag-netic field of full flux penetration through single layers of NbTiN and bilayers of NbTiN/AlN on bulk Nb.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE19
About •	Received ※ 24 August 2022 — Revised ※ 01 September 2022 — Accepted ※ 08 September 2022 — Issue date ※ 15 September 2022
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THPOGE22	Medium Temperature Treatments of Superconducting Radio Frequency Cavities at DESY	840
THOPA07	use link to see paper's listing under its alternate paper code
	L. Steder, C. Bate, H. Remde, D. Reschke, J. Schaffran, L. Trelle, H. Weise, M. Wiencek DESY, Hamburg, Germany M. Wenskat University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	Over the last years several different approaches to increase the performance of superconducting radio frequency (SRF) cavities by heat treatments have been developed and tested. At DESY, the R&D aims for cavities with enlarged quality factors while maintaining high accelerating gradients, since an envisaged upgrade of the European XFEL requires both. For this purpose, medium temperature (mid-T) treatments around 300 °C seem to be very promising. Lately, the furnace infrastructure at DESY was refurbished and now a niobium-retort furnace capable of carrying 1.3 GHz nine-cell cavities can be used for R&D studies. Vertical test results of single-cell cavities treated in this furnace at medium temperatures are presented and compared to four cavities treated similarly in a furnace at the company Zanon Research & Innovation Srl (Zanon). All mentioned cavities show enlarged quality factors but at the same time reduced gradients compared to their reference measurements before the mid-T treatment. The DESY treatments were accompanied by small niobium samples for surface analyses, which are also presented. Furthermore, the influence of post-treatment high pressure water rinsings is studied.
	Slides THPOGE22 [1.277 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE22
About •	Received ※ 19 August 2022 — Revised ※ 23 August 2022 — Accepted ※ 27 August 2022 — Issue date ※ 15 September 2022
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THPOGE23	Vertical Electro-Polishing of 704 MHz Resonators Using Ninja Cathode: Gradients Over 40 MV/m Achieved on ESS Single-Cell Cavity	844
THOPA08	use link to see paper's listing under its alternate paper code
	F. Éozénou, M. Baudrier, E. Cenni, E. Fayette, L. Maurice, C. Servouin CEA-DRF-IRFU, France H. Hayano, H. Ito, S. Kato, T. Kubo, H. Monjushiro, T. Saeki KEK, Ibaraki, Japan Y.I. Ida, K. Nii, T.Y. Yamaguchi MGH, Hyogo-ken, Japan G. Jullien CEA-IRFU, Gif-sur-Yvette, France
	CEA, KEK and Marui Galvanizing Company have been collaborating to apply the Vertical Electropolishing (VEP) process of elliptical SRF cavities to a 704MHz single-cell ESS-type cavity, using a rotating so called and patented "Ninja" cathode. First presented results* were promising with a gradient of 27MV/m achieved, without any heat treatment applied. The performance has been pushed further since. The cavity has undergone a heat treatment at 650°C during 10h, followed by a final VEP sequence and a baking at 120°C during 48h hours. The achieved gradient at 2K was 44MV/m (power limitation), and the quality factor Q₀ exceeding 5·10¹⁰ up to 10 MV/m. The superiority of VEP compared to standard "BCP" chemical treatment is demonstrated and we intend now to scale the process to 5-Cell β=0.86 ESS cavity. We also intend to push further the performance by applying "2-step baking" (75°C and 120°C) proposed by FNAL, which was successfully applied at CEA Saclay on 1300MHz single-cell resonators with gradients above 50MV/m achieved after VEP bulk treatment. * TUPCAV001, SRF 2021
	Slides THPOGE23 [0.868 MB]
	Poster THPOGE23 [0.918 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE23
About •	Received ※ 24 August 2022 — Revised ※ 01 September 2022 — Accepted ※ 09 September 2022 — Issue date ※ 16 September 2022
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Paper

Title

Page

Study on the Multipactor Barriers of the SARAF-Phase 2 Low-Beta and High-Beta Superconducting Cavities

802

G. Ferrand, L. Maurice
CEA-IRFU, Gif-sur-Yvette, France
M. Baudrier, N. Pichoffpresenter
CEA-DRF-IRFU, France

CEA is committed to delivering a Medium Energy Beam Transfer line and a superconducting linac (SCL) for SARAF accelerator in order to accelerate 5 mA beam of either protons from 1.3 MeV to 35 MeV or deuterons from 2.6 MeV to 40 MeV. The SCL contains 13 half-wave resonator (HWR) low beta cavities (β= 0.09) at 176 MHz and 14 HWR high-beta cavities (β = 0.18) at 176 MHz. The low-beta and high-beta series were qualified in 2021 and 2022 respectively. This contribution will focus on the observation of the multipactor barriers for all cavi-ties. It will present series of data obtained during the conditioning of these cavities

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE01

About •

Received ※ 27 July 2022 — Revised ※ 23 August 2022 — Accepted ※ 07 September 2022 — Issue date ※ 15 September 2022

Cite •

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

THPOGE02

Investigation of HiPIMS-Coated S(I)S Structures for SRF Cavities

805

SUPCPA02

use link to see paper's listing under its alternate paper code

A.Ö. Sezgin, X. Jiang, M. Vogel
University Siegen, Siegen, Germany
C.Z. Antoine
CEA-IRFU, Gif-sur-Yvette, France
S. Keckert, J. Knobloch, O. Kugeler, D.B. Tikhonov
HZB, Berlin, Germany
J. Knobloch
University of Siegen, Siegen, Germany
O.B. Malyshev
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R. Ries, E. Seiler
Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
L.G.P. Smith
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

The sustainable next generation particle accelerators require innovative solutions to overcome the current technological challenges set by existing bulk niobium superconducting radio-frequency (SRF) cavities. Thin film-based multilayer structures in the form of superconductor-insulator-superconductor (SIS) may be the long-sought-after breakthrough for higher performance SRF cavities by enhancing both accelerating gradients and quality factors. In order to understand better the underlying mechanisms of SIS structures to be coated onto (S)RF cavities, we study various material properties with the resultant superconducting properties of high-power im-pulse magnetron sputtering (HiPIMS)-coated S(I)S structures of Nb-(AlN)-NbN with different thicknesses which are designed to be coated mainly on OFHC copper (Cu) samples for more efficient SRF cavities. This contribution presents materials properties of the aforementioned HiPIMS-coated S(I)S structures as well as the superconducting and RF behaviours of these multilayers which are assessed comparatively via DC and AC magnetization techniques.

Poster THPOGE02 [0.747 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE02

About •

Received ※ 25 August 2022 — Revised ※ 30 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 02 September 2022

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

THPOGE03

Design & Multiphysics Analysis of Three-cell, 1.3 GHz Superconducting RF Cavity for Electron Beam Accelerator to Treat Wastewater

809

SUPCGE04

use link to see paper's listing under its alternate paper code

P. Kumar, A. Pathak, R. Varma
IIT Mumbai, Mumbai, India

To treat industrial effluents including contaminants of emerging concern (CECs), Irradiation treatment by electron beam accelerator has shown promising results. Our aim is to design and develop a superconducting linear electron accelerator. A 1.3 GHz, three cell conduction cooled, TM class superconducting cavity has been proposed to accelerate a 100 mA electron beam from 100 keV to 4.5 MeV. The main aim of the design is to optimize the cavity for low heat loss and high accelerating gradient. The optimized ratio of peak surface electric and magnetic field to accelerating field for cavity are Epk/E_acc= 2.72 and Hpk/E_acc= 4.11 mT/(MV/m). The optimized Geometry factor (G) and R/Q values for this cavity are 246.7 and 306.4 ohms respectively. Here we also addressed other multiphysics issues such as Lorentz force detuning (LFD), Higher order modes (HOMs) and Multipacting. The multiphysics analysis helps to estimate the degree of these challenges. The final Lorentz detuning factor of the cavity has been reduced to 0.12 Hz/(MV/m)2, HOMs of 2.18 and 2.9 GHz modes are dominating except the main mode and Multipacting phenomena is not found at 15 MV/m of accelerating gradient.

Poster THPOGE03 [1.121 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE03

About •

Received ※ 22 August 2022 — Revised ※ 25 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 14 October 2022

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

THPOGE05

Some Interesting Observations During Vertical Test on ESS-HB-704 SRF Cavities

812

K.D. Dumbell, A.E.T. Akintola, R.K. Buckley, M.J. Ellis, S. Hitchen, P.C. Hornickel, C.R. Jenkins, J. Lewis, A.J. May, P.A. McIntosh, K.J. Middleman, A.J. Moss, S.M. Pattalwar, M.D. Pendleton, P.A. Smith, A.E. Wheelhouse, S. Wilde
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
M.D. Hancock, J. Hathaway, C. Hodgkinson, G. Jones, M. Lowe, D.A. Mason, G. Miller, J. Mutch, A. Oates, J.T.G. Wilson
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

The vertical test stand in use at Daresbury has three cavities loaded horizontally at different heights. The jacketed cavities are supplied with liquid helium from a header tank at the top of the configuration. A few cavities have been tested in different positions and the results have been analysed. The pressure of the helium inside the jacketed cavities is affected by the height of the liquid helium column above the jacket and using results from earlier analysis during cool-down enables the pressure of the cavity to be determined from the frequency of operation. Analysis of the effects may allow for corrections to the frequency to be made. In addition to the above observations there have also been some challenges in the operation at higher power as the phase of the self-excited loop driving the system, has been seen to change. This paper discusses some of the observation, analysis of those observations and challenges that are being addressed in the continuing use of this facility.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE05

About •

Received ※ 10 August 2022 — Revised ※ 13 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 15 September 2022

Cite •

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

THPOGE09

Split Thin Film SRF 6 GHz Cavities

814

B.S. Sian, G. Burt, D.J. Seal
Lancaster University, Lancaster, United Kingdom
G. Burt, O.B. Malyshev, D.J. Seal, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom
O.B. Malyshev, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H.S. Marks
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

Many current accelerators use cavities that are manufactured as two half cells that are electron beam welded together, the weld is across the peak surface current of the cavity. This weld can lead to large increases in surface resistance and limit the performance of thin film coated cavities. Many problems with the coating process for thin film Superconducting Radio Frequency (SRF) cavities are also due to this weld. Thin film SRF cavities can perform as well as bulk niobium cavities if the cavity is manufactured seamlessly, without any weld, as they have a more uniform surface, however, they are much more difficult and expensive to manufacture. A cavity with a split longitudinally, parallel to the direction of the electric field, would not need to be welded. These seamless cavities are easier to manufacture and coat. This opens the possibilities to coat with new materials and multilayer coatings. These cavities may allow SRF cavities to operate at significantly better parameters (higher quality factor and maximum accelerating field) than current state of the art cavities. This work discusses development and testing of longitudinally split seamless cavities at Daresbury Laboratory.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE09

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Received ※ 25 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 12 September 2022 — Issue date ※ 15 October 2022

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THPOGE10

RF Characterisation of Bulk Niobium and Thin Film Coated Planar Samples at 7.8 GHz

818

SUPCPA04

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D.J. Seal, G. Burt, O.B. Malyshev, B.S. Sian, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom
G. Burt, D.J. Seal, B.S. Sian
Lancaster University, Lancaster, United Kingdom
E. Chyhyrynets, C. Pira
INFN/LNL, Legnaro (PD), Italy
O. Hryhorenko, D. Longuevergne
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
O.B. Malyshev, E.A. Marshall, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H.S. Marks
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

Research is ongoing into the use of superconducting thin films to replace bulk niobium for future radio frequency (RF) cavities. A key part of this research requires measuring the RF properties of candidate films. However, coating and testing thin films on full-sized cavities is both costly and time-consuming. Instead, films are typically deposited on small, flat samples and characterised using a test cavity. A cost-effective facility for testing such samples has recently been built and commissioned at Daresbury Laboratory. The facility allows for low power surface resistance measurements at a resonant frequency of 7.8 GHz, temperatures down to 4 K and sample surface magnetic fields up to 1 mT. A brief overview of this facility as well as recent results from measurements of both bulk Nb and thin film coated samples will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE10

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Received ※ 11 August 2022 — Revised ※ 19 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 16 September 2022

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THPOGE13

Design of Production PIP-II SSR1 Cavities

822

C.S. Narug, J. Bernardinipresenter, M. Parise, D. Passarelli
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the Fermi National Accelerator Laboratory, managed and operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
The testing and manufacturing process of the PIP-II Single Spoke Resonators Type 1 (SSR1) prototype jacketed cavity presented opportunities for refinement of the production series. Experience from the prototype cavity and the design of other cavities at Fermilab were used. The mechanical design of the production jacketed cavity has been modified from the prototype design to allow for improvements in overall performance, structural behavior, and manufacturability of the weld joints.

Poster THPOGE13 [1.199 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE13

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Received ※ 14 August 2022 — Revised ※ 23 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 02 September 2022

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THPOGE15

Measuring the Seebeck Coefficient at Cryogenic Temperatures for LCLS-II-HE Project

825

SUPCPA01

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L. Shpani, M. Ge, A.T. Holic, M. Liepe, J. Sears, N.M. Verboncoeur
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work is supported by the DOE LCLS-II HE Project.
The Seebeck effect plays a crucial role during the cooldown procedure in SRF based accelerators, like LCLS-II at SLAC. The temperature-dependent Seebeck coefficient quantitatively measures the strength of electric potential induced by thermal gradients in metals. This effect is present in cryomodules and drives thermoelectric currents generating magnetic fields. These fields can get trapped in cavities and cause additional dissipation in RF fields. We have therefore designed and commissioned an experimental setup that does continuous measurements of the Seebeck coefficient for cryogenic temperatures ranging from 200K down to below 10K. We present results of the measurements of this coefficient for materials commonly used in cryomodules, such as niobium, titanium, niobium-titanium, silicon bronze, and stainless steel.

Poster THPOGE15 [0.959 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE15

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Received ※ 27 August 2022 — Revised ※ 04 September 2022 — Accepted ※ 26 September 2022 — Issue date ※ 29 September 2022

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THPOGE16

Evaluation of Single-Cell Cavities Made of Forged Ingot Niobium at Jefferson Lab

828

P. Dhakal, G. Ciovati, G.R. Myneni
JLab, Newport News, Virginia, USA
G. Ciovati, B.D. Khanal
ODU, Norfolk, Virginia, USA
G.R. Myneni
BSCE, Yorktown, Virginia, USA

Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Currently, fine grain niobium (Nb) (grain size ~ 50 um) and large grain Nb (grain size of a few cm) are being used for the fabrication of superconducting radio frequency (SRF) cavities. Medium grain forged ingot with grain size of a few hundred um may be beneficial for cost-effectiveness as well as providing better performance for future SRF-based accelerators. Forged ingot Nb with medium grain size is a novel production method to obtain Nb discs used for the fabrication of superconducting radio frequency cavities. We have fabricated two 1.5 GHz single cell cavities made from forged Nb ingot with a residual resistivity ratio of ~100. The cavities were chemically and mechanically polished and heat-treated in the temperature range of 650-1000 C before the rf test. One of the cavities reached an accelerating gradient of 34 MV/m with a quality factor Q > 1e10, while the second cavity was limited at 14 MV/m, likely due to a weld defect at the equator.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE16

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Received ※ 22 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 03 September 2022 — Issue date ※ 15 September 2022

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THPOGE18

Design of a 1.3 GHz RF-Dipole Crabbing Cavity for International Linear Collider

832

S.U. De Silva, J.R. Delayen
ODU, Norfolk, Virginia, USA
R.A. Rimmer
JLab, Newport News, Virginia, USA

The International Liner Collider (ILC) requires crabbing systems to increase the luminosity of the colliding electron and positron bunches. There are several frequency options for the crabbing cavity. We have designed a 1.3 GHz compact 1-cell and 2-cell rf-dipole crabbing cavity to compensate for luminosity degradation due to large crossing angle. This paper presents the 1-cell and 2-cell cavities designed to meet the current specifications including the fundamental power coupler and higher order mode couplers.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE18

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Received ※ 11 August 2022 — Revised ※ 26 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 16 September 2022

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THPOGE19

Field Shielding of NbTiN Based Multilayer Structure for Accelerating Cavities

836

SUPCRI06

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I.H. Senevirathne, J.R. Delayen, A.V. Gurevich
ODU, Norfolk, Virginia, USA
D.R. Beverstock
The College of William and Mary, Williamsburg, Virginia, USA
D.R. Beverstock, J.R. Delayen, A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA

Funding: NSF Grants PHY-1734075 and PHY-1416051, and DOE Awards DE-SC0010081 and DE-SC0019399
Over the past few decades, bulk niobium (Nb) has been the material of choice for superconducting radio frequen-cy (SRF) cavities used in particle accelerators to achieve higher accelerating gradients and lower RF losses. Multi-layer (SIS) structures consisting of alternating thin layers of superconductor(S) and insulator(I) deposited on a bulk Nb have been proposed to enhance the peak surface magnetic field and sustain a higher accelerating gradient. In this study, multilayers based NbTiN and AlN deposited on bulk Nb are used to test the proposed enhancement using the DC magnetic Hall probe technique. The tech-nique detects a penetrating magnetic field through the multilayer sample as it is placed under an external mag-netic field produced by a magnetic coil. This work re-ports the characterization and measurements of the mag-netic field of full flux penetration through single layers of NbTiN and bilayers of NbTiN/AlN on bulk Nb.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE19

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Received ※ 24 August 2022 — Revised ※ 01 September 2022 — Accepted ※ 08 September 2022 — Issue date ※ 15 September 2022

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THPOGE22

Medium Temperature Treatments of Superconducting Radio Frequency Cavities at DESY

840

THOPA07

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L. Steder, C. Bate, H. Remde, D. Reschke, J. Schaffran, L. Trelle, H. Weise, M. Wiencek
DESY, Hamburg, Germany
M. Wenskat
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Over the last years several different approaches to increase the performance of superconducting radio frequency (SRF) cavities by heat treatments have been developed and tested. At DESY, the R&D aims for cavities with enlarged quality factors while maintaining high accelerating gradients, since an envisaged upgrade of the European XFEL requires both. For this purpose, medium temperature (mid-T) treatments around 300 °C seem to be very promising. Lately, the furnace infrastructure at DESY was refurbished and now a niobium-retort furnace capable of carrying 1.3 GHz nine-cell cavities can be used for R&D studies. Vertical test results of single-cell cavities treated in this furnace at medium temperatures are presented and compared to four cavities treated similarly in a furnace at the company Zanon Research & Innovation Srl (Zanon). All mentioned cavities show enlarged quality factors but at the same time reduced gradients compared to their reference measurements before the mid-T treatment. The DESY treatments were accompanied by small niobium samples for surface analyses, which are also presented. Furthermore, the influence of post-treatment high pressure water rinsings is studied.

Slides THPOGE22 [1.277 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE22

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Received ※ 19 August 2022 — Revised ※ 23 August 2022 — Accepted ※ 27 August 2022 — Issue date ※ 15 September 2022

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THPOGE23

Vertical Electro-Polishing of 704 MHz Resonators Using Ninja Cathode: Gradients Over 40 MV/m Achieved on ESS Single-Cell Cavity

844

THOPA08

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F. Éozénou, M. Baudrier, E. Cenni, E. Fayette, L. Maurice, C. Servouin
CEA-DRF-IRFU, France
H. Hayano, H. Ito, S. Kato, T. Kubo, H. Monjushiro, T. Saeki
KEK, Ibaraki, Japan
Y.I. Ida, K. Nii, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
G. Jullien
CEA-IRFU, Gif-sur-Yvette, France

CEA, KEK and Marui Galvanizing Company have been collaborating to apply the Vertical Electropolishing (VEP) process of elliptical SRF cavities to a 704MHz single-cell ESS-type cavity, using a rotating so called and patented "Ninja" cathode. First presented results* were promising with a gradient of 27MV/m achieved, without any heat treatment applied. The performance has been pushed further since. The cavity has undergone a heat treatment at 650°C during 10h, followed by a final VEP sequence and a baking at 120°C during 48h hours. The achieved gradient at 2K was 44MV/m (power limitation), and the quality factor Q₀ exceeding 5·10¹⁰ up to 10 MV/m. The superiority of VEP compared to standard "BCP" chemical treatment is demonstrated and we intend now to scale the process to 5-Cell β=0.86 ESS cavity. We also intend to push further the performance by applying "2-step baking" (75°C and 120°C) proposed by FNAL, which was successfully applied at CEA Saclay on 1300MHz single-cell resonators with gradients above 50MV/m achieved after VEP bulk treatment.
* TUPCAV001, SRF 2021

Slides THPOGE23 [0.868 MB]

Poster THPOGE23 [0.918 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE23

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Received ※ 24 August 2022 — Revised ※ 01 September 2022 — Accepted ※ 09 September 2022 — Issue date ※ 16 September 2022

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