Diego Bettoni
(FE)
10/8/18, 9:30 AM
Perspective of thin film cavities in international projects
Cristian Pira
(LNL)
10/8/18, 9:40 AM
Perspective of thin film cavities in international projects
Dr
Anne-Marie Valente-Feliciano
(Jefferson Lab)
10/8/18, 9:50 AM
Perspective of thin film cavities in international projects
Dr
Oleg Malyshev
(STFC Daresbury Laboratory)
10/8/18, 10:20 AM
Perspective of thin film cavities in international projects
The ARIES H2020 collaboration has started in May 2017. One of the main goals of ARIES is to developing and demonstrating novel concepts and further improving existing accelerator technologies. A successful proposal for a work package on systematic studying and developing the superconducting thin film for superconducting RF cavities joint a team of 8 partners (research groups) from 7 countries....
Dr
Oliver Kugeler
(Helmholtz-Zentrum-Berlin)
10/8/18, 10:45 AM
Perspective of thin film cavities in international projects
The greatest challenges for wide-spread adoption of new applications of superconductivity remain the limited understanding of how to apply the fundamental principles on an engineering level and the capability to deploy the technology cost effectively on a large-scale.
EASITrain offers a cross-sectoral training program that is a fine blend of engineering, fundamental research and the...
Dr
Anne-Marie Valente-Feliciano
(Jefferson Lab)
10/8/18, 12:00 PM
Nb thin film technology
With the development of energetic vacuum deposition techniques, high quality Nb films have been produced supporting the promise of high RF performance. In energetic condensation, the controlled incoming ion energy enables a number of processes such as desorption of adsorbed species, enhanced mobility of surface atoms and sub-implantation of impinging ions, thus producing improved film...
Vanessa Andreina Garcia Diaz
(LNL)
10/8/18, 12:25 PM
Nb thin film technology
Thick films shows the possibility to obtain a mitigation of a Q-slope in Nb on Cu superconductive resonant cavities. In the framework of EASITrain project and CERN-INFN-STFC collaboration, the multilayer technique was applied in order to deposit a 70-microns thick film of Niobium onto 6 GHz seamless copper cavities. In this contribution, we report the results and challenges of the RF...
Dr
Fabio Avino
(CERN)
10/8/18, 12:50 PM
Nb thin film technology
The Wide Open Waveguide (WOW) Crab cavity [1] has been designed in the framework of the Future Circular Collider study. It features a thin Nb film sputtered on bulk copper [2]. The main advantages with respect to bulk Nb include the improved thermal stability, and the reduction of the cavity frequency sensitivity to the external liquid He bath pressure variations as well as to the Lorentz...
Dr
Alban Sublet
(CERN)
10/8/18, 2:30 PM
Nb thin film technology
Superconducting thin film coatings offer a valuable alternative to conventional bulk niobium cavities mainly by reducing the cost of raw material and enhancing the heat exchange efficiency thanks to the copper substrate thermal conductivity. The current and future superconducting radiofrequency (SRF) cavities designs and working frequencies lead to a variety of shapes and sizes to be coated....
Dr
Teng Tan
(IMP, CAS)
10/8/18, 2:55 PM
Nb thin film technology
The possibility that CIADS uses only Nb/Cu cavities has been discussed at IMP. A 325 MHz dummy QWR cavity has been fabricated at IMP for technique demonstration. The cavity has been coated for a few runs, with small samples attached to the inner surface and bare cavity only. The small samples manifested a complete superconducting coverage. Vertical testing results suggested the Nb/Cu technique...
Giorgio Keppel
(LNL)
10/8/18, 3:20 PM
Nb thin film technology
In the framework of the ALPI Upgrade for SPES project, new cryostats with 8 new high beta QWR cavities needed to be produced. In order to carry out this upgrade, a refurbishing of the sputtering system for QWR coating was performed. Now the sputtering system is working and first test coating on quarts’ substrate are in progress. Simultaneously the chemical plant and QWR cold test facility...
Ruggero Vaglio
(NA)
10/8/18, 4:15 PM
Theoretical modelling of RF behavior
Recently, the improvement of RF superconducting cavities performances has motivated a considerable research effort to elucidate the effect of trapped magnetic flux. Here we will show that by introducing a non-linear pinning force in the Gittleman-Rosenblum equations for the RF power dissipation due to an external trapped magnetic field in a superconductor, we can describe most of the common...
Dr
Akira Miyazaki
(CERN and the University of Manchester)
10/8/18, 4:40 PM
Theoretical modelling of RF behavior
Since their invention, the performance of Nb film cavities has always been limited by a strong Q-slope. Recent tests at CERN of the newly developed seamless Quarter-Wave Resonator (QWR) showed an interesting decomposition of the Q-slope, which might help to explain/cure this limitation. One is caused by non-linear trapped flux oscillation in the residual component, whose surface resistance...
Dr
Mattia Checchin
(Fermilab)
10/8/18, 5:05 PM
Theoretical modelling of RF behavior
In this study, the radio-frequency complex response of trapped vortices in superconductors calculated for small values of applied radio-frequency field, will be presented. In agreement with experimental data on bulk niobium radio-frequency cavities, the calculated surface resistance shows a non-monotonic trend as a function of the mean-free-path and a sigmoidal-like trend as a function of the...
Dr
Takayuki Kubo
(KEK and ODU)
10/8/18, 5:30 PM
Theoretical modelling of RF behavior
We propose a theory of the nonlinear surface resistance of a dirty superconductor in a strong RF field, taking into account realistic materials features, such as magnetic and nonmagnetic impurities, subgap states originating from finite quasiparticle lifetimes, and a proximity-coupled normal layer at the surface. The Usadel equations with the RF pair-breaking current are solved to obtain the...
A.V. Butenko
(JINR, Dubna, Russia)
10/8/18, 5:55 PM
Perspective of thin film cavities in international projects
The New Injector Linac for Nuclotron-Nica is the proposed replacement for LU-20 accelerator. The possibility of old DTL LU-20 replacement by the new superconducting (SC) linac of 30 MeV energy for protons and ≥7.5 MeV/nucleon for deuterium beam is discussed now. The development of the SRF technologies is the key task of new Russian - Belarusian collaboration. The collaboration of JINR, NRNU...
Prof.
Xiaoxing Xi
(Temple University)
10/9/18, 9:00 AM
Other superconducting materials beyond niobium
MgB2 is a promising superconductor to replace Nb for SRF cavities. Clean MgB2 thin films have a low residual resistivity (<0.1 µΩcm) and a high Tc of 40 K, promising a low BCS surface resistance. Its thermodynamic critical field Hc is higher than Nb, potentially leading to a higher maximum accelerating filed. The lower critical field Hc1 of MgB2 is lower than Nb, but it can be enhanced by...
Mr
Stewart Leith
(Universität Siegen)
10/9/18, 9:25 AM
Other superconducting materials beyond niobium
Considerable research is currently underway to utilise alternative materials to bulk Nb in SRF cavities. This is with the aim to increase their performance to that required by future accelerators. In this contribution, the results of two investigations into dc magnetron sputtered Nb thin films on Cu substrates are summarized, as well as initial results from research which has been conducted...
Mr
David Beverstock
(Jefferson Lab)
10/9/18, 9:50 AM
Other superconducting materials beyond niobium
Further enhancement of superconducting accelerating cavity performance calls upon the development of materials beyond bulk niobium (Nb). Superconducting RF (SRF) is a surface phenomenon; for most superconducting materials the RF penetration depth is in the range of hundreds of nanometers. Due to the field penetration enhancement occurring in films with a thickness smaller than their nominal...
Mr
Thomas Oseroff
(Cornell University)
10/9/18, 10:15 AM
Other superconducting materials beyond niobium
A TE mode niobium sample host cavity was used to characterize the RF performance of large 5” diameter thin film samples at 4 GHz. Exciting results were obtained from industry partner Ultramet’s CVD Nb3Sn grown on a copper substrate. These results indicate that slight alterations to the deposition process and use of higher purity precursors could lead to high-performance Nb3Sn coatings on...
Mr
Sebastian Keckert
(Helmholtz-Zentrum Berlin)
10/9/18, 10:40 AM
Other superconducting materials beyond niobium
RF-surface resistance measurements have been performed on an S-I-S multilayer sample.
The sample was prepared at JLab using DC-magnetron sputtering of a 75 nm NbTiN layer on a 15 nm AlN insulator layer on bulk niobium. The sample (and sputtered area) was a circular disc of 75 mm diameter, welded on an 85 mm high Nb pipe of the same outer diameter. This geometry allowed performing RF...
Dr
Emanuela Barzi
(Fermi National Accelerator Laboratory)
10/9/18, 11:30 AM
Md Nizam Sayeed
(Old Dominion University)
10/9/18, 11:55 AM
Other superconducting materials beyond niobium
Nb3Sn-coated Nb SRF cavities are studied due to their potential of providing a higher accelerating gradient over Nb SRF cavities. Magnetron sputtering can be a feasible alternative to conventional tin vapor diffusion process to fabricate Nb3Sn for SRF cavities. By depositing Nb and Sn layers separately and annealing afterward, the stoichiometry of the coated films can be controlled to create...
UTTAR PUDASAINI
(College of William and Mary)
10/9/18, 12:20 PM
Other superconducting materials beyond niobium
Nb3Sn-coated SRF cavities can potentially achieve superior performance in terms of quality factor, accelerating gradient, and operating temperature. Tin vapor diffusion process of Nb3Sn coating on Nb is a simple, yet efficacious technique to fabricate Nb3Sn-coated SRF cavities. The process comprises two¬ steps: “nucleation” followed by “deposition”. The crucible with Sn/SnCl2 and the substrate...
Dr
reza valizadeh
(ASTeC, STFC)
10/9/18, 12:45 PM
Other superconducting materials beyond niobium
Nb3Sn alloy is a type II superconductor with maximum Tc of 18 K and predicted superheating field of 400 mT and potentially may offer improvements in both cryogenic efficiency and maximum accelerating field. Hence, Nb3Sn thin film can be an alternative superconducting coating either as a single or multilayer for SRF cavity production.
Nb3Sn has been deposited from stoichiometric alloy target...
Dr
Marco Arzeo
(CERN)
10/9/18, 1:10 PM
Other superconducting materials beyond niobium
Superconducting radio frequency (SRF) cavities, made of niobium films on copper (Nb/Cu), are currently employed for a large variety of particle accelerators. At the same time, the Nb/Cu technology, being very cost effective, also represents one of the main options for upcoming machines like the future circular collider (FCC).
While research and development continue on the Nb/Cu...
Cristian Pira
(LNL)
10/9/18, 2:40 PM
Advanced preparation of substrates and atmospheric plasmas
Thin film technology moves the surface preparation from Nb to Cu, because the Nb thin film cannot be chemical treated. For the Nb on Cu resonant cavities two principal copper cleaning and polishing treatments were studied: one is the electropolishing (EP) and the other one is the chemical polishing with SUBU solution. The influence of surface preparation is deeply studied in bulk Nb cavities...
Martina Martinello
(Fermilab)
10/9/18, 3:05 PM
Advanced preparation of substrates and atmospheric plasmas
Field emission is one the major limitations to the maximum usable accelerating gradient of SRF cavities in cryomodules. Taking advantage of the plasma chemistry, field emitting and decreasing the field emission. A collaboration between FNAL, SLAC and ORNL was established to develop a plasma processing system capable to minimize and overcome the problem of field emission in LCLS-II cryomodules....
Mr
Oleksandr Hryhorenko
(IPNO)
10/9/18, 3:30 PM
Advanced preparation of substrates and atmospheric plasmas
The reduction of construction and operation costs are major aims for future superconducting radio-frequency (SRF) applications. So as to reduce the construction cost of the particle accelerators, the standard expensive chemical treatments (electropolishing (EP) or buffered chemical polishing (BCP)) of bulk Niobium (Nb) cavities can be significantly reduced or even suppressed thanks to...
Prof.
Arturs Medvids
(Riga Technical University)
10/9/18, 3:55 PM
Advanced preparation of substrates and atmospheric plasmas
The properties of Nb thin films deposited on planar Cu substrate were studied after its laser annealing. Five samples were prepared employing different substrate preparation techniques and were subsequently coated with 3-µm thick Nb film with the same deposition parameters. Afterwards, the Nb films were irradiated using Nd:YAG laser in order to increase crystallinity and improve adhesion of...
Oscar Azzolini
(LNL)
10/9/18, 4:50 PM
Advances in cavity substrate fabrication
In the framework of the FCC study, niobium-coated copper cavities are considered to operate at 400 MHz. Spinning is a potential alternative to conventional shaping methods of copper half cells.
A step by step presentation of the complete spinning process will be explained, observing the effects of the stresses induced by the forming and the actions chosen to fight this specific behaviour of...
Mr
Jean-Francois Croteau
(I-Cube)
10/9/18, 5:15 PM
In the framework of CERN’s Future Circular Collider (FCC), fabrication of high-performance superconducting radiofrequency (SRF) cavities is crucial to attain energy levels relevant for breakthrough research in particle physics. Damage to the inner surface of copper and niobium cavities must be minimized to ensure proper growth of the superconducting film and prevent quenching during operation....
Dr
Claire Z. Antoine
(CEA)
10/10/18, 9:00 AM
RF and material characterization for SRF films
Developing thin films deposited with complex superconductors like Nb3Sn or multilayers requires being able to test the maximum field achievable on numerous samples. In classical magnetometer where the sample is immersed in homogenous field, there is always some ambiguity resulting from the fact that the penetration of field can start on the back or the edges of the samples.
We have tried to...
Mr
Thomas Proslier
(Commissariat de l'énergie atomique)
10/10/18, 9:25 AM
RF and material characterization for SRF films
I will present recent analysis of tunneling spectroscopy data measured on cut out samples from a N doped cavity, and from commonly processed hot and cold spot regions of a BCP cavity. The hot spot samples reveal small gap area consistent with a proximity effect model along with spectroscopic signature of magnetic impurities, caracteristic of two level systems. The cold and N doped samples on...
Mr
Dmitry Tikhonov
(Helmholtz-Zentrum Berlin (HZB))
10/10/18, 9:50 AM
RF and material characterization for SRF films
At the present time more and more low temperature superconducting materials and compounds are being developed around the world for new applications in future accelerators and industry. However, the production processes and recipes are not fully developed and require measurement tools for studies and optimization. The Quadrupole Resonator (QPR) is a cavity that is able to perform the most...
Prof.
Steven Anlage
(University of Maryland)
10/10/18, 10:15 AM
RF and material characterization for SRF films
Based on the needs of the SRF community to identify and evaluate defects on Nb surfaces, a novel near-field magnetic microwave microscope was successfully built using a magnetic writer from a conventional magnetic recording hard-disk drive [1]. This magnetic writer can create an RF magnetic field in the 100 mT range, localized and strong enough to drive Nb into the mixed state, and may have...
Dr
Alexei Katashev
(profesosr)
10/10/18, 11:10 AM
RF and material characterization for SRF films
Photothermostimulated exoelectron emission (PTSE), being observed when solid specimen is simultaneously heated and excited by photons with energy close to photoemission threshold, often is related to the annealing of structural defects and hereby, could become the tool to test quality, or amount of imperfections, of the superconductive Nb films.
The present study explores PTSE of the Nb...
Dr
sepideh Aliasghari
(research fellow)
10/10/18, 11:35 AM
RF and material characterization for SRF films
S. Aliasghari1,2, P. Skeldon2, A. Gholinia2, R. Valizadeh1,
1 ASTeC, STFC Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD, UK.
2 Corrosion and Protection Group, School of Materials, The University of Manchester, Manchester M13 9PL, UK.
Defects on the niobium superconducting radio frequency (SRF) can have an important impact on quality factor at low accelerating fields....
Dr
antonio cassinese
(università di Napoli)
Superconducting films beyond SRF
We review r.f. measurements of the surface impedance Zs=Rs+iXs of YBCO films films deposited on sapphire or MgO . The measurements are performed by a microstrip dielectric resonator and cavities techniques using a meander line geometry. The power dependence of Zs is studied at different temperatures and frequencies in the range 1-18 GHz. The effects of a d.c. magnetic field applied with...
