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Articles 31 - 60 of 90
Full-Text Articles in Physics
Field Emission Migration In Cebaf Srf Cavities Using Deep Learning, K. Ahammed, J. Li, A. Carpenter, R. Suleiman, C. Tennant, L. Vidyaratne
Field Emission Migration In Cebaf Srf Cavities Using Deep Learning, K. Ahammed, J. Li, A. Carpenter, R. Suleiman, C. Tennant, L. Vidyaratne
Electrical & Computer Engineering Faculty Publications
The Continuous Electron Beam Accelerator Facility (CEBAF) operates hundreds of superconducting radio frequency (SRF) cavities in its two main linear accelerators. Field emission can occur when the cavities are set to high operating RF gradients and is an ongoing operational challenge. This is especially true in newer, higher gradient SRF cavities. Field emission results in damage to accelerator hardware, generates high levels of neutron and gamma radiation, and has deleterious effects on CEBAF operations. So, field emission reduction is imperative for the reliable, high gradient operation of CEBAF that is required by experimenters. Here we explore the use of deep …
Nb₃Sn Coating Of A 2.6 Ghz Srf Cavity By Sputter Deposition Technique, M. S. Shakel, Wei Cao, H. Elsayed-Ali, G. V. Eremeev, U. Pudasaini, A. M. Valente-Feliciano
Nb₃Sn Coating Of A 2.6 Ghz Srf Cavity By Sputter Deposition Technique, M. S. Shakel, Wei Cao, H. Elsayed-Ali, G. V. Eremeev, U. Pudasaini, A. M. Valente-Feliciano
Electrical & Computer Engineering Faculty Publications
Nb₃Sn is of interest as a coating for SRF cavities due to its higher transition temperature Tc ~18.3 K and superheating field Hsh ~400 mT, both are twice that of Nb. Nb₃Sn coated cavities can achieve high-quality factors at 4 K and can replace the bulk Nb cavities operated at 2 K. A cylindrical magnetron sputtering system was built, commissioned, and used to deposit Nb₃Sn on the inner surface of a 2.6 GHz single-cell Nb cavity. With two identical cylindrical magnetrons, this system can coat a cavity with high symmetry and uniform thickness. Using Nb-Sn multilayer sequential sputtering followed by …
Design, Commissioning And Preliminary Results Of A Magnetic Field Scanning System For Superconducting Radiofrequency Cavities, Ishwari Parajuli, Jeffrey Nice, Gianluigi Ciovati, William Clemens, Jean Delayen, Alex Gurevich
Design, Commissioning And Preliminary Results Of A Magnetic Field Scanning System For Superconducting Radiofrequency Cavities, Ishwari Parajuli, Jeffrey Nice, Gianluigi Ciovati, William Clemens, Jean Delayen, Alex Gurevich
College of Sciences Posters
Superconducting radiofrequency (SRF) cavities are one of the building blocks of modern particle accelerators. Such cavities are typically made of bulk niobium, operate at liquid helium temperature (2 - 4 K) and have some of the highest quality factors found in Nature. One of the leading source of residual losses, which limits the quality factor in SRF cavities, is trapped magnetic flux from either residual ambient magnetic field or thermoelectric currents. The flux trapping mechanism depends on different niobium surface preparations and cool-down conditions. Suitable diagnostic tools are not yet available to study the effects of such conditions on magnetic …
Nb3Sn Coating Of Twin Axis Cavity For Accelerator Applications, Jayendrika K. Tiskumara, Subashini U. De Silva, Jean Delayen, U. Pudasaini, C. E. Reece, H. Park, G. Eremeev
Nb3Sn Coating Of Twin Axis Cavity For Accelerator Applications, Jayendrika K. Tiskumara, Subashini U. De Silva, Jean Delayen, U. Pudasaini, C. E. Reece, H. Park, G. Eremeev
Physics Faculty Publications
A Superconducting twin axis cavity consisting of two identical beam pipes that can accelerate and decelerate beams within the same structure has been proposed for the Energy Recovery Linac (ERL) applications. There are two niobium twin axis cavities at JLab fabricated with the intention of later Nb₃Sn coating and now we are progressing to coat them using vapor diffusion method. Nb₃Sn is a potential alternate material for replacing Nb in SRF cavities for better performance and reducing operational costs. Because of advanced geometry, larger surface area, increased number of ports and hard to reach areas of the twin axis cavities, …
Design Of An Rf-Dipole Crabbing Cavity System For The Electron-Ion Collider, Subashini U. De Silva, Jean R. Delayen, H. Park, F. Marhauser, J. Henry, R. A. Rimmer
Design Of An Rf-Dipole Crabbing Cavity System For The Electron-Ion Collider, Subashini U. De Silva, Jean R. Delayen, H. Park, F. Marhauser, J. Henry, R. A. Rimmer
Physics Faculty Publications
The Electron-Ion Collider requires several crabbing systems to facilitate head-on collisions between electron and proton beams in increasing the luminosity at the interaction point. One of the critical rf systems is the 197 MHz crabbing system that will be used in crabbing the proton beam. Many factors such as the low operating frequency, large transverse voltage requirement, tight longitudinal and transverse impedance thresholds, and limited beam line space makes the crabbing cavity design challenging. The rf-dipole cavity design is considered as one of the crabbing cavity options for the 197 MHz crabbing system. The cavity is designed including the HOM …
Beam Dynamics Study In A Dual Energy Storage Ring For Ion Beam Cooling*, B. Dhital, Y. S. Derbenev, D. Douglas, A. Hutton, Geoffrey A. Krafft, F. Lin, V. S. Morozov, Y. Zhang
Beam Dynamics Study In A Dual Energy Storage Ring For Ion Beam Cooling*, B. Dhital, Y. S. Derbenev, D. Douglas, A. Hutton, Geoffrey A. Krafft, F. Lin, V. S. Morozov, Y. Zhang
Physics Faculty Publications
A dual energy storage ring designed for beam cooling consists of two closed rings with significantly different energies: the cooling and damping rings. These two rings are connected by an energy recovering superconducting RF structure that provides the necessary energy difference. In our design, the RF acceleration has a main linac and harmonic cavities both running at crest that at first accelerates the beam from low energy E_{L} to high energy E_{H} and then decelerates the beam from E_{H} to E_{L} in the next pass. The purpose of the harmonic cavities is to extend the bunch length in a dual …
Wavelength Swept Photonic Crystal Laser, Sharon Marie Butler
Wavelength Swept Photonic Crystal Laser, Sharon Marie Butler
Theses
Photonics has become integral to society, based on its ability to sense the environment, to manipulate materials and to transport information. The dominance of silicon electronics has made silicon photonics a compelling vision, but difficulties with light emission have caused delays in implementation and an enduring role for III-V materials. The research conducted in this Ph.D. thesis involves study and utilisation of a combination of the optical gain of Indium Phosphide with the precision and energy of silicon nanophotonics in a novel family of lasers. A continuously tunable akinetic reflective filter is exploited to obtain a wavelength swept laser. The …
Eic Crab Cavity Multipole Analysis, Q. Wu, Y. Luo, B. Xiao, Subashini De Silva, J. A. Mitchell
Eic Crab Cavity Multipole Analysis, Q. Wu, Y. Luo, B. Xiao, Subashini De Silva, J. A. Mitchell
Physics Faculty Publications
Crab cavities are specialized RF devices designed for colliders targeting high luminosities. It is a straightforward solution to retrieve head-on collision with crossing angle existing to fast separate both beams after collision. The Electron Ion Collider (EIC) has a crossing angle of 25 mrad, and will use local crabbing to minimize the dynamic aperture requirement throughout the rings. The current crab cavity design for the EIC lacks axial symmetry. Therefore, their higher order components of the fundamental deflecting mode have a potential of affecting the long-term beam stability. We present here the multipole analysis and preliminary particle tracking results from …
Nb3Sn Coating Of Twin Axis Cavity For Srf Applications, J. K. Tiskumara, Jean R. Delayen, G. V. Eremeev, U. Pudasaini, C. E. Reece
Nb3Sn Coating Of Twin Axis Cavity For Srf Applications, J. K. Tiskumara, Jean R. Delayen, G. V. Eremeev, U. Pudasaini, C. E. Reece
Physics Faculty Publications
The twin axis cavity with two identical accelerating beams has been proposed for energy recovery linac (ERL) applications. Nb3Sn is a superconducting material with a higher critical temperature and a higher critical field as compared to Nb, which promises a lower operating cost due to higher quality factors. Two niobium twin axis cavities were fabricated at JLab and were proposed to be coated with Nb3Sn. Due to their more complex geometry, the typical coating process used for basic elliptical cavi-ties needs to be improved to coat these cavities. This development advances the current coating system at …
Using Ai For Management Of Field Emission In Srf Linacs, A. Carpenter, P. Degtiarenko, R. Suleiman, C. Tennant, D. Turner, L. S. Vidyaratne, Khan Iftekharuddin, Md. Monibor Rahman
Using Ai For Management Of Field Emission In Srf Linacs, A. Carpenter, P. Degtiarenko, R. Suleiman, C. Tennant, D. Turner, L. S. Vidyaratne, Khan Iftekharuddin, Md. Monibor Rahman
Electrical & Computer Engineering Faculty Publications
Field emission control, mitigation, and reduction is critical for reliable operation of high gradient superconducting radio-frequency (SRF) accelerators. With the SRF cavities at high gradients, the field emission of electrons from cavity walls can occur and will impact the operational gradient, radiological environment via activated components, and reliability of CEBAF’s two linacs. A new effort has started to minimize field emission in the CEBAF linacs by re-distributing cavity gradients. To measure radiation levels, newly designed neutron and gamma radiation dose rate monitors have been installed in both linacs. Artificial intelligence (AI) techniques will be used to identify cavities with high …
Effect Of A Mean Free Path On Nonlinear Losses Of Trapped Vortices Driven By A Rf Field, Manula Randhika Pathirana Walive Pathiranage, Alex Gurevich
Effect Of A Mean Free Path On Nonlinear Losses Of Trapped Vortices Driven By A Rf Field, Manula Randhika Pathirana Walive Pathiranage, Alex Gurevich
Physics Faculty Publications
We report extensive numerical simulations on nonlinear dynamics of a trapped elastic vortex under rf field, and its dependence on electron mean free path li. Our calculations of the field-dependent residual surface resistance Ri(H) take into account the vortex line tension, the linear Bardeen-Stephen viscous drag and random distributions of pinning centers. We showed that Ri(H) decreases significantly at small fields as the material gets dirtier while showing field independent behavior at higher fields for clean and dirty limit. At low frequencies Ri(H) increases smoothly with the field amplitude at small H and levels off at higher fields. The mean …
Initial Studies Of Cavity Fault Prediction At Jefferson Laboratory, L.S. Vidyaratne, A. Carpenter, R. Suleiman, C. Tennant, D. Turner, Khan Iftekharuddin, Md. Monibor Rahman
Initial Studies Of Cavity Fault Prediction At Jefferson Laboratory, L.S. Vidyaratne, A. Carpenter, R. Suleiman, C. Tennant, D. Turner, Khan Iftekharuddin, Md. Monibor Rahman
Electrical & Computer Engineering Faculty Publications
The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Laboratory is a CW recirculating linac that utilizes over 400 superconducting radio-frequency (SRF) cavities to accelerate electrons up to 12 GeV through 5-passes. Recent work has shown that, given RF signals from a cavity during a fault as input, machine learning approaches can accurately classify the fault type. In this paper we report on initial results of predicting a fault onset using only data prior to the failure event. A data set was constructed using time-series data immediately before a fault (’unstable’) and 1.5 seconds prior to a fault (’stable’) gathered …
Development And Applications Of Condensed Phase Cavity Ring-Down Spectroscopy For Studies Of Electrochemical And Interfacial., Shadi Ahmad Alnaanah
Development And Applications Of Condensed Phase Cavity Ring-Down Spectroscopy For Studies Of Electrochemical And Interfacial., Shadi Ahmad Alnaanah
Electronic Theses and Dissertations
This dissertation reports the development of ultra-sensitive platforms based on the laser cavity ring-down spectroscopic (CRDS) technique to enable optical and spectroelectrochemical investigations in the condensed phase of matter at challenging scenarios. Firstly, an electrically-active solid/liquid interface for the evanescent-wave cavity ring-down spectroscopy (EW-CRDS) was developed to specroelectrochemically investigate redox events. By coating the interface of total internal reflection of the EW-CRDS platform with a high quality optically transparent and electrically conductive indium tin oxide thin film (ITO), we demonstrated that sufficiently long ring-down times can be achieved to allow for spectroelectrochemical investigations of redox species at solid/liquid interfaces at …
Water Entry Of Spheres At Various Contact Angles, Nathan B. Spiers, Mohammad M. Mansoor, Jesse Belden, Tadd T. Truscott
Water Entry Of Spheres At Various Contact Angles, Nathan B. Spiers, Mohammad M. Mansoor, Jesse Belden, Tadd T. Truscott
Mechanical and Aerospace Engineering Faculty Publications
It is well known that the water entry of a sphere causes cavity formation above a critical impact velocity as a function of the solid-liquid contact angle (Duez et al. 2007). Using a rough sphere with a contact angle of 120◦, Aristoff & Bush (2009) showed that there are four different cavity shapes dependent on the Bond and Weber numbers (i.e., quasi-static, shallow, deep and surface). We experimentally alter the Bond number, Weber number and contact angle of smooth spheres and find two key additions to the literature: 1) Cavity shape also depends on the contact angle; 2) …
Measurement Of Surface Resistance Properties With Coaxial Resonators - Review, Hyekyoung Park, Subashini De Silva, J. R. Delayen
Measurement Of Surface Resistance Properties With Coaxial Resonators - Review, Hyekyoung Park, Subashini De Silva, J. R. Delayen
Physics Faculty Publications
Achieving ever decreasing surface resistance at higher field in superconducting RF accelerating structures is one of most outstanding developments in modern accelerators. The BCS theory has been used widely to estimate the surface resistance and to direct the technology. However, recent research results show that the behavior of the surface resistance further deviates from the BCS theory. So far the study on surface resistance was performed usually with cavities of single frequency which limited the study of frequency dependent surface resistance. The Center for Accelerator Science at Old Dominion University has designed and built several half wave coaxial cavities to …
Design Of A Proof-Of-Principle Crabbing Cavity For The Jefferson Lab Electron-Ion Collider, Hyekyoung Park, Subashini U. De Silva, Salvador I. Sosa Guitron, Jean R. Delayen
Design Of A Proof-Of-Principle Crabbing Cavity For The Jefferson Lab Electron-Ion Collider, Hyekyoung Park, Subashini U. De Silva, Salvador I. Sosa Guitron, Jean R. Delayen
Physics Faculty Publications
The Jefferson Lab design for an electron-ion collider (JLEIC) requires crabbing of the electron and ion beams in order to achieve the design luminosity. A number of options for the crabbing cavities have been explored, and the one which has been selected for the proof-of-principle is a 952 MHz, 2-cell rf-dipole (RFD) cavity. This paper summarizes the electromagnetic design of the cavity and its HOM characteristics.
Two-Energy Storage-Ring Electron Cooler For Relativistic Ion Beams, Bhawin Dhital, Jean R. Delayen, Y. S. Derbenev, D. Douglas, Geoffrey A. Krafft, F. Lin, V. S. Morozov, Y. Zhang
Two-Energy Storage-Ring Electron Cooler For Relativistic Ion Beams, Bhawin Dhital, Jean R. Delayen, Y. S. Derbenev, D. Douglas, Geoffrey A. Krafft, F. Lin, V. S. Morozov, Y. Zhang
Physics Faculty Publications
An electron beam based cooling system for the ion beam is one of the commonly used approaches. The proposed two’energy storage-ring electron cooler consists of damping and cooling sections at markedly different energies connected by an energy recovering superconducting RF structure. The parameters in the cooling and damping sections are adjusted for optimum cooling of a stored ion beam and for optimum damping of the electron beam respectively. This paper briefly describes a two cavities model along with a third cavity model to accelerate and decelerate the electron beam in two energy storage ring. Based on our assumed value of …
Overview Of Srf Deflecting And Crabbing Cavities, Subashini De Silva
Overview Of Srf Deflecting And Crabbing Cavities, Subashini De Silva
Physics Faculty Publications
Developments over the past few years on novel superconducting deflecting and crabbing cavities have introduced advanced rf geometries with improved performance, in comparison to the typical squashed elliptical cavities operating in TM110 type mode. These new structures are compact geometries operating in either TEM type or TE11-like mode. One of the key applications of such cavities is the use of crabbing systems for circular colliders in increasing the luminosity. Crabbing systems are an essential component in future colliders with intense beams and proposed electron-ion colliders. High luminosity upgrade of LHC is planned to implement crabbing systems at two interaction points. …
Simulation And Measurements Of Hom Filter Of The Larp Prototype Rf-Dipole Crabbing Cavity Using An Rf Test Box, Subashini U. De Silva, Jean R. Delayen, Z. Li
Simulation And Measurements Of Hom Filter Of The Larp Prototype Rf-Dipole Crabbing Cavity Using An Rf Test Box, Subashini U. De Silva, Jean R. Delayen, Z. Li
Physics Faculty Publications
The RF-Dipole Crabbing Cavity designed for the LHC High Luminosity Upgrade includes two higher order mode (HOM) couplers. One of the HOM couplers is an rf filter, which is a high pass filter designed to couple to the horizontal dipole modes and accelerating modes up to 2 GHz, while rejecting the fundamental operating mode at 400 MHz. The coupler consists of a high pass filter circuit where the rejection of the operating mode and transmission of HOMs are sensitive to dimensional deviations. An rf test box has been designed to measure the transmission of the rf filter in order to …
Analysis Of Higher Order Multipoles Of The 952.6 Mhz Rf-Dipole Crabbing Cavity For The Jefferson Lab Electron Ion Collider, Subashini U. De Silva, J. R. Delayen, V. S. Morozov, H. Park, S. Sosa
Analysis Of Higher Order Multipoles Of The 952.6 Mhz Rf-Dipole Crabbing Cavity For The Jefferson Lab Electron Ion Collider, Subashini U. De Silva, J. R. Delayen, V. S. Morozov, H. Park, S. Sosa
Physics Faculty Publications
The crabbing system is a key feature in the Jefferson Lab Electron-Ion Collider (JLEIC) required to increase the luminosity of the colliding bunches. A local crabbing system will be installed with superconducting rf-dipole crabbing cavities operating at 952.6 MHz. The field non-uniformity across the beam aperture in the crabbing cavities produces higher order multipole components, similar to that which are present in magnets. Knowledge of higher order mode multipole field effects is important for accurate beam dynamics study for the crabbing system. In this paper, we quantify the multipole components and analyse their effects on the beam dynamics.
Initial Implementation Of A Machine Learning System For Srf Cavity Fault Classification At Cebaf, A. Carpenter, K. M. Iftekharuddin, T. Powers, Y. Roblin, A. Solopava Shabalina, C. Tennant, L. Vidyaratne
Initial Implementation Of A Machine Learning System For Srf Cavity Fault Classification At Cebaf, A. Carpenter, K. M. Iftekharuddin, T. Powers, Y. Roblin, A. Solopava Shabalina, C. Tennant, L. Vidyaratne
Electrical & Computer Engineering Faculty Publications
The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Laboratory is a high power Continuous Wave (CW) electron accelerator. It uses a mixture of of SRF cryomodules: older, lower energy C20/C50 modules and newer, higher energy C100 modules. The cryomodules are arrayed in two anti-parallel linear accelerators. Accurately classifying the type of cavity faults is essential to maintaining and improving accelerator performance. Each C100 cryomodule contains eight 7-cell cavities. When a cavity fault occurs within a cryomodule, all eight cavities generate 17 waveforms each containing 8192 points. This data is exported from the control system and saved for review. Analysis …
Design And Commissioning Of A Magnetic Field Scanning System For Srf Cavities, Ishwari Prasad Parajuli, Gianluigi Ciovati, W. A. Clemens, Jean R. Delayen, J. Nice, Alex V. Gurevich
Design And Commissioning Of A Magnetic Field Scanning System For Srf Cavities, Ishwari Prasad Parajuli, Gianluigi Ciovati, W. A. Clemens, Jean R. Delayen, J. Nice, Alex V. Gurevich
Physics Faculty Publications
Trapped magnetic vortices are one of the leading sources of residual losses in SRF cavities. Mechanisms of flux pinning depend on the materials treatment and cool-down conditions. A magnetic field scanning system using flux-gate magnetometers and Hall probes has been designed and built to allow measuring the local magnetic field of trapped vortices normal to the outer surface of 1.3 GHz single-cell SRF cavities at cryogenic temperatures. Such system will allow inferring the key information about the distribution and magnitude of trapped flux in the SRF cavities for different material, surface preparations and cool-down conditions.
Beam-Beam Effect: Crab Dynamics Calculation In Jleic, He Huang, Vasiliy Morozov, Yves Roblin, Amy Sy, Fanglei Lin, Yuhong Zhang, Balša Terzić, Salvador Sosa, Isurumali Neththikumara
Beam-Beam Effect: Crab Dynamics Calculation In Jleic, He Huang, Vasiliy Morozov, Yves Roblin, Amy Sy, Fanglei Lin, Yuhong Zhang, Balša Terzić, Salvador Sosa, Isurumali Neththikumara
Physics Faculty Publications
The electron and ion beams of a future Electron Ion Collider (EIC) must collide at an angle for detection, machine and engineering design reasons. To avoid associated luminosity reduction, a local crabbing scheme is used where each beam is crabbed before collision and de-crabbed after collision. The crab crossing scheme then provides a head-on collision for beams with a non-zero crossing angle. We develop a framework for accurate simulation of crabbing dynamics with beam-beam effects by combining symplectic particle tracking codes with a beam-beam model based on the Bassetti-Erskine analytic solution. We present simulation results using our implementation of such …
Measurement Of The Magnetic Field Penetration Into Superconducting Thin Films, Iresha Harshani Senevirathne, Gianluigi Ciovati, Jean R. Delayen
Measurement Of The Magnetic Field Penetration Into Superconducting Thin Films, Iresha Harshani Senevirathne, Gianluigi Ciovati, Jean R. Delayen
Physics Faculty Publications
The magnetic field at which first flux penetrates is a fundamental parameter characterizing superconducting materials for SRF cavities. Therefore, an accurate technique is needed to measure the penetration of the magnetic field directly. The conventional magnetometers are inconvenient for thin superconducting film measurements because these measurements are strongly influenced by orientation, edge and shape effects. In order to measure the onset of field penetration in bulk, thin films and multi-layered superconductors, we have designed, built and calibrated a system combining a small superconducting solenoid capable of generating surface magnetic field higher than 500 mT and Hall probe to detect the …
Maximum Performance Of Cavities Affected By The High-Field Q-Slope (Hfqs), G. Ciovati, A.V. Gurevich, I. P. Parajuli
Maximum Performance Of Cavities Affected By The High-Field Q-Slope (Hfqs), G. Ciovati, A.V. Gurevich, I. P. Parajuli
Physics Faculty Publications
The performance of high-purity, bulk niobium SRF cavities treated by chemical processes such as BCP or EP is limited by the so-called high-field Q-slope (HFQS). Several models and experimental studies have been proposed and performed over the years to understand the origin of these anomalous losses but a general consensus on what these origins are is yet to be established. In this contribution, we present the results from the RF tests of several 1.3 GHz single-cell cavities limited by the HFQS and tested using a variable input coupler. This allowed to maintain close to critical coupling even at high field …
Precision Spectroscopy Of Beryllium, Advik D. Vira
Precision Spectroscopy Of Beryllium, Advik D. Vira
Theses, Dissertations, and Projects
We report on the calibration and absolute frequency results for the 2s2p1P1 state in neutral atomic beryllium-9. We start off with a discussion of the method used to calibrate the laser, which includes a detailed explanation of the basic physics involved, and then discuss the results for the lowest singlet state in neutral beryllium-9. We discuss a way to predict the spectra using optical Bloch equations and then present and analyze the experimental results. We found the absolute frequency for the 1P1 state to be 42565.4487(30) cm-1, which is in agreement with the current best theoretical estimateof42565.441(11)cm-1 [49]. Amoresophisticatedanalyticaltechniqueisproposed; however, …
Determination Of The Field-Dependence Of The Surface Resistance Of Superconductors From Cavity Tests, Jean R. Delayen, Subashini De Silva, Hyekyoung Park
Determination Of The Field-Dependence Of The Surface Resistance Of Superconductors From Cavity Tests, Jean R. Delayen, Subashini De Silva, Hyekyoung Park
Physics Faculty Publications
Cryogenic tests of superconducting cavities yield an average surface resistance as a function of the peak surface magnetic field. An analytical formalism has been developed to extract the actual field dependence of the surface resistance from cavity tests and is applied to coaxial cavities and cavities of more complex geometries.
Rf Tests Of Rf-Dipole Prototype Crabbing Cavities For Lhc High Luminosity Upgrade, Subashini De Silva, Hyekyoung Park, Jean R. Delayen, Zi Li
Rf Tests Of Rf-Dipole Prototype Crabbing Cavities For Lhc High Luminosity Upgrade, Subashini De Silva, Hyekyoung Park, Jean R. Delayen, Zi Li
Physics Faculty Publications
The superconducting rf-dipole crabbing cavity is one of the two crabbing cavity designs proposed for the LHC high luminosity upgrade. The proof-of-principle (P-o-P) rf-dipole cavity operating at 400 MHz has demonstrated performance exceeding the design specifications. The prototype cavity for SPS beam test has been designed to include the fundamental power coupler, HOM couplers, and all the ancillary components intended to meet the design requirements. The crab cavities will be installed in the SPS beam line prior to the installation in LHC; this will be the first crabbing cavity operation on a proton beam. The fabrication of two prototype rf-dipole …
Investigation Of The Surface Resistance Of Niobium Between 325 Mhz And 1300 Mhz Using A Coaxial Half-Wave Cavity, Hyekyoung Park, Jean R. Delayen, Subashini De Silva
Investigation Of The Surface Resistance Of Niobium Between 325 Mhz And 1300 Mhz Using A Coaxial Half-Wave Cavity, Hyekyoung Park, Jean R. Delayen, Subashini De Silva
Physics Faculty Publications
The Center for Accelerator Science at Old Dominion University has built a half-wave coaxial cavity (*) to measure the surface resistance of niobium as a function of frequency, temperature, rf field, preparation techniques, over a wide range of frequencies of interest for particle accelerators. The characteristics of the half-wave coaxial cavity provide these information on a same surface. The preliminary results showed clearly the frequency dependence of residual surface resistance (**). After establishing baseline, we have conducted a study of low temperature baking effect on the surface resistance under controlled environment. This paper will describe the details of the test …
Magnetron Sputtering Of Nb3Sn For Srf Cavities, Md. N. Sayeed, H. Elsayed-Ali, G. V. Eremeev, M. J. Kelley, U. Pudasaini, C. E. Reece
Magnetron Sputtering Of Nb3Sn For Srf Cavities, Md. N. Sayeed, H. Elsayed-Ali, G. V. Eremeev, M. J. Kelley, U. Pudasaini, C. E. Reece
Electrical & Computer Engineering Faculty Publications
Nb3Sn is a potential candidate for surface material of SRF cavities since it can enable the cavity to operate at higher temperatures with high quality factor and at an increased accelerating gradient. Nb-Sn films were deposited using magnetron sputtering of individual Nb and Sn targets onto Nb and sapphire substrates. The as-deposited films were annealed at 1200 °C for 3 hours. The films were characterized for their structure by X-ray Diffraction (XRD), morphology by Field Emission Scanning Electron Microscopy (FESEM), and composition by Energy Dispersive X-ray Spectroscopy (EDS) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The …