Open Access. Powered by Scholars. Published by Universities.®
- Institution
- Keyword
-
- Cavity (6)
- Atomic force microscopy (3)
- Cavities (3)
- Ion (3)
- Simulation (3)
-
- Superconductivity (3)
- Superconductors (3)
- Conductivity (2)
- Cryogenics (2)
- Dipole (2)
- Electronic instability (2)
- Electronic mechanisms (2)
- Emittance (2)
- HOM (2)
- Josephson junctions (2)
- Lattice (2)
- Magnetic fields (2)
- Magnetic flux (2)
- Motion (2)
- Nanosecond pulsed laser (2)
- Niobium (2)
- Physics (2)
- Spin degrees of freedom (2)
- Superconducting RF (2)
- Superconducting devices (2)
- Surface composition (2)
- Transition (2)
- Vortices (2)
- Absorption (1)
- Absorption measurements (1)
Articles 1 - 30 of 53
Full-Text Articles in Physics
Machine-Assisted Discovery Of Integrable Symplectic Mappings, T. Zolkin, Y. Kharkov, S. Nagaitsev
Machine-Assisted Discovery Of Integrable Symplectic Mappings, T. Zolkin, Y. Kharkov, S. Nagaitsev
Physics Faculty Publications
We present a new automated method for finding integrable symplectic maps of the plane. These dynamical systems possess a hidden symmetry associated with an existence of conserved quantities, i.e., integrals of motion. The core idea of the algorithm is based on the knowledge that the evolution of an integrable system in the phase space is restricted to a lower-dimensional submanifold. Limiting ourselves to polygon invariants of motion, we analyze the shape of individual trajectories thus successfully distinguishing integrable motion from chaotic cases. For example, our method rediscovers some of the famous McMillan-Suris integrable mappings and ultradiscrete Painlevé equations. In total, …
Superheating Field In Superconductors With Nanostructured Surfaces, W. P. M. R. Pathirana, A. Gurevich
Superheating Field In Superconductors With Nanostructured Surfaces, W. P. M. R. Pathirana, A. Gurevich
Physics Faculty Publications
We report calculations of a dc superheating field Hsh in superconductors with nanostructured surfaces. Numerical simulations of the Ginzburg-Landau (GL) equations were performed for a superconductor with an inhomogeneous impurity concentration, a thin superconducting layer on top of another superconductor, and superconductor-insulator-superconductor (S-I-S) multilayers.The superheating field was calculated taking into account the instability of the Meissner state with a nonzero wavelength along the surface, which is essential for realistic values of the GL parameter κ. Simulations were done for the materials parameters of Nb and Nb3Sn at different values of κ and the mean free paths. We …
Serpentine Micromixers Using Extensional Mixing Elements, George Tomaras, Chandrasekhar R. Kothapalli, Petru S. Fodor
Serpentine Micromixers Using Extensional Mixing Elements, George Tomaras, Chandrasekhar R. Kothapalli, Petru S. Fodor
Physics Faculty Publications
Computational fluid dynamics modeling was used to characterize the effect of the integration of constrictions defined by the vertices of hyperbolas on the flow structure in microfluidic serpentine channels. In the new topology, the Dean flows characteristic of the pressure-driven fluid motion along curved channels are combined with elongational flows and asymmetric longitudinal eddies that develop in the constriction region. The resulting complex flow structure is characterized by folding and stretching of the fluid volumes, which can promote enhanced mixing. Optimization of the geometrical parameters defining the constriction region allows for the development of an efficient micromixer topology that shows …
Nonlinear Meissner Effect In Nb3Sn Coplanar Resonators, Junki Makita, C. Sundahl, Gianluigi Ciovati, C. B. Eom, Alex Gurevich
Nonlinear Meissner Effect In Nb3Sn Coplanar Resonators, Junki Makita, C. Sundahl, Gianluigi Ciovati, C. B. Eom, Alex Gurevich
Physics Faculty Publications
We investigated the nonlinear Meissner effect (NLME) in Nb3Sn thin-film coplanar resonators by measuring the resonance frequency as a function of a parallel magnetic field at different temperatures. We used low rf power probing in films thinner than the London penetration depth λ(B) to significantly increase the field onset of vortex penetration and measure the NLME under equilibrium conditions. Contrary to the conventional quadratic increase of λ(B) with B expected in s-wave superconductors, we observed a nearly linear increase of the penetration depth with B. We concluded that this behavior of λ(B) is due to weak linked grain …
Magnetic Field Penetration Technique To Study Field Shielding Of Multilayered Superconductors, Iresha Harshani Senevirathne, Alex Gurevich, Jean R. Delayen, A-M Valente-Feliciano
Magnetic Field Penetration Technique To Study Field Shielding Of Multilayered Superconductors, Iresha Harshani Senevirathne, Alex Gurevich, Jean R. Delayen, A-M Valente-Feliciano
Physics Faculty Publications
The SIS structure which consists of alternative thin layers of superconductors and insulators on a bulk niobium has been proposed to shield niobium cavity surface from high magnetic field and hence increase the accelerating gradient. The study of the behavior of multilayer superconductors in an external magnetic field is essential to optimize their SRF performance. In this work we report the development of a simple and efficient technique to measure penetration of magnetic field into bulk, thin film and multilayer superconductors. Experimental setup contains a small superconducting solenoid which can produce a parallel surface magnetic field up to 0.5 T …
Improvised Centrifugal Spinning For The Production Of Polystyrene Microfibers From Waste Expanded Polystyrene Foam And Its Potential Application For Oil Adsorption, Marco Laurence M. Budlayan, Jonathan N. Patricio, Jeanne Phyre B. Lagare, Susan D. Arco, Arnold C. Alguno, Antonio M. Basilio, Felmer S. Latayada, Rey Y. Capangpangan
Improvised Centrifugal Spinning For The Production Of Polystyrene Microfibers From Waste Expanded Polystyrene Foam And Its Potential Application For Oil Adsorption, Marco Laurence M. Budlayan, Jonathan N. Patricio, Jeanne Phyre B. Lagare, Susan D. Arco, Arnold C. Alguno, Antonio M. Basilio, Felmer S. Latayada, Rey Y. Capangpangan
Physics Faculty Publications
A straightforward approach to recycle waste expanded polystyrene (EPS) foam to produce polystyrene (PS) microfibers using the improvised centrifugal spinning technique is demonstrated in this work. A typical benchtop centrifuge was improvised and used as a centrifugal spinning device. The obtained PS microfibers were characterized for their potential application for oil adsorption. Fourier transform infrared spectroscopy results revealed similarity on the transmission bands of EPS foam and PS microfibers suggesting the preservation of the EPS foam’s chemical composition after the centrifugal spinning process. Scanning electron microscopy displayed well-defined fibers with an average diameter of 3.14 ± 0.59 μm. At the …
Effect Of Random Pinning On Nonlinear Dynamics And Dissipation Of A Vortex Driven By A Strong Microwave Current, W.P.M.R. Pathirana, Alex Gurevich
Effect Of Random Pinning On Nonlinear Dynamics And Dissipation Of A Vortex Driven By A Strong Microwave Current, W.P.M.R. Pathirana, Alex Gurevich
Physics Faculty Publications
We report numerical simulations of a trapped elastic vortex driven by a strong ac magnetic field H(t)=Hsinωt parallel to the surface of a superconducting film. The surface resistance and the power dissipated by an oscillating vortex perpendicular to the film surface were calculated as functions of H and ω for different spatial distributions, densities, and strengths of pinning centers, including bulk pinning, surface pinning, and cluster pinning. Our simulations were performed for both the Bardeen-Stephen viscous vortex drag and the Larkin-Ovchinnikov (LO) drag coefficient η(v) decreasing with the vortex velocity v. The local residual surface resistance Ri(H) …
Development And Characterization Of Nb₃N/Al₂0₃ Superconducting Multilayers For Particle Accelerators, Chris Sundahl, Junki Makita, Paul B. Welander, Yi-Feng Su, Fumitake Kametani, Lin Xie, Huimin Zhang, Lian Li, Alex Gurevich, Chang-Beom Eom
Development And Characterization Of Nb₃N/Al₂0₃ Superconducting Multilayers For Particle Accelerators, Chris Sundahl, Junki Makita, Paul B. Welander, Yi-Feng Su, Fumitake Kametani, Lin Xie, Huimin Zhang, Lian Li, Alex Gurevich, Chang-Beom Eom
Physics Faculty Publications
Superconducting radio-frequency (SRF) resonator cavities provide extremely high quality factors > 1010 at 1-2 GHz and 2 K in large linear accelerators of high-energy particles. The maximum accelerating field of SRF cavities is limited by penetration of vortices into the superconductor. Present state-of-the-art Nb cavities can withstand up to 50 MV/m accelerating gradients and magnetic fields of 200-240 mT which destroy the low-dissipative Meissner state. Achieving higher accelerating gradients requires superconductors with higher thermodynamic critical fields, of which Nb3Sn has emerged as a leading material for the next generation accelerators. To overcome the problem of low vortex penetration …
One-Dimensional Lateral Force Anisotropy At The Atomic Scale In Sliding Single Molecules On A Surface, Yuan Zhang, Daniel J. Trainer, Badri Narayanan, Yang Li, Anh T. Ngo, Sushila Khadka, Arnab Neogi, Brandon Fisher, Larry A. Curtiss, Subramanian K.R.S. Sankaranarayanan, Saw Wai Hla
One-Dimensional Lateral Force Anisotropy At The Atomic Scale In Sliding Single Molecules On A Surface, Yuan Zhang, Daniel J. Trainer, Badri Narayanan, Yang Li, Anh T. Ngo, Sushila Khadka, Arnab Neogi, Brandon Fisher, Larry A. Curtiss, Subramanian K.R.S. Sankaranarayanan, Saw Wai Hla
Physics Faculty Publications
Using a q+ atomic force microscopy at low temperature, a sexiphenyl molecule is slid across an atomically flat Ag(111) surface along the direction parallel to its molecular axis and sideways to the axis. Despite identical contact area and underlying surface geometry, the lateral force required to move the molecule in the direction parallel to its molecular axis is found to be about half of that required to move it sideways. The origin of the lateral force anisotropy observed here is traced to the one-dimensional shape of the molecule, which is further confirmed by molecular dynamics simulations. We also demonstrate that …
Magnetic Field Sensors For Detection Of Trapped Flux In Superconducting Radio Frequency Cavities, Ishwari Prasad Parajuli, Gianluigi Ciovati, Jean R. Delayen
Magnetic Field Sensors For Detection Of Trapped Flux In Superconducting Radio Frequency Cavities, Ishwari Prasad Parajuli, Gianluigi Ciovati, Jean R. Delayen
Physics Faculty Publications
Superconducting radio frequency (SRF) cavities are fundamental building blocks of modern particle accelerators. They operate at liquid helium temperatures (2–4 K) to achieve very high quality factors (1010–1011). Trapping of magnetic flux within the superconductor is a significant contribution to the residual RF losses, which limit the achievable quality factor. Suitable diagnostic tools are in high demand to understand the mechanisms of flux trapping in technical superconductors, and the fundamental components of such diagnostic tools are magnetic field sensors. We have studied the performance of commercially available Hall probes, anisotropic magnetoresistive sensors, and flux-gate magnetometers with …
Flux Expulsion In Niobium Superconducting Radio-Frequency Cavities Of Different Purity And Essential Contributions To The Flux Sensitivity, P. Dhakal, Gianluigi Ciovati, Alex Gurevich
Flux Expulsion In Niobium Superconducting Radio-Frequency Cavities Of Different Purity And Essential Contributions To The Flux Sensitivity, P. Dhakal, Gianluigi Ciovati, Alex Gurevich
Physics Faculty Publications
Magnetic flux trapped during the cooldown of superconducting radio-frequency cavities through the transition temperature due to incomplete Meissner state is known to be a significant source of radio-frequency losses. The sensitivity of flux trapping depends on the distribution and the type of defects and impurities which pin vortices, as well as the cooldown dynamics when the cavity transitions from a normal to superconducting state. Here we present the results of measurements of the flux trapping sensitivity on 1.3 GHz elliptical cavities made from large-grain niobium with different purity for different cooldown dynamics and surface treatments. The results show that lower …
Electron Tunneling And X-Ray Photoelectron Spectoscopy Studies Of The Superconductiong Properties Of Nitrogen-Doped Niobium Resonator Cavities, Eric M. Lechner, Basu Dev Oli, Junki Makita, Gianluigi Ciovati, Alex Gurevich, Maria Iavarone
Electron Tunneling And X-Ray Photoelectron Spectoscopy Studies Of The Superconductiong Properties Of Nitrogen-Doped Niobium Resonator Cavities, Eric M. Lechner, Basu Dev Oli, Junki Makita, Gianluigi Ciovati, Alex Gurevich, Maria Iavarone
Physics Faculty Publications
We use scanning tunneling microscopy (STM) and spectroscopy (STS), and x-ray photoelectron spectroscopy (XPS) to investigate the effect of nitrogen doping on the surface electronic and chemical structures of cutouts from superconducting Nb radio-frequency cavities. The goal of this work is to get insights into the fundamental physics and materials mechanisms behind the striking decrease of the surface resistance with the radio-frequency magnetic field, which has been observed on N-doped Nb cavities. Our XPS measurements reveal significantly more oxidized Nb 3d states and a thinner metallic suboxide layer on the N-doped Nb surfaces, which is also confirmed by tunneling spectroscopy …
Superconductivity In La₂Ni₂In, Jannis Maiwald, Igor I. Mazin, Alex Gurevich, Meigan Aronson
Superconductivity In La₂Ni₂In, Jannis Maiwald, Igor I. Mazin, Alex Gurevich, Meigan Aronson
Physics Faculty Publications
We report here the properties of single crystals of La2Ni2In. Electrical resistivity and specific heat measurements concur with the results of density functional theory calculations, finding that La2Ni2In is a weakly correlated metal, where the Ni magnetism is almost completely quenched, leaving only a weak Stoner enhancement of the density of states. Superconductivity is observed at temperatures below 0.9 K. A detailed analysis of the field and temperature dependencies of the resistivity, magnetic susceptibility, and specific heat at the lowest temperatures reveals that La2Ni2In is a dirty type-II …
Recent Results From Nb₃Sn Single Cell Cavities Coated At Jefferson Lab, U. Pudasaini, M. J. Kelley, Gianluigi Ciovati, G.V. Eremeev, M. J. Kelley, C. E. Reece, Ishwari Prasad Parajuli, Md. Nizam Sayeed
Recent Results From Nb₃Sn Single Cell Cavities Coated At Jefferson Lab, U. Pudasaini, M. J. Kelley, Gianluigi Ciovati, G.V. Eremeev, M. J. Kelley, C. E. Reece, Ishwari Prasad Parajuli, Md. Nizam Sayeed
Physics Faculty Publications
Because of superior superconducting properties (Tc ~ 18.3K, Hs h~ 425 mT and Δ ~ 3.1 meV) compared to niobium, Nb₃Sn promise better RF performance (Q₀ and Eacc) and/or higher operating temperature (2 K Vs 4.2 K) for SRF cavities. Nb₃Sn-coated SRF cavities are produced routinely by depositing a few micron-thick Nb₃Sn films on the interior surface of Nb cavities via tin vapor diffusion technique. Early results from Nb₃Sn cavities coated with this technique exhibited precipitous low field Q-slope, also known as Wuppertal slope. Several Nb₃Sn single cell cavities coated at JLab appeared to exhibit …
Transient Transmission Oscillations In Doped And Undoped Lithium Niobate Induced By Near-Infrared Femtosecond Pulses, Bryan J. Crossman, Gregory J. Taft
Transient Transmission Oscillations In Doped And Undoped Lithium Niobate Induced By Near-Infrared Femtosecond Pulses, Bryan J. Crossman, Gregory J. Taft
Physics Faculty Publications
Transient transmission oscillations in X-cut and Z-cut congruent, iron-doped, and magnesium-doped lithium niobate samples were measured using 50 fs, 800 nm, 0.5 nJ pulses from a self-mode-locked Ti:sapphire laser in an optical pump–probe system. Several Raman-active oscillation modes excited by these pulses were observed as changes in the transmitted probe intensity versus time delay between the pump and probe pulses. The samples were rotated to determine how the incident polarization of the pump pulses affects the mode excitations. The observed Raman-active oscillations correspond to previously reported symmetry modes measured with traditional, continuous-wave, Raman spectroscopy using the same scattering …
Current-Driven Production Of Vortex-Antivortex Pairs In Planar Josephson Junction Arrays And Phase Cracks In Long-Range Order, Francisco Estellés-Duart, Miguel Ortuño, Andrés M. Somoza, Valerii M. Vinokur, Alex Gurevich
Current-Driven Production Of Vortex-Antivortex Pairs In Planar Josephson Junction Arrays And Phase Cracks In Long-Range Order, Francisco Estellés-Duart, Miguel Ortuño, Andrés M. Somoza, Valerii M. Vinokur, Alex Gurevich
Physics Faculty Publications
Proliferation of topological defects like vortices and dislocations plays a key role in the physics of systems with long-range order, particularly, superconductivity and superfluidity in thin films, plasticity of solids, and melting of atomic monolayers. Topological defects are characterized by their topological charge reflecting fundamental symmetries and conservation laws of the system. Conservation of topological charge manifests itself in extreme stability of static topological defects because destruction of a single defect requires overcoming a huge energy barrier proportional to the system size. However, the stability of driven topological defects remains largely unexplored. Here we address this issue and investigate numerically …
Probing The Wave Nature Of Light-Matter Interaction, D. E. Boone, C. H. Jackson, A. T. Swecker, J. S. Hergenrather, K. S. Wenger, O. Kokhan, Balša Terzić, I. Melnikov, I. N. Ivanov, E. C. Stevens, G. Scarel
Probing The Wave Nature Of Light-Matter Interaction, D. E. Boone, C. H. Jackson, A. T. Swecker, J. S. Hergenrather, K. S. Wenger, O. Kokhan, Balša Terzić, I. Melnikov, I. N. Ivanov, E. C. Stevens, G. Scarel
Physics Faculty Publications
The wave-particle duality of light is a controversial topic in modern physics. In this context, this work highlights the ability of the wave-nature of light on its own to account for the conservation of energy in light-matter interaction. Two simple fundamental properties of light as wave are involved: its period and its power P. The power P depends only on the amplitude of the wave’s electric and magnetic fields (Poynting’s vector), and can easily be measured with a power sensor for visible and infrared lasers. The advantage of such a wave-based approach is that it unveils unexpected effects of light’s …
Cryogenic Probe Station At Old Dominion University Center For Accelerator Science, Junki Makita, Jean R. Delayen, Alex Gurevich, Gianluigi Ciovati
Cryogenic Probe Station At Old Dominion University Center For Accelerator Science, Junki Makita, Jean R. Delayen, Alex Gurevich, Gianluigi Ciovati
Physics Faculty Publications
With a growing effort in research and development of an alternative material to bulk Nb for a superconducting radiofrequency (SRF) cavity, it is important to have a cost effective method to benchmark new materials of choice. At Old Dominion University's Center for Accelerator Science, a cryogenic probe station (CPS) will be used to measure the response of superconductor samples under RF fields. The setup consists of a closed-cycle refrigerator for cooling a sample wafer to a cryogenic temperature, a superconducting magnet providing a field parallel to the sample, and DC probes in addition to RF probes. The RF probes will …
Electromagnetic Design Of A Superconducting Twin Axis Cavity, S. U. De Silva, H. Park, J. R. Delayen, F. Marhauser, A. Hutton
Electromagnetic Design Of A Superconducting Twin Axis Cavity, S. U. De Silva, H. Park, J. R. Delayen, F. Marhauser, A. Hutton
Physics Faculty Publications
The twin-axis cavity is a new kind of rf superconducting cavity that consists of two parallel beam pipes, which can accelerate or decelerate two spatially separated beams in the same cavity. This configuration is particularly effective for high-current beams with low-energy electrons that will be used for bunched beam cooling of high-energy protons or ions. The new cavity geometry was designed to create a uniform accelerating or decelerating fields for both beams by utilizing a TM110 dipole mode. This paper presents the design rf optimization of a 1497 MHz twin-axis single-cell cavity, which is currently under fabrication.
Modeling Local Crabbing Dynamics In The Jleic Ion Collider Ring, Salvador Sosa Guitron, Vasiliy Morozov, Jean Delayen
Modeling Local Crabbing Dynamics In The Jleic Ion Collider Ring, Salvador Sosa Guitron, Vasiliy Morozov, Jean Delayen
Physics Faculty Publications
The Jefferson Lab Electron-Ion Collider (JLEIC) design considers a 50 mrad crossing angle at the Interaction Point. Without appropriate compensation, this could geometrically reduce the luminosity by an order of magnitude. A local crabbing scheme is implemented to avoid the luminosity loss: crab cavities are placed at both sides of the interaction region to restore a head-on collision scenario. In this contribution, we report on the implementation of a local crabbing scheme in the JLEIC ion ring. The effects of this correction scheme on the stability of proton bunches are analyzed using the particle tracking software elegant.
Trim Tuning Of Sps-Series Dqw Crab Cavity Prototypes, S. Verdú-Andrés, J. Skaritka, Q. Wu, A. Ratti, S. Baurac, C. H. Boulware, T. Grimm, J. Yancey, W. Clemens, E. A. Mcewen, H. Park
Trim Tuning Of Sps-Series Dqw Crab Cavity Prototypes, S. Verdú-Andrés, J. Skaritka, Q. Wu, A. Ratti, S. Baurac, C. H. Boulware, T. Grimm, J. Yancey, W. Clemens, E. A. Mcewen, H. Park
Physics Faculty Publications
The final steps in the manufacturing of a superconducting RF cavity involve careful tuning before the final welds to match the target frequency as fabrication tolerances may introduce some frequency deviations. The target frequency is chosen based on analysis of the shifts induced by remaining processing steps including acid etching and cool down. The baseline fabrication of a DQW crab cavity for the High Luminosity LHC (HL-LHC) envisages a first tuning before the cavity subassemblies are welded together. To produce a very accurate final result, subassemblies are trimmed to frequency in the last machining steps, using a clamped cavity assembly …
Wakefield Analysis Of Superconducting Rf-Dipole Cavities, Subashini De Silva, Jean Delayen
Wakefield Analysis Of Superconducting Rf-Dipole Cavities, Subashini De Silva, Jean Delayen
Physics Faculty Publications
RF-dipole crabbing cavities are being considered for a variety of crabbing applications. Some of the applications are the crabbing cavity systems for LHC High Luminosity Upgrade and the proposed Electron-Ion Collider for Jefferson Lab. The design requirements in the current applications require the cavities to incorporate complex damping schemes to suppress the higher order modes that may be excited by the high intensity proton or electron beams traversing through the cavities. The number of cavities required to achieve the desired high transverse voltage, and the complexity in the cavity geometries also contributes to the wakefields generated by beams. This paper …
Dynamic Transition Of Vortices Into Phase Slips And Generation Of Vortex-Antivortex Pairs In Thin Film Josephson Junctions Under Dc And Ac Currents, Ahmad Sheikhzada, Alex Gurevich
Dynamic Transition Of Vortices Into Phase Slips And Generation Of Vortex-Antivortex Pairs In Thin Film Josephson Junctions Under Dc And Ac Currents, Ahmad Sheikhzada, Alex Gurevich
Physics Faculty Publications
We present theoretical and numerical investigations of vortices driven by strong dc and ac currents in long Josephson junctions described by a nonlinear integro-differential equation which takes into account nonlocal electrodynamics of films, vortex bremsstrahlung, and Cherenkov radiation amplified by the attraction of vortices to the edges of the junction. This work focuses on the dynamics of vortices in Josephson junctions in thin films where the effects of Josephson nonlocality are essential but London screening is negligible. We obtained an exact solution for a vortex driven by an arbitrary time-dependent current in an overdamped junction where the vortex turns into …
Imaging Of Super-Fast Dynamics And Flow Instabilities Of Superconducting Vortices, L. Embon, Y. Anahory, Ž L. Jelić, E. O. Lachman, Y. Myasoedov, M. E. Huber, G. P. Mikitik, A. V. Silhanek, M. V. Milošević, A Gurevich, E. Z. Zeldov
Imaging Of Super-Fast Dynamics And Flow Instabilities Of Superconducting Vortices, L. Embon, Y. Anahory, Ž L. Jelić, E. O. Lachman, Y. Myasoedov, M. E. Huber, G. P. Mikitik, A. V. Silhanek, M. V. Milošević, A Gurevich, E. Z. Zeldov
Physics Faculty Publications
Quantized magnetic vortices driven by electric current determine key electromagnetic properties of superconductors. While the dynamic behavior of slow vortices has been thoroughly investigated, the physics of ultrafast vortices under strong currents remains largely unexplored. Here, we use a nanoscale scanning superconducting quantum interference device to image vortices penetrating into a superconducting Pb film at rates of tens of GHz and moving with velocities of up to tens of km/s, which are not only much larger than the speed of sound but also exceed the pair-breaking speed limit of superconducting condensate. These experiments reveal formation of mesoscopic vortex channels which …
Cryogenic Rf Test Of The First Srf Cavity Etched In An Rf Ar/Cl2 Plasma, J. Upadhyay, A. Palczewski, S. Popovic, A.-M. Valente-Feliciano, Do Im, H. L. Phillips, L. Vuskovic
Cryogenic Rf Test Of The First Srf Cavity Etched In An Rf Ar/Cl2 Plasma, J. Upadhyay, A. Palczewski, S. Popovic, A.-M. Valente-Feliciano, Do Im, H. L. Phillips, L. Vuskovic
Physics Faculty Publications
An apparatus and a method for etching of the inner surfaces of superconducting radio frequency (SRF) accelerator cavities are described. The apparatus is based on the reactive ion etching performed in an Ar/Cl2 cylindrical capacitive discharge with reversed asymmetry. To test the effect of the plasma etching on the cavity rf performance, a 1497 MHz single cell SRF cavity was used. The single cell cavity was mechanically polished and buffer chemically etched and then rf tested at cryogenic temperatures to provide a baseline characterization. The cavity's inner wall was then exposed to the capacitive discharge in a mixture of …
Bunch Splitting Simulations For The Jleic Ion Collider Ring, R. Gamage, T. Satogata
Bunch Splitting Simulations For The Jleic Ion Collider Ring, R. Gamage, T. Satogata
Physics Faculty Publications
We describe the bunch splitting strategies for the proposed JLEIC ion collider ring at Jefferson Lab. This complex requires an unprecedented 9:6832 bunch splitting, performed in several stages. We outline the problem and current results, optimized with ESME including general parameterization of 1:2 bunch splitting for JLEIC parameters.
Tio2-Based Nanomaterials For Advanced Environmental And Energy-Related Applications, Xujie Lü, Baoyu Xia, Yefeng Yang, Hao Tang
Tio2-Based Nanomaterials For Advanced Environmental And Energy-Related Applications, Xujie Lü, Baoyu Xia, Yefeng Yang, Hao Tang
Physics Faculty Publications
No abstract provided.
Analyses Of 476 Mhz And 952 Mhz Crab Cavities For Jlab Electron Ion Collider, Hyekyoung Park, A. Castilla, J. R. Delayen, S. U. De Silva, V. Morozov
Analyses Of 476 Mhz And 952 Mhz Crab Cavities For Jlab Electron Ion Collider, Hyekyoung Park, A. Castilla, J. R. Delayen, S. U. De Silva, V. Morozov
Physics Faculty Publications
Center for Accelerator Science at ODU has designed, fabricated and successfully tested a crab cavity for MEIC at Jefferson Lab*. This proof of principle cavity was based on the earlier MEIC design which used 748.5 MHz RF system. The updated MEIC design** utilizes the components from PEP-II. It results in the change on the bunch repetition rate of stored beam to 476.3 MHz. The ion ring collider will eventually require 952.6 MHz crab cavity. This paper will present the analyses of crab cavities of both 476 MHz and 952 MHz options. It compares advantages and disadvantages of the options which …
Measurements Of Rf Properties Of Thin Film Nb3Sn Superconducting Multilayers Using A Calorimetric Technique, S. Sosa-Guitron, A. Gurevich, J. Delayen, E. Chang Beom, C. Sundahl, G. V. Eremeev
Measurements Of Rf Properties Of Thin Film Nb3Sn Superconducting Multilayers Using A Calorimetric Technique, S. Sosa-Guitron, A. Gurevich, J. Delayen, E. Chang Beom, C. Sundahl, G. V. Eremeev
Physics Faculty Publications
Results of RF tests of NB3SN thin film samples related to the superconducting multilayer coating development are presented. We have investigated thin film samples of Nb3Sn/Al2O3/Nb with Nb3Sn layer thicknesses of 50 nm and 100 nm using a Surface Impedance Characterization system. These samples were measured in the temperature range 4 K-19 K, where significant screening by Nb3Sn layers was observed below 16-17 K, consistent with the bulk critical temperature of Nb3Sn.
Effects Of Plasma Processing On Secondary Electron Yield Of Niobium Samples, M. Basovic, S. Popovic, M. Tomovic, L. Vuskovic, A. Samolov, F. Cuckov
Effects Of Plasma Processing On Secondary Electron Yield Of Niobium Samples, M. Basovic, S. Popovic, M. Tomovic, L. Vuskovic, A. Samolov, F. Cuckov
Physics Faculty Publications
Impurities deposited on the surface of Nb during both the forming and welding of accelerator cavities add to the imperfections of the sheet metal, which then affects the overall performance of the cavities. This leads to a drop in the Q factor and limits the maximum acceleration gradient achievable per unit length of the cavities. The performance can be improved either by adjusting the fabrication and preparation parameters, or by mitigating the effects of fabrication and preparation techniques used. We have developed the experimental setup to determine Secondary Electron Yield (SEY) from the surface of Nb samples. Our aim is …