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Full-Text Articles in Physics
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 …
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 …
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.
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 …
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 …