College of Sciences
PhD in Physics
Radio Frequency (RF) Cavities are used in particle accelerators and they are typically formed from or coated with superconducting materials. High purity niobium is the material of choice for SRF cavities and niobium cavities operate at their theoretical field limits. SRF researchers have begun a significant R&D effort to develop alternative materials to continue to keep up with the demands of new accelerator facilities. To achieve high performance with high accelerating gradient, cavity material should have an ability to persist in superconducting state under high magnetic field without magnetic flux penetration through the cavity wall. Therefore, the magnetic field at which first flux penetrates is a fundamental parameter to characterize superconducting materials for SRF cavities. This leads to investigate a simple, efficient, and accurate technique 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 first flux penetration through the superconducting sample. This setup can be used to study various promising alternative materials to niobium, especially SIS multilayer coatings on niobium that have been recently proposed to enhance the accelerating gradient by delaying the flux penetration into niobium surface.
SRF cavity, Niobium, Superconductivity, Magnetic field penetration, Thin films
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Senevirathne, Iresha Harshani and Delayen, Jean, "The Magnetic Field Penetration Measurement of Thin Film and Multilayered Superconductors for SRF Cavities" (2021). College of Sciences Posters. 17.