Engineering topics

Valente-Feliciano, A.-M.

Publications and source records attributed to Valente-Feliciano, A.-M..

3 records

DOE OSTI2023

INVESTIGATION OF THE MULTILAYER SHIELDING EFFECT THROUGH NbTiN-AlN COATED BULK NIOBIUM

Superconducting radio frequency (SRF) cavities, composed of bulk niobium (Nb), are extensively utilized in particle accelerators. To optimize their performance and extend their operational range, thin films of superconducting materials are applied to the Nb surfaces. This study focuses on investigating the magnetic field penetration characteristics of NbTiN-AlN coating on bulk niobium. The experimental setup involves measuring the magnetic field penetration across flat superconducting samples at cryogenic temperatures. One key parameter of interest is the field just before the first flux penetration, Bp which enables the observation of the multilayer shielding effect on bulk niobium under high magnetic fields. The study reveals a significant enhancement in Bp of the NbTiN-AlN coated Nb samples compared to bare Nb samples. This property holds critical importance for achieving high field performance in SRF cavities. Furthermore, the study explores the relationship between coating thickness and Bp corroborating the theoretical predictions.

Senevirathne, I. H.↗

DOE OSTI2023

SRF Thin Films: Not just for Cavities

Recent years have seen renewed interest and activities in developing SRF cavity materials based on thin film technologies. In this framework, considerable progress has been achieved in the development of high quality films and layered structures along with associated deposition techniques such as ECR, HiPIMS, and ALD. Beyond cavity applications, the developments in SRF thin film technologies find a variety of applications in the fields of superconducting metamaterials, electronics, sensors and quantum devices. High quality Nb films with high RRR open the way for enhanced coherence times for quantum qbits. Other SRF thin films such as NbTiN are developed for superconducting backend processes for future generations of computing hardware and radiation-hard sensors for nuclear and high-energy physics. The unifying theme across these technologies is that the same physics and material properties such as extreme low loss, stability, and manufacturability are required. This talk will present an overview of the emerging applications of SRF films and structures beyond accelerator cavities.

Valente-Feliciano, A.-M.↗

DOE OSTI2022

Magnetic Field Penetration Technique to Study High Field Shielding of Multilayered Superconductors

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 super-conductors 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 and Hall probes to detect penetrated magnetic field across the superconducting sample. This system was calibrated and used to study the effect of niobium sample thickness on the field of full magnetic flux penetration. We determined the optimum thickness of the niobium substrate to fabricate the multilayer structure for the measurements in our setup. This technique was used to measure penetration fields of Nb₃Sn thin films and Nb₃Sn/Al₂O₃ multi-layers deposited on Al₂O₃ wafers.

Senevirathne, I. H.↗