Development and characterization of Nb3Sn/Al2O3 superconducting multilayers for particle accelerators.
Chris Sundahl1, Junki Makita2, Paul B Welander3
1Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA.
Scientific Reports
|April 9, 2021
Summary
Researchers developed novel niobium-tin (Nb3Sn) multilayers on aluminum oxide for next-generation particle accelerators. These advanced superconducting radio-frequency (SRF) cavities show promise for higher accelerating gradients, overcoming limitations of current niobium technology.
Area of Science:
- Materials Science
- Superconductivity
- Particle Accelerator Technology
Background:
- Superconducting radio-frequency (SRF) cavities are crucial for high-energy particle accelerators, offering high quality factors (>10^10) at 1-2 GHz and 2 K.
- The performance of current niobium (Nb) SRF cavities is limited by vortex penetration into the superconductor, restricting accelerating gradients to ~50 MV/m and magnetic fields to 200-240 mT.
- Niobium-tin (Nb3Sn) is a promising material for next-generation accelerators due to its higher thermodynamic critical fields, but suffers from low vortex penetration fields.
Purpose of the Study:
- To develop and characterize stoichiometric Nb3Sn/Al2O3 multilayers for SRF cavities.
- To overcome the intrinsic limitations of Nb3Sn by creating a multilayer structure with dielectric interlayers.
- To provide a materials platform for high-performance superconducting multilayers that can achieve higher accelerating gradients.
Main Methods:
- Developed an adsorption-controlled co-sputtering process for Nb3Sn/Al2O3 multilayers using high temperatures and high tin overpressure.
- Utilized cross-sectional scanning electron transmission microscopy to analyze the multilayer structure and interdiffusion.
- Performed low-field radio-frequency (RF) measurements to assess superconducting and RF properties at 4.2 K.
Main Results:
- Successfully grew stoichiometric Nb3Sn/Al2O3 multilayers with no observable interdiffusion between the Nb3Sn and Al2O3 layers.
- Achieved superconducting and RF properties comparable to cavity-grade niobium at 4.2 K.
- Demonstrated the potential of these multilayers to overcome the intrinsic limits of niobium cavity technology.
Conclusions:
- The developed Nb3Sn/Al2O3 multilayers offer a promising materials platform for advanced SRF cavities.
- This multilayer approach could enable higher accelerating gradients in future particle accelerators.
- Further optimization of these superconducting multilayers is expected to push the boundaries of accelerator performance.
