Conveners
M1OrD - Focused Session: Superconducting Thin Films for SRF and Magnets Applications
- Lance Cooley (FNAL)
- Emanuela Barzi (FNAL)
Recent advances in the Nb technology have resulted in the development of superconducting radio-frequency (SRF) resonant cavities capable of producing accelerating fields up to 50 MV/m and achieving very high quality factors exceeding 1010 @ 1-2 GHz and 2K. At such strong RF fields, the density of screening currents flowing at the inner surface of the Nb cavities approaches the fundamental...
Several particle accelerators like the LHC at CERN use superconducting cavities to increase the energy of charged particles produced by sputter coating a thin niobium film on a copper substrate. Coating technologies used are diode and DC magnetron sputtering (dcMS). Compared to the bulk niobium technology the performance of such thin film cavities is limited by the field dependent RF residual...
MgB2 thin films grown by hybrid physical-chemical vapor deposition (HPCVD) have been investigated for SRF cavity applications. Clean MgB2 thin films have a low residual resistivity (<0.1 µΩcm) and a high Tc of 40 K, promising a low BCS surface resistance. Its thermodynamic critical field Hc is higher than Nb, potentially leading to a higher maximum accelerating filed. The lower critical field...
Bulk Niobium (Nb) SRF (superconducting radio frequency) cavities are currently the preferred method for acceleration of charged particles at accelerator facilities around the world. However, bulk Nb cavities suffer from variable RF performance, have high cost and impose material & design restrictions on other components of a particle accelerator. Since SRF phenomena occurs at surfaces within a...
A novel patented electro-chemical technique to produce Nb3Sn thin films was reproduced in US labs. The Nb3Sn phase is obtained in a two-electrode cell, by electrodeposition from aqueous solutions of Sn layers and Cu intermediate layers onto Nb substrates. Current densities are between 20 mA/cm2 and 50 mA/cm2, and bath temperature is between 40C and 50C. Subsequent thermal treatments in inert...
Theoretical interest has stimulated efforts to grow and characterize thin multi-layer superconductor/insulator/superconductor (SIS) structures for their potential capability of supporting otherwise inaccessible surface magnetic fields in SRF cavities. The technological challenges include realization of high quality superconductors with sharp, clean, transition to high quality dielectric...
