10th International Workshop on Thin Films and New Ideas for Pushing the Limits of RF Superconductivity

Session

SRF Thin Film Characterization

Sep 21, 2022, 10:50 AM

CEBAF Center auditorium

Conveners

SRF Thin Film Characterization: 1

• Lorena Vega (CERN)

SRF Thin Film Characterization: 2

• Eric Lechner (Jefferson Lab)

SRF Thin Film Characterization: 3

• Tsuyoshi Tajima (Los Alamos National Laboratory)

SRF Thin Film Characterization: 4

• Claire Antoine (CEA)

32. Advanced characterization of SRF samples

Sebastian Keckert (Helmholtz-Zentrum Berlin)

9/21/22, 10:50 AM

SRF Thin Films Characterization: Cryogenic & RF measurements

Measuring the surface resistance of samples is key for identifying and optimizing suitable materials and coated structures for SRF cavities with performances beyond the limits of niobium. The Helmholtz-Zentrum Berlin (HZB) routinely operates a Quadrupole Resonator (QPR) for the characterization of SRF samples. Over the past years, the setup has been continuously improved and now allows...

33. Optimization of Quadrupole Resonator geometry at JLab

SARRA BIRA

9/21/22, 11:20 AM

SRF Thin Films Characterization: Cryogenic & RF measurements

Nowadays, the most used superconducting cavities are generally made of bulk Niobium. The high quality of today’s processes uses an accelerating gradient very close to Niobium limit. New materials such as Nb3Sn, NbN and MgB2 that have higher critical temperature and magnetic field must be investigated to improve acceleration capabilities. As these materials could only be used as thin films, the...

17. RF Characterisation of Bulk Niobium and Thin Film Coated Samples at 7.8 GHz

Daniel Seal (Cockcroft Institute, Lancaster University (Remote))

9/21/22, 11:50 AM

SRF Thin Films Characterization: Cryogenic & RF measurements

A cost-effective facility for testing planar thin film samples under RF conditions has recently been commissioned at Daresbury Laboratory. This facility utilises a bulk Nb choked test cavity operating at 7.8 GHz, housed within a dry, liquid helium free cryostat. It is used to make low power surface resistance measurements of 10 cm diameter samples at temperatures down to 4 K and sample surface...

9. Temperature Mapping of Niobium-coated 1.3 GHz Copper Cavities

Antonio Bianchi (CERN)

9/22/22, 9:00 AM

SRF Thin Films Characterization: Cryogenic & RF measurements

CERN has pioneered development of thin film superconducting radio-frequency cavities for particle accelerators. This technology has been applied in LEP II, LHC and more recently in HIE-ISOLDE. Many efforts are put in place at CERN in view of its potential implementation in the FCC machines. However, niobium thin film cavities historically feature a progressive degradation of performance by...

27. SPLIT SRF THIN FILM 6 GHZ CAVITIES

Taaj Sian (Lancaster University (Remote))

9/22/22, 9:30 AM

SRF Thin Films Characterization: Materials, Surfaces & Structures

Many current accelerators use cavities that are manufactured as two half cells that are electron beam welded together, the weld is across the peak surface current of the cavity. This weld can lead to large increases in surface resistance and limit the performance of thin film coated cavities. Many problems with the coating process for thin film Superconducting Radio Frequency (SRF) cavities...

10. Stress-induced omega (ω) phase transition in Nb thin films

Jaeyel Lee (Fermilab)

9/22/22, 10:00 AM

SRF Thin Films Characterization: Materials, Surfaces & Structures

We analyzed omega (ω) phase transition in Nb thin film deposited by high power impulse magnetron sputtering (HiPIMS) using transmission electron microscopy (TEM) [1]. ~170 nm Nb thin film is deposited on Si (100) substrate and it showed a typical columnar structure with (110) texture on the surface. TEM analysis revealed that the Nb thin films contain ~1 vol.% of hexagonal structured omega...

20. A DC magnetic field penetration facility for the characterisation of planar multilayer structures for superconducting radiofrequency applications

Daniel Turner (Lancaster University/Cockcroft Institute (Remote))

9/22/22, 10:50 AM

SRF Thin Films Characterization: Cryogenic & RF measurements

The material of choice for current SRF accelerators is bulk Nb which is reaching the theoretical limits in terms of maximum accelerating gradient, Eacc. One method to increase Eacc is to use superconductor-insulator-superconductor, SIS, structures, where the thin films on the surface are smaller than the London penetration depth to screen the applied field, Bapp, such that the thicker...

35. Development 3rd Harmonic Magnetometer at Jefferson Lab

David Beverstock (Jefferson Lab)

9/22/22, 11:20 AM

The development of specialized materials is required to surpass the material limits of bulk Nb superconducting radio frequency (SRF) cavities. Indeed, SRF is a surface phenomenon in superconducting materials with an RF penetration depth of hundreds of nanometers. At these thicknesses, thin films can be tuned to achieve specific superconducting and RF properties. Layering thin films provide...

7. DC MAGNETIC HALL PROBE TECHNIQUE TO CHARACTERIZE THE MATERIALS FOR ACCELERATING CAVITIES

Harshani Senevirathne (Old Dominion University)

9/22/22, 11:50 AM

SRF Thin Films Characterization: Cryogenic & RF measurements

The maximum accelerating gradient of niobium radio frequency cavities are currently reaching their theoretical limits. It can be enhanced by increasing the cavity’s peak surface magnetic field at which the magnetic field penetrating into the superconductor in the form of vortices. To delay the penetrating of vortices into the bulk Nb, SIS structure which is superconductor (S) and insulator (I)...

29. Experimental evidence for counter current flow in superconductor-superconductor bilayers

Md Asaduzzaman (University of Victoria, BC, Canada)

9/22/22, 1:55 PM

Beyond Nb: Alternate materials and mulilayer structures

We report evidence for counter current flow in superconductor-superconductor (SS) bilayers from depth-resolved measurements of their Meissner screening profiles using the low energy muon spin rotation (LE-$\mu$SR) technique. In these experiments, the implantation depth of the muons can be tuned/adjusted/controlled between $\sim 10$ nm and $\sim 150$ nm, below the surface, wherein their...

46. STM for SRF Thin Films

Prof. Maria Iavarone (Temple University (Remote))

9/22/22, 2:25 PM

44. SRF Thin Films: Characterization: Discussion

9/22/22, 3:10 PM