Sputtered Au-Ta films with tunable electrical resistivity

Gold-tantalum alloy films are attractive for hohlraums used in indirect drive magnetized inertial confinement fusion. A high electrical resistivity of over similar to 100 mu omega cm at cryogenic temperatures is an essential requirement for allowing an externally imposed pulsed magnetic field to soak through a hohlraum and magnetize the fusion fuel. Here, we systematically study properties of Au-Ta alloy films in the entire compositional range from pure Au to pure Ta with thicknesses up to 30 mu m. These films are made by direct current magnetron co-sputtering on planar substrates. Films are characterized by a combination of high-energy ion scattering, x-ray diffraction, electron microscopy, nanoindentation, and electrical transport measurements. Results show that an alloy with similar to 80 at.% of Ta forms a metallic glass exhibiting a maximum electrical resistivity of similar to 300 mu omega cm with a weak temperature dependence in the range of 5-400 K. The deposition of a film with similar to 80 at.% of Ta onto a sphero-cylindrical substrate for hohlraum fabrication is also demonstrated.

Automated summary

Gold-tantalum alloy films are promising for use in magnetized inertial confinement fusion. Through systematic study, an alloy with around 80% tantalum was found to form a metallic glass exhibiting high electrical resistivity at low temperatures, making it suitable for applications requiring pulsed magnetic fields.