Multilayer ALD Films for SRF Cavities

The advancement of nuclear physics research relies on advances in accelerator performance, and much of that depends on improvements in superconducting radio frequency (SRF) cavities. While the operating gradients of niobium SRF cavities have increased from about 2 MV/m in the late 1970¿s to more than 40 MV/m today, they are approaching a theoretical limit near 50 MV/m, where the critical magnetic field for niobium is reached. Previous work has suggested a method of surpassing this limit by using multilayer¿s of superconductor-insulator-superconductor thin films. This project will produce single layer and multilayer NbN/Al2O3 films on niobium by atomic layer deposition. The SRF properties of these films will be evaluated by testing at Thomas Jefferson National Laboratory. Commercial Applications and other Benefits as described by the awardee: SRF cavities are used for many areas of nuclear physics and high energy physics research, as well as for medium and low energy particle accelerators, and free electron lasers. Cavities manufactured from alternate materials that support increased accelerating gradients would provide better performance, shorter linacs, and lower cost. Commercial markets for advanced accelerators include industrial processing, medical diagnostics, and pharmaceutical research.