Evaporated lithium surface coatings in NSTX

Modeling of plasma/lithium-surface interactions in NSTX: Status and key issues

We are studying lithium sputtering, evaporation, transport, material mixing, and surface evolution for the National Spherical Torus Experiment (NSTX) for various surfaces and plasma conditions. Lithium modeling is complex, particularly for NSTX short pulse, multiple material, variable plasma conditions. Cases examined include: (1) liquid lithium divertor (LLD) with planned high heating power/lo...

Varying the pre-discharge lithium wall coatings to alter the characteristics of the ELM-free H-mode pedestal in NSTX

LUDOX® Colloidal Silica in Coatings Lithium Polysilicate in Coatings

LUDOX® colloidal silicas are aqueous dispersions of very small silica particles in the low nanometer size range. Many grades are offered in this family, giving broad flexibility for specific performance targets. This bulletin aims to inform the formulator about the unique properties of LUDOX® colloidal silica and to offer starting points for applications such as anticorrosive coatings and archi...

Titanium monoxide ultra-thin coatings evaporated onto polycrystalline copper films

We evaporated polycrystalline copper thin films of thickness between 10 and 100nm on silicon substrates with their native oxide under ultra-high-vacuum conditions. Some of them were exposed to air for a period ranging from 1 day to 2 weeks. X-ray photoelectron spectroscopy (XPS) revealed a clean copper surface with a trace of oxygen. These films that were exposed to air presented oxides in the ...

Simulations of diffusive lithium evaporation onto the NSTX vessel walls

A model for simulating the diffusive evaporation of lithium into a helium filled NSTX vacuum vessel is described and validated against an initial set of deposition experiments. The DEGAS 2 based model consists of a three-dimensional representation of the vacuum vessel, the elastic scattering process, and a kinetic description of the evaporated atoms. Additional assumptions are required to accou...