Scandium oxide coated polycrystalline tungsten studied using emission microscopy and photoelectron spectroscopy

Thermionic electron emission from 200 to 500 nm thick coatings of scandium oxide on tungsten foil have been examined in thermionic emission microscopy, spectroscopic photoelectron microcopy, synchrotron radiation and ultraviolet photoelectron spectroscopy (UPS). A clear dependence of the scandium oxide-W electron yield on the grain orientation of the polycrystalline tungsten is observed in thermionic emission and photoelectron emission.

► Polycrystalline tungsten imaged with spectroscopic thermionic emission microcopy.
► Scandium oxide coated tungsten grains observed during thermionic emission.
► Direct visualization of the surface electron yield due to oxide coatings.
► Findings related to thermionic cathodes.