Abstract
We believe that palladium has a potential of supplying hydrogen molecules to the apex of the needle electrode of a field-ionization-type proton beam source, because it has the highest hydrogen permeability among metals. With the intention of realizing palladium as a proton source, the hydrogen permeability of fine sharp palladium needles is experimentally measured. The fine sharp needle structure showed high hydrogen permeability such as in bulk palladium.
