  Metal anodes in high power source (HPS) devices erode during operation due to
hydrogen outgassing and plasma formation, both of which are thermally driven
phenomena generated by the electron beam impacting the anode s surface. This
limits the lowest achievable pressure in an HPS device, which reduces its
efficiency. Laser surface melting the 304 stainless steel anodes by a
continuous wave fiber laser showed a reduction in hydrogen outgassing by a
factor of ~4 under 50 keV electron bombardment, compared to that from untreated
stainless steel. This is attributed to an increase in the grain size (from 40 -
3516 micrometer2), which effectively reduces the number of characterized grain
boundaries that serve as hydrogen trapping sites, making such laser treated
metals excellent candidates for use in vacuum electronics.
