抄録
High temperature field emission pattern of various nickel sleeve materials used for oxide-coated cathode are observed with a Muller type electron microscope and the effect of reducing impurities in the material, migration effect of magnesium in particular, on the emission is studied.
The patterns observed on crystal faces of pure Ni and Si-W-Ni are stable but those of Mg-Ni and Mg-W-Ni are found very unstable. This unstableness originates from (010) face with Mg-Ni, from (100) face with Mg-W-Ni, and the more the Mg content, the more the unstableness; it varies also with the face. Migration of Mg seems therefore to have an intimate relation with the unstableness of field emission pattern.
