AN INVESTIGATION ON SECONDARY EMISSION PROPERTIES OF IMPREGNATED BARIUM SCANDATE DISPENSER CATHODES

A scanning electron probe is used to study the secondary emission property of the impregnated barium scandate dispenser cathode, the influence of the activation on the secondary emission property, the secondary emission image and the secondary emission distribution over the surface of the cathode. At optimal activity, m =3.56, Epm= 700eV. The activation has larger effect on the when the activation temperature is higher than 1100℃. The distribution over the surface of the cathode is non-uniform. The half-peak width of the distribution curve over the surface is 0.4. The experimental phenomena are discussed in relation to the surface analysis of the cathode, Thbe theoretically derived binomial distribution curves over the surface are better fitted with the experminental results.