Spectral Emissivity and Electron Emission Constants of Thoria Cathodes

A method is described for forming cathodes by means of a cataphoresis process wherein a thin layer of thoria is deposited over an underlying metal. A temperature scale determination yields for the relation between true temperature (°K) and brightness temperature (°C) at λ = 0.65 micron: T_t = 1.172T_b + 177.5. Electron emission studies yield for the constants of the Richardson equations: $$\begin{array}{c}\text{A=2.63\hspace{0.17em}}\mathrm{amp.}/{\mathrm{cm}}^2/{\mathrm{deg.}}^2\text{;\hspace{0.17em}Φ=2.67\hspace{0.17em}}\mathrm{volts\; for\; d.c.\; emission},\\ \text{A=5.62\hspace{0.17em}}\mathrm{amp.}/{\mathrm{cm}}^2/{\mathrm{deg.}}^2\text{;\hspace{0.17em}Φ=2.55\hspace{0.17em}}\mathrm{volts\; for\; pulsed\; emission}.\end{array}$$ Information was also obtained regarding the resistivity of thoria at high temperatures.