Dependence of H− production upon the work function of a Mo surface in a cesiated hydrogen discharge

The photoelectric work function of a cesiated molybdenum converter surface in a cesiated hydrogen discharge and the negative-hydrogen-ion (H−) current produced at the surface were simultaneously measured. With the negative bias potential of the converter constant, the H− yield increased exponentially as the work function was decreased by introducing Cs into the discharge. The yield of H− current was always higher for a higher bias potential on the surface, provided the measured surface work function was nearly the same. When the concentration of Cs in a discharge was nearly constant, the bias potential of the surface at which the H− production became maximum was observed. At this bias potential, the surface work function was close to the work-function minimum.