Cold emission of negative ions from the graphite with the rough surface

The negative ions fraction in the low field emission as function of cathode temperature, residual gas composition and pressure is analyzed. Simultaneous mass analysis of emitted negative ions and residual gas during cathode heating is carried out. The intensity of the emitted negative ions increases linearly with partial pressure of various gases in the range 10
^-5
-10
^-7
Torr. A simple model based on secondary negative ion emission of adsorbed atoms under positive ion bombardment of cathode is proposed.