Control of emission current from a Li W < 111 > field emitter by sequential deposition of Li

For a W < 111 > field electron emitter deposited with liquid Li, a field-st abilized cone of liquid Li is formed on the emitter tip and an electron bea m with several hundreds of microamperes is emitted from the cone apex. Howe ver, the emission current decreases gradually with time because of the evap oration of deposited Li and the lifetime is about an hour. In order to prol ong the lifetime, in this paper, we tried sequential deposition of Li whose amount corresponded to consumption by thermal evaporation. As a result, el ectron emission with a fluctuation of about 10% continued for more than 10 h. The critical pressure for stable electron emission was also investigated . An abrupt decrease of emission current was observed at the exposure of ab out 1 1 of dry air. The decrease is probably caused by the solidification o f the Liquid Li at the emitter surface. (C) 1999 Elsevier Science B.V. All rights reserved.