The field emission characteristics of electrochemically fabricated single-tip emitters was studied. It was found that high-pressure operation significantly enlarged the effective emission area and emission current density. This phenomenon contributed to the bombardment of ions generated by residual gas molecules interacting with emitted electrons. High pressure operation was suggested to be a method of activating LaB6 field emitters.

Field Emission Characteristics of LaB6 Single Tip Emitter. Qi, K.C., Lin, Z.L., Cao, G.C., Cheng, J.B., den Engelsen, D.: High Power Laser and Particle Beams, 2007, 19[3], 511-4