Cathode Surface Morphology Effects on Field Emission: Vacuum Breakdown Creation of Field Emitters

The effect of stainless steel cathode surface morphology on field electronic emission in high vacuum (~10^-5 Pa) is studied. The surface rugosity is shown to affect the emission intensity; high-aspect ratio surface features lead to locally enhanced electric field, thereby increasing the field electronic emission. A breakdown in the vacuum, caused either by impact of charged dust particles or other impurities, or by overheating and vaporization of field emitters, can lead to cratering on the cathode surface. This cratering drastically changes the local surface rugosity, enhancing the local field and leads to greater emission intensity. Treatment of the cathode surface by glow discharge at higher pressure is known to reduce field emission by ionic bombardment and sputtering of emission sites; an image of such a glow-type discharge in the same apparatus used to study field emission is presented.