Effect of natural surface roughness on electron emission from metal in electric field

The existence of electron emission at fields some hundreds of times smaller than expected theoretically for an ideal metal surface one explains by emission increase due to local field enhancement at the sharp metallic point protruding from cathode surface. This paper offers a new mechanism explaining anomalous field emission by effect of natural roughness of crystal face of metal surface with atomic sizes (10(-8)-10(-7) cm). It is shown that natural roughness with size about a few period of crystal lattice leads to production of emission sites where work function is significantly less than work function at a perfectly smooth surface. The Richardson-Dashman thermo-fleld emission theory with Schottky correction is used for the calculations of current density at the sites. The electrical field change is evoked by natural roughness of crystal face is taken into account. An estimate of emission current in term of emission sites is performed. Then density of emission sites on metal surface is computed by using the statistical theory. Total emission current is determined as current averaged over emission sites distribution on metal surface. It is shown that the thermo-field electron emission from such sites play most important role in total emission at average electric field strength on surface 10(5)-10(6)V/CM.