Field-emission from parabolic tips: current distributions, the net current and effective emission area

Field emission from nano-structured emitters primarily takes place from the tips. Using recent results on the variation of enhancement factor around the apex (Biswas et al, Ultramicroscopy 185, 1-4 (2018)), analytical expressions for surface distribution of net emitted electrons as well as the total and normal energy distributions are derived in terms of the apex radius $R_a$ and the local electric field at the apex $E_a$. Formulae for the net emitted current and effective emission area in terms of these quantities are also obtained.