infrared millimeter terahertz waves scientific conferences

Sub-cycle cold-field electron emission is demonstrated using field enhancement of an intense THz pulse at the apex of a polycrystalline tungsten nanotip. Simultaneous and quantitative measurement of the electron bunch charge and energy distribution provide a means to test Fowler-Nordheim emission theory under extreme field conditions. Very high bunch charges (>106 electrons/pulse) are observed at energies > 3 keV. A significant THz field-induced sharpening of the nanotip is also observed, from 125 nm to 35 nm radius.