Field Emission and Vacuum Breakdown

A survey is given on the development of the surface of field emitters during the process of explosive emission. Solid cathodes have been compared to liquid cathodes. The surfaces have been probed by application of sequences of nanosecond voltage pulses with different polarity (the first pulse serving for excitation of the surface, the following for measuring the emission current). As a result it has been firmly established that maintenance of the emission process is due to formation of liquid micropoints by the electrostatic forces of the applied field.