Influence of the Electric Field on Secondary Electron Emission Yield

Abstract

We present results of the investigation of secondary electron emission from spherical amorphous carbon grains of 3 to 6 micrometers in diameter affected by a high surface field. In our experiment, we have applied a technique based on levitation of a single charged grain in the quadrupole trap. This grain was charged by an electron beam with an energy tunable up to 10 keV. During this process, the grain charge is continuously monitored. If the grain is charged by an appropriate energetic electron beam, its charge (and the corresponding surface potential and surface electric field) is set to a value when the yield of secondary emission is equal to unity (crossover point). The investigations reveal that the energy corresponding to the crossover point changes proportionally to the grain potential. This effect was attributed to an increase of the yield of secondary emission due to a large electric field at the grain surface. Moreover, the measurement of the net current on the grain induced by electrons with the energy between first and second crossover points indicates similar increase of the yield.