Continuum-regime field charging in an electron swarm

Free electron field charging of particles in nonelectronegative gases was measured as a function of: (1) the applied electric field strength (from 0.25 to 4.82 kV/cm); (2) the particle radius (from 0.22 to 0.91 cm); (3) the charging current (from 1.5 to 80 mu A); and (4) the exposure time (from 1.0 to 4.0 ms, and also 5 s). The measured free-electron saturation charge values strongly support the hypothesis that electron field charging has the same saturation charge limit as ionic field charging. The electron field charging rate measurements support the following hypothesis. If the charge carrier number density is kept constant, the characteristic charging time ( tau ) is inversely proportional to the mobility of the carrier. If the charging current density is constant, then tau is independent of the mobility of the carrier (for the same E). The free electron particle charging results strongly suggest that ionic field charging theory adequately describes the field charging of particles by free electrons if the high mobility of the electrons is taken into account.< >