2013 Volume 8 Pages 2401028
Secondary electron emission (SEE) from a spherical metallic dust particle by electron incidence was analyzed according to the OML (Orbit Motion Limited) model. As the observed dust speed in fusion plasmas (<100 m/s) is much slower than electron thermal speed, its effect to the SEE current is negligibly small. It is clarified that there is a window of electron temperature, where the ratio of the SEE current to the absorbed electron current exceeds unity; for graphite 80 eV < Te < 326 eV and the maximum of the ratio ∼1.10 at Te ∼ 165 eV, for tungsten 32 eV < Te, the maximum ∼2.47 at Te ∼358 eV. These excesses come from the inverse proportion of the incident angle to the dust particle.