On electron backscattering from dust grains in fusion plasmas

Electron backscattering is identified as an important aspect of dust dynamics in fusion plasmas. Previously published experimental data on the backscattering of electrons with fusion relevant energies from solid targets are reviewed. Simple analytical expressions are proposed which, with a minimum number of parameters, can fit the experimental results with high accuracy. The contribution of electron backscattering to dust charging and heating is calculated. It is concluded that, especially for high-Z materials such as tungsten, electron backscattering leads to effective cooling of the grains, thus reducing the dust bulk temperature and enhancing dust lifetime and transport. (paper)