Past Special Lecture

21 September 2004
Gian Luca Delzanno
The role of electron emission (either thermionic, secondary or photoelectric) in charging an object immersed in a plasma is investigated, both theoretically and numerically. In fact, recent work [1] has shown how electron emission can fundamentally affect the shielding potential around the object. In particular, depending on the physical parameters of the system (that were chosen such to correspond to common experimental conditions), the shielding potential can develop an attractive potential well. The conditions for the formation of the well will be reviewed, based on a theoretical model of electron emission from the grain. Furthermore, simulations will be presented regarding specific laboratory, space and astrophysical applications. [1] G.L. Delzanno, G. Lapenta, M. Rosenberg, Phys. Rev. Lett., 92, 035002 (2004).