11:30
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).