Role sekundární emise v nabíjení prachových zrn

Student: Ivana Richterová
Školitel: Doc. RNDr. Zdeněk Němeček, DrSc.
Stav práce: obhájená

Small dust grains represent an initial material for building of all macroscopic objects in space. The grains are immersed in the interplanetary or interstelar plasma and thus they are charged. Since resulting electrostatic forces usually exceed the gravity and other forces, knowledge of the grain charge is principal for all estimations.

The dust grains gain/lose an electric charge by many processes. Among them, a group of different kinds of emissions can be distinguished. Mechanisms of these processes are more or less known for planar surfaces but the influence of a severe curvature of dust surface or grain size was never studied in a systematic way.

The ultra-high vacuum chamber equipped with an electrodynamic quadrupole allows us to trap a single dust grain and expose it to the electron and/or ion beam. Since the oscillation frequency of the dust grain is proportional to its specific charge, we can determine all basic characteristic of charging processes.

The study will be devoted to the measurements of equilibrium potentials of dust grains from different materials and to the interpretation of results in frame of present models. A development of a new model of the interaction of electrons with the grain material is expected.