Dust particles (glass, tungsten, and nickel) with sizes ranging from 0.25 to 3μm were levitated in a Paul-trap and charged by ions or electrons. For ions the particle potential is limited at field strength of about 1×109 V m-1 by a temperature-dependent discharge mechanism. The particles interaction with 2 to 20 keV electrons always leads to positive surface potentials which can be explained in terms of a decreased absorption of electrons by small particles. Micrometer sized agglomerates were used for the investigation of the electrostatic fragmentation. Fragmentation takes place in a twofold manner: small surface ‘flufl’ can be removed or the parent particle can be disrupted into smaller agglomerates.