Electron Dynamics in the near Wake of a Conducting Body

The temporal behavior of the near wake of an electrically floating disc is studied experimentally using a pulsed plasma stream. The time evolution of the electron and ion current density profiles, reveal the presence of electron and ion streams within one body radius downstream of the disc during the early stage of the wake formation process. The trajectory of the electron streams depends on the body potential and is found to be more complicated than that of the ions. Since the ions appear inside the wake at an earlier time than the electrons, the electron streams may be associated with the space charge of the ions which are attracted into the near wake by the highly negative body potential.