Langmuir probes at high frequencies in a magnetized plasma: a theoretical and experimental study

Since the early days of plasma physics, Langmuir probes are used as a standard instrument to diagnose plasma density, electron temperature and floating potential. In the presence of a strong magnetic field, the shape of the current-voltage characteristic is determined by the extent to which the current can spread in the direction perpendicular to the flux tube, and by the geometry of the magnetic and electrostatic sheath. In this dissertation, it is both experimentally and in numerical simulations shown for the first time that additional, capacitive components of the Langmuir current flow, which shed a new light onto the properties of both the flux tube and the sheath. (orig.)