Analysis of current voltage characteristics for Langmuir probes immersed in an ion beam

Movable electrical probes were used to diagnose the beam flux profile and potential of ion beams since the early 60s. Experimental measurements of beam plasmas can provide essential data related to the space charge neutralisation, but the current voltage characteristics obtained from such electrical probes is dominated by beam-ion impact and ion-induced secondary emission. In this work we present an analysis of the Langmuir chracteristics obtained in a negative ion beam. We identify and discuss separately the contributions to the collected current given by secondary-plasma ions and electrons, by stripped electrons, beam ions and ioninduced secondary electron emission. We present the beam-plasma parameters obtained at different beam energies in NIO1.