Spatial profile measurements of ion-confining potentials using novel position-sensitive ion-energy spectrometer arrays

The first experimental demonstration of simultaneous measurements of temporally and spatially resolved ion-confining potentials φc and end-loss-ion fluxes IELA has been carried out during a single plasma discharge alone by the use of newly designed ion-energy-spectrometer arrays installed in both end regions of the GAMMA 10 tandem mirror. This position-sensitive ion-detector structure is proposed to obtain precise ion-energy spectra without any perturbations from simultaneously incident energetic electrons into the arrays. The relation between φc and IELA is physically interpreted in terms of Pastukhov’s potential confinement theory. In particular, the importance of axisymmetric φc formation is found for the plasma confinement.