Relation of the Spatial Profile of Ion Confining Potentials with the Improvement in Plasma Confinement Using Novel Ion-Energy Spectrometer Arrays in Gamma 10

Abstract

In tandem-mirror experiments, plasma-confining potentials produced by electron-cyclotron heatings (ECH) play one of the most critical roles in the improvement of simple-mirror plasma confinement. For the observations of spatially resolved ion spectrum distributions require ion-sensitive and reproducible rigid detector-array units from a practical viewpoint. These data are, in turn, physically of importance for plasma confinement investigations including potential effects on plasma confinement as well as transport analysis in relation to the potential profiles. From these motivations, the relation of spatial distributions of ion-confining potentials ɸc. and end-loss-ion fluxes IELA is investigated by the use of newly designed ion-energy-spectrometer arrays installed in both end regions of GAMMA 10. Axisymmetric profiles of ɸc are found to have a good correlation with axisymmetric plugging distributions in IELA. These are consistently interpreted in terms of the Pastukhov theory of the relation between ɸc and IELA. For these axisymmetric plasmas, particle-balance calculations show ignorable radial-loss-ion fluxes I⊥ as compared to IELA. This result (i.e. IELA>>I⊥ is consistent with the assumption of the Pastukhov theory in which the axial particle loss alone is taken into account.