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

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 ɸ_c. and end-loss-ion fluxes I_ELA is investigated by the use of newly designed ion-energy-spectrometer arrays installed in both end regions of GAMMA 10. Axisymmetric profiles of ɸ_c are found to have a good correlation with axisymmetric plugging distributions in I_ELA. These are consistently interpreted in terms of the Pastukhov theory of the relation between ɸ_c and I_ELA. For these axisymmetric plasmas, particle-balance calculations show ignorable radial-loss-ion fluxes I_⊥ as compared to I_ELA. This result (i.e. I_ELA>>I_⊥ is consistent with the assumption of the Pastukhov theory in which the axial particle loss alone is taken into account.