Thermal Barrier Formation and Plasma Confinement in the Axisymmetrized Tandem Mirror GAMMA 10

In the axisymmetrized tandem mirror GAMMA 10, thermal-barrier and plug potentials have been formed in the axisymmetric mirror cells at both ends and directly measured with Au neutral-beam probes and end-loss analyzers. Strong end-loss reduction associated with the potential formation results in enhancement of the axial particle confinement time 100 times over the mirror confinement time without plugging, in reasonable agreement with Pastukhov formula. An empirical scaling on nonambipolar radial ion confinement time in the axisymmetrized field configuration is presented.