High-Density Plasma Production in the GAMMA 10 Central Cell with ICRF Heating on Both Anchor Cells

In the GAMMA 10 tandem mirror, divertor simulation experiments that utilize particle flux toward the west end region (called end-loss flux) have been implemented. Since a positive correlation has been reported between the end-loss flux and the central-cell density, an increase of the central-cell density is important for obtaining a higher end-loss flux on the divertor simulation experiments. By arranging the ion cyclotron range of frequency (ICRF) systems so as to excite strong ICRF waves in both anchor cells simultaneously, we have succeeded in producing high-density plasmas (line density of 1.2×10¹⁴ cm⁻²) in both anchor cells. As a result, a higher central-cell density of 4.4×10¹² cm⁻³ and a higher end-loss flux of more than 10²³ m⁻²s⁻¹ have been obtained. One of the possible mechanisms of the high density production is a formation of positive potentials on both anchor cells. Plasmas in the central cell are confined due to those potentials.