L-mode-edge negative triangularity tokamak (NTT) reactor

The negative triangularity tokamak (NTT) is a unique reactor concept based on 'power-handling-first' philosophy with the heat exhaust problem as the leading concern. The present paper exposes a reactor concept using L-mode edge based on NTT configuration, providing merits of no (or very weak) edge-localized modes, larger particle flux and large major radius for power handling. It is shown that a reasonably compact (R-p from 9 m to 7 m) NTT reactor is possible by achieving higher confinement improvement (H-H = 1.5) and/or by utilizing reasonably higher magnetic field (B-max = 15.5 T). Current physics basis and critical issues on its scientific and technical feasibility are discussed.