Transport of the plasma with neoclassical internal transport barrier on CHS

The plasma with neoclassical internal transport barrier (N-ITB) has been observed for electron cyclotron heated (ECH) plasma in the Compact Helical System Heliotron/Torsatron. The N-ITB is characterized by the peaked electron temperature, with a large temperature gradient (0.43 keV cm -1 ) and a large electric field shear at the barrier location. The transport analysis shows that the electron thermal conductivity in plasma with N-ITB is lower than that without N-ITB at the transport barrier. The neoclassical transport is calculated from the analytical model for the neoclassical particle flux. In the ECH plasma with N-ITB, the electron thermal conductivity χ e is at the level of the neoclassical χ e at the barrier transport which demonstrates that the anomalous transport is reduced to a level well below the neoclassical transport.