Plasma-confinement physics study in compact helical system

In a CHS experiment, various types of transport barrier have been studied. An internal transport barrier (ITB) for electrons in a stellarator was first found in CHS, and the ITB for improved ion confinement was also found. H-mode (edge transport barrier) study in CHS showed many common features in transition to tokamak experiments, although the magnetic surface quantities are very different. Discharges with a combination of ETB and ITB were also found. Two heavy ion beam diagnostics in CHS showed a new direct measurement of zonal flow structure in toroidal confinement. The relation between the fluctuation and the transport barrier was also studied.