On Radial Electric Field Structure in CHS Torsatron/Heliotron

The radial electric field structure in helical system is discussed taking into account the effects of the orbit loss and charge exchange loss in addition to the neoclassical fluxes. Analysis is made for the CHS torsatron/heliotron, in which the radial electric field Er was estimated experimentally. It was found that the fast ion orbit loss and charge exchange loss have strong influence on the profile of the radial electric field, particularly near the plasma periphery. The absolute value of Er in the experiments is still more negative than the theoretical prediction.