Edge transport and the low-to-high transition in tokamaks with D-shaped magnetic flux surfaces

This is the authors' abstract. We don't add key points for this paper.

Nonlinear, three-dimensional numerical simulations of finite-β drift-ballooning turbulence in the edge of tokamaks with D-shaped magnetic flux surfaces are presented. The simulations are based on the reduced Braginskii equations. The turbulent transport in tokamaks with D-shaped magnetic flux surfaces is directly compared to that in tokamaks with circular magnetic flux surfaces. The energy flux can be extremely different depending on the shape of the magnetic flux surfaces. While a tokamak with circular flux surfaces exhibits exceedingly poor confinement, an otherwise identical tokamak with D-shaped flux surfaces is in the high (H) mode where the transport rate is small. The magnitude of the energy flux in these two cases differs by a multiplicative factor larger than 1000.