Turbulence in the Divertor Region of Tokamak Edge Plasma

Results of recent modeling of tokamak edge plasma with the turbulence code BOUT are presented. In previous studies with BOUT the background profiles of plasma density and temperature were set as flux surface functions. However in the divertor region of a tokamak the temperature is typically lower and density is higher than those at the mid-plane. To account for this in the present study a poloidal variation of background plasma density and temperature is included to provide a more realistic model. For poloidally uniform profiles of the background plasma the calculated turbulence amplitude peaks near outer mid-plane, while in the divertor region the amplitude is small. However, present simulations show that as the background plasma profiles become more poloidally non-uniform the amplitude of density fluctuations, (tilde n)i, starts peaking in the divertor. It is found that in the divertor region the amplitude of ni fluctuations grows approximately linearly with the local density of the background plasma, ni0, while the amplitude of Te and φ fluctuations is positively correlated with the local electron temperature, Te0. Correlation analysis shows that plasma turbulence is isolated by the x-points