Modifying COGENT to Study Snowflake Divertors

The snowflake divertor concept entails modifying the poloidal field system of a tokamak to produce a 2nd-order null in magnetic-field strength in place of the conventional 1st-order null x point within the equilibrium magnetic-field separatrix. It more effectively spreads the divertor heat load and offers a number of other advantages. We describe plans to modify the COGENT edge kinetic code to study snowflake divertors. COGENT employs mapped multi-block grid technology to handle the geometric complexity of the conventional divertor configuration. To simulate snowflake divertors, the number of grid blocks is increased from 8 to 12, consistent with the modified topology of the exact snowflake configuration. We examine the applicability of the modified structure to study configurations that are not exactly snowflakes, the so-called ``snowflake-plus'' and ``snowflake-minus'' configurations. Initial applications of the modified code will be assessment of collisionless orbit dynamics and neoclassical transport.