Design and initial measurements from the Shape and Volume Rise Divertor in DIII-D

A new divertor has been designed and installed in the DIII-D tokamak to enable pumping for plasma shapes with high elongation (k~1.9) and upper triangularity (d~0.9), which is predicted to enable access to very high confinement "Super-H" modes. A semi-analytic pumping model for attached target plasmas was used to optimize the pump duct geometry. New pump duct baffling tiles are mounted on copper pedestals that are connected to the cooled vessel wall, precluding the need for new cooled structures to be installed in-vessel. This enables rapid installation and allows flexibility for iterative divertor installations, but requires innovative baffling solutions to prevent neutral gas leakage between tiles. Calculations predict as much as 10^18 atoms per second of copper contamination in the main chamber due to energetic neutrals sputtering unshielded copper, which informed the addition of protective coverage of copper surfaces with line of sight to the plasma. Initial measurements and analysis from Langmuir probes and neutral pressure gauges are presented.