THE DIII-D RADIATIVE DIVERTOR PROJECT, STATUS AND PLANS

New divertor hardware is being designed and fabricated for the Radiati ve Divertor modification of the DIII-D tokamak. The installation of th e hardware has been separated into two phases, the first phase startin g in October of 1996 and the second and final phase, in 1998. The phas ed approach enables the continuation of the divertor characterization research in the lower divertor while providing pumping for density con trol in high triangularity, single- or double-null advanced tokamak di scharges. When completed, the Radiative Divertor Project hardware will provide pumping at all four strike points of a double-null, high tria ngularity discharge and provide baffling of the neutral particles from transport back to the core plasma. By puffing neutral gas into the di vertor region, a reduction in the heat flux on the target plates will be demonstrated without a large rise in core density. This reduction i n heat flux is accomplished by dispersing the power with radiation in the divertor region. Experiments and modeling have formed the basis fo r the new design. The capability of the DIII-D cryogenic system is bei ng upgraded as part of this project. The increased capability of the c ryogenic system will allow delivery of liquid helium and nitrogen to t hree new cryopumps. Physics studies on the effects of slot width and l ength can be accomplished easily with the design of the Radiative Dive rtor. The slot width can be varied by installing graphite tiles of dif ferent geometry. The change in slot length, the distance from the X-po int to the target plate, requires relocating the structure vertically and can be completed in about 6-8 weeks. Radiative Divertor diagnostic s are being designed to provide comprehensive measurements for diagnos ing the divertor. Minimal modifications are required to diagnostics fo r the Phase 1 installation. More extensive diagnostic changes are plan ned for the Phase 2 installation. These Phase 2 diagnostics will be re quired to fully diagnose the high triangularity discharges in the dive rtor slots.