Overview of the divertor design and its integration into RTO/RC-ITER

The design of the divertor and its integration into the reduced technical o bjectives/reduced cost-international thermonuclear energy reactor (RTO/RC-I TER) is based on the experience gained from the 1998 design of internationa l thermonuclear energy reactor (ITER) and on the research and development p erformed throughout the engineering design activities (EDA). This paper giv es an overview of the layout and functional design of the RTO/RC-ITER diver tor, including the integration into the machine and the remote replacement of the divertor cassettes. Design guidelines are presented which have allow ed quick preparation of divertor layouts suitable for further study using t he B2-EIRENE edge plasma code. As in the 1998 design, the divertor is segme nted into cassettes, and the segmentation, which is three per sector, is dr iven by access through the divertor level ports. Maintaining this access an d avoiding interference with poloidal field coils means that the divertor l evel ports need to be inclined (7 degrees). This opens up the possibility o f incorporating inboard and outboard baffles into the divertor cassettes. T he cassettes are transported in-vessel by making use of the toroidal rails onto which the cassettes are finally clamped in position. Significant reduc tion of the space available between the X-point and the vacuum vessel resul ts in re-positioning of the toroidal rails in order to retain sufficient de pth for the inner and outer divertor legs. This, in turn, requires some cha nges to the remote handling (RH) concept. Remote handling (RH) is now based on using a cantilevered articulated gripper during the radial movement of the cassettes inside the RH ports. However, the principle to use a cassette toroidal mover (CTM) for in vessel handling is unchanged, hence maintainin g the validity of previous EDA research and development. The space previous ly left below the cassettes for RH was also used for pumping. Elimination o f this space has led to re-siting of the pumping channel between the plasma facing components (PFC) and the cassette body (P. Ladd, C. Ibbott, G. Jane schitz, E. Martin, Design of the RTO/RC-ITER primary pumping system, this c onference). This gives a somewhat better conductance from the private flux region to the pumping ports than in the previous design. Diagnostic access in the divertor now also uses the cut-outs provided for pumping instead of the space below the cassettes. Developments, in particular in the area of t he PFCs, aimed at reducing the cost of the divertor are reported in C. Ibbo tt, A. Antipenkov, S. Chiocchio, G. Federici, H. Heidl, G. Janeschitz, E. M artin, R. Tivey, Design issues and cost implications of RTO/RC-ITER diverto r, this conference. (C) 2000 Elsevier Science B.V. All rights reserved.