Divertor design and its integration into ITER

Abstract

The physics of the ITER edge and divertor plasma is strongly coupled with the divertor and the fuel cycle design. Owing to the limited space available the design as well as the remote maintenance approach for the ITER divertor are highly optimized to allow maximum space for the divertor plasma. Several auxiliary systems (e.g., in-vessel viewing instruments and glow discharge electrodes) as well as a part of the pumping and fuelling system have to be integrated together with the divertor into the lower level of ITER. Two main options exist for the choice of the plasma facing material in the divertor, i.e. tungsten and CFC. On the basis of already existing R&D results it is likely that the material choice will be mainly determined by physics considerations and material issues (e.g., C-T co-deposition). The requirements for the ITER fuel cycle arise from plasma physics as well as from the envisaged operation scenarios. Owing to the complex dynamic relationship of the fuel cycle subsystems among themselves and with the plasma, codes are employed for their optimization. These interacting issues are elaborated on the latest design status discussed.

Effect of conditions for gas recirculation on divertor operation in ITER

“…The ITER divertor consists of 54 modules (cassettes) [1] that are to be assembled remotely inside the vacuum vessel. For technical reasons the poloidal gaps between the cassettes cannot be sealed perfectly, and therefore unintended particle fluxes will occur between the divertor and the gas volume inside the cassette.…”

Advanced divertor concept design and analysis for HL-2M

“…An asymmetric divertor target geometry is proposed which is compatible with the configurations shown above. In the standard divertor configuration shown in figure 6 (a), the lower divertor target geometry with inner and outer vertical target plates and a dome baffle in the private flux region has been designed with minimized conductance for neutral particle leakage from the divertor region into the main chamber [13] , and with a 'V' shape similar to the ITER divertor, to further reduce the heat load [14,15] . The upper target plate is designed to suit the advanced divertor configurations shown in figure 1 (inverted) and figure 6 (b) and is therefore different from the lower target geometry.…”

The physics of the International Thermonuclear Experimental Reactor FEAT

“…The major features of the ITER divertor have been derived from experience in existing devices and include a closely baffled configuration with vertical targets, incorporating a V shape in the strike point region, and a high conductance between the inner and outer divertor legs. 36 It is designed to promote partial detachment in the vicinity of the strike points to minimize the peak heat flux, to permit neutrals to flow between the inner and outer legs to further reduce the heat flux at the outer strike point, and to produce a high neutral pressure to enhance helium exhaust. CFC is used as a plasma facing material in the high heat flux areas, while tungsten is used in other areas of the divertor and beryllium in the main chamber.…”