Design of a flexible divertor for the DTT facility

The standard Single Null Divertor (SND) configuration with tungsten monoblocks targets can face some difficulties in providing a solution scalable towards the realization of the fusion reactor based on H-mode tokamak configuration. To provide a safer solution the adoption of alternative divertor magnetic configurations (ADCs) or liquid metallic targets have been considered to mitigate the stationary heat load on targets. Additionally different plasma scenarios have been considered to avoid the huge transient energy release due to the type-I ELMs of the high confinement H-mode tokamak configuration.

The new high field superconducting divertor tokamak test facility (DTT) is presently in construction to specifically study power exhaust solutions in reactor relevant regimes. The first DTT divertor will be based on full tungsten monoblocks bonded on cooling tubes. To test and compare a wide set of different power exhaust solutions the divertor has been designed to be compatible with the standard SN configuration but also with some ADCs like the X divertor (XD) and the hybrid Super-X/long leg SN. Additionally as a solution to avoid ELMs the L-mode negative triangularity (NT) operation has been considered important to explore.

The DTT divertor shape has been optimized with the aim of the edge codes SOLEDGE2D and SOLPS in terms of closure, grazing angle and pumping capability for the standard SN configuration but with the ability to accept a family of different configurations (ADCs and NT) in a relatively optimized way.