Speaker
Description
The SPARC tokamak, a high field (12 T), high current (8.7 MA) machine designed to achieve an energy gain Q of 11 in H-mode with DT fuel, is currently under assembly and will be expected to be in operation in 2027. As the expected heat-flux width for SPARC is in the range between 0.3 and 0.6 mm, the power exhaust is extremely difficult due to upstream steady-state parallel heat fluxes of about 10 GW/m2. As such, it is essential that power exhaust is optimized during operational planning with interpulse feedback on performance. The Boundary Digital Twin (BDT) is a novel toolchain that couples physics and engineering models to meet this challenge.
For reliable calculations of the power exhaust defining the operating window for SPARC, the required inputs for predictions can be provided by simulation workflows like SOLPS-NN or HEAT which provide the 2D radiation pattern or the parallel heat flux to the targets. In order to accommodate the requirements for interpulse timescales and for PFC integrity lifetime tracking, the specialised HEAT code is used.
In addition, a set of synthetic instrumentations (shunts, IR, TCs, bolometry) have been created for comparison with experimental measurements. These comparisons will help to identify incomplete or new physics details. An important aspect is the energy balance and 2D/3D energy distribution, which is essential for a correct assessment of PFC integrity and for the energy gain mission. To reliably perform this task in the challenging environment of SPARC, a synergy of IR and thermocouple measurements, two independent approaches for determining tile-resolved energy distribution loads and the global energy balance, is being implemented. For the complex 3D data visualization, a graphics render engine is used in addition to standard plotting libraries. We present the Boundary Digital Twin, the roadmap for development, and its planned application as an operational tool for SPARC.