The Divertor Tokamak Test Facility (DTT), currently under construction in Frascati, is an experimental device aimed at investigating and validating advanced power exhaust solutions for magnetic confinement fusion reactors. In full power operational configuration (I=5.5 MA, Bt=5.85 T, R=2.1 m, a=0.7 m, Paux=45 MW), DTT will require a set of advanced cryogenic pellet injection systems to address multiple and complementary plasma control needs, including plasma fueling, Edge-Localized Mode (ELM) pacing, and disruption mitigation through high-speed/low-speed and shattered pellet injection from low and high field side direction. For each of these systems, hydrogen isotopes pure or mixed with impurity species (e.g. neon and argon) will be solidified at cryogenic temperatures into cylindrical pellets and injected into the plasma at velocities of the order of hundreds of m/s, depending on the application.
This work presents an overview of the pellet injection systems foreseen for DTT, outlining the available technologies, injection schemes and associated technological issues.  
Preliminary implementation concepts for the various systems are described, including injector layouts, guide tube routing, and machine interfaces. The proposed allocations and design choices take into account relevant results and recommendations from previous studies and experimental activities jointly carried out at Oak Ridge National Laboratory (ORNL), using an existing ENEA/ORNL facility. These results provide valuable insights into system performance and support the validation of the proposed design solutions for the DTT pellet injection systems.
 

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