Optimization of ICRF physics and technology for SPARC Q>1 mission

Ion Cyclotron Range of Frequencies (ICRF) heating is the sole auxiliary heating source for SPARC, essential for achieving high-performance scenarios and fusion energy gain. SPARC is a medium-sized high-field tokamak, with B0 = 12.2 T, ne0 ≈ 4 × 10^20 m^−3 and Te0 ≈ 20 keV. The 22 SPARC ICRF solid-state amplifiers deliver up to 2 MW each at 120 MHz to 14 4-strap antennas. In preparation for the first campaign, scenarios leading to Q>1 plasma are analysed. A feeding optimisation study addresses challenges of efficient power delivery to plasma with a limited number of transmitters per antenna in the first campaign, with suitable wave spectrum, and minimisation of fields leading to increased sputtering. Efficient power absorption is predicted in the 3He minority and 2nd harmonic T heating scenario, with power partitioning defined by the ICRF wave spectrum and plasma parameters. Modelling tools improvement and cross-validation, i.e. COMSOL, Stix and TORIC codes, ensures reliable physics predictions. Ongoing integrated modelling aims to couple ICRF core modelling, Fokker-Planck fast ion calculations and transport studies on the one side and ICRF edge models, transport and impurities on the other side. Initial ARC ICRF modelling identifies possible experiments in SPARC to prepare for ARC.