Diagnostics for characterization of neutral beams parameters at TCV

Abstract Injection of high-energy neutral beams (NBIs) of hydrogen isotopes is a well-established method for plasma heating, current drive, and diagnosis of magnetic confinement fusion devices, including tokamaks, stellarators and open systems. NBI diagnostics provide essential information for operation, protection, characterization, and optimization of neutral beams, both on test facilities and during plasma experiments. The TCV tokamak is equipped with three neutral beam injectors (NBIs) — two for heating and one for plasma diagnostics — all designed, manufactured, and commissioned by the Budker Institute (Novosibirsk, Russia). Several diagnostic systems have been developed and implemented by the TCV team for in-situ optimization and characterization of these neutral beams. Calorimetry, thermography, and spectroscopy are used to determine beam profiles and velocity distributions, which are crucial for minimizing beam losses before injection into the tokamak vessel and to accurately calculate beam deposition profiles in plasma.