  Gyrokinetic simulations conducted by Mazzi et al. reveal the suppression of
turbulence in fusion plasmas through the destabilization of Toroidal Alfv\'en
Eigenmodes (TAEs) by megaelectronvolt ions. Our analysis demonstrates that the
authors' numerical findings are strongly influenced by the selected simulation
settings, calling into question their claim that the resulting heat
conductivity aligns with the TRANSP power balance. Specifically, we assert that
the numerical results presented by Mazzi et al. are a direct consequence of the
inadequacy of resolution employed in their numerical simulations. Notably,
there are three primary factors contributing to this issue: (i) the employed
radial box size is insufficient, leading to an undesirable impact of the
boundary conditions on the simulations; (ii) the adoption of a higher minimum
toroidal mode number fails to accurately resolve the entire range of TAEs,
resulting in an underestimation of TAE drive and introducing spurious effects
on wave-particle resonances; (iii) an insufficient resolution in the magnetic
moment direction exacerbates these challenges. Upon addressing the
aforementioned numerical issues, a significant increase in heat conductivity
for each plasma species was observed by more than tenfold, diverging from the
expected values derived from the TRANSP power balance calculations.
Consequently, our results raise serious doubts on the authors' assertion of
enhanced performance in the presence of strongly unstable TAEs, emphasizing the
need for a reevaluation of their claims.
