  In tokamak plasmas, the interaction among the micro-turbulence, zonal flows
(ZFs) and energetic particles (EPs) can affect the turbulence saturation level
and the consequent confinement quality and thus, is important for future
burning plasmas. In this work, the EP anisotropy effects on the ZF residual
level are studied by using anisotropic EP distributions with dependence of
pitch. Significant effects on the long wavelength ZFs have been found when
small to moderate width around the dominant pitch in the EP distribution
function is assumed. In addition, it is found that ZF residual level is
enhanced by barely passing/trapped and/or deeply trapped EPs, but it is
suppressed by well passing and/or intermediate trapped EPs. Numerical
calculation shows that for ASDEX Upgrade plasmas, typical EP distribution
functions can bring in -5%~+10% mitigation/enhancement in ZF residual level,
depending on the EP distribution functions.
