Alfv\'en Eigenmode Induced Fast Ion Transport in \mbox{DIII-D} Resulting From Finite Larmor Radius Effects

Alfv\'en Eigenmode (AE) induced fast-ion redistribution and loss are commonly observed in DIII-D. In those experiments the perpendicular wave vector times the fast-ion Larmor radius is of order unity ($k_\perp\rho_i\sim 1$), which allows fast ion orbits to traverse the AE mode structures asymmetrically causing a significant change in magnetic moment. Full-orbit simulations of the expected transport in DIII-D plasmas show that this effect can lead to fast-ion radial diffusion constants of 5~m$^2$/s at the measured mode amplitudes. This level of diffusion is not captured with a guiding center approximation and is in agreement with that deduced in DIII-D experiments when AE activity was present.