title: Enhanced localized energetic-ion losses resulting from single-pass interactions with Alfvén eigenmodes.
abstract: We report the first observation of prompt neutral beam-ion losses due to nonresonant scattering induced by toroidal and reversed shear Alfvén eigenmodes in the DIII-D tokamak. The coherent losses are of full energy beam ions expelled from the plasma on their first poloidal orbit. The first-orbit loss mechanism causes enhanced, concentrated losses on the first wall exceeding nominal levels of prompt losses. The loss amplitude scales linearly with the mode amplitude. The data provide a novel and direct measure of the radial excursion or scatter of particles induced by individual modes and may shed light on the mechanism for the scattering of energetic particles in interstellar medium.
authors: University of California-Irvine, Irvine, California 92697, USA. chenxi@fusion.gat.com
authors: X
authors: X
authors: Chen
authors: M E
authors: ME
authors: Austin
authors: R K
authors: RK
authors: Fisher
authors: W W
authors: WW
authors: Heidbrink
authors: G J
authors: GJ
authors: Kramer
authors: R
authors: R
authors: Nazikian
authors: D C
authors: DC
authors: Pace
authors: C C
authors: CC
authors: Petty
authors: M A
authors: MA
authors: Van Zeeland