Coherent Beam-Ion Losses During Instabilities in \mbox{DIII-D}

A scintillator-based fast-ion loss detector (FILD) was installed on DIII D in 2010 [1] and successfully measured coherent losses produced by fast-ion driven instabilities. Loss signals at mode frequencies were observed for off-axis fishbones [2], toroidal Alfv\'en eigenmodes (TAEs) [3], reversed-shear AEs (RSAEs) [3], and energetic-particle driven geodesic acoustic modes. Modeling of the TAE and RSAE experiments indicate that the observed losses are predominately counter-passing ions that are scattered onto lost trapped-ion orbits by the AEs [4]. The original FILD detector is $\sim$45$^\circ$ below the midplane. For the 2011 campaign, a second FILD detector is installed at $\theta \approx 0^\circ$ and has already observed prompt losses. Observations of coherent losses from the pair of FILD detectors will be reported.\par \vskip6pt \noindent [1] R.K.~Fisher, et al., Rev.\ Sci.\ Instrum.\ {\bf 81} (2010) 10D307.\par \noindent [2] W.W.~Heidbrink, et al., Plasma Phys.\ Control.\ Fusion {\bf 53} (2011) 085028.\par \noindent [3] D.C.~Pace, et al., Plasma Phys.\ Control.\ Fusion {\bf 53} (2011) 062001.\par \noindent [4] M.A.~Van~Zeeland, et al., Phys.\ Plasmas {\bf 18} (2011) in press.