Near midplane scintillator-based fast ion loss detector on DIII-D

Abstract

A new scintillator-based fast-ion loss detector (FILD) installed near the outer midplane of the plasma has been commissioned on DIII-D. This detector successfully measures coherent fast ion losses produced by fast-ion driven instabilities (500 kHz). Combined with the first FILD at ∼45° below the outer midplane [R. K. Fisher, Rev. Sci. Instrum. 81, 10D307 (2010)10.1063/1. 3490020], the two-detector system measures poloidal variation of losses. The phase space sensitivity of the new detector (gyroradius r L ∼ 1.5-8 cm and pitch angle α ∼ 35°-85°) is calibrated using neutral beam first orbit loss measurements. Since fast ion losses are localized poloidally, having two FILDs at different poloidal locations allows for the study of losses over a wider range of plasma shapes and types of loss orbits. © 2012 American Institute of Physics.