Evaluation of Measurement Signal of Heavy Ion Beam Probe of Energetic-Particle Driven Geodesic Acoustic Modes

Abstract

In order to observe spatial profiles of energetic particle driven modes, measurement signal of Heavy Ion Beam Probe (HIBP) is formulated theoretically, focusing on effects of the fast ion density fluctuation and attenuation of the injected beam (line-integral effect). Obtained formula is applied to the density fluctuation measurement of energetic-particle driven geodesic acoustic modes (EGAMs). Intensity of the fluctuation obtained by the HIBP can be up-down asymmetric in the poloidal cross-section due to the effect of the fast ion density fluctuation, when the electron loss cross-section of HIBP due to fast ions is comparable to that due to electrons. A possibility to measure the fast ion density by HIBP is discussed, and the experimental guideline for the specification of the resonance which drives the EGAM is presented.