Array of neutral particle analyzers at DIII-D

Local measurements of the fast-ion distribution in auxiliary-heated plasmas are key to understanding the behavior of energetic particles under a variety of conditions, such as beam-ion transport during Alfven instabilities and the acceleration of beam ions by fast waves. For the first time at DIII-D, line-averaged and local measurements of the energetic-particle density (for E=5-75 keV) are possible using an array of four compact charge-exchange analyzers [P. Beiersdorfer et al., Rev. Sci. Instrum. 58, 2092 (1987)]. The installation consists of three vertically viewing analyzers with fixed sightlines, measuring particles with chi=90 degrees (where chi is the angle between the particle's velocity and the toroidal direction), and one horizontally viewing analyzer with a variable sightline, measuring particles with 2 degrees less than or similar to chi less than or similar to 60 degrees. All the analyzers can make passive measurements while three detectors, with sightlines that intersect deuterium heating beams, can make active charge-exchange measurements. (C) 1997 American Institute of Physics.