ARRAY OF NEUTRAL PARTICLE ANALYZERS AT DIII-D

Local measurements of the fast-ion distribution in auxiliary-heated pl asmas are key to understanding the behavior of energetic particles und er a variety of conditions, such as beam-ion transport during Alfven i nstabilities and the acceleration of beam ions by fast waves. For the first time at DIII-D, line-averaged and local measurements of the ener getic-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 ver tically viewing analyzers with fixed sightlines, measuring particles w ith chi=90 degrees (where chi is the angle between the particle's velo city and the toroidal direction), and one horizontally viewing analyze r with a variable sightline, measuring particles with 2 degrees less t han or similar to chi less than or similar to 60 degrees. All the anal yzers can make passive measurements while three detectors, with sightl ines that intersect deuterium heating beams, can make active charge-ex change measurements. (C) 1997 American Institute of Physics.