title: Design of solid state neutral particle analyzer array for National Spherical Torus Experiment-Upgrade.
abstract: A new compact, multi-channel Solid State Neutral Particle Analyzer (SSNPA) diagnostic based on silicon photodiode array has been designed and is being fabricated for the National Spherical Torus Experiment-Upgrade (NSTX-U). The SSNPA system utilizes a set of vertically stacked photodiode arrays in current mode viewing the same plasma region with different filter thickness to obtain fast temporal resolution (∼120 kHz bandwidth) and coarse energy information in three bands of >25 keV, >45 keV, and >65 keV. The SSNPA system consists of 15 radial sightlines that intersect existing on-axis neutral beams at major radii between 90 and 130 cm, 15 tangential sightlines that intersect new off-axis neutral beams at major radii between 120 and 145 cm. These two subsystems aim at separating the response of passing and trapped fast ions. In addition, one photodiode array whose viewing area does not intersect any neutral beams is used to monitor passive signals produced by fast ions that charge exchange with background neutrals.
authors.affiliation: Department of Physics and Astronomy, University of California - Irvine, Irvine, California 92697, USA.
authors.forename: D
authors.initials: D
authors.lastname: Liu
authors.affiliation: Department of Physics and Astronomy, University of California - Irvine, Irvine, California 92697, USA.
authors.forename: W W
authors.initials: WW
authors.lastname: Heidbrink
authors.affiliation: Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: K
authors.initials: K
authors.lastname: Tritz
authors.affiliation: Department of Physics and Astronomy, University of California - Irvine, Irvine, California 92697, USA.
authors.forename: Y B
authors.initials: YB
authors.lastname: Zhu
authors.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
authors.forename: A L
authors.initials: AL
authors.lastname: Roquemore
authors.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Medley