Compact and multi-view solid state neutral particle analyzer arrays on National Spherical Torus Experiment-Upgrade
- Departments of Physics and Astronomy, University of California, Irvine, California 92697 (United States)
- Departments of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States)
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
A compact and multi-view solid state neutral particle analyzer (SSNPA) diagnostic based on silicon photodiode arrays has been successfully tested on the National Spherical Torus Experiment-Upgrade. The SSNPA diagnostic provides spatially, temporally, and pitch-angle resolved measurements of fast-ion distribution by detecting fast neutral flux resulting from the charge exchange (CX) reactions. The system consists of three 16-channel subsystems: t-SSNPA viewing the plasma mid-radius and neutral beam (NB) line #2 tangentially, r-SSNPA viewing the plasma core and NB line #1 radially, and p-SSNPA with no intersection with any NB lines. Due to the setup geometry, the active CX signals of t-SSNPA and r-SSNPA are mainly sensitive to passing and trapped particles, respectively. In addition, both t-SSNPA and r-SSNPA utilize three vertically stacked arrays with different filter thicknesses to obtain coarse energy information. The experimental data show that all channels are operational. The signal to noise ratio is typically larger than 10, and the main noise is x-ray induced signal. The active and passive CX signals are clearly observed on t-SSNPA and r-SSNPA during NB modulation. The SSNPA data also indicate significant losses of passing particles during sawteeth, while trapped particles are weakly affected. Fluctuations up to 120 kHz have been observed on SSNPA, and they are strongly correlated with magnetohydrodynamics instabilities.
- OSTI ID:
- 22596567
- Journal Information:
- Review of Scientific Instruments, Vol. 87, Issue 11; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CHARGE EXCHANGE
COMPACTS
FLUCTUATIONS
GEOMETRY
KHZ RANGE 100-1000
MAGNETOHYDRODYNAMICS
NEUTRAL PARTICLE ANALYZERS
NEUTRAL PARTICLES
NOISE
NSTX DEVICE
PARTICLES
PLASMA
SAWTOOTH OSCILLATIONS
SIGNALS
SIGNAL-TO-NOISE RATIO
SILICON
SOLIDS
SPHERICAL CONFIGURATION
THICKNESS
X RADIATION