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Updated: Jun 7, 2026

Methods for Measuring the Orientation and Rotation Rate of 3D-printed Particles in Turbulence
Published on: June 24, 2016
Measurement of poloidal velocity on the National Spherical Torus Experiment (invited)
1Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA. rbell@pppl.gov
Abstract:
A diagnostic suite has been developed to measure the impurity poloidal flow using charge exchange recombination spectroscopy on the National Spherical Torus Experiment. Toroidal and poloidal viewing systems measure all the quantities required to determine the radial electric field. Two sets of up/down symmetric poloidal views are used to measure both the active emission in the plane of the neutral heating beams and the background emission in a radial plane away from the neutral beams. Differential velocity measurements isolate the line-integrated poloidal velocity from apparent flows due to the energy-dependent charge exchange cross section. Six f/1.8 spectrometers measure 276 spectra to obtain 75 active and 63 background channels every 10 ms. The local measurements from a similar midplane toroidal viewing system are mapped into two dimensions to allow the inversion of poloidal line-integrated measurements to obtain local poloidal velocity profiles. The radial resolution after inversion is 0.6-1.8 cm from the plasma edge to the center.
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