High speed fast-ion D-alpha spectrometer for the NSTX-U tokamak

Aidan Edmondson; Ryan Albosta; Benedikt Geiger; Thomas Gallenberger; David Smith; W W Heidbrink; B Stratton

doi:10.1063/5.0219190

High speed fast-ion D-alpha spectrometer for the NSTX-U tokamak

Rev Sci Instrum. 2024 Sep 1;95(9):093527. doi: 10.1063/5.0219190.

Authors

Aidan Edmondson¹, Ryan Albosta¹, Benedikt Geiger¹, Thomas Gallenberger¹, David Smith¹, W W Heidbrink², B Stratton³

Affiliations

¹ Department of Nuclear Engineering and Engineering Physics, UW, Madison, Wisconsin 53706, USA.
² Department of Physics and Astronomy, UC, Irvine, California 92697, USA.
³ Princeton Plasma Physics Laboratory, Princeton, New Jersey 08536, USA.

PMID: 39292158
DOI: 10.1063/5.0219190

Abstract

Here, we present the design and first calibration results of a new single-channel Fast-Ion D-Alpha (FIDA) spectrometer to be employed at the National Spherical Torus Experiment Upgrade (NSTX-U). The Czerny-Turner-type spectrometer uses a custom-designed aspherical lens setup instead of mirrors and achieves excellent spectral resolution, with high photon throughput through a round-to-linear fiber bundle, and camera frame rates around 8.4 kHz. The spectrometer uses a blocking bar to avoid saturation effects of the cold D-alpha emission line and will allow for detailed studies of the fast-ion confinement in NSTX-U. Expected synthetic spectra predicted with the TRANSP and FIDASIM codes show that the spectral range from 648.5 to 658 nm will sufficiently cover halo, the red-shifted beam emission, and the blue-shifted portion of FIDA emission in NSTX-U, which is sufficient for fast-ion transport studies of co-rotating fast ions.