Nova Photonics designed, built and presently operates a motional Stark effect diagnostic system on the National Spherical Torus eXperiment (NSTX) at the Princeton Plasma Physics Laboratory. NSTX is a U.S. Department of Energy User Facility, and Nova Photonics provides measurements of the magnetic field pitch angle profile in the device to scientists from Princeton and many university and industrial collaborators. The experiment operates at magnetic fields in the 0.4 T range, and previous MSE systems were deployed only at fields of a few tesla or more. The difference posed significant challenges for the measurement, and it was only through our development of an appropriate optical filter that the measurement was made possible.


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