Large Area Divertor Temperature Measurements Using A High-speed Camera With Near-infrared FiIters in NSTX
Authors: B.C. Lyons, F. Scotti, S.J. Zweben, T.K. Gray, J. Hosea, R. Kaita, H.W. Kugel, R.J. Maqueda, A.G. McLean, A.L. Roquemore, V.A. Soukhanovskii and G. Taylor
Abstract: Fast cameras already installed on the National Spherical Torus Experiment (NSTX) have be equipped with
near-infrared (NIR) filters in order to measure the surface temperature in the lower divertor region. Such a
system provides a unique combination of high speed (> 50 kHz) and wide fi eld-of-view (> 50% of the divertor).
Benchtop calibrations demonstrated the system's ability to measure thermal emission down to 330 oC. There is
also, however, signi cant plasma light background in NSTX. Without improvements in background reduction,
the current system is incapable of measuring signals below the background equivalent temperature (600 - 700
oC). Thermal signatures have been detected in cases of extreme divertor heating. It is observed that the
divertor can reach temperatures around 800 oC when high harmonic fast wave (HHFW) heating is used.
These temperature profiles were fi t using a simple heat diffusion code, providing a measurement of the heat
flux to the divertor. Comparisons to other infrared thermography systems on NSTX are made.
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Submitted to: PPPL Reports
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Download PPPL-4612 (pdf 1.89 MB 6 pp)
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