Magee R M, Den Hartog D J, Fiksel G, Kumar S T A, Craig D
University of Wisconsin, 1150 University Avenue, Madison, Wisconsin 53706, USA.
Rev Sci Instrum. 2010 Oct;81(10):10D716. doi: 10.1063/1.3478665.
Charge exchange recombination spectroscopy measurements of the poloidal component of the C(+6) temperature and flow in the Madison Symmetric Torus have been vital in advancing the understanding of the ion dynamics in the reversed field pinch. Recent work has expanded the diagnostic capability to include toroidal measurements. A new toroidal view overcomes a small signal-to-background ratio (5%-15%) to make the first localized measurements of the parallel component of the impurity ion temperature in the core of the reversed field pinch. The measurement is made possible through maximal light collection in the optical design and extensive atomic modeling in the fitting routine. An absolute calibration of the system allowed the effect of Poisson noise in the signal on line fitting to be quantified. The measurement is made by stimulating emission with a recently upgraded 50 keV hydrogen diagnostic neutral beam. Radial localization is ∼4 cm(2), and good temporal resolution (100 μs) is achieved by making simultaneous emission and background measurements with a high-throughput double-grating spectrometer.
