Two-dimensional spectroscopic measurement of hydrogen emission in JT-60U divertor plasmas

In JT-60U divertor plasmas, deuterium Balmer-series line emission has been measured with a wide-spectral-band spectrometer, which has 92 viewing chords with a ∼1cm spatial resolution. Two-dimensional spatial distribution of the Balmer line intensities has been reconstructed using a computer tomography technique (maximum entropy method). In an inner-detached and outer-attached divertor plasma, the intensity of Dβ and Dy lines were stronger above the strike point in the inner divertor and near the strike point in the outer divertor. The ratio of the Dy line intensity to the Dp line intensity was 0.3 - 0.5 above the strike point in the inner divertor and 0-0.2 near the strike point in the outer divertor. It suggested that the line emission were attributed to the plasma recombination above the strike point in the inner divertor and the plasma ionization near the strike point in the outer divertor.