Responsivity calibration of the LoWEUS spectrometer.

We performed an in situ calibration of the relative responsivity function of the Long-Wavelength Extreme Ultraviolet Spectrometer (LoWEUS), while operating on the Lithium Tokamak Experiment (LTX) at Princeton Plasma Physics Laboratory. The calibration was accomplished by measuring oxygen lines, which are typically present in LTX plasmas. The measured spectral line intensities of each oxygen charge state were then compared to the calculated emission strengths given in the CHIANTI atomic database.

High-resolution time-resolved extreme ultraviolet spectroscopy on NSTX.

We report on upgrades to the flat-field grazing-incidence grating spectrometers X-ray and Extreme Ultraviolet Spectrometer (XEUS) and Long-Wavelength Extreme Ultraviolet Spectrometer (LoWEUS), at the National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Laboratory. XEUS employs a variable space grating with an average spacing of 2400 lines/mm and covers the 9-64 Å wavelength band, while LoWEUS has an average spacing of 1200 lines/mm and is positioned to monitor the 90-270 Å wavelength band. Both spectrometers have been upgraded with new cameras that achieve 12.

Experimental setup for tungsten transport studies at the NSTX tokamak.

Tungsten particles have been introduced into the National Spherical Torus Experiment (NSTX) in Princeton with the purpose to investigate the effects of tungsten injection on subsequent plasma discharges. An experimental setup for the study of tungsten particle transport is described where the particles are introduced into the tokamak using a modified particle dropper, otherwise used for lithium-powder injection. An initial test employing a grazing-incidence extreme ultraviolet spectrometer demonstrates that the tungsten-transport setup could serve to infer particle transport from the edge to the hot central plasmas of NSTX.

X-ray spectroscopy of Cu impurities on NSTX and comparison with Z-pinch plasmas.

X-ray spectroscopy of mid-Z metal impurities is important in the study of tokamak plasmas and may reveal potential problems if their contribution to the radiated power becomes substantial. The analysis of the data from a high-resolution x-ray and extreme ultraviolet grating spectrometer, XEUS, installed on NSTX, was performed focused on a detailed study of x-ray spectra in the range 7-18 Å. These spectra include not only commonly seen iron spectra but also copper spectra not yet employed as an NSTX plasma impurity diagnostic.