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 angstrom wavelength band, while LoWEUS has an average spacing of 1200 lines/mm and is positioned to monitor the 90-270 angstrom wavelength band. Both spectrometers have been upgraded with new cameras that achieve 12.5 ms time resolution. We demonstrate the new time resolution capability by showing the time evolution of iron in the NSTX plasma. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4731753]