SPRED spectrograph upgrade

This paper discusses two improvements to the SPRED mutichannel EUV spectrographs used on TFTR and PBX; A new 2100 g/mm grating covering the 100-320 angstrom 0 region with 0.4 angstrom resolution (FWHM) has been added to the existing 450 g/mm grating (100-1100 angstrom with 2.0 angstrom resolution), and the TFTR SPRED has been absolutely calibrated using synchrotron radiation from the NBS SURF II facility and branching ratio measurements; the PBX system has been calibrated using branching ratios and line ratios from charge exchange recombination excited lines. The availability of high resolution spectra in the 100-320 angstrom range allows more reliable measurements of metallic ion emissions and, when the instrument views across a neutral beam as in PBX, provides a complete spectroscopic inventory of both low- and high-Z impurities in a single discharge