Penning source for calibration of x-ray and EUV optics and spectrometers at wavelengths as short as 50 A
We report on the development and evaluation of a redesigned version of the Penning gas discharge source of x-ray and EUV radiation previously described by Finley et al. The most significant new features are the use of stronger permanent magnets and spill-proof quick- disconnect water cooling line fittings. Using aluminum cathodes and Ar discharge gas, and with a 0.5 mm by 5 mm exit aperture on the source, we obtained an absolute flux in the bright Al IV line at 129.73 A of order 5 multiplied by 1011 s-1 sr-1, and of order 5 multiplied by 109 s-1 sr-1 for the Ar I line at 56 A. Detailed spectral analysis of the lines near 56 A is reported. The application of this source to the prelaunch calibration of the AXAF x-ray astronomy observatory is discussed, with emphasis on use of the narrow line at 56 A for calibrating the spectral resolution of the AXAF transmission grating spectrometers.