A Continuous Emission Source Covering the 50 to 300 Angstrom Band

Abstract

Because of the growing importance of extreme ultraviolet radiation, there is considerable interest in high intensity laboratory sources for this spectral range. A variety of sources have been proposed for these wavelengths, and many of these are described in the classic book of Samson (1967). Most of these sources have substantial limitations, especially those that are intended for use below 1200 Å. We (Paresce et al. 1971) and others have developed continuous discharge sources which are stable and maintenance-free and which provide a large number of intense lines at wavelengths down to ~300 Å. Soft X-ray sources of the type developed and refined by Henke (1975) are capable of producing substantial amounts of soft X-ray radiation. However, these sources have severe limitations for use at wavelengths longer than ~50 Å. For example, much of the radiation produced is continuum radiation with rather low flux at any specific line. In addition, the flux is peaked at shorter wavelengths. When dispersed by a grazing incidence monochromator, wavelengths at first order and many higher orders emerge from the exit slit, rather than a true monochromatic flux which is usually desired. Essentially the only sources available that can provide reasonable flux levels at wavelengths between 50 and 300 Å are capacitive discharge sources with attendant problems of severe electromagnetic interference, and plasma discharge sources.