In order to develop short-wavelength (extreme ultra violet (XUV) or soft X-
ray) laser devices of tabletop size, the characteristics of a capillary tub
e discharge are examined. The polyacetal (CH2O)(n) capillaries with diamete
r and length of 2 mm and 60 mm, respectively, are filled with methane (CH4)
gas up to 5 Pa, and powered by a Marx generator pulse-forming line system.
Time-integrated XUV spectra are analyzed using a flat-field grazing-incide
nce spectrometer equipped with a 1200 line/mm grating. Although the experim
ental conditions are rather different from those published, spectral shapes
with the same features are obtained. The spatial distribution of the 18.2
nm transition intensity of Carbon VI and its dependence on the discharge pa
rameters such as the capillary length, the diameter and the discharge volta
ge are discussed.