  Water window emission spectra of two laboratory nitrogen plasma sources were
examined with a free standing grating spectrometer (FSGS). The highest line
intensities at the wavelength 2.88 nm achievable with the sources were
compared. Pulse energies for this line were judged as 0.02 mJ/srad and 0.16
mJ/srad with laser produced plasma system and pinching discharge plasma,
respectively. The spectral resolution was found about 0.01 nm at 3rd order of
spectral lines around wavelength 2.5 nm.
