Soft x-ray Ar ^+ 8 laser excited by low-voltage capillary discharge

We demonstrated the operation of a 46.9-nm capillary discharge Ar ^+ 8-laser excited by electrical pulses at a very low voltage (35 - 45 kV), which is approximately two times lower than previously reported. The decrease in pulse voltage not only allows for further reduction in the size of the laser's excitation part, but also a principal shift to the experimental methods, techniques, and technologies used in ordinary pulsed gas lasers operating in the ultraviolet, visible, and infrared regions of the spectra. In an argon-filled alumina capillary with an inner diameter of 3.1 mm and a length of 22 cm, laser pulses with an energy of 4 µJ and a duration of 1.6 ns were generated. The laser produces a beam with a Gaussian intensity distribution and an FWHM divergence of 1.9 mrad. The results could be particularly useful in the development of compact, practical soft x-ray capillary lasers for use in small laboratories at educational and research institutions.