The extreme ultraviolet (XUV) emission from dense plasmas generated with sub- 10-fs laser pulses with varying peak intensities up to 3× 1016 W cm2 is investigated for different target materials. K shell spectra are obtained from low Z targets (carbon and boron nitride). In the spectra, a series limit for the hydrogen- and helium-like resonance lines is observed, indicating that the plasma is at high density and that pressure ionization has removed the higher levels. In addition, L shell spectra from titanium targets were obtained. Basic features of the K and L shell spectra are reproduced with computer simulations. The calculations include hydrodynamic simulation of the plasma expansion and collisional radiative calculations of the XUV emission.
- extreme ultraviolet emissions
- dense plasmas
- laser pulses
- intense subpicosecond laser pulses
- laser energy