Mechanisms and origin of continuum and line emission from carbon plasmas produced by ultrashort laser pulses

We report on a detailed experimental study of the x-ray continuum and line emission from subpicosecond UV-laser-produced carbon plasmas. By using well defined laser pulse conditions and various angles of incidence and intensities (up to ) the spectra of the plasma emission have been observed in the soft x-ray region (10 - 100 Å) which is of particular interest for many applications based on a laser-plasma x-ray source. The experiment shows that the x-ray yield, the x-ray pulse duration, the spectral region and the bandwidth etc differ significantly between the continuum and the line emission. The different scalings observed for the experimental parameters have been related to the mechanism of laser pulse absorption and of the conversion process of the absorbed energy into x-ray emission. The results have also been compared to previous measurements on aluminium plasmas.