Short-pulse, high-intensity laser-plasma interactions are investigated experimentally with temporally and spectrally resolved soft x-ray diagnostics. The emitted x-ray spectra from solid targets with various atomic numbers are characterized for a laser pulse width τ1 ~ 400 fs. With low contrast (105), the x-ray spectrum in the λ = 40-100 A ̊ spectral region is dominated by line emission, and the x-ray pulse duration is found to be characteristic of a long-scalelength, low-density plasma. Bright, picosecond, broadband emission, characteristic of a short-scale-length, high-density plasma, is produced only when a high laser contrast (1010) is used. It is demonstrated experimentally that the pulse width of laser-produced x-ray radiation may be varied down to the picosecond time scale by adjusting the incident ultrashort-pulse laser flux. The results are found to be in qualitative agreement with the predictions of both a code-independent model of radiation from a collisionally dominated two-level ion and a hydrodynamics code coupled to a detailed-configuration atomic physics model. X-ray film measurements of conversion efficiency, along with pinhole camera measurements of the emission region, reveal very high x-ray brightness.
|Original language||English (US)|
|Number of pages||11|
|Journal||Journal of Quantitative Spectroscopy and Radiative Transfer|
|State||Published - 1995|
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics