Numerical investigation of laser interaction with a target in a vacuum, including the spectral composition of the radiation emitted by the generated plasma

Numerical calculations are performed for a one-dimensional plane time-dependent radiation--gasdynamic problem concerning the interaction of a pulse of radiation from a neodymium laser with an aluminum target in a vacuum. Detailed data tables are used for the absorption coefficients of the aluminum plasma (containing 103 quantum--energy intervals), derived taking bound--bound transitions into account. In order to speed up the calculations, a method is used for averaging the radiative transfer equations, which enables detailed account to be taken of the spectral and angular distributions of the radiation. The dependences of the fundamental parameters on the laser power are determined. A comparison between the results obtained and those of previous calculations of a similar multigroup problem is made using absorption coefficients but neglecting the spectral lines. The high radiative efficiency of a low-temperature plasma, reaching tens of percent of the laser intensity, is confirmed. It is shown that the spectrum of the radiation emitted by the plasma in vacuum is characterized by a complex line structure