X-ray line spectral signatures of plasmas driven by high-intensity ultra-short laser pulses

In this dissertation we report on our atomic-kinetics and X-ray line spectra modeling work in the context of plasmas generated by high-intensity, ultrashort-duration pulsed lasers. We focus on characterizing the properties of X-ray line emissions (i.e., intensity, broadening, and polarization) as signatures of plasma conditions, discuss the relevant atomic processes, and introduce atomic kinetics as a means for their quantitative assessment. This also requires the knowledge of detailed line shapes including the effects of Doppler and natural broadening, Stark broadening, line shifts and radiation transport. A suite of time-dependent, collisional-radiative atomic kinetics and spectral codes, CRAK/SPECTRUM, were developed. We applied these codes to the analysis of K-shell aluminum X-ray line spectra recorded in experiments using layered targets performed at the Max-Planck-Institut für Quantenoptik. Modeling calculations indicate that red line shifts observed in these experiments cannot be explained by shifts in the centers of gravity of composite spectral features due to enhanced satellite contributions, but are consistent with line shift effects in resonance and satellite lines.; We discuss the mechanism of polarized X-ray line emission in plasmas, its connection to plasma anisotropy, and introduce an atomic kinetics model and code (POLAR) based on the population kinetics of magnetic sublevels. POLAR represents a multi-level, multi-process approach to the problem of polarized spectra in plasmas, and hence it is well suited for plasma applications where cascade effects and alignment transfer can become important. Polarization degrees of X-ray spectral lines computed with POLAR were successfully benchmarked against calculations done with other formalisms, and experimental results obtained at the EBIT facility of Lawrence Livermore National Laboratory. We investigate the polarization of He-like Si X-ray satellite lines as spectral signatures of anisotropy in the electron distribution function. A comprehensive modeling study has been performed taking into account hydrodynamics and electron kinetics. We find that two satellite lines connecting singlet states develop a noticeable polarization while the triplet lines remain unpolarized. These results suggest a scenario where triplet lines could be used as a reference while the singlets could be used as polarized markers of plasma anisotropy.