L-shell X-ray Absorption Properties Of Magnesium And Aluminum Samples Feature Plasma

For the typical physics states of the laser plasma, it is difficult to obtain the plasma parameters directly. Spectroscopic diagnostics play an important role in the field of plasma diagnostics. The emission and absorption spectra can be used. The main absorption mechanisms include photoexcitation (bound-bound transition), photoionization (bound-free transition), and inverse bremsstrahlung (free-free transition), which relate to the atomic structre. Based on unresolved transition array model(UTA), we developed a method to calculate the transmission spectra of the sample plasma. The depression of ionization potential (DIP) is considered in solving the Saha-equations, and the quantum effect theory is used to treat the atomic states with high principal quantum numbers..The L-shell X-ray absorption measurement of Mg and Al sample plasma has been performed on "Xing-Guang II" high power laser facility, in which point projection spectroscopy (pps) techniques and multi-layered target were employed. The gold is chosen as the backlighter for its unique pseudocontinuous spectrum from the O-band emission. The absorption lines of Li-like Is22s-ls23p transition arrays and Be-like 2p2-2p3d 2s2-2s3p transition arrays are clearly observed in experiment I, and the absorption lines of Li-like 2s-3p 2p-3d transition arrays Be-like 2s2-2s3p 2s2p-2s3d 2p2-2p3d transition arrays and the B-like 2s22p-2s23d transition arrays in experiment II.The electron temperature of Mg sample characteristic plasma is determined 50~60eV, and the mass density 0.01?.002g/cm3. In local thermodynamic equilibrium(LTE), the predicted transmission spectrum is calculated and the calculation results are in agreement with the experiment. With the comparison between the calculations and experimental results in experiment II, we infer that the electron temperature of the Al sample plasma is about 34eV.