Research On Intensity Distribusion Of 69.8nm Laser Pumped By Capillary Discharge

X-ray laser is a kind of laser which has a short length. It has the advantages of short pulse, high brightness, good coherence, narrow frequency range. X-ray laser is highly applied to some fields such as integrated circuit lithography, X-ray imaging, laser plasma diagnostics. There are many kinds of schemes for the realization of X-ray laser, and the capillary discharge-pumped desktop X-ray laser opens a new field for the miniaturization and practicality of X-ray laser.At present, Ne-like Ar 46.9nm, Ne-like Ar 69.8nm, Ne-like S 60.8nm and Ne-like Cl 52.9nm soft X-ray laser have been achieved by the Capillary discharge pumping scheme. The research technique of Ne-like Ar 46.9nm laser is relatively mature, but there are relatively few reports on Ne-like Ar 69.8nm laser which has the same gain medium(Ar8+)with Ne-like Ar 46.9nm laser. In this paper, the research on intensity distribution of the Ne-like Ar 69.8nm laser was studied theoretically and experimentally.In theory, for two different electron density distribution profiles, one is quartic with slight depression at the axis and the other is parabolic. First of all, the propagation of Ne-like Ar 69.8nm laser in cylindrical plasma column was studied with the geometrical optics approximation method. Then gain length product and spatial intensity distribution from the end and side of plasma column were calculated. After that, the spatial intensity distribution of Ne-like Ar 69.8nm laser under the different plasma states was studied by changing the plasma parameters such as electron density, plasma column radius, the plasma column length.In experiment, the spatial intensity distribution of 69.8nm laser at different conditions was studied by changing the discharge parameters such as current, initial gas pressure, and capillary length. Compared with the theoretical calculation, the distribution of the plasma parameters such as electron density, plasma column radius corresponding to the spatial intensity distribution curves obtained by experiment under different conditions was analyzed.Research on intensity distribution characteristics of capillary discharge-pumped desktop X-ray laser can be used to determine the distribution characteristics of different plasma physical parameters, which is of great significance for realizing the gain amplification and improving beam quality of soft X-ray laser.