Influence Of Assistant Gas He On Output Characteristics Of 46.9nm Laser Pumped By Capillary Discharge

X-ray laser has an irreplaceable role in many microscopic fields due to its short wavelength,high single-photon energy and large instantaneous pulse power.In many X-ray laser pumping schemes,the capillary discharge scheme has been widely used by various countries due to its advantage of long gain area,high energy conversion efficiency,and simple structure and small size.Since 1994,when the first Ne-like Ar 46.9 nm laser was produced,many groups have explored the laser time and spatial distribution.However,there are few studies on the effect of assistant gases on 46.9nm laser pumped by capillary discharge.In this paper,under the condition of gain saturation,the influence of the assistant gas He 46.9nm laser by capillary discharge has been explored theoretically and experimentally.In this paper,geometrical optics approximation method is used in theory to simulate the propagation trajectory of the 46.9 nm laser beam in the plasma column under different electron density distributions.Afterwards,the spatial distribution of the laser when the electron density distribution is different parabolic and with different degrees of depression is calculated.We also calculated the effect of different sags of gain on the spatial distribution of the laser when the electron density distribution is parabolic and concave.We summarize the variation of laser spatial distribution under different electron density distributions and gain distributions.In experimentally,we measured the laser intensity under different Ar pressures and found the pressure range that can produce 46.9nm laser.We measured the effect of different Ar gas pressure on the spatial distribution of the laser,and summarized the relationship between the laser divergence angle and the initial Ar gas pressure.Then,we measured the influence of the auxiliary gas He on the laser intensity,and the He-doped proportion of the laser was found to be the strongest.Finally,we measured the influence of the assist gas He on the laser spatial distribution.Comparing the experimental results with the theoretical calculation results,the possible causes of the effects of the assist gas on the laser are analyzed.The study of the influence of the assistant gas He 46.9nm laser by capillary discharge helps to increase the laser output and improve the beam quality,which is of great significance for the application of soft X-rays.