Effect Of Initial Plasma Diameter On Z-pinch Process And 46.9nm Laser

Capillary discharge pumping is an effective and economical solution to generate Xray laser.In order to improve the intensity of capillary discharge 46.9nm laser and expand its application range,this paper simulated the Z-pinch process of different initial diameter plasma,and measured the pulse characteristic and spatial distribution of 46.9nm laser,and inquired the effect of the initial plasma diameter on Z-pinch process and 46.9nm laser.In theory,a one-dimensional Lagrangian magneto-hydrodynamics(MHD)code is used to simulate Z-pinch process of the plasma with initial diameter of 3.2mm,4.0mm and 4.8mm under the main pulse current amplitude of 30 k A.The temporal evolution of plasma condition under different initial pressure have been calculated.The effects of the initial pressure and initial plasma diameter on the plasma condition at lasing time and laser gain are analyzed by using the simulation results.In the experiment,the Ne-like Ar 46.9nm laser pulses were measured with the ceramic capillaries of 3.2mm,4.0mm and 4.8 mm inner diameter and the main current of 30 k A.The effects of capillary inner diameter on lasing time,pulse amplitude and pulse width of 46.9nm laser were scrutinized,and the reasons for laser enhancement were analyzed.When the main current amplitude was increased from 30 k A to 36 k A with the 4.8mm inner diameter capillary,the laser intensity was measured.According to analysis,increasing the inner diameter of the capillary in a certain range and increasing the amplitude of the main current with a large inner diameter capillary were effective ways to improve the intensity of 46.9nm laser.Using the Ce:YAG fluorescent screen to transform the 46.9nm laser into visible light and captured by camera,the spots of 46.9nm laser produced by ceramic capillaries of 3.2mm,4.0mm and 4.8mm inner diameter were measured.The changing rule of laser spot with initial pressure,capillary inner diameter and main current were summarized,and the reasons for the change of spot shape were explained.