Study of Z-pinch dynamic hohlraum shadowgraphy

Abstract

In order to obtain the dynamic evolution image of tungsten array for foam padding, and to research the form of interaction between tungsten plasma and foam column, a shadow imaging system of four-frame ultraviolet probe laser (266 nm) is designed on 1 MA pulse power device. The time resolution of the system is 2.5 ns, and static space resolution is superior to 70 μm. The radial shadowgraphy image reveals the whole process from the melting and expansion of solid wire to the interaction between the precursor plasma and the foam, from the pinch to rebound inflation. The image shows the continuous interaction between tungsten plasma and foam in the form of Raining within a time of about 50 ns, the plasma shell structure is not found in the whole period of pinch. The quantitative analysis indicates that the minimum pinching speed of the foam column is 1.0×106 cm/s, and maximum pinching speed is 6.0×106 cm/s, and the axial stagnation diameter is about 1 mm. Shadowgram mainly shows the inverse bremsstrunlung effect of interaction between laser and plasma through simulation calculating, and main tungsten plasma interacting with foam column image is shown through synchronizing radial power profile.