Experiments for thermomechanical effects based on Z-pinch X-ray sources

Responses of materials and structures to intense pulsed X-ray radiation, such as thermal shock wave propagation and blowoff impulse generation are referred to collectively as X-ray thermomechanical effects, which have been applied to radiation hardening, astrophysics, and planetary science. Preliminary experiments for thermomechanical effects have been performed utilizing wire array Z-pinch X-ray sources on a pulsed power facility with a drive current of about 10 MA. A total X-ray radiation energy of about 230 kJ was produced by a nested aluminum wire array of 20 mm in outer diameter, and theK-shell yield of about 30 kJ for aluminum was measured. An X-ray energy fluence up to 732 J/cm2 was produced on an irradiated target which was positioned at 5 cm away from the X-ray source center. The irradiated target was an aluminum disk 2 mm in thickness and 10 mm in diameter, backed by an aluminum liner. The total weight of the disk and liner was 585 mg. An all-fiber photonic Doppler velocimeter (PDV) was used to monitor the motion of the rear surface of the irradiated target. The velocity history measured by PDV suggested a free-face velocity of 2.12 km/s when the shock wave arrived at the rear surface of the target, and the final velocity of the target is 180 m/s. Based on the Hugoniot relationships and the law of momentum conservation, a stress of the thermal shock wave of 19.2 GPa and a blowoff impulse per unit target area of 1341 Pa·s were deduced. Furthermore, a consequent coupling coefficient of 1.83 Pa·s·cm2/J was estimated from the measurements of blowoff impulse and the X-ray energy fluence. Finally, discussions on the reliability and uncertainty of the measurement were presented. These experimental results described here preliminarily validated the feasibility of the application of PDV to the research of X-ray thermomechanical effect.