Laser-plasma jet driven sub-millimeter diameter aluminum flyer and its gesture diagnosis

Abstract

Laser-driven flyer has been studied for decades as it is promising in many application areas, such as EOS measurements under ultrahigh pressure, material dynamic properties under high strain rate, high-speed impact simulation for aircraft protection, as well as explosive ignition. However, the planarity and integrity of flyers are determined by indirect VISAR or witness slab results due to its high speed and small dimension. For further and widely application, it is very important to obtain direct experimental proof of the flyer gesture and configuration. Thus, the acceleration and gesture investigation of aluminum flyer driven by laser plasma was studied at Xingguang-III laser facility. X-ray radiography was achieved by irradiation of picosecond laser upon the copper wire target. Shadowgraph of flyer and plasma was realized by incidence of a bunch of infrared laser through the flyer flight path. In additon, PDV was employed to measure flyer velocity simultaneously. Radiography, shadowgraph and velocity of typical small aluminum flyer was obtained. By optimizing the thickness of both CH ablation layer and vacuum gap, the flyer is slowly accelerated via consecutive stress wave produced by plasma colliding. The aluminum flyer has a thickness of 20μm and diameter of about 500μm, respectively. The whole flyer still sustains integrated shape after a great angle of rotation due to uneven plasma loading. The flight distance is about 400μm, giving an average velocity of 2.2km/s. The planarity of the flyer is good except a little bend at the two sides due to side rarefaction of plasma. The study verifies that the laser plasma collision can generate sub-millimeter-diameter metal flyer with integrated shape and several km/s of velocity, shows promising in EOS and explosive ignition application.