Flyer acceleration by a high-power KrF laser with a long pulse duration

Abstract

The experiments of flyer acceleration by the irradiation of a high power laser are carried out using the ASHURA system at the Electrotechnical Laboratory, in which the laser has a short wavelength (∼249 nm) and a long pulse duration (∼30 ns). Three-layered targets (aluminum–polyimide–tantalum) are irradiated. The laser ablates the aluminum and polyimide layers and the rear layer (tantalum) is accelerated as a flyer. It is suggested that the tantalum flyer is in a condensed state for the duration of flight. The flyer velocity estimated from the acceleration profile is at least 8 km/s. One-dimensional numerical simulation indicates that the terminal flyer velocity becomes higher than 15 km/s. The energy conversion from laser energy to flyer kinetic energy is more efficient than that in the previous experiments using the three-layered targets with a longer wavelength and a shorter pulse duration (1–2 ns). Thus, it is found that a facility with a long pulse duration and a short wavelength is suitable for the realization of a fast flyer keeping its state in a condensed phase.