Generation of ultra-high-pressure shocks by collision of a fast plasma projectile driven in the laser-induced cavity pressure acceleration scheme with a solid target

Abstract

A novel, efficient method of generating ultra-high-pressure shocks is proposed and investigated. In this method, the shock is generated by collision of a fast plasma projectile (a macro-particle) driven by laser-induced cavity pressure acceleration (LICPA) with a solid target placed at the LICPA accelerator channel exit. Using the measurements performed at the kilojoule PALS laser facility and two-dimensional hydrodynamic simulations, it is shown that the shock pressure $ Gbar can be produced with this method at the laser driver energy of only a few hundred joules, by an order of magnitude lower than the energy needed for production of such pressure with other laserbased methods known so far. V C 2015 AIP Publishing LLC. [http://dx.

Production of sub-gigabar pressures by a hyper-velocity impact in the collider using laser-induced cavity pressure acceleration

“…The correctness and accuracy of the PALE code used for the simulations was verified for various laser-based schemes of shock generation, in particular for the LICPA-based collider. In that case, the verification was made by the comparison of parameters of craters produced in a massive Al target by the impact of Al projectiles of various masses calculated using the code with the ones obtained from measurements performed at the PALS laser facility, and a very good qualitative and quantitative agreement between the numerical and experimental results was found (Badziak et al, 2015a). The code was also used to simulate the shock generation in a CH/Cu target by the direct target irradiation by the PALS laser beam and fairly good agreement (within ~ 30 %) between the results of the PALE simulations and the results of measurements was obtained as well (Koester et al, 2013;Badziak et al, 2015b).…”

“…The simulations were performed for the same LICPA accelerator parameters as the ones used in the experiment carried out recently at the PALS laser facility (Badziak et al, 2015a). The accelerator walls were made of gold and the main accelerator dimensions were as follows: the cavity length L c = 0.4 mm, the channel length L Ch = 2 mm, the cavity diameter D c = 0.3 mm, and the channel diameter D Ch = 0.3 mm.…”

“…How much of the ablating plasma energy is transformed into the projectile kinetic energy depends on the time of projectile acceleration and can be to some extend controlled by changing the channel's length. More detailed discussion of the process of projectile acceleration in the LICPA scheme can be found in our previous papers (Badziak et al, 2012(Badziak et al, , 2015(Badziak et al, , 2015a.…”

“…As compared to other laser-based schemes of shock generation, in particular those using the hyper-velocity impact for the shock generation, the LICPA-driven collider has several significant advantages, in particular: a) very high energetic efficiency of projectile acceleration,  acc = E p /E L , which can reach tens of percent both for a short-wavelength (< 0.5µm) and a long-wavelength (~1µm) laser (Badziak et al, 2012); b) high density of the projectile at the moment of the impact, which ensures the efficient transfer of the projectile energy to the impacted (dense) target and the generated shock (Badziak et al, 2012(Badziak et al, , 2015a; c) capability of accelerating the projectile to very high velocities; in the hydrodynamic acceleration regime (driven by the hot plasma pressure) (Badziak et al, 2012), the projectile velocity can be a few times higher than in the conventional ablative acceleration (AA) scheme (the temperature of plasma in the cavity can be up to a factor ~ 10 higher than that of the freely expanding plasma) and can potentially reach the value well above 1000 km/s, while in the photon-pressure acceleration regime, the projectile can be accelerated even to sub-relativistic velocities (Badziak et al, 2012); d) existing of additional propelling of the projectile during and after the collision by the pressure still stored in the guiding channel; e) no significant pre-heating of the impacted target by X-rays or hot electrons (especially when they are produced from a low-Z ablator), since the high-density projectile can effectively absorb them. Taking into account the above-mentioned properties of the LICPA-based collider, it could be expected that the laser-to-shock energy conversion efficiency  ls in the collider will be even by an order of magnitude higher than for other schemes of shock generation used so far and, as a result, the laser energies needed for generating the shocks of the required energy or pressure will be much lower than the energies needed in other schemes.…”

“…In this scheme -referred to as the laser-induced cavity pressure acceleration -LICPA -a projectile placed in a cavity is irradiated by a laser beam introduced into the cavity through a hole and then accelerated in a guiding channel by the pressure created in the cavity by the laser-produced hot plasma or by the photon pressure of the laser pulse trapped in the cavity. It has been demonstrated (Badziak et al, 2015(Badziak et al, , 2015a) that by the impact of the projectile driven by the LICPA mechanism into the solid target, an ultra-high-pressure shock can be generated in the target with the laser beam energy much lower than that required for producing such a shock with other laser-based methods used so far.…”