Interaction of laser radiation with a low-density structured absorber

Explosion and Dynamic Transparency of Low-Density Structured Polymeric Targets Irradiated by a Long-Pulse KrF Laser

“…Formula ( 1) is exactly valid for a strong instantaneous point massless explosion. It was also used to estimate the energy load in the foam explosion produced by a nanosecond pulse [32]. In our case of a long 100 ns laser pulse, which was comparable with a hydrodynamic time scale, after a rapid foam explosion, the produced plasma cloud quickly became transparent to UV radiation, and only a small fraction of the laser energy was released in the foam.…”

“…A direct electron acceleration in self-produced or preliminary drilled capillaries was observed up to a few hundred keV [49], which was associated with a longitudinal component of the electric field in a corrugated waveguide, which retarded the light in phase with electrons [50]. It is expected that the 2D hydrodynamics of low-density foam targets for a 100 ns laser pulse would be rather different from the case of 1D geometry typical for the most laser-foam interaction studies [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] carried out with ns-scale laser pulses. In addition, most plastic materials have a steep rise in absorbance around the KrF laser wavelength [48], which should decrease the plasma formation time for foams.…”

“…Laser-foam interaction, including the ionization dynamics of foams, have been studied experimentally and theoretically in many works, mostly with Nd: glass lasers at a wavelength of λ = 1060 nm, sometimes at second (2ω) or third (3ω) harmonics (see, for example, [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]). It is commonly assumed that foams are initially transparent for laser radiation and that plasma originates from the evaporation and ionization of pore septa.…”