Excitation of high-intensity terahertz surface modes of plasma slab under action of p-polarized two-frequency laser radiation.

The excitation of the terahertz (THz) high-intensity surface modes when the two-frequency p-polarized laser radiation interacts with a plasma slab is studied. It was found that the significant amplification of the laser field in the plasma slab occurs when p-polarized laser radiation is incident at the angle of total reflection. It is shown that, under the action of laser radiation ponderomotive forces, the resonant excitation of the THz mode of the plasma slab occurs if the frequency difference of the laser fields coincides with the eigenfrequency of the surface mode. It is established that the giant increase in the energy flux density of the THz mode occurs when p-polarized laser radiation is incident at the angle of total reflection on the near-critical plasma slab with rare electron collisions if the conditions of resonant excitation are satisfied. It is shown that in this case the energy flux density of THz mode can significantly exceed the laser intensity.

Ultrafast target charging due to polarization triggered by laser-accelerated electrons.

A significant step has been made towards understanding the physics of the transient surface current triggered by ejected electrons during the interaction of a short intense laser pulse with a high-conductivity target. Unlike the commonly discussed hypothesis of neutralization current generation as a result of the fast loss of hot electrons to the vacuum, the proposed mechanism is associated with excitation of the fast current by electric polarization due to transition radiation triggered by ejected electrons. We present a corresponding theoretical model and compare it with two simulation models using the finite-difference time-domain and particle-in-cell methods. Distinctive features of the proposed theory are clearly manifested in both of these models.