Anomalous inhibition of electron transport in laser-matter interaction at subrelativistic intensities

Electron transport in femtosecond laser-irradiated solid targets is investigated by means of one-dimensional particle-in-cell simulations that include a model of collisional ionization, binary collisions and field ionization, while treating ions as individual particles. In particular, heat and particle fluxes in conductor and insulator targets are compared at the onset of relativistic laser intensities, i.e., at 7=10 ¹⁷cm ². Simulations show that fast electrons generate a longitudinal electric field of the order 10 ¹¹ V/m in the bulk material that acts to inhibit heat flux in insulators, while the electric fields observed in metals are weaker and electrons penetrate deeper into the target. The bulk heat transport is found to be similar in both materials and mainly Spitzer-like, with a noticeable contribution by fast electrons.