Ultrafast evolution of electric fields from high-intensity laser-matter interactions

Abstract

The interaction of high-power ultra-short lasers with materials offers fascinating wealth of transient phenomena which are in the core of novel scientific research. Deciphering its evolution is a complicated task that strongly depends on the details of the early phase of the interaction, which acts as complex initial conditions. The entire process, moreover, is difficult to probe since it develops close to target on the sub-picosecond timescale and ends after some picoseconds. Here we present experimental results related to the fields and charges generated by the interaction of an ultra-short high-intensity laser with metallic targets. The temporal evolution of the interaction is probed with a novel femtosecond resolution diagnostics that enables the differentiation of the contribution by the high-energy forerunner electrons and the radiated electromagnetic pulses generated by the currents of the remaining charges on the target surface. Our results provide a snapshot of huge pulses, up to 0.6 teravolt per meter, emitted with multi-megaelectronvolt electron bunches with sub-picosecond duration and are able to explore the processes involved in laser-matter interactions at the femtosecond timescale.

Review on TNSA diagnostics and recent developments at SPARC_LAB

“…The fields present a temporal duration of a few picoseconds and a peak electric field amplitude ∼0.6 TV/m on target. The values obtained are in good agreement with PIC simulations [31] . This innovative diagnostic enables discrimination between the signal carried by the fast electrons and the emitted wave generated by currents in the target.…”

“…Indeed, since a larger emitting area produces wider EM radiation, its radial extent is directly proportional to the horizontal size of the detected signal; meanwhile, the signal thickness is directly proportional to the average duration of the detected radiation, which, for the signals reported in Figure 16, is 6 ± 1 ps. Furthermore, its peak value of the electric field has been found equal to 0.8 MV/m on our EOS crystal, corresponding to approximately 0.6 TV/m on target, as confirmed by particle-in-cell (PIC) simulations [31] . In addition, this field value allows only electrons with energies higher than 3 MeV to escape, in agreement with our measurements [31] .…”

“…Furthermore, its peak value of the electric field has been found equal to 0.8 MV/m on our EOS crystal, corresponding to approximately 0.6 TV/m on target, as confirmed by particle-in-cell (PIC) simulations [31] . In addition, this field value allows only electrons with energies higher than 3 MeV to escape, in agreement with our measurements [31] .…”

“…In the following, we provide a review of the different diagnostics employed in laser-target interaction experiments related to electron, proton and ion acceleration. Finally, we present our recently developed non-destructive, single-shot, temporally resolved diagnostic [28][29][30][31] based on electro-optical sampling (EOS) [32] , able to record with femtosecond resolution ultrashort EMPs and fast electrons emitted from solid targets during the interaction, previously adopted just in accelerator physics. Our diagnostic is able to provide a more detailed picture of this phenomenon at the sub-picosecond timescale, highlighting its ultra-fast dynamics.…”

Laser produced electromagnetic pulses: generation, detection and mitigation

“…However, because of a strong divergence of the electron bunch and X-rays, the intensity of these secondary emissions is much weaker than that of the primary one. The electric field induced in an electro-optical crystal by an ejected electron bunch was measured in references [46,47] .…”