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

Area of Science:

• Physics of laser-matter interactions
• Plasma physics
• Surface phenomena

Background:

• Understanding transient surface currents is crucial for laser-plasma physics.
• Existing theories often focus on neutralization currents from hot electron loss.
• A novel mechanism for current generation requires investigation.

Purpose of the Study:

• To propose and validate a new theoretical model for transient surface current generation.
• To differentiate the proposed mechanism from existing neutralization current hypotheses.
• To investigate the role of electric polarization and transition radiation in current excitation.

Main Methods:

• Development of a theoretical model for transient surface current physics.
• Comparison of the theoretical model with simulation data.
• Utilizing finite-difference time-domain (FDTD) and particle-in-cell (PIC) simulation methods.

Main Results:

• The proposed theory successfully explains transient surface current generation.
• Distinctive features of the new theory are evident in both FDTD and PIC simulations.
• The mechanism involves electric polarization and transition radiation, not solely neutralization.

Conclusions:

• A novel mechanism involving electric polarization and transition radiation explains transient surface currents.
• The proposed theory offers a new perspective on laser-induced surface currents.
• Simulation results validate the theoretical model, highlighting its distinct predictions.