Modeling terahertz emission from the target rear side during intense laser-solid interactions

Area of Science:

• Physics
• Plasma Physics
• Laser-Matter Interaction

Background:

• Relativistic laser-solid target interactions are known sources of terahertz (THz) radiation.
• Broadband THz radiation is emitted from both front and rear surfaces of laser-irradiated targets.
• Experimental generation of high-power, ultrashort THz pulses from the rear surface is established, but the underlying physics remains unclear.

Purpose of the Study:

• To present a numerical model for simulating relativistic laser-solid target interactions.
• To elucidate the physical mechanisms responsible for broadband THz radiation generation at the target rear surface.
• To reproduce and explain key aspects of experimental observations.

Main Methods:

• Development of a numerical model focusing on charged particle dynamics at the target rear surface.
• Simulation of the evolution of the charge separation field.
• Analysis of the model to identify dominant contributors to THz emission.

Main Results:

• The numerical model successfully reproduces several experimental findings.
• The model highlights the crucial role of charged particle dynamics and charge separation fields.
• Key physical processes contributing to broadband THz emission from the rear surface are identified.

Conclusions:

• The presented numerical model provides a framework for understanding THz generation in laser-solid interactions.
• Charged particle dynamics and charge separation fields are critical for rear-surface THz emission.
• This work advances the understanding of high-power THz pulse generation mechanisms.