Control of laser heating in clusters through variation in temporal pulse shape

Area of Science:

• Physics
• Atomic and Molecular Physics
• Plasma Physics

Background:

• High-intensity laser interactions with atomic clusters are key to understanding energy deposition and particle acceleration.
• The temporal profile of femtosecond laser pulses can significantly influence plasma dynamics.

Purpose of the Study:

• To investigate the impact of laser pulse temporal shape on atomic cluster expansion dynamics.
• To quantify the effect of pulse shaping on ion energies generated from laser-cluster interactions.

Main Methods:

• Experiments using femtosecond lasers (70-240 fs, ~10^16 Wcm^-2) interacting with rare gas clusters (Xe, Kr, Ar).
• Simulations complementing experimental data to analyze cluster expansion.
• Varying the laser pulse shape by introducing a low-intensity shoulder on the rising or falling edge.

Main Results:

• The temporal profile of the laser pulse critically affects cluster expansion dynamics.
• Significant variations (up to a factor of 2) in ion energies were observed due to changes in pulse shape.
• Chirp sign determined the position of the intensity shoulder, influencing interaction outcomes.

Conclusions:

• Laser pulse shaping is a vital parameter for controlling laser-matter interactions in atomic clusters.
• Understanding pulse dynamics is essential for optimizing ion yield and energy in laser-driven cluster experiments.
• This research provides insights into fundamental physics governing femtosecond laser-cluster interactions.