Channel optimization of high-intensity laser beams in millimeter-scale plasmas

Area of Science:

• Plasma Physics
• Laser-Plasma Interactions
• High-Intensity Laser Science

Background:

• Laser-produced plasmas are crucial for inertial confinement fusion and high-energy-density physics.
• Understanding laser-plasma channel formation is key to controlling energy deposition and particle acceleration.
• Previous simulations suggested longer laser pulses enhance plasma channel penetration.

Purpose of the Study:

• To investigate relativistic laser channeling in large-scale laser-produced plasmas.
• To determine the effects of laser focal location, intensity, and plasma temperature on channel formation.
• To compare channel penetration for different laser pulse durations.

Main Methods:

• Experiments conducted at the OMEGA EP facility using kilojoule laser pulses at relativistic intensities (>10^18 W/cm^2).
• Utilized large density scale length plasmas (∼390-570 μm).
• Varied laser focal location, intensity, and plasma temperature.

Main Results:

• Deeper channeling observed in hotter plasmas and at lower plasma densities, consistent with expectations.
• Shorter (10 ps) intense laser pulses demonstrated deeper penetration than longer-duration pulses.
• This contradicts findings from previous large-scale particle-in-cell simulations.

Conclusions:

• Laser pulse duration is a critical factor in relativistic laser-plasma channeling, with shorter pulses yielding greater penetration.
• Experimental results challenge existing theoretical models and simulation predictions.
• Findings have significant implications for optimizing laser-plasma interactions in high-intensity regimes for applications like fusion energy and particle acceleration.