Simulation of free-space optical guiding structure based on colliding gas flows

Area of Science:

• Plasma Physics
• Fluid Dynamics
• Laser-Plasma Interactions

Background:

• Preformed plasma channels with parabolic density profiles are crucial for stable optical guiding of high-intensity laser pulses.
• Conventional high-voltage discharge capillaries for channel formation suffer from limited guiding length and opaque walls, hindering plasma diagnostics.

Purpose of the Study:

• To propose and investigate a novel method for creating preformed plasma channels in free space using colliding gas flows.
• To demonstrate the formation of a stable, long-lived parabolic density profile suitable for laser guiding.

Main Methods:

• Utilizing the collision of several gas flows to create an on-axis density depression surrounded by higher density walls.
• Employing offset gas flows to generate a novel vortex structure with a long-lived parabolic density profile.
• Conducting detailed two-dimensional (2D) fluid dynamics simulations to analyze the properties and stability of the guiding structure.

Main Results:

• A novel vortex structure exhibiting a long-lived parabolic density profile was successfully created by offsetting gas flows.
• The resulting ionized plasma density profile demonstrates a near-parabolic dependence, suitable for optical guiding.
• 2D fluid dynamics simulations confirmed the properties and stability of the proposed guiding structure.

Conclusions:

• The free-space gas channel method offers a promising alternative to discharge capillaries for creating plasma channels for laser guiding.
• The demonstrated vortex structure and its parabolic density profile are advantageous for extended and stable optical guiding of high-intensity laser pulses.
• This technique potentially simplifies plasma diagnostics due to the free-space nature of the channel.