Filamentation in low pressure conditions

Area of Science:

• Physics
• Optics
• Atmospheric Science

Background:

• Long-range outdoor laser applications often utilize filamentation.
• High-altitude propagation presents unique environmental conditions, specifically low pressure.
• Understanding pressure effects on filamentation is crucial for application design.

Purpose of the Study:

• To investigate the impact of low-pressure conditions on laser filamentation.
• To analyze the scaling of filament preconditions with decreasing pressure.
• To determine the feasibility of high-altitude laser filamentation.

Main Methods:

• Theoretical analysis of filamentation preconditions scaling with pressure.
• Numerical simulations of laser pulse propagation at low pressures.
• Presentation of pressure-scaled filament properties.

Main Results:

• Critical power increases and transition numerical aperture (NA) decreases with reduced pressure.
• High-altitude filamentation necessitates higher laser energy and longer focal lengths compared to sea level.
• Simulations confirm filamentation is achievable at pressures as low as 0.0035 atm (38.5 km altitude).

Conclusions:

• Laser filamentation is feasible in the low-pressure environment of high altitudes.
• Design considerations for high-altitude laser applications must account for pressure-dependent changes in filament properties.
• Further research can optimize laser parameters for effective high-altitude filamentation.