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Fine scale thermal blooming instability: a linear stability analysis.
Applied Optics
|June 16, 2010
Summary
Laser pulse length significantly impacts thermal blooming instability. Shorter pulses suppress small perturbations via acoustics, while longer pulses are limited by wind shear and turbulence, affecting high-power laser beam propagation.
Area of Science:
- Physics
- Optics
- Fluid Dynamics
Background:
- High-power laser beams can experience thermal blooming instability.
- Understanding this instability is crucial for trans-atmospheric laser applications.
Purpose of the Study:
- To investigate the effect of laser pulse length on thermal blooming instability.
- To analyze how factors like viscosity, diffusion, wind shear, and turbulence influence instability growth.
Main Methods:
- Calculation of asymptotic gain for sinusoidal perturbations.
- Analysis as a function of pulse length and perturbation wavenumber.
- Inclusion of fluid dynamic effects and heuristic turbulence estimation.
Main Results:
- Short laser pulses reduce small wavenumber perturbations through acoustic effects.
- Long laser pulses exhibit limited perturbation growth due to wind shear and turbulence.
- A higher wavenumber cutoff for perturbations is observed with shorter pulses, beyond which thermal diffusion dominates.
Conclusions:
- Laser pulse length is a critical parameter in mitigating thermal blooming instability.
- Acoustic effects, diffusion, viscosity, wind shear, and turbulence collectively shape instability dynamics.
- Tailoring pulse length can control perturbation growth and enhance laser beam stability.
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