Pressure effect in a shock-wave-plasma interaction induced by a focused laser pulse

Area of Science:

• Fluid dynamics
• Plasma physics
• Laser-matter interaction

Background:

• The Richtmyer-Meshkov instability (RMI) is a key phenomenon in fluid dynamics, often studied in the context of inertial confinement fusion and astrophysical plasmas.
• Understanding the behavior of laser-induced plasma bubbles interacting with shock waves is crucial for applications ranging from inertial confinement fusion to advanced propulsion systems.
• Previous studies have explored RMI but the specific influence of ambient pressure on laser plasma bubble-shock wave interactions requires further investigation.

Purpose of the Study:

• To experimentally investigate the effect of ambient pressure on the interaction between a laser plasma bubble and a shock wave.
• To analyze the formation and evolution of the vortex structure under varying ambient pressures.
• To determine the self-similarity of the fundamental vortex structure in relation to laser energy and ambient pressure.

Main Methods:

• Utilized framing Schlieren visualization to capture the dynamic interaction.
• Generated a sharp plasma interface without separation materials to avoid artifacts.
• Systematically varied ambient pressure to observe its effects on the instability development.

Main Results:

• A sharp plasma interface was successfully formed without introducing unwanted disturbances.
• The fundamental vortex structure, driven by baroclinic effects, exhibited self-similarity with respect to the laser energy-ambient pressure ratio.
• Increased ambient pressure led to the enhancement of high-wave-number instabilities, which consequently contaminated the observed self-similarity.

Conclusions:

• Ambient pressure plays a critical role in modulating the development of instabilities in laser plasma bubble-shock wave interactions.
• While a self-similar vortex structure is observed, its integrity is compromised at higher ambient pressures due to enhanced small-scale instabilities.
• The findings provide valuable insights into controlling and predicting plasma behavior under varying environmental conditions.