Acoustic shock waves emitted from two interacting laser generated plasmas in air

Area of Science:

• Physics
• Acoustics
• Plasma Physics

Background:

• Laser-induced air breakdown generates shock waves.
• Studying interactions of multiple plasma sources offers insights into fluid dynamics.
• Acoustic shock waves (ASW) can be used to probe plasma interactions.

Purpose of the Study:

• To investigate the acoustic shock wave (ASW) generated by the interaction of two simultaneous laser-induced air breakdown events.
• To analyze how ASW characteristics depend on plasma separation distance and laser pulse energy.
• To compare acoustic pressures from dual-source plasma events with single-source events.

Main Methods:

• Utilized an acoustic detection technique with a microphone to capture ASW from plasma interaction zones.
• Conducted experiments with varying separation distances between two plasma sources.
• Varied incident laser energy from 25 to 100 mJ in ratios of 1:1 to 1:4.

Main Results:

• Dual plasma sources produced higher peak sound pressures than single sources.
• Peak sound pressures increased linearly with plasma separation distance up to a saturation point for equal energy sources.
• Unequal energy sources exhibited a complex pressure response: increase, saturation, decay, and a subsequent increase with separation distance.

Conclusions:

• Acoustic shock wave interactions are significantly influenced by laser pulse energy and plasma separation distance.
• The observed pressure dynamics suggest fluid-like interaction phenomena between plasma sources.
• This acoustic detection method provides a valuable tool for studying complex plasma interactions.