High-energy laser pulses for extended duration megahertz-rate flow diagnostics

Area of Science:

• Fluid dynamics and advanced optical measurement techniques.

Background:

• High-speed optical diagnostics for supersonic and hypersonic flows demand laser sources with high pulse intensity and repetition rates.
• Existing laser systems often struggle to meet the combined requirements for energy and speed in dynamic flow analysis.

Purpose of the Study:

• To develop and characterize a burst-mode Nd:YAG laser system for enhanced optical diagnostics.
• To improve the energy and pulse count of 532 nm pulse trains for extended duration, megahertz-rate flow diagnostics.

Main Methods:

• Implementation of a burst-mode Nd:YAG laser system.
• Characterization of laser performance, including pulse energy and repetition rate.
• Demonstration using megahertz-rate laser-induced breakdown spectroscopy (LIBS) in a Mach 2 turbulent jet.

Main Results:

• Achieved a ~100x increase in overall energy and a 30x increase in high-energy pulses for 532 nm pulse trains.
• Delivered unprecedented energies near 1 J/pulse at 532 nm over a 1.1 ms burst at a 100 kHz repetition rate.
• Successfully demonstrated the system's capability for megahertz-rate LIBS in a Mach 2 turbulent jet.

Conclusions:

• The developed burst-mode laser system significantly enhances capabilities for optical diagnostics of highly dynamic flows.
• The system enables advanced flow analysis at megahertz rates, pushing the boundaries of current diagnostic techniques.
• This advancement is crucial for detailed studies of supersonic and hypersonic phenomena.