Development of a Next-Generation Pulse Burst Laser System for Time-Resolved Fluid Dynamics and Combustion Measurements

Abstract

In this paper we will describe recent advances made in our laboratory in the development of next-generation pulse burst laser system (PBLS) for turbulent fluid dynamics/combustion and high-speed flow measurements. We will discuss important changes made from previous PBLS systems in an effort to optimize laser performance at repetition rates in the tens of kilohertz regime. The new PBLS is designed to produce a unique combination of high pulse energies (~1 J/pulse at 532 nm), high repetition rates (> 10 kHz), and long pulse burst durations (> 25 ms). The system has been designed to target high-repetition rate laser diagnostic methods such as PLIF, Rayleigh scattering, and Raman scattering imaging that require high laser pulse energies and are not possible with commercial (“diode-pumped”) high-speed laser systems. Results using an existing PBLS at OSU demonstrate the utility of such systems and an initial assessment of the performance of the new PBLS is discussed. Specifically, we discuss the fundamental changes in the new, next-generation system which include (1) narrow-linewidth pulsed oscillator as the system’s master oscillator, (2) a parallel path design to delay gain saturation, (3) spatial filtering/relay imaging optics to mitigate thermal lensing and preserve beam quality, and (4) the addition of new flashlamp power supplies to significantly extend burst durations and hence record lengths.