Development of Laser Diagnostics in Turbulent Pool Fires and Low-Pressure Plasmas

Dr. Kraig Frederickson

Sandia National Laboratories, Albuquerque

Computational simulations are frequently used to predict and understand the dynamics of many different systems. However, development of these simulations requires high-fidelity experimental data for validation and verification. The fire science and plasma physics communities have traditionally used physical probes, such as thermocouples or Langmuir probes as diagnostic tools, but these probes have limited spatial and temporal resolution and in many cases can be quite intrusive. Additionally, thermocouples may suffer from bias errors, such as thermal lag and radiative cooling, as large as 40% when employed in high-temperature (2000 K) fires, while the accuracy of Langmuir probes suffer from uncertainties on the same order of magnitude because of ion motion around the probe and ion interaction with the probe. As predictive simulations become more developed, the diagnostic techniques used must become more sophisticated to match the resolution needs of the modeling community. Laser-based diagnostics show the potential to acquire nonintrusive, high spatially and temporally resolved measurements within environments relevant to the fire and plasma communities. This seminar will present recent development of a joint temperature/soot and an electron density diagnostic within large-scale turbulent pool fires and low-pressure helium plasmas. The pool fire measurements utilize Coherent anti-Stokes Raman Scattering (CARS) and Laser-Induced Incandescence (LII) to determine the gas temperature and soot volume fraction, respectively. A Laser Collision-Induced Fluorescence technique is employed to extract the electron density and temperature within low-pressure helium plasmas.

Speaker Biography:Since 2007, Dr. Kraig Frederickson works as post-doctoral researcher at Sandia National Laboratories, doing development of laser-based diagnostics for large-scale turbulent pool fires (CARS/LII) and low-pressure plasmas (LCIF). Dr. Kraig Frederickson received his Ph.D in physical chemistry under the instruction of Dr. Walter Lempert, Ohio State University. His Ph.D research was about using optical/laser diagnostics to investigate plasma kinetics and plasma-based applications such as the Electric Discharge Oxygen Iodine Laser and isotope separation. Before that, he got his Bachelor’s in chemistry and physics from Pacific Lutheran University.

Friday, March 6th 2009 at 12:00 noon

Center for High Technology Materials, Room 101

A light lunch will be served at the talk.