Advanced Diagnostics for Combustion and Propulsion Systems
Speaker: Peter Barker, University College London
Series: Crocco Colloquium
Location: Bowen Hall Room 222
Date/Time: Friday, November 16, 2012, 3:30 p.m. - 4:30 p.m.
Laser-based diagnostics has become an extremely important tool for fast and accurate measurements of gas properties in combustion, gas flows, and plasmas. In this seminar I will describe my research that is developing new, fast and non-invasive methods for measurements in neutral gases. This work utilizes optical forces to manipulate the motion of atoms and molecules in a gas. When these forces are weak we can gently perturb the system from its equilibrium and measure the response of the gas by light scattering. This process allows fast nanosecond measurements of temperature, density, and viscosity. When much stronger optical forces are applied we are able to briefly trap and transport gases to produce jets and molecular beams, which are shaped by pulses of light. We have demonstrated exquisite control over these beams and are able to produce micro-jets with a very well defined temperature and speed. I will provide an overview of this field and describe important experiments that demonstrate the utility of light forces for gas dynamic measurements.
Peter Barker has a background in atomic and molecular physics and laser-induced phenomena in gases. He was awarded a PhD in Physics from the University of Queensland, Australia, in 1996. From 1997 to 2001 he was a Postdoctoral Research Associate in the Applied Physics Group in the Mechanical and Aerospace Engineering Department at Princeton University. At Princeton, he began to study the manipulation of atoms and molecules in optical fields and was also involved in developing a new type of wind tunnel for accelerating gases to hypersonic speeds using lasers and electron beams. In 2001 he took up a faculty position in the Physics Department at Heriot-Watt University in Scotland. In 2006 he moved to University College London as Professor where he continues to develop coherent laser scattering methods for gas phase diagnostics and techniques for manipulating gases using strong optical fields.