13 April 2021, 14:00 - 15:30
- Eastern Daylight Time (UTC - 04:00)
Metrology is a founding pillar and a driving force of scientific discovery and understanding. The ability to accurately measure quantities of interest has always been one of the ultimate tests in verifying or subverting scientific hypotheses, ultimately advancing the scientific understanding and engineering applications. Although much progress has been made in all fields of science and engineering over the last century, the state of the art in the metrology of gas and plasma flows has largely remained unchanged, being perturbative and not accurate to the level modern science and engineering requires. In this talk I will discuss the laser diagnostic efforts developed to tackle the matter, by concentrating on the research efforts of our group in this field by utilizing Coherent Rayleigh-Brillouin scattering (CRBS).
CRBS is a four-wave mixing diagnostic technique that relies on the creation of an optical lattice in a medium due to the interaction between polarizable particles and intense laser fields. Single shot CRBS1 has been demonstrated to be the coherent analog of spontaneous Rayleigh-Brillouin scattering in measuring the temperature, pressure, bulk and shear viscosity, speed of sound and polarizability of a gas or gas mixture2. Additionally, CRBS3 has facilitated the in situ measurements of ~5 nm nanoparticles produced in an arc discharge. In this talk, an overview on the theory and experimental aspects of single shot CRBS will be presented. Furthermore, I will demonstrate our recent work in utilizing CRBS for neutral gas flow velocimetry with measurable velocities down to 5-10 ms-1, applicable to atomic and molecular gases and gas mixtures4. Finally, I will discuss the feasibility and working progress towards the use of single shot (CRBS) as a plasma flow and temperature measuring technique for partially ionized gases.
Alexandros Gerakis is a Senior Research & Technology Associate at the Luxembourg Institute of Science & Technology (LIST). He obtained his BSc from the School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Greece and his Master’s degree from St Andrews and Herriot-Watt Universities, in "Photonic and Optoelectronic Devices". He holds a PhD in Physics from University College London. Prior to joining LIST, he postdoc’d at Harvard University, was an Associate Research Physicist at the Princeton Plasma Physics Laboratory and an Assistant Professor at the Aerospace Engineering Department, Texas A&M University, leading the “Optical Probing & Manipulation” Group.