A Free Online VKI Seminar - Single shot coherent Rayleigh-Brillouin scattering: Neutral gas & plasma flow multi-point thermodynamic characterization (temperature, density and flow velocity) in a non-resonant, non-intrusive and seed-less way

A Free Online VKI Seminar

Single shot coherent Rayleigh-Brillouin scattering: Neutral gas & plasma flow multi-point thermodynamic characterization (temperature, density and flow velocity) in a non-resonant, non-intrusive and seed-less way

Our Guest Speaker: Dr. Alexandros Gerakis, Senior Research & Technology Associate, Luxembourg Institute of Science and Technology

Abstract: Metrology is a founding pillar and a driving force of scientific discovery and understanding. Albeit its key importance in all aspects of science and engineering, the field is still dominated by the use of mechanical, intrusive probes for flow velocity and pressure measurements. To tackle the matter, which is of key importance to the development of a plethora of science and engineering fields, our group is developing single shot coherent Rayleigh-Brillouin scattering (CRBS) as an alternative, non-intrusive probe for neutral and plasma flow thermodynamic characterization.

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, as well as nanoparticles produced in an arc discharge³. In this talk, an overview on the theory and experimental aspects of single shot CRBS will be presented along with our recent work in measuring simultaneously the temperature, density (and thus the pressure) and flow velocity^4,5 of neutral species in a neutral gas flow and radially across a glow discharge. Finally, the feasibility and working progress towards the use of CRBS as a thermodynamic characterization technique for partially/fully ionized gases as well as of liquid flows will be discussed. 

References:

1. Gerakis, A., Shneider, M. N., and Barker, P. F., “Single-shot coherent Rayleigh-Brillouin scattering using a chirped optical lattice,” Opt. Lett., Vol. 38, No. 21, 2013, pp. 4449–4452.
2. Gerakis, A., Shneider, M. N., and Stratton, B. C., “Remote-sensing gas measurements with coherent Rayleigh-Brillouin scattering,” Applied Physics Letters, Vol. 109, No. 3, 2016, p. 31112.
3. Gerakis, A., Yeh, Y.-W., Shneider, M. N., Mitrani, J. M., Stratton, B. C., and Raitses, Y., “Four-Wave-Mixing Approach to In Situ Detection of Nanoparticles,” Phys. Rev. Applied, Vol. 9, 2018, p. 014031.
4. Gerakis, A., Bak, J., Randolph, R., Shneider, M. N., “Demonstration of single shot laser velocimetry with coherent Rayleigh-Brillouin scattering”, AIAA Scitech 2021 Forum, 2021, p. 0224.
5. Gerakis, A., Bak, J., Randolph, R., Shneider, M. N., “Seedless, non-resonant gas flow velocimetry with single shot coherent Rayleigh-Brillouin scattering”, Phys. Rev. Applied, Manuscript accepted

Short Biography: Alexandros Gerakis is a Senior Research & Technology Associate at the Luxembourg Institute of Science & Technology (LIST) and a 2021 FNR ATTRACT Fellow. Prior to joining LIST, he was an Assistant Professor at the Aerospace Engineering Department, Texas A&M University, leading the “Optical Probing & Manipulation” Group (he remains an Adjunct Professor with the Department), an Associate Research Physicist at the Princeton Plasma Physics Laboratory, while he postdoc’d at Harvard University. He holds a PhD in Physics from University College London, UK, a Master’s degree from St Andrews and Herriot-Watt Universities, UK, in "Photonic and Optoelectronic Devices" and a BSc from the School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Greece. Dr. Gerakis' research focuses on the development of advanced laser concepts for particle manipulation and diagnostics with a plethora of uses in neutral and plasma flows, nanotechnology, propulsion, quantum optics and fundamental atomic, molecular and optical physics. Over the years his research has been funded by the NSF, DOE, ONR and NASA in the USA, and the FNR in Luxembourg.