Supervision: Hervé Lissek,Han Miao

Project type:

Assigned

A plasmacoustic transducer is a membrane-less loudspeaker resorting to a thin layer of ionized air (plasma) put in motion inside a very intense alternating electric field, owing to the Corona Discharge (CD) principle. Such a transducer outperforms any existing loudspeaker resorting to membranes in terms of time response, but its downside is a high-pass frequency response in free field, limiting its use as a broadband loudspeaker. Indeed, the plasma-acoustic transduction makes it an ideal particle velocity source, the sound radiation properties of which is intrinsically high-pass. However, when turned into an active "plasmacoustic metalayer" capable of interacting with an exogenous sound field (absorption/reflection/transmission), owing to a feedback control of the particle velocity as a function of the net acoustic pressure, the achievable performance are outstanding, thanks to the absence of any mechanical component. But this requires a very accurate model of the multiphysics electric-plasma-acoustic system.

The main objective of this project is to improve the physical model of the CD transducer allowing better controlling the sound radiation properties as a loudspeaker, as well as the sound manipulation capabilities as a plasmacoustic metalayer. We will especially focus on the plasma-acoustic transduction which has been simplified up to now as a linear combination of a bulk dipolar "force" source and a bulk monopolar "heat" source, without examining the microscopic distribution of sources. Then the plasma-acoustic transduction can be coupled to an electric conditioning and the sound radiation environment, to yield a full electric-plasma-acoustic model used for design and optimization purpose, both as a loudspeaker and a "metalayer". The model will be then challenged with experimental measurements.

Content:

• theory (plasma-acoustic transduction, sound radiation, active sound absorption) (30%)
• numerical models (COMSOL Multiphysics, Matalb/Simulink) (40%)
• experimental work (sound source characterization, sound absorption measurements) (30%)