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Dusty plasma characterization and nanoparticles metrology

par Caroline CHAMPENOIS - publié le

séminaire du laboratoire
mercredi 8 février 2017, 16:00 service 322 campus Saint-Jérôme

Laïfa Boufendi,
GREMI, Orléans

abstract :
Laser light scattering technique in its different configurations faces various scientific and technological difficulties to be the dedicated method to give alone the appropriate method for dust nanoparticles metrology. Indeed in this size range the scattering cross section is very small and the scattered photons are completely merged in the noise. Moreover dealing with industrial reactors no view ports are available. For this purpose, methods based on the influence of dusts on the discharge and plasma electrical characteristics, such as the self-bias voltage or the discharge current harmonics, have been developed and used to detect the presence of dust particles in the plasma gas phase. Using the variations of these electrical parameters, it is possible to determine in real time the evolution of the mean size and concentration of the particles that are trapped in the plasma gas phase. The smallest measurable dust grain is about 5 nm. For this purpose, parameters such as the electron density and effective coupled power to the plasma are determined from the plasma impedance. This opens the way to the development of sensitive and robust industrial tools for nanoparticles characterization.

In this presentation, dust particle nucleation, growth and behavior in PK4 reactor will be presented. The nucleation takes place close to the anode that is used for gas injection. Cyclic formation is observed and the particles are swept away by the gas flow and may be some thermophoretic effects.

contact : Sergey Khrapak


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