How the emission spectroscopy can determine the effects of dust particles on a plasma
Résumé
Dusty plasmas [1] are found in many astrophysical environments such as comet tails, planetary nebulae and rings or in fusion devices like the future ITER. In industrial and laboratory reactors, these dust particles [2] become a huge problem, particularly in microelectronics. However, these particles could be used in many industrial applications related to nanotechnology. So it is important to study the production of these solid particles.
At GREMI laboratory, several methods are used to create dust particles in a plasma. They are mainly based on reactive gases or material sputtering. In this work, experiments are performed in a capacitively-coupled RF discharge in the PKE-Nefedov reactor [3], where dust particles are grown by sputtering a polymer layer in Ar or Kr plasmas.
The presence of dust particles in plasmas can strongly change their properties like the light emission. This modification is due to a change in the plasma parameters such as electron temperature and density. Emission spectroscopy is used to analyze the light emission, more precisely to study the spatiotemporal evolution of the Ar emission and the molecules involved in the dust particle growth like: CN, CH and C2. When dust particles are growing in the plasma, a laser at 685 nm is also used to highlight their presence. Their localization is determined by recording the scattered light with the spectrometer. Other diagnostics are also used to follow dust particle growth like a CCD camera and the measurement of the discharge current.
[1] M. Mikikian, L. Couëdel, M. Cavarroc, Y. Tessier, L. Boufendi, Eur. Phys. J. Appl. Phys. 49, 13106 (2010)
[2] R.M. Roth, K.G. Spears, G.D. Stein, G. Wong, Appl. Phys. Lett 46, 253 (1985)
[3] M. Mikikian, L. Boufendi, A. Bouchoule, H.M. Thomas, G.E. Morfill, A.P. Nefedov, V.E. Fortov, the PKE- Nefedov Team, New J. Phys. 5, 19 (2003)