Numerical analysis of promossing techniques of nanoparticle generation : laser ablation vs spark discharge at atmospheric pressure
Résumé
Laser ablation (LA) and spark discharge (SD) techniques are commonly used for nanoparticle formation. On one hand, the main advantage of the LA method is the high ablation rate and in the possibilities of changing laser parameters and background conditions. On the other hand, the major advantage of the SD technique is in the possibility of using several facilities in parallel to increase the yield of nanoparticles [1]. To optimize these processes, we consider different stages involved and analyze the resulting plasma and nanoparticle (NP) parameters. Thus, laser ablation includes [2]
(i) laser-induced material heating and laser plume formation;
(ii) plasma plume formation and its expansion in a background gas;
(iii) particle ejection, formation by expansion-driven nucleation and growth during diffusion.
Then, spark discharge is numerically analyzed. The model consists of several parts as follows
(i) streamer formation and its propagation at atmospheric pressure;
(ii) gas breakdown, plasma column formation and its expansion;
(i) electrode heating, evaporation and erosion;
(ii) particle formation by collisional growth.
Based on the performed calculations, we analyze nanoparticle parameters, such as mean size and mean density. The performed analysis shows how the experimental conditions are connected with the resulted nanoparticle characteristics in agreement with several previous experiments [3,4].
Support from the European Union Seventh Framework Program (FP7/2007-2013) under grant agreement n° 280765 (BUONAPART-E) is gratefully acknowledged.
[1] T.E. Itina and A. Voloshko, Nanoparticle formation by laser ablation in air and by spark discharges at atmospheric pressure, Appl. Phys. A. vol. 113, no3, pp. 473-478,(2013) .
[2] T.E. Itina, M.E. Povarnitsyn, A. Voloshko, Laser-based synthesis of nanoparticles: role of laser parameters and background conditions, SPIE Proc. Vol. 8969, Synthesis on Photonics of Nanoscale Materials XI, 896905 (2014)
[3] A. Pereira, P. Delaporte, M. Sentis, W. Marine, A. L. Thomann, C. Boulmer-Leborgne, J. Appl. Phys. Vol. 98, pp. 064902 (2005).
[4] N. S. Tabrizi, Q. Xu, N. M. van der Pers, A. Schmidt-Ott, J. Nanopart. Res. Vol. 12, pp. 247-259 (2010).