HR: 11:35h
AN: AE42A-06    [Abstracts]
TI: Photoionization Models Based on Radiative Transfer and Helmholtz Equations for Sprite Streamer Modeling
AU: * Liu, N
EM: nul105@psu.edu
AF: The Pennsylvania State University, Department of Electrical Engineering, University Park, PA 16802, United States
AU: Pasko, V P
EM: vpasko@psu.edu
AF: The Pennsylvania State University, Department of Electrical Engineering, University Park, PA 16802, United States
AU: Célestin, S
AF: EM2C UPR 288 Ecole Centrale Paris, Grande voie des vignes, Châtenay-Malabry, 92295, France
AU: Bourdon, A
AF: EM2C UPR 288 Ecole Centrale Paris, Grande voie des vignes, Châtenay-Malabry, 92295, France
AU: Ségur, P
AF: Université de Toulouse, LAPLACE, CNRS, INPT, UPS, 118 route de Narbonne, Toulouse, 31062, France
AU: Marode, E
AF: Ecole Supérieure d'électricité, LPGP, UMR CNRS 8578, Plateau du moulon, 3 rue Joliot Curie, Gif-sur-Yvette, 91192, France
AB: Sprite streamers are driven by highly nonlinear space charge waves [Raizer, 1991, p. 327], and develop in a self- consistent manner. The photoionization produced by UV photons originating from a region of high electric field in the streamer head is responsible for creation of seed electrons in front of the head of a propagating streamer, and is believed to play a critical role in the spatial advancement of both positive and negative streamers. The accurate and efficient evaluation of the effects of photoionization remains one of the most challenging tasks in streamer modeling. In the current literature, it is a common practice to evaluate the photoionization effects using an integral model proposed by Zheleznyak et al. [High Temp., 20, 357, 1982] for non-thermal discharges in air. Recently, two different approaches to account for the photoionization effects have been proposed to avoid the calculation of the global quadrature over the simulation domain. The first approach is based on the direct numerical solution of radiative transfer equation [Ségur et al., Plasma Source Sci. Technol. 15, 648, 2006]. The second approach is built on the solution of a set of Helmholtz equations [Luque et al., Appl. Phys. Lett., 90, 081501, 2007]. In this talk, we discuss the photoionization models based on differential equation approaches, and develop improved models based on the same principles by more accurately accounting for the spectral dependence of the photoionization [Bourdon et al., Plasma Sources Sci. Technol. 16, 656, 2007; http://www.iop.org/EJ/abstract/0963-0252/16/3/026/]. We report modeling results on streamers obtained by using the developed photoionization models and compare them with those obtained by using the Zheleznyak integral model. We emphasize that the actual advantage of differential models advanced in our study in comparison with the integral model lies in the simplicity of implementation of this type of models, and in unquestionable simplicity of extension of these models to complex two- and three-dimensional simulation geometries, involving, for example, branching of sprite streamers, and the presence of obstacles on the streamer path (i.e., ionospheric inhomogeneities, dust particles, aerosols, etc).
DE: 3304 Atmospheric electricity
DE: 3324 Lightning
DE: 3344 Paleoclimatology (0473, 4900)
DE: 7823 Ionization processes (2423)
SC: Atmospheric and Space Electricity [AE]
MN: 2007 Fall Meeting