Eur. Phys. J. Appl. Phys. 33, 15–21 (2006) DOI: 10.1051/epjap:2005086 THE EUROPEAN PHYSICAL JOURNAL APPLIED PHYSICS Electrical model of the atmospheric pressure glow discharge (APGD) in helium I. Enache a , N. Naud´e, J.P. Cambronne, N. Gherardi b , and F. Massines Laboratoire de G´enie ´ Electrique de Toulouse, Universit´e Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex, France Received: 5 April 2005 / Received in final form: 20 September 2005 / Accepted: 29 September 2005 Published online: 30 November 2005 – c  EDP Sciences Abstract. This work is a contribution to the understanding of mechanisms controlling the Atmospheric Pressure Glow Discharge (APGD). The approach consists in developing an electrical model of the discharge based on electrical circuit compounds. This model takes into account the main phenomena of the discharge including the memory effect and the creation of the cathode fall. It allows to have a general view of the process and can be easily associated to the power supply with short computational duration; it is also an interesting tool for the optimization of the whole process. PACS. 52.80.Hc Glow; corona – 84.30.Jc Power electronics; power supply circuits – 84.30.Bv Circuit theory (including computer-aided circuit design and analysis) 1 Introduction Dielectric Barrier Discharges (DBD) at atmospheric pres- sure are used for industrial applications since a long time [1]. A disadvantage of these discharges is that they are usually a juxtaposition of many micro discharges. Con- sequently, for surface treatment for example, the result is not totally reproducible. Recently, homogeneous DBD at atmospheric pressure have been obtained in particu- lar conditions concerning the gas, the electrode configura- tion, the gas gap and the power supply parameters [2–4]. The gas can be either nitrogen or noble gases like ar- gon or helium. In nitrogen the discharge is a Townsend one (APTD) [5,6] while in noble gases it is a glow one (APGD) [7–9]. Previously, the electrical behavior of the APTD has been described with an electrical model based on electrical circuit compounds [10,11]. This model has successfully improved the understanding of the basic phe- nomena controlling the discharge behavior allowing to in- crease the power dissipated in the gas by avoiding the discharge destabilization. According to the same philosophy, the present work is focused on the APGD in helium. The aim is to find a sim- ple representation of the APGD behavior using electrical elements in order to determine the major mechanisms con- trolling the discharge and to have a tool for power supply optimization. After a description of the experimental setup used for discharge characterization, an analysis of the electrical measurements is presented. From this, the different com- pounds of the electrical model of the APGD are chosen a e-mail: enache@lget.ups-tlse.fr b e-mail: gherardi@lget.ups-tlse.fr and quantitatively determined. Then, the experimental measurements are compared to simulation results of this model to validate the approach. 2 Experimental set-up The experimental arrangement used for this study is shown in Figure 1 [11]. The APGD is obtained in a cell made of two dielectric tubes metallized on an internal face and an alumina plate metallized on backside on two ar- eas of 10 mm width and 60 mm length each one. The tubes dielectric permeability is 8.67 × 10 -11 F/m while the alumina plate one is 8.41 × 10 -11 F/m. The two met- allized bars are at the same potential and constitute the high voltage electrodes. The electrodes coated on the alu- mina plate are connected to the ground through a 50 Ω resistor which enables the measurement of the discharge current. The discharge is generated in helium N55 (purity 99.9995%) at atmospheric pressure in a gas gap of 5 mm. As a gas flow of 3 l/min is added between the two bars, a slight pumping maintains the atmospheric pressure. The power supply is made of a low frequency genera- tor providing a reference waveform amplified by a linear amplifier (Crest Audio model 8001, 2800 W) and a trans- former (Montoux, ratio = 150, 600 VA, 60 V/9 kV). The electrical model of the power supply and the transformer in particular have been established and presented in [11]. The discharge is characterized by electrical measurements. The voltage applied to the electrodes is measured by means of a high voltage probe (Tektronix P6015, band- width: 75 MHz, ratio: 1000). The discharge current is mea- sured through a 50 Ω resistor in series with the electrode. The current and the voltage applied to the electrodes are Article published by EDP Sciences and available at http://www.edpsciences.org/epjap or http://dx.doi.org/10.1051/epjap:2005086