Modelling of negative point-to-plane corona loudspeaker

In this paper, electrical and acoustical characteristics of negative point-to-plane corona discharge loudspeakers are investigated. In the rst part, the electrical behaviour of point-to-plane corona discharges is modelled by a three-parameters (r(i), r(u), C(u)) equivalent circuit. An experimental set-up for estimating these electrical parameters has been developed and improved. Based on the experimental results, evolution of the parameters with discharge conditions has been traced. In the second part, the electrode gap in negative point-to-plane corona discharges is divided into an ionisation region near the point, and a drift region. In each region, interactions between charged and neutral particles in the ionised gas lead to a perturbation of surrounding air, and so generate an acoustic field. For each region, seen as a separate acoustic source, an acoustical model is developed. An experimental set-up for measuring acoustic pressure has been developed, and allows us to confirm expectations based on directivity pattern, monopolar and dipolar directivities being associated to the ionisation and drift region respectively.