Method to measure the inner electrical values of a DBD including space charge field

In a DBD it is not possible to measure the electrical values of the plasma directly. To determine them it is necessary to separate the capacitive from the real current component within the gap. To overcome this problem Liu and Neiger have published an analytical method to determining the plasma values from the lamp voltage and current. This method is very complex and needs some simplification to differentiate and integrate the voltage and current values over time so that a real time analysis is not possible. Based on this model, Roth and Schwarz developed an electrical setup to measure the inner values directly. We have developed this method further and have now the possibility to determine the plasma voltage, current for pulsed operation. Based on this measurement method we have developed an electrical model to describe the role of space charges inside the gap. With the model it is possible to amount the electrical field of space charges integrated as voltage u_charge. The difference between the determined voltage u_charge and the measured gap voltage describes the effective exciting voltage u_excite. Examples of sinusoidal and pulsed excitation show that this model could describe the development of space charges correctly. The new defined ignition voltage u_excite,max shows, despite the old definition of u_gap,max, no dependence on the voltage waveform and describes the behavior of preionization correctly.