Publication details
Selection of special dielectric substrates for electrostatic voltage measurement
| Authors | |
|---|---|
| Year of publication | 2021 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | The recently developed method [1] for measurement of ignition voltage turned out to be a great tool for investigating properties of new dielectric barrier materials, e.g. Mg dopped alumina [2]. The main advantage of this method is its safety and production of large statistical datasets due to the repetitive discharge ignition. In other words, the applied voltage periodically changes, and the discharge is turned on for time t1 and turned off for time t2 (relaxation). The variation of times t1 and t2, however, can lead to interesting results. Such data can be seen in Fig. 1, where an evolution for every relaxation time is shown for three different materials as the average over 20 individual measurements. Tested materials are widely used 96 % Alumina and pure Alumina dopped with 3 vol.% and 5 vol.% of Cr. We varied the relaxation time t2 from 7 s to 247 s, while the discharge time t1remained fixed at 57s. The plot shows normalized voltage, where data for every barrier has been normalized by their maximum value (Elceram 5,4 kV, 3Cr 6,5 kV and 5Cr 66,3 kV). The first explanation for such behaviour could be thermal effects. However, the measured time evolution of the cooling does not show any significant differences between ceramics. Moreover, in the simplest approximation the ignition voltage of the discharge is a function of instantaneous temperature [3]. Therefore, thermal effects cannot be the only explanation of tendency in Fig 1. It is known that after the discharge phase, a remaining surface charge can be present on the surface of the ceramics [4], which now seems to be the best candidate to explain shown behaviour of the ignition voltage. In such a case, the charge trapping properties of Cr-dopped Alumina ceramics would be proven. Moreover, the study repetitive discharge ignition on various barrier materials could be an alternative for direct potential measurement using a sensitive electrostatic voltmeter. |