The influence of the voltage rise rate on the breakdown of an atmospheric pressure helium nanosecond parallel-plate discharge

The influence of the voltage rise rate on a nanosecond discharge in atmospheric pressure helium is investigated. The experiment is performed with a parallel-plate discharge configuration. The voltage rise rate is varied between 0.17 kV ns(-1) and 0.42 kV ns(-1). It is found that the rise rate of both the discharge current and the emission intensity increases drastically with the voltage rise rate. This demonstrates the remarkable capability of generating high energy electrons in the discharges with a high voltage rise rate. These arguments are supported by the increase in the measured effective electron temperature during the breakdown processes, namely similar to 18 eV when dV/dt is similar to 0.17 kV ns(-1) and similar to 33 eV when dV/dt is similar to 0.42 kV ns(-1). Furthermore, a higher voltage rise rate results in a shorter rise time of both the discharge current and the emission intensity. Since the breakdown process evolves in the form of a cathode directed ionization wave, a shorter rise time indicates faster propagation of the ionization wave. In addition, a simple fluid model is proposed and its predicted results agree reasonably well with the important discharge parameters measured in the experiment, such as the breakdown voltage, the rise rate and rise time of the discharge current.