Effect of RF Fields on Electrical Breakdowns Produced by High-Voltage Pulses in Air at Ambient Conditions

Wireless devices are increasingly used in industry to optimize development and to reduce weight. However, various aspects of wireless device design have an effect on the potential for ignition which include the antenna/receiver's geometry, power, and operational frequency. For a safe integration of wireless devices in flammable leakage zones, a better understanding of radio frequency (RF) fields on ignition hazard is required. There are three ignition scenarios connected with the usage of wireless sensors. First, a direct ignition can occur when an antenna acts as an electrode and generates electrical discharges. Fortunately, this scenario is highly improbable due to the low power of wireless sensors. A second possible scenario is a coupling of RF fields with a large metallic structure. This metallic structure (e.g., a chassis or a net of electrical wires), may act as an antenna by intercepting energy from a surrounding electromagnetic field (wireless sensors) and start resonating at its frequency. The third possible ignition scenario is a coupling of RF signals with parasitic electrical discharges (static electricity, lightning). This effect may lead to an increase of the discharge volume and the energy deposition, which can be the reason for an undesirable ignition1. This study focuses on this scenario. The effect of RF signals at 2.45 GHz on electrical discharges produced by a high-voltage pulse, ranging from 500 ns to $200\ \mu \mathrm{s}$, in a pin-to-pin configuration in air at ambient conditions is investigated. An analysis of the effect of the RF power on the energy deposited by the discharge and the breakdown voltage is performed. The results show that for very short pulses (500 ns), RF signals with a power as large as 50 W do not affect the discharges, while for longer pulses, RF signals start to affect both, the breakdown voltage and the energy deposition.