Influence of pulse width on energy deposition and temperature in nanosecond-pulsed discharges

Nanosecond-pulsed discharges are a promising method to enhance combustion but can generate significant levels of electromagnetic interference (EMI). Modifying the discharge pulse width is an unexplored option to reduce EMI, but few studies have examined how changing the pulse width affects discharge parameters such as energy and temperature. This study addresses this issue by systematically investigating how the pulse width affects the energy per pulse, breakdown time, rotational temperature, and vibrational temperature in air across different frequencies, flow velocities, and gap distances in a plasma-assisted flow tube. It is observed that the pulse width has a substantial impact on the voltage and current waveforms, energy per pulse, and temperatures at high pulse repetition frequencies. At lower frequencies, however, the influence of the pulse width is significantly reduced. Additionally, increasing the flow velocity (especially at higher frequencies) or the gap distance increases the energy per pulse and prolongs the breakdown time for all pulse widths. The measurements provided in this work can be used to improve numerical modeling of plasma-assisted combustion in flowing systems.