Methane conversion using a high-frequency pulsed plasma: Discharge features

The pulsed plasma of methane was experimentally characterized using single and sequential pulse modes. At a single pulse mode, only pulsed corona and streamer discharges occurred at a low pulse voltage. A pulsed spark discharge developed after the pulsed streamer discharge at a high pulse voltage. An image analysis indicated that the weak luminescence could be found by the latter period of the poised corona discharge. The pulsed streamer and spark discharges bridged the discharge gap and emitted a relatively strong light. At a sequential pulse mode, the streamer or spark discharge developed easily and evenly at a low pulse voltage, as the pulse frequency increased in comparison with that at the single pulse mode. The high-frequency pulsed plasma was more practical than other plasmas due to its relatively high energy efficiency at room temperature and atmospheric pressure.