More valuable C2 hydrocarbon and hydrogen can be produced from cracking methane by plasma technology. It is very important to optimize the plasma discharge parameters to increase methane conversion efficiency.In this paper

methane cracking by coaxial DBD reactor driven by homemade pulse power supply（microsecond pulse and nanosecond pulse）was characterized. The influence of power parameters and gas flow rate on breakdown voltage

discharge images

Lissajous figures and pulse energy and power were well studied

which provides solid experimental references for methane conversion. The results showed that

the initial breakdown voltage decreased with the pulse repetition rate increase

but this relationship was more evident under nanosecond pulse power. Discharge intensity increased with the pulse repetition rate increase and the microsecond pulse power could bring more intensity of discharge. Under the same applied voltage

the repetition frequency and gas flow rate had no influence on the Lissajous figures and the figures under microsecond pulse power was more close to typical parallelogram. The discharge energy was correlated with applied voltage when under the same gas flow rates and pulse repetition frequencies. The discharge energy in the single discharge was not dependent on the repetition frequency when kept the same gas flow rate and applied voltage. Besides

higher instantaneous energy was obtained by nanosecond pulse power supply compared to microsecond pulse power supply. The experiments showed that pulse power could be used to crack methane in the DBD reactors and it can get higher system efficiency under the nanosecond pulse power.