• • At 90 W input power and 200 mL/min inlet gas flow rate, single-pass CH4 conversion reaches 46.6% with H2 yield of 23.3%, demonstrating electron-driven cracking with limited Joule heating contribution.
• • Increasing inlet gas flow rate from 200 to 800 mL/min raises reaction energy intensity by ~2.8 times, indicating enhanced convective heat transfer and shortened residence time that suppress deep CH4 cracking.
• • BOLSIG+ calculations identify electron-induced vibrational excitation as the dominant CH4 activation pathway, where stepwise energy accumulation drives C–H bond dissociation.
• • The overall CH4 cracking process is delineated into three stages: methane activation, radical evolution, and product formation, providing a mechanistic framework for optimizing DBD reactor design.