Direct Combinational Measurements of the Electron Density and Electric Field in Secondary Streamer Discharge under Atmospheric-Pressure Air

The electron density and electric field govern physical and chemical reactions in a secondary streamer discharge under atmospheric-pressure air. We present direct combinational measurements of these essential quantities and demonstrate their consistency by solving the continuity equation for electrons. The measurements enabled validity examination of previous computational studies and clarified contradictions; the prominence was a near-cathode phenomenon measured during primary-to-secondary transition, which caused unpredicted ionization inside the positive secondary discharge. The thorough comparison revealed that a fundamental governing mechanism to be established for the secondary discharge is current continuity.