Abstract
UDC 621.3.022:621.396.6:533.93
DOI https://doi.org/10.52577/eom.2026.62.1.27
The article presents the results of a computational and experimental determinationы of the electrophysical conditions for the emergence of a leader channel during an electrical breakdown of a long air gap in a point-to-plane two-electrode discharge system (TEDS) using a standard high-voltage aperiodic switching pulse with a time shape of Tm/Тp ≈ 200 μs /1990 μs and a positive polarity. A novel engineering approach to the substantiated selection of the key indicator of the streamer-leader transition in a long air gap in the TEDS is proposed, allowing to formulate the fundamental conditions for its onset and the emergence of a positive leader in the TEDS. Calculation relationships have been obtained for determining: the radius ri of the zone of an active impact ionization by air electrons near the potential electrode of the TEDS; the electron density nes in the channel of the developed streamer in the specified air ionization zone; the maximum electron temperature Tms in the channel of this streamer, transformed into a positive leader. The high-voltage experiments carried out confirmed the emergence in a long air gap of the TEDS (lmin = 1.5 m; Ud ≈ 611.6 kV) near its potential steel point electrode (r0 ≈ 15 mm; rc ≈ 3 mm) of a bright spherical zone with a radius of ri ≈ 30 mm of an intense ionization by electron impacts on the air, from which a plasma channel of a positive leader continuously develops towards the grounded steel plane of the TEDS at a speed of vL ≈ 105 m/s.
Keywords: long air gap, high pulse voltage, electrical breakdown, streamer, leader, streamer-leader transition, calculation, experiment.