Open AccessDouble-propagation mode in short-gap spark discharges driven by HV pulses with sub-ns rise time
Author(s) -
Hans Höft,
Markus M. Becker,
Juergen F. Kolb,
T. Huiskamp
Publication year - 2020
Publication title -
plasma sources science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 108
eISSN - 1361-6595
pISSN - 0963-0252
DOI - 10.1088/1361-6595/aba112
Subject(s) - tungsten , rise time , streak camera , amplitude , electric field , electrode , materials science , spark gap , voltage , streamer discharge , optics , streak , atmospheric pressure , atomic physics , chemistry , physics , laser , meteorology , quantum mechanics , metallurgy
The object of this study is the investigation of spark discharges ignited by unipolar positive rectangular high voltage (HV) pulses with 200 ps rise time and (15 ± 2) kV amplitude with 3 ns duration full width at half maximum in synthetic air in a 1.2 mm pin-to-pin gap (tungsten electrodes) at atmospheric pressure. The discharge development was recorded by synchronised iCCD and streak camera measurements in single-shot operation, revealing a two-stage propagation mode. The discharge started with a fast initial breakdown across the entire gap (∼10 mm ns −1 ) during the HV slope, followed by a much slower (∼0.1 mm ns −1 ) propagation originating from both electrodes towards the gap centre. The combination of high-resolution diagnostics with numerical modelling indicated that the initial breakdown phase is caused by the rapid increase of electric field strength during the steep HV slope, which leads to the simultaneous fast propagation of a positive and a negative streamer.