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Analyses of electron runaway in front of the negative streamer channel
Author(s) -
Babich L. P.,
Bochkov E. I.,
Kutsyk I. M.,
Neubert T.,
Chanrion O.
Publication year - 2017
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2017ja023917
Subject(s) - bremsstrahlung , ionization , physics , electron , atomic physics , electric field , front (military) , streamer discharge , radiation , plasma , channel (broadcasting) , computational physics , voltage , cathode , ion , optics , nuclear physics , electrical engineering , meteorology , quantum mechanics , engineering
X‐ray and γ‐ray emissions, observed in correlation with negative leaders of lightning and long sparks of high‐voltage laboratory experiments, are conventionally connected with the bremsstrahlung of high‐energy runaway electrons (REs). Here we extend a focusing mechanism, analyzed in our previous paper, which allows the electric field to reach magnitudes, required for a generation of significant RE fluxes and associated bremsstrahlung, when the ionization wave propagates in a narrow, ionized channel created by a previous streamer. Under such conditions we compute the production rate of REs per unit streamer length as a function of the streamer velocity and predict that, once a streamer is formed with the electric field capable of producing REs ahead of the streamer front, the ionization induced by the REs is capable of creating an ionized channel that allows for self‐sustained propagation of the RE‐emitting ionization wave independent of the initial electron concentration. Thus, the streamer coronas of the leaders are probable sources of REs producing the observed high‐energy radiation. To prove these predictions, new simulations are planned, which would show explicitly that the preionization in front of the channel via REs will lead to the ionization wave propagation self‐consistent with RE generation.